View
991
Download
6
Category
Preview:
DESCRIPTION
Training Report Npcil Rawatbhata
Citation preview
AREPORT ON VOCATIONAL TRAINING
NUCLEAR POWER CORPORATION OF INDIA LTDNUCLEAR POWER CORPORATION OF INDIA LTD..(A Government of India Enterprise)
Rajasthan Atomic Power Station
DURING THE PERIOD
FROM 11th JUNE 2012 TO 10th JULY 2012
SUBMITED TO: Mr. M. M. GUPTA SUBMITTED BY
UMESH KUMAR MEHARB.TECH. (III Year) BRANCH: - ECE
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
1
PREFACE
As we know that an engineer has to serve an industry, for that one must be aware of industrial
environment, their management, problems and the way of working out their solutions at the
industry.
After the completion of the course an engineer must have knowledge of interrelation between
the theory and the practical. For this, one must be familiar with the practical knowledge with
theory aspects.
To aware with practical knowledge the engineering courses provides a six weeks industrial
training where we get the opportunity to get theory applying for running the various process and
production in the industry.
I have been lucky enough to get a chance for undergoing this training at RAJASTHAN
ATOMIC POWER STATION. It is a constituent of board of NPCIL. This report has been
prepared on the basis of knowledge acquired by me during my training period of 30 days at the
plant.
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
2
ACKNOWLEDGEMENT
It was highly educative and interactive to take training at
RAJASTHAN ATOMIC POWER STATION. As technical knowledge
is incomplete without practical knowledge, I couldn’t find any place
better than this to update myself.
I am very much thankful to the Site director Mr. C.P. Jhamb &Training
superintendent Mr. D. Chanda for allowing me for the industrial training
at RAPS. Thanks to Mr. A.P. Jain for their guidance during my project.
I also take the opportunity to thanks Nuclear training Centre for
providing lecture on overview of the plant and providing me Orange
qualification.
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
3
INTRODUCTION
India's Nuclear power developments are under the purview of the
Nuclear Power Corporation of India, a government-owned entity under
the Department of Atomic Energy India. The corporation is responsible
for designing, constructing, and operating nuclear-power plants. In
1995 there were nine operational plants with a potential total capacity
of 1,800 megawatts, about 3 percent of India's total power generation.
There are two units each in Tarapur, north of Bombay in Maharashtra;
in Rawatbhata in Rajasthan; in Kalpakkam near Madras in Tamil Nadu;
and in Narora in Uttar Pradesh; and one unit in Kakrapur in
southeastern Gujarat. However, of the nine plants, all have been faced
with safety problems that have shut down reactors for periods ranging
from months to years. The Rajasthan Atomic Power Station in
Rawatbhata, India was closed indefinitely, as of February 1995.
Moreover, environmental problems, caused by radiation leaks, have
cropped up in communities near Rawatbhata. Other plants operate at
only a fraction of their capacity, and some foreign experts consider
them the most inefficient nuclear-power plants in the world.
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
4
MISSIONTo develop nuclear power technology and
produce in a self-reliant manner nuclear
power as a safe, environmentally benign and
an economically viable source of electrical
energy to meet the growing electricity needs
of the country
**********
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
5
VISIONNPCIL has its vision to have an
installed nuclear power capacity
of 20,000 MW(e) by the year
2020. This capacity could be
achieved by the development of
more 220 MW(e) & 550 MW(e)
units of Pressurized heavy water
reactors, importing light water
reactors and by the introduction
of fast breeder reactors.
**************
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
6
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
7
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
8
Prime Minister
DAE Atomic Energy Commission
NPCIL
Atomic energy Regulatory board
TAPS 1&2
India Rare Earth
TAPP 3&4
BARC
RAPS 1& 2
Heavy Water Board
RAPS 3 & 4
ECIL
RAPP 5 & 6
UCIL
MAPS
Nuclear fuel complex
NAPS
Indra Gandhi center for advance research
KAPS
KAIGA PS 1& 2
Center for advance technology
KAIGA Proj. 3& 4
KKPS
RAPS LOCATION AND SITE CONDITIONS
RAPS is located on the eastern bank of Rana Pratap Sagar lake (R.P.S) upstream of the R.P.S dam across the chambal river at an elevation of 388 mt. above mean sea level with a latitude of 24053’ north and a longitude of 76036’ east. The plant site is about 64 KM from Kota city. The place has an average rainfall of 825mm as per records. The maximum wind velocity records so far is 129 km/hr at 120 m. the most predominant wind direction is at 7.90m and 120m heights is North of south west and west of south west respectively.The site has no population with in its vicinity of radius of 5km. It however does have a population of about 58 thousand distributed in the radius of 15 Km. the only nearby major industry is HEAVY WATER PLANT (H.W.P).
NUCLEAR ENERGY: Mass defect converted into energy through nuclear reaction. Two processes produce this:1) Nuclear fission.2) Nuclear fusion.A neutron it splits into two big parts hits when a heavy nucleus likes that of uranium – 235 & in addition 2 or 3 neutrons are released. However, the mass of the parts is slightly less than the mass of the uranium nucleus. The mass that is destroyed is converted into energy (200Mev/ fission). This process is called nuclear fission reaction.It is much more likely if neutrons are slow, in a reactor, some of the neutrons produced are absorbed so that for every neutron causing fission, only one is left. This neutron in turn collides with another U235 nucleus & causes fission. A chain reaction is thus set up. Also, the neutrons have to be slowed down. The fuel in a nuclear reactor consists of Uranium that may be natural or enriched in which proportion of U235 is increased. Either light water (for enriched uranium) or heavy water (for natural uranium) may be used as a moderator, for slowing down the neutrons. The energy released is absorbed by the water (either light or heavy). This coolant in turn transfers its energy to the light water. Ultimately water is turned into steam at high pressure that is used to derive turbines as in any conventional power plant. India has six Nuclear Power Plants;
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
9
At Tarapur in Maharastra. At Rawatbhata near Kota in Rajasthan At Kalpakkam near Madras in Tamil Nadu. At Narora in Uttar Pradesh At Kakarpara near Surat in Gujarat At Kaiga near Karwar in Karnataka.The reactors at Tarapur use enriched uranium as fuel & light water as moderator and coolant, all others use uranium and heavy water. Nuclear Power Plant under construction is two units of 500 MW at Tarapur and two similar units at Rawatbhata near Kota. Nuclear fission has become commercially viable and is being exploited in several countries.
SOME IMPORTANT NUCLEAR REACTIONS:
1) 92U238+0n1-----92U239+r------93Np239-------94Pu239
Typical fission reaction: 2) 92U235+0n1------38Sr90+54Xe144+20n1+r+200MeVReactor poisoning reaction: 3) 52Te 135 ----53I135-----54Xe135-----55Cs135---56Ba135
(Stable)We know that about 200MeV of energy is released during per fission.This energy is divided in the following way:1) K.E. of the fission fragments: 167MeV.2) K.E. of neutrons: 5MeV.3) Energy of gamma released at fission: 5MeV. 4) Energy of gamma rays released on n–capture: 10MeV.5) Gamma decay energy: 7MeV.6) Beta – decay energy: 5MeV. ---------------------------- TOTAL =199MeV. ----------------------------
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
10
THREE STAGES OF INDIAN NUCLEAR POWER PROGRAMME:
1) INTRODUCTION:India figured in the nuclear power map of the world in 1969, when two boiling water reactors (BWRS) were commissioned at Tarapur (TAPS-1&2) these reactors were built on the turnkey basis .The main objective of setting these units was, largely to prove the techno-economic viability of nuclear power. The nuclear power programme formulated embarked on the three-stage nuclear power programme, linking the fuel cycle of pressurized heavy water reactor (PHWR) & Fast breeder reactors (FBR) for judicious utilization of our reserves of Uranium & Thorium. The emphasis of the programme is self –reliance and thorium utilization as a long -term objective.
The three stages of our Nuclear power programme are:
1) STAGE I:- This stage envisages construction of natural Uranium, Heavy water moderator & cooled pressurized heavy water reactors (PHWR). Spent fuel from these reactors is reprocessed to obtain plutonium.
2) STAGE II: - This stage envisages on the construction of Fast breeder reactors (FBR) fuelled by plutonium & depleted U produced in stage I. These reactors would also breed U233 from thorium.
3) STAGE III = This stage would comprise power reactors using U233- Thorium as fuel, which is used as a blanket in these type of reactors.
The PHWR was chosen due to the following:
1) It uses natural uranium as fuel. Use of natural uranium available in India, helps cut heavy investments on enrichments, as uranium enrichment is capital intensive.
2) Uranium requirement is the lowest & plutonium production is the highest.
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
11
3) The infrastructure available in the country is suitable for undertaking manufacture of the equipment.The short –term goal of the programme was to complement the generation of electricity at locations away from coalmines. The long-term policy is based on recycling nuclear fuel and harnessing the available Thorium resources to meet country’s long-term energy demand and security. As a part of PHWR Programme (STAGE I) second nuclear power plant was taken up as a joint Indo-Canadian venture this plant was built at Rawatbhata (Rajasthan) two units laid a milestone in the history of India all the components were taken up in India and the import content reduced considerably. Moreover, Canadians withdrew in 1974; Indian engineers did balance design & commissioning of the Unit 2.
2) CHALLENGES FACED:
The industry was new to the manufacturing techniques & stringent quality requirements of the nuclear components like calandria, end shield, steam generators, fuelling machine, and heavy water pumps. The requirement of convectional power plant equipment was of much larger capacity than those being manufactured in the country. To achieve self –sufficiency in this field in the long run, the department of atomic energy established extensive research & development facilities covering diverse areas for supporting technology absorption. Facilities, from prospecting to mining to fabrication of fuel & zirconium alloy components, for manufacture of precision reactor components & production of heavy water were also set up. Supply of equipments of international nuclear standard was also a problem so momentous efforts were put into development of such manufacturing industries. Extensive R&D set up were established for metallurgical studies of both fresh as well as radioactive material, non –destructive testing, environmental & seismic qualification of safety analysis, preparation &development of validation of computer codes, etc.
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
12
Technologies for inspection of the reactor components, repair &replacement using robotics & life extension programme of the operating reactors, have also been successfully developed. To summaries, the concerted efforts put in by DAE, its constituent units & NPCIL, together with Indian industries & institutions have led to development & full capabilities to design, manufacturing of equipment, construction, operation & maintenance of nuclear power plant. Today India is amongst the select band of few countries of the world that have developed such capabilities.
3. Status of nuclear power generation & future plans: The nuclear power programme in India up to year 2020 is based on installation of a series of 235 MWe &500Mwe pressurized heavy water reactor (PHWR) UNITS, 1000MWe light water reactors (LWR) UNITS & fast breeder reactors (FBR) units. NPCIL plans to contribute about 10% of the total additional needs of power of about 10000MWe per year i.e. 1000 MWe per year in the coming two five –year plans. The total installed capacity of nuclear generation would increase to more than 20000 MWe in year 2020 from the present level of 2720 MWe. The basic design of the 220/500MWe units in similar; however, a number of significant design changes have been made progressively from the first unit at Rajasthan to the 500 MWe units. These design changes have been made from the consideration of currently prevailing safety criteria, seismicity, improve availability requirement of in- service inspection, ease of maintenance etc., as appropriate to the conditions in India. DESCRIPTION OF STANDARD INDIAN PHWR:
1) LAYOUT: The nuclear power stations in India are generally planed as two units modules, sharing common facilities such as service building, spent fuel storage bay & other auxiliaries like heavy water upgrading, waste management facilities etc. . Separate safety related systems & components are however provided for each unit. Such an arrangement retains independence for safe operation of each unit & simultaneously permits optimum use of space, finance & construction time. The lay out for a typical
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
13
220MWe station as given in figure 1, shows two reactor building, active service building including spent fuel bay, safety related electrical & control buildings and the two turbine buildings. Orienting turbine building radial to the reactor building provides protection from the effect of turbine missiles. Other safety related building s &structures are also located as not to fall in the trajectory of missiles generated from the turbine. The buildings and structures have also been physically separated on the basis of their seismic classification.Sectional views of the reactor building are shown in figure 2 depicting general layout inside the reactor building.
2) REACTOR: In concept, the Indian pressurized heavy water reactor is a pressure tube type reactor using heavy water moderator, heavy water coolant & natural uranium dioxide fuel. The reactor as shown in the cut away view in figure 3 consists primarily of calandria a horizontal cylindrical vessel. It is penetrated by a large number of zircaloy pressure tubes (306 for 235MWe reactor), arranged in a square lattice. These pressure tubes, also refer as coolant channels, contain the fuel & hot high – pressure heavy water coolant. The pressure tubes are attached to the alloy steel and fitting assemblies at either end by special role expended joints. A typical pressure tube assembly is shown figure 4 .End – shields are the integral parts of the calandria and are provided at each end of the calandria to attenuate the radiation emerging from the reactor, permitting access to the fuelling machine vaults when the reactor is shutdown. The end fittings are supported in the end shield lattice tubes through bearing, which permit their sliding. The calandria is housed in a concrete vault, which is lined with zinc metallised carbon steel & filled with chemically treated demineralised light water for shielding purposes. The end shields are supported in openings vault wall, and form part of the vault enclosure at these openings. Removable shield plugs fitted in the end fittings provide axial shielding to individual coolant channels.
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
14
3) REACTIVITY CONTROL MECHANISMS:
Due to the use of natural uranium fuel & on-load refueling, the PHWR’s do not need a large excess reactivity. Correspondingly the devices required for control of reactivity in the core need not have large reactivity worth’s. Standard reactors designs are provided with four systems for reactivity control, viz.1) Regulating rods 2) Shim rods 3) Adjuster rods for xenon override 4) Natural boron addition in the moderator to compensate for the excess reactivity in a fresh core &for absence of xenon after a long shutdown.The reactivity control devices are installed in the low- pressure moderator region & so they are not subjected to potentially severe hydraulic & thermal forces in the event of postulated accidents. Furthermore, the relatively spacious core lattice of PHWR allows sufficient locations to obtain complete separation between control & protective functions. The regulating systems are thus fully independent with its own power supplies, instrumentations & triplicated control channels. Cobalt & stainless steel absorber elements have been utilized in the reactivity control mechanisms. For 220MWe standardized design, two diverse, fast acting & independent shutdown systems have been adopted. This feature provides a high degree of assurance that plant transients requiring prompt shutdown of the reactor will be terminated safely. The primary shutdown system consists of 14 mechanical shut off rods of cadmium sandwiched in stainless steel &makes the reactor sub- critical in less than 2 secs. Fail-safe features like gravity fall &spring assistance have been incorporated in design if mechanical shut off rods. The second shutdown system, which is also fast acting, comprises 12 liquid poison tubes, which are filled with lithium penta borate solution under helium pressure. The trip signal actuates a combination of fast acting valves and causes poison to be injected simultaneously in 12 interstitial liquid poison tubes of calandria.
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
15
4) FUEL DESIGN:
Fuel assemblies in the reactor are short length (half metre long) fuel bundles. Twelve of such bundles are located in each fuel channel. The basic fuel material is in the form of natural uranium dioxide a pellet, sheathed &sealed in thin zircaloy tubes. Welding them to end plates to form fuel bundles assembles these tubes. Figure 5 shows the 19- element fuel bundle being used in 220 MWe PHWRs. 5) FUEL HANDLING:
On –power fuelling is a feature of all PHWRs, which have very low excess reactivity. In this type of reactor, refueling to compensate for fuel depletion & for over all flux shaping to give optimum power distribution is carried out with the help of 2 fueling machines, which work in conjunction with each other on the opposite ends of a channel. One of the machines is used to fuel the channel while the other one accepts the spent fuel bundles. In addition, the fueling machines facilitate removal of failed fuel bundles. Each fuelling machine is mounted on a bridge & column assembly. Various mechanisms provided along tri- directional movement (X, Y&Z direction) of fueling machine head and make it possible to align it accurately with respect to channels. Various mechanisms have been provided which enables clamping of fueling machine head to the end fitting, opening & closing of the respective seal plugs, shield plugs &perform various fuelling operations i.e. receiving new fuel in the magazine from fuel transfer system, sending spent fuel from magazine to shuttle transfer station, from shuttle transfer station to inspection bay & from inspection bay to spent fuel storage bay.
6) PRIMARY HEAT TRANSPORT (PHT) SYSTEM:
The system, which circulates pressure coolant through the fuel channels to remove the heat generated in fuel, is referred as Primary Heat Transport System. The major components of this system are the reactor fuel channels, feeders, two reactor inlet headers, two reactor outlet headers, four pumps &interconnecting pipes & valves. The headers steam generators & pumps are
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
16
located above the reactor and are arranged in two symmetrical banks at either end of the reactor. The headers are connected to fuel channels through individual feeder pipes. Figure 6 depicts schematically the relative layout of major equipment in one bank of the PHT system .the coolant circulation is mentioned at all times during reactor operation, shutdown & maintenance.
7) MODERATOR SYSTEM:
The heavy water moderator is circulated through the calandria by aid of a low temperature & low – pressure moderator system. This system circulates the moderator through two heat exchangers, which remove heat dissipated by high – energy neutrons during the process of moderation. The cooled moderator is returned to the calandria via. Moderator inlet nozzles. The high chemical purity and low radioactivity level of the moderator are maintained through moderator purification system. The purification system consists of stainless steel Ion – Exchange Hoppers, eight numbers in 220MWe contains nuclear grade, mixed Ion - Exchange resin (80% anion & 20% cation resins) .the purification system is also utilized for removable of chemical shim, boron to effect start –up of reactor Helium is used as a cover – gas over the heavy water in calandria. The concentration deuterium in this cover- gas is control led by circulating it using a sealed blower and passing through the recombination containing catalyst Alumina – coated with 0.3% Palladium.
7) FUEL:
The use of natural uranium dioxide fuel with its low content of fissile material (0.72% U-235) precludes the possibility of a reactivity accident during fuel handling or storage. Also, in the core there would no significant increase in the reactivity, in the ever of any mishaps causing redistribution of the fuel by lattice distortion or otherwise.The thermal characteristics namely the low thermal conductivity and high specific heat oh UO2 permit almost all the heat generated in a fast power transient to be initially absorbed in the fuel. Furthermore, high melting point of UO2 permits several full power
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
17
seconds of heat to be safely absorbed above that contained at normal power.Most of the fission products remain bound in the UO2 matrix and may get released slowly only at temperatures considerably higher than the normal operating temperatures. Also on the account of the uranium dioxide being chemically inert to the water coolant medium, the defected fuel releases limited amount of radioactivity to the primary coolant system.The use of 12 short length fuel bundles per channels in a PHWR, rather than full – length elements covering the whole length of the core, subdivides the escapable radioactive facility in PHWR has also the singular advantage of allowing the defected fuel to be replaced by fresh fuel at any time. The thin Zircalloy – 2/4 cladding used in fuel elements is designed to collapse under coolant pressure on to the fuel pellets. This feature permits high pellet - clad gap conductance resulting in lower fuel temperatures & consequently lower fission gas release from the UO2 matrix into pellet – clad gap.
REACTOR AUXILIARIES
END SHIELD COOLING SYSTEM
There are two End Shields provided at both the ends of calandria performing the following functions.(i) Providing supports for calandria tubes and pressure tubes.(ii) Provides radiation and thermal shielding for fuelling machine vaults so that the fuelling machine vaults can be accessible during shutdown.Heat is removed from the end shields to moderator and calandria vault water. However the bulk of the heat is removed by End shield cooling system.
The basic requirements of the end shield cooling system are:
(i)To maintain calaridria side tube sheet (CSTS) of end shield at an averagetemperature of 67deg centigrade.
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
18
(ii)To maintain temperature difference between various parts of end shieldwithin permissible limits.(iii) To avoid stagnant pockets of coolant, in end shield, which could causecorrosion problems.(iv)To avoid overheating and hot spots which could lead to damage of endshield.(v)To provide venting of end shield for uniform shielding in accessible andS/D accessible areas.
The End Shield Cooling System is a closed loop system Consisting of end shields, circulating pumps, and heat exchangers. An auxiliary loop exists for the control of water chemistry.There are two end shields where the heat is generated due to radiation and conduction from other reactors component i.e. End fittings, Feeders, convection andradiation across insulation gaps. (Almost 50% of the
heat load is from PHT). A total of 1.4 MW of heat loadexists for each end shield. This heat is removed by
__ circulation of demineralised water through the EndShields. The End Shields consist of two compartments called front and rear compartments. DM Water (900 LPM)enters the front compartment (the compartment facing the calandria) from five inlets at the top. Front Compartment is further divided into five separate columns. DM Water passes through these columns at a velocity of 37.7 cm/sec and flows into the annulus space between the outer and inner shells of End shield.
CALANDRIA VAULT COOLING SYSTEM
In RAPS calandria vault (the space between the calandria and steel lined structural wall) is full of demineralised (DM) water. DM water filled calandria vault provides radiation, biological and thermal shielding, and also acts as heat sink in case of serious contingency. Filling of calandria vault with DM water eliminated Argon-41 activity of earlier Indian PHWRs which had air filled
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
19
calandria vaults (RAPS 1&2 AND MAPS). This drastically cuts the exposure of public in the vicinity of Indian Nuclear Power Plants.
The dimensions of the calandria vault are such that a minimum water thickness of 1.35 meters is ensured between the calandria and concrete vault.This ensures adequate shielding.
FUNCTIONS OF THE CALANDRIA VAULT COOLING SYSTEMi)To remove heat generated in vault water.
ii)To provide thermal shielding and biological shield under all condition.
iii) To maintain uniform temperature in the vault structure below permissible limit under all condition.
iv) Provide an environment compatible with the material used for components within vault.
Heat appearing in calandria vault water is removed by a closed loop cooling system. Water at 42.5deg cen. is distributed through perforated header laid out in the bottom of the vault and warm water at 46.2deg cen. leaves the vault through header at the top.
VAPOUR SUPPRESSION SYSTEM
Large pooi of water (2200M3, 2.4m deep) at the basement of the reactor building is provided to limit peak pressure inside volume Vi during LOCA (Loss of coolant accident) or MSLB(Main steam line break) by condensinghigh enthalpy steam. Volume Vi is connected to the suppression pool via an annular space between the RB structure wall and inner containment wall.The suppression pool is provided with a re circulation system to protect against corrosion and biological growth.
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
20
ANNULUS GAS MONITORING SYSTEM
The annulus gas monitoring system of RAPP 3&4 provides a means of monitoring the leakage (if any) of heavy water either from PHT or from moderator system due to failure of coolant tube calandria tube or rolled joints. It is a closed loop recirculating system which maintains flow of C02 gas through the annulus gap between coolant tithe and calandria tithe. Apart from leak detection, the annulus gas also acts as a thermal barrier, separating the hot high pressure coolant tubes and the comparatively cooler low pressure calandria tubes. By reducing heat transfer between coolant tube and calandria tube, heat removal requirements from moderator system are minimized as well as the reduction in loss of heat from PHT system. In addition, the annulus gas minimizes corrosion and hydrides formation in the coolant tubes or in the garter spring spacers by providing a dry 02 doped gas atmosphere in the annulus.
LIQUID POISON INJECTION SYSTEM
For prolonged shutdown of reactor (1) for maintenance jobs or (ii) when reactor has tripped on reactivity transient which do not permit restart of reactor within poison override time, LPIS is actuated so that sub criticality margin is maintained under all conditions. LPIS adds a bulk amount of liquid poison directly to the moderator to keep the reactor under shutdown state for prolonged duration. This is an independent process system and is the replacement of (i) ALPAS bulk addition mode (at NAPP and KAPP) which required moderator circulation and (ii) gravity addition of boron (GRAB)The LPIS works on pneumatic pressurization of boron solution by helium. The system consists of poison tank
and helium tank. When a command for poison addition is received the pressure balance valves and siphon break valves close and injection valves open. This causes the pressurisation of poison tank by helium stored in helium tank. This in turn causes injection of
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
21
boron poison directly into the moderator through two nozzles in calandria at 75%FT level
D2O EVAPORATION AND CLE~AN UP SYSTEM
D20 evaporation and clean up system purifies downgraded heavy water to a level which is not harmful to heavy water upgrading system by removing all the impurities. The heavy water collected from various leakages and spills contains a number of impurities which normally arise from— Surf ace from which D20 is collected. Corrosion products produced inside the reactor D20 system.Products resulting from radiolytic process. Organic material from ion exchange resin dueteration and breakdown.D20 evaporation and cleanup system is designed to clean the downgraded heavy water chemically so that it can be fed to upgrading plant. Cleanup system comprises of oil water separation stage, filtration stage and ion exchange stage.
HEAVY WATER UPGRADING SYSTEM
Heavy water is used as moderator and primary heat transport fluids in PHWRs. Heavy water is highly hygroscopic. Hence it leaks from the system, it gets downgraded on exposure to atmosphere. Such leaked heavy water collected from various points in the reactor is to be upgraded before use in reactor, since the isotopic purity required for moderator heavy water is as maximum as achievable.
FIRE FIGHTING SYSTEM
Fire protection system in a nuclear power plant is meant To prevent damage to various equipment or system due to fire.To ensure decay heat removal of the reactor. To minimize the release of radioactivity to environment in the event of a fire.To provide backup PW cooling to various systems. To ensure personnel spray supply.Fire protection system consists of fire fighting water system, carbon dioxide fire protection system and portable fire protection system.
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
22
FIRE WATER SYSTEM
Fire water system comprises of constantly pressurized fire hydrant system and sprinkler system. Automatic sprinklers have been provided for oil filled transformers and non-automatic sprinklers are provided for oil systems, cable vaults and cable tunnels. Hydrant system covers the whole plant for outdoor and indoor supply of firewater. Water for both hydrant and sprinkler system is supplied by the firewater pumps from the sumps located in the cooling water pump house(CWPH).
ACTIVE PROCESS WATER SYSTEM
Active process water system provides direct means of heat transport from equipment and heat exchangers in the primary heat transport system, moderator system and reactor auxiliary system to ultimate heat sink during all operational stages of the plant and accident condition like LOCA. Thus it forms the secondary part in the ultimate heat removal system. It is a safety-related system. Reliability and continuous heat removal is achieved by designing the system for SSE/OBE by providing redundancy in rotating equipment, Class III power supply to all safety related electric motor driven equipment and backup supply from fire water system to meet static component failure This system is potentially active since there is a possibility of leakage of active primary fluid to this system through various heat exchangers.
RB VENTILATION SYSTEM
RB is designed as a double containment structure in order to prevent ground level release during accident conditions. Primary containment houses all equipments and piping of nuclear systems. Secondary containment envelops the primary containment with an annular radial gap of 2 meters.PC is divided into two volumes. Vi containing the systems having high enthalpy fluids comprising of F/M vaults, pump room, dome region and includes FMSA when they are in contact with F/M
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
23
vaults. These areas are not accessible during normal plant operation. No ventilation is provided for this volume but closed loop heavy water vapour recovery system is provided to recover D20 that escapes from high enthalpy systems. The remaining area constitutes volume V2. Volume V2 is separated from Vi by a leak tight barrier and pressure suppression pool. The volume Vi is maintained at negative pressure with respect to V2 by maintaining continuously a small purge to the stack. Volume V2 is normally accessible except moderator room, FMSA and DN monitoring rooms.
HEAVY WATER VAPOUR RECOVERY SYSTEM
Heavy water vapour arising out of spills/leakages from primary heat transport, moderator and fuelling machine circuits is recovered from building atmosphere by adsorption on molecular sieve beds. Vapour recovery system is an important feature of the station heavy water management schemes. Following are the criteria for design and operation of vapour recovery system— To effect economy in reactor operating costs by efficient recovery of heavy water that escapes into the building atmosphere.To minimise heavy water loss and tritium loss and tritium release through stack.To minimise tritium activity levels in various areas of the reactor building.
To keep the volume Vi area under negative pressure with respect to volume V2 area for preventing the spread of activity from volume Vi to volume V2.
CALANDRIA
The calandria is horizontal vessel housed in a rectangular calandria vault. The calandria is a single walled austenitic stainless steel vessel. The main shell is stepped down in diameter at each end and
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
24
site welded to their cylindrical extensions of the end shields on each side of the reactor.
END SHIELD
The end shields are cylindrical boxes whose extensions are welded to the calandria side tube sheet at the calandria end and fueling machine side tube sheets at fueling machine end of the end shield during shop fabrication. The box is pierced by 306 lattice tubes arranged on 228.6mm square pitch. The space inside the end shield is divided into two compartments by a 38mm thick baffle plate and fueling machine side tube sheet is filled with 10mm dia spherical mild steel balls and light water in the 57:43 ratio.
CALANDRIA TUBE
The calandria tubes are manufactured from Zircalloy2 strip that is cylindrically formed and seam welded. The seams are then leveled by rolling. The primary functions of the calandria tubes in a reactor system are-
1.To separate the relatively cold moderator from hot coolant tubes to minimize heat losses.2.To support the horizontal coolant tubes (through garter springs) and prevent the excessive sag caused by creep. To act as containment vessel for the contents of the channel in the unlikely but postulated instance of a pressure (coolant) tube rupture accident.
COOLANT TUBE
Coolant tube is the most important structural component inside the reactor core. Coolant tubes are manufactured from Zr-Nb. Each end of the coolant tube is joined to a special type 403SS end
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
25
fitting. Such 306 Nos. of parallel coolant tubes are placed horizontally inside the reactor core at the square lattice distance of 228. 6mm.
END FITTINGS
The end fittings on either end of the reactor identical and connected at the ends.
GARTER SPRING SPACERS
Four numbers of garter spring for each coolant channel and located in the annulus space between coolant and calandria tubes.
SEAL PLUG
The function of the sealing plug is to close the ends of the coolant assemblies and prevent the escape of heavy water from the end fittings. During fuel changes it is necessary to remove these plugs.
SHIELD PLUG
The shield plug which normally resides in the end fitting serves the three functions of providing — Radiation shielding at the ends of the coolant tubes Means of locating the fuel in the fuel channel and stopping the fuel column from following the seal plugs when they are withdrawn during fuel changes. The turbine is of the horizontal tandem compound, reheating, impulse type, running at 3000 rpm, with special provision for extraction of moisture. The turbine has a maximum continuous and economic rating of 220 MW, The turbine comprises of one HP cylinder and two double flow LPCylinders thus providing 4 LP flow in parallel. Thetas are five impulse stages in the HP cylinder and six stages foreach of the LP cylinders. The turbine cylinders and generator is solidly coupled together in line, with a single thrust bearing on HP shaft between No, 2 bearing (HP rotor bearing) and the HP~LP. Coupling each rotor is supported in two main bearing. A solid forged steel rotor is provided in the HP cylinder whilst the LP rotor have shrunk and keyed on discs, The nozzle plates of the HP
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
26
cylinder are welded assemblies incorporating machined nozzle segments, The LP diaphragms are cast iron with cast-in nozzle division plates. Steams packed labyrinth glands are provided for each cylinder, Live steam at a pressure of 580 psig and temp 482.60F (saturated) is supplied to the HP cylinder of the turbine through two separately anchored steam chests each containing a steam strainer a combined stop and emergency valve and two throttle (or governing) valves, The chests are connected to the HP cylinder through loop at allow axial movement of this Cylinder, and ensure that no excessive thrust loads from the piping are transmitted to the HP cylinder. Extraction steam is taken for feed heating purpose before stages 4&5 and at the exhaust of the H.P cylinder after expansion is led two moisture separators in parallel which reduce the moisture content of the steam before it is reheating is two live steam reheaters, The steam from the reheaters Having a pressure of 47.5 psig and temperature of 43OoF passes through governor operated butterfly interceptor valves before entering the two double flow LP cylinders. An interceptor’s valve is provided in the line from each reheater to the LP inlets, The LP cylinder of turbine is of four flow design: each two flow LP has a central admission belt with outward direction of steam flows. Steam is supplied to the two flow provision via the separator and reheater in each HP cylinder .the exhausts from the LP bleeding combines into a condenser, which is maintained at vacuum 27.5” hg.
Steam is extracted from double flow L1~ cylinder before stages 24 and b for feed heating and before stage 6 for a moisture extractor, The over all length of the Turbine generators 100 and the outside diameter of the last row of blade is 100”. A data logger monitors all turbine and ancillaries parameter.
STEAM CYCLE:
Steam for the turbine through two steam lines or header to the two stem lines or header to the two combined stop and emergency valves. A10” balance line connected line connect the header the C.S.E. valves. During normal operation the C~S.E. valves are fully
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
27
open to permit steam flow to inlet steam chest and then to the two governor valves. Governor valve position controls turbine speed and load and thus are made responsive to the governor valves (two on each bank) are connected by means of balance lines and the steam passes to the H.P. inlet nozzles, trough the H.P. cylinder. The to governor valves in each steam chest are in parallel i.e., there is common inlet and outlet manifold for both of the two governor valves in a steam chest. Also lines from each steam chest joint and go to both top and bottom of H.P, cylinder This arrangement in conjunction with the 10” balance line ensures uniform steam take off from each of the 8 boiler and uniform distribution to each portion of H~P. cylinder, After expansion, the steam leaves the H~P. cylinder and passes through the separator, reheater, LP emergency stops valves and interceptor valves, before entering LP cylinders. Also to relief valves are installed after each of the two re heaters. In the event of governor or interceptor valve malfunction the relief valve will open and vent the steam to atmosphere preventing over pressurizing the separator or reheaters,
The interceptor valves remain full open normal operation and admit the steam to LP cylinder from where it is exhausted to the condenser, not all of the steam to the LP cylinders from where it is exhausted to condenser. Not all of the steam admitted to turbine by the governor valves is expanded through the turbine and exhausted to main condenser At different points on the turbine, steam is bled off or Extracted and passed to feed water heat exchangers. Heating the feed water by extraction steam has two beneficial results; one is an increase in the heat cycle efficiency and the minimum permissible inlet feed temp. to boiler is 24OoF, The RAPS turbine has six extractions feed heaters three including deaerators heatersFed from the H.P, cylinder, and are called lob pressure heaters if they are in the feed line before the boiler feed pumps and are called high pressure if they are in the feed line after the pumps. Five of the extraction lines have spring closed check valves. These check valves close on a turbine trip to prevent entrained stream in the extraction lines and heaters from backing up into the turbine and causing it to over speed. Entrained steam from the (one, remaining extraction line and heater was calculated to give only a small increase so check valves were omitted
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
28
CONDENSING SYSTEM: GENERAL.
The circulating water in the condenser condenses the exhaust steam from LP Turbines. The condensate is recycled through boilers. The air gases are removed from the condensate by the air ejectors. The condensing system is provided to supply condensate from the deaerators under all condition of operation. The maximum flow of condensate to deaerators at 100% turbine load is i 900.000lbs/hr, the design temp. are 91 5oF in the condenser hot well and 245oF at the deaerators inlet
DESCRIPTION
Condensate system comprises of main condenser two 100% capacity condensate extraction pumps and two 21/4% duty emergency pump, 2 moisture Extractor, gland steam and high level reserve feed water tank with their associate fittings, pipelines and instrumentationThe condensate extraction pumps take suction from the condenser hot well and discharge through the moisture extractors, drain cooler and LP heaters, the condensate flow is controlled by the control valve part of the Condensate front the condensate pump discharge header flow changes the gland steam condenser and air ejectors and returns to main condensate line before it enters the moisture extractors. The flow in this line is controlled by means of regulating control valve which maintains a fixed differential pressure across the gland steam condenser having been designed to have the same pressure deferential tar its design flow as the air ejector. A condensate recirculation line back to the condenser is provided. This take off is located downstream of the condenser. The condensate pumps also supply boiler feed pump gland seal water and water f or the turbine spray cooling. One 21/2% capacity auxiliary condensateExtraction pump takes water from the condenser hot well and discharge into the same system as the 100% pumps.
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
29
SAFETY DESIGN PRINCIPALS
It has been ensured that systems, components & structures having a bearing on reactor safety are designed to meet stringent performance & reliability requirements. These requirements are met by adopting the following design principles:a) The quality requirements for design, fabrication, construction & inspection for these systems are of the high order, commensurate with their importance to safety.b) The safety related equipment inside the containment building is designed to perform its function even under the elevated pressure & temperature &steam environment conditions expected in the event of postulated loss of coolant accidents (LOCA).c) Physical & functional separation is assured between process systems & safety systems.d) Adequate redundancy is provided in systems such that the minimum safety functions can be performed even in the event of single active components in the system.e) To minimize the probability of unsafe failures f) Provisions are incorporated to ensure that active components in the safety systems are testable periodically.g) All the supplies /services (electric, compressed air or water) to these systems, necessary for the performance of their safety functions are assured & ‘safety grade’ sources.
SAFETY & SEISMIC CLASSIFICATION OF SYSTEMS:
SAFETY CALSSIFICATION:In the design of Indian PHWRs, it is required to grade various systems, equipment & structures in their importance to safety & reliability. The safety gradation consists of four different safety classes depending upon the nature of safety functions to be performed by the various items of the plant.
SAFETY CLASS I: It is the highest safety class & includes equipment & structures needed to accomplish safety functions necessary to prevent release of substantial core fission product
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
30
inventory. This includes reactor shutdown systems & primary heat transport system.
SAFETY CLASS II: Includes equipment, which performs those safety functions, which become necessary to mitigate the consequences of an accident involving release of substantial core fission product inventory from fuel. This class also includes those items, which are required to prevent escalation of anticipated operational occurrences to accident conditions. Boiler feed water & steam system, emergency core cooling system, reactivity control provisions & reactor containment building are included in this class.
SAFETY CLASS III: Includes systems that perform functions, which are needed to support the safety functions of safety class II & I. Also, it includes systems & functions required to control the release of radioactivity from sources located outside the reactor building. Process water-cooling system include induced draft cooling towers, air supply system, shield cooling system primary coolant purification ion exchange columns & filters etc. are included in this category.
SAFETY CLASS IV: Includes those items & systems, which do not fall within the above classes but are required to limit the discharge of radioactive material & airborne radioactivity below the prescribed limits .D2O upgrading, waste management, dueteration &service building ventilation systems are classified as class IV safety systems.
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
31
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
32
1.0 DESIGN DESCRIPTION:
COIS is a data acquisition and display equipment for providing the
operator with process alarm messages, status, trend curves, history
displays and printouts of groups of process variables etc.
. A three-tier system design consisting of Display Stations, Data
Acquisition Computers and I/O subsystem has been adopted to
improve the reliability and availability. This makes the different
subsystems to be hardware independent on each other. A high speed
Ethernet LAN (Local Area Network) is used for communication
between the subsystems.
10 of the Display Stations are Utility CRTs (UCRTs) and the
remaining 2 are Alarm CRTs (ACRTs). They are Intel 80386
microprocessor based systems doing most of the user interface job.
These systems are having high resolution (Super VGA-1024 x 768
pixels) 19” monitors, which give a good pictorial representation of the
data.
Data Acquisition Computers are based on Intel Pentium which UNIX
SVR 4.2 as the Operating system. Both the DACs work in dual
redundant hot standby mode. They mainly acquire the data from I/O
subsystems and other Computer Systems like PLC, DPHS, RADAS
etc. and pass the required data to display stations. They do the
logging of the history data and take care of the printer tasks. They
also do the network management of both the LANs. They also direct
the I/O systems to govern the field outputs as required.
I/O subsystems are Motorola 68020 CPU based systems. Each I/O
subsystem has 2 CPUs working in dual redundant mode. They mainly
do the scanning and alarm checking of the field inputs connected to
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
33
them and pass on the data to DACs. They also change the field
outputs as per the directive from DACs.
The network topology is designed in such a way that a single break
anywhere in the network (broken cable or failed n/w equipment) will
not result in a collapse of the total system, but will allow the system to
continue to work at a degraded level. The significant aspects of the
designed network topology are:
a). Thicknet cable is used as it is much more rugged than the
thinnet cable.
b). Transceivers that are used to connect different nodes to the
network are piercing type tap boxes, which facilitate the
connection without a cut in the cable.
c). A significant component in the topology is “Repeater”.
Repeater is an active component that can be used to connect
different cables of networks. It isolates the remaining network
from a fault in any of the other cables. This has given rise to a
fault tolerant network. The network is divided into 4 parts each
connecting ¼ of the system. The various failures considered
their effect is described below:
i). If any transceiver or the cable connecting the transceiver
to the node fails, only that node will fail & reset of the
system will continue to work as usual. If the connection
with the Master DAC fails, the hot standby DAC will
take over and the system will not be affected.
ii). If any one of the cables of LAN1 - a, b, c or d fails than
¼ of inputs/outputs (of the nodes connected to that part
of the network) will be lost & the system will continue to
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
34
work with 75% of inputs/outputs data. If more than one
cable fails, COIS still will work with the reduced
capacity accordingly.
iii). If any one of the cables of LAN-2 – a, b, c or d fails, then
¼ of display stations will not be available. Display
stations are connected in these four cables in such a way
that CRTs on adjacent Main Control Room panels are
connected to different cables and will not fail
simultaneously. ACRTs are connected to different
repeaters and hence will not fail simultaneously. If more
than one cables fail, COIS will still work with the
corresponding reduction in display stations.
1.1 Inputs/Outputs
There are various types of plant inputs to the COIS viz. analog inputs
and digital inputs. Each plant input is also referred to as “point” the
COIS also provides voltage free relay contacts as outputs.
Analog inputsThere are 1256 analog inputs to the COIS. These include about 10%
spare points. The approximate distribution into different categories is
as follows: -
RTD’S 392 points
Thermocouples 16 points
Volts/Current Inputs 824 points
Thermistor 8 points
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
35
Exact details of description, input range, alarm priority, process range
and processing required etc. for each analog input are available in the
COIS analog input..
For the current inputs the terminating resistors (of value as specified
in analog input list) are a part of the COIS. Among the 824 voltage or
current inputs, any number may be voltage input. Thus all of these
824 inputs can be arranged to take a current or voltage input. Input
impedance of voltage inputs is greater than 1 Ohm. Linearisation and
lead resistance compensation wherever necessary, e.g. for RTD and
thermocouple inputs, will be performed by the COIS. All RTD inputs
will use 3 wire RTDs in the field. Provision will be use 3 wire RTDs
in the field. Provision will be made to terminate a 3 wire RTD at each
RTD input point.
Cold junction compensation for thermocouple will also be provided
by the COIS. These analog inputs are numbered in the range of 000 to
1299.
1.1.1 Digital (contact) Inputs
There are 1136 digital inputs of contact type. There are two types of
contact inputs as follows:
1.1.1.1 Voltage free contact inputs: There are 736 voltage free
contact inputs. These contacts represent alarm or status inputs.
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
36
1.1.1.2 Shared contact inputs: There are 400 field contact inputs
which are shared between the window Annunication system (WAS)
and the COIS. These contacts represent alarm events.
1.1.2 Digital (Voltage level) Inputs
There are 656 voltage level inputs representing the status of valves
(open or closed).
State Voltage
Level 0 Between 0 volts and 2 volts
Level 1 Between 40 volts and 48 volts.
The input impedance presented by COIS to these inputs will not be
less than 10K ohm.
1.1.3 Input Data from other computer systems
COIS receives data from other computers viz. Digital Recording
System (DRS), Radiation Data Acquisition System (RADAS),
Electrical DAS and PLC’s via LAN thorough gateways. In the COIS,
these input parameters are numbered as follows:
(1) Radiation Data Acquisition System:
Analog points: 3601 to 3799
Digital points: 3001 to 3999
(2) Electrical DAS:
Analog & contact points: 7001 to 9499
(3) PLC’s Digital points representating : 1301 to 1999
Status of hand switch position & 5901 to 5999
(4)Digital Recording System (DRS)
a) Normal/Disturbance Analog inputs : 2801 to 2899
b) Visicorder Function Analog inputs : 2901 to 2999
c) Contact inputs of ESR function : 9501 to 3499
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
37
d) Dual Process Hot Standby : 9501 to 9699
Analog inputs
(5)Other Computer Systems
a) Analog inputs : 9701 to 9899
b) Contact/digital inputs : 9901 to 9999
Note: There are no physical inputs corresponding to these points.
Values of these points are provided to the COIS periodically by the
above systems. For all displays and logging functions except alarm
functions, these points are treated as the field COIS inputs.
1.1.4 The COIS will also provide 224 outputs of voltage free relay
contacts. Ten or these contacts are used for Fuel Failure Monitoring
function described in Sec. testing function described in section 5.11.
The remaining contacts will be used for miscellaneous purposes like
giving time synchronizing pulses to other computer based systems,
annunciation of the failure of the COIS, indication of which computer
system is faulty etc.
1.1.5 Ethernet
The COIS will provide Ethernet LAN connectivity for connection to
other computer systems.
1.1.6 The COIS will also provide, on operator’s demand, processed
data outputs called calculated analog variables, for e.g. selected
channel differential temperatures and DNM detector outputs etc.
These variables will be numbered in the range of 6001 to 6699.
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
38
1.2 Accuracy, Noise Rejection, Contact Debounce and Isolation.
1.2.1 For all digital and analog inputs, a very high isolation between
the transducer circuit and the COIS is provided to avoid problems in
the transducer circuit due to ground faults etc.
1.2.2 Overall accuracy of analog data acquisition for any point will
be 0.25% of span or better. This accuracy will be maintained even in
the presence of common mode noise (Max.) + 15V d.c./50Hz. on the
input. A low pass filter will be provided on each analog input to
suppress normal mode (predominantly) 50Hz. noise. Protection will
be provided against following conditions for different categories of
analog input.240V AC (Max.), 50Hz common mode voltage on any
thermocouple inputs.
For RTD inputs: Depending on RTD bridge excitation
network
Or + 50V d.c./a.c. (Whichever is more) common mode or
normal
mode voltage.+ 250V d.c./a.c. common mode or + 50V
dc/ac
normal mode voltage on any other type of analog inputs.
1.2.3 Processing of potential free contact type inputs will not be
affected even under a max. common mode voltage of + 15V d.c./50Hz
a.c. on any input. Beyond 15V, protection is provided for a max. +
250V d.c. /a.c. common mode voltage. For providing the above
common mode voltage capabilities, opto-isolators are used for digital
inputs.
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
39
1.2.4 In case of digital (contact) inputs and digital (voltage level)
inputs input status changes lasting less than 50 milliseconds will be
ignored by the system.
Note: Sampling interval for all analog & contact inputs will be
adjustable to any of the following: 5 sec. 10 sec., 30 sec., with the
normal interval specified in the above table. This adjustable could be
on an individual basis or on group basis (Group = type of input).
For all analog inputs, five samples will be taken within the sampling
interval and the average of these five samples will be taken as the
value for that sampling interval.
There will also be a provision for averaging over last five sampling
intervals for selected number of analog inputs (max. 100Nos.). These
average values will be used in all displays and printouts.
1.3 Alarm Function
The computer system will check some of the analog inputs and almost
all of 736 digital alarm inputs in the 656 Digital (voltage) inputs for
alarm events. Many analog points are only for periodic logging and
BG display etc. and are not checked for alarm at all. And some points
have to be checked for alarm at all. And some points have to be
checked for only low alarm limit or only high alarm limit i.e. both
alarms are not required. Some COIS points are inhibited from
reporting to ACRTs as alarms, i.e. these points are not displayed on
the ACRTs when the status of these points changes. But this does not
prevent them from displaying their status in BGs, tabular trends etc.
The remaining point will have both low and high alarm limits. Some
of contact (digital) inputs are for status monitoring only and will not
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
40
be checked for alarm. The remaining points will be checked for
alarms. The frequency of alarm checking will be same as that or the
point for data acquisition. The alarm events are defined as follows:
1. An analog input going above a high limit (HL) or falling
below a low limit (LL) or a digital input sent to alarm state
since previous scan is referred to as an “Alarm” occurrence.
2. Analog input returning between its high and low point or
a digital input going to normal state since previous scan is
referred to as “return to normal” occurrence. This is also
referred to as ‘Normal’ occurrence is short.
As for as ACRT display or output on alarm printer are concerned,
analog points will be limited to only “low”, “High” and “Bad” states.
BL (Bad Low) than lower end of span Lost. Such additional alarms
will store in the computer memory and arranged as CRT concealed
alarm pages for display purposes.
Capacity for such 100 additional alarms is provided. A suitable
audiovisual indication for the alarm in the concealed pages is
provided. Operator will be able to call up for display any of the ACRT
concealed alarm pages on any of the two ACRTs or on both ACRTs
will be different and independent. Provision will be made for scrolling
up or down (one line at a time) of ACRT display. Latest ‘alarm/’
return to normal’ message line will also be displayed on the last line
of all the ACRT pages. Provision will be made so that the operator
can retain on the screen the most important/of immediate
interest/relevant alarms only on the screen and put the rest of them in
concealed alarm pages. Provision will also be made to list the alarms
on any UCRT for a selected USI or a range of USIs keyed in by the
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
41
operator. This is called “alarm” display management”. Each input
point will be given a priority number of 1 or 2. Inputs with priority of
2. It will be possible for the operator to call up the summary of
existing alarms on any UCRT. It will also be possible to call this
summary as total or only of alarms with a priority 1 or only of alarms
with a priority 2. Provision will be made to list all alarms for a
selected USI or range of USIs keyed in by the operator.
Operator will be able to ‘tell’ the COIS any analog/digital inputs
which are to be ignored (i.e. as if those do not exist) for alarm
function. Such ‘ignored’ inputs will be resumed automatically in 30
minutes or whenever desired by the operator, whichever is earlier.
Such operator commands will get immediately logged on Alarm
Printer.
The system will maintain a list of such “alarm-disabled points. It will
be possible to add/delete points in this “disabled list”.
The COIS will have the following two codes of alarm processing.
1) Mode 1: Under this mode repetitive alarms are suppressed.
2) Mode 2: Under this mode, repetitive alarms are also reported
(without any suppression) lost. Such additional alarms will be
stored in the computer memory and arranged as CRT concealed
alarm pages for display purposes.
Capacity for such 100 additional alarms (i.e. approx. 5 concealed
alarm pages) is provided. A suitable audiovisual indication for the
alarm in the concealed pages is provided. Operator will be able to call
up for display any of the ACRTs or on both ACRTs i.e. the pages
selection keys for both the ACRTs will be different and independent.
Provision will be made for scrolling up or down (one line at a time) of
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
42
ACRT display. Latest ‘alarm/’ return to normal’ message line will
also be displayed on the last line of all the ACRT pages. Provision
will be made so that the operator can retain on the screen the most
important/of immediate interest/relevant alarms only on the screen
and put the rest of them in concealed alarm pages. Provision will also
be made to list the alarms on any UCRT for a selected USI or a range
of USIs keyed in by the operator. This is called “alarm display
management”. Each input point will be given a priority number of 1
or 2. Inputs with priority 1 being more important than those with a
priority of 2. It will be existing alarms on any UCRT. It will also be
possible to call this summary as total or only of alarms with a priority
1 or only of alarms with a priority 2. Provision will be made to list all
alarms for a selected USI or range of USIs keyed in by the operator.
Operator will be able to ‘tell’ the COIS any analog/digital inputs
which are to be ignored (i.e. as if those do not exist) for alarm
function. Such ‘ignored’ inputs will be resumed automatically in 30
minutes or whenever desired by the operator, whichever is earlier.
Such operator commands will get immediately logged on Alarm
Printer.
The system will maintain a list of such “alarm-disabled points. It will
be possible to add/delete points in the “disabled list”.
i) Mode 1: Under this mode repetitive alarms are
suppressed.
ii) Mode 2: Under this mode, repetitive alarms are also
reported (without any suppression). The operator through a
password can select alarm-processing mode 1 or 2.
1) Alarm processing under mode 1:
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
43
Under some abnormal field conditions, some of the points
(analog/contact) may oscillate between alarm and normal states
and hence any cause large number of alarm/normal messages
on the alarm printer & ACRT’s. Hence, it is required that not
more than six message (status changes) are generated by any
point in any quarter of an hour. For this purpose, the COIS will
set the “status change” count of each to zero, every quarter of
an hour. Any point which changes status (from normal to
alarm/bad or alarm/bad to normal etc.) 6 times in any quarter of
the hour, will be automatically disabled from alarm scanning
for the remaining part of the quarter hour. But the COIS will
freeze the status only with alarm/bad status i.e. if 6th message is
normal message, the COIS will disable alarm scanning of the
point after 7th message (i.e. Alarm message) is reported. This
period for checking max. NO. Of alarm generation will be
programmable between ¼ of an hour to a selected period will
also be adjustable between 4 and 10.
Alarm processing under mode 2 :
All alarm messages are reported without any suppression.
1.3.1 There are about 400 Nos. digital inputs (shared input contacts)
which are scanned only for the logging of their status changes on the
alarm printer and mag. Tape cartridge/disk cartridge (i.e. CRT display
and audio ann. Is not required for these). (Note: These are the window
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
44
annunciator points numbered in the range of 4001 to 4999). These are
scanned every one second.
1.3.2 Latest Alarm Message Display Function on UCRTs
The latest “Alarm”/”Normal” message displayed on the ACRTs will
also be displayed on the bottom-most line of all the UCRTs also. No
flashing of the alarm message or any audio is required on the UCRTs.
However, successive alarm message will be displayed in alternate red
and pink colours on UCRTs (e.g. first alarm message in red colour,
second in pink colour and third in red again and so on). Normal
message will always be shown in green colour. Any alarm/normal
message will be continuously displayed until another alarm/normal
message is generated to replace the previous one. Operator will
provide a facility to switch off this alarm/normal message display on
any UCRT whenever required.
1.3.3 Valve Status Monitoring
There are 656 Nos. voltage level inputs representing the valve status
(open or closed). These inputs are scanned once every 1-second for
displaying the actual status of the valves in the Mimics and for
logging their status changes on printer used for alarm logging. Status
changes are recorded on magnetic tape also.
Each valve to be monitored for its status on COIS will have one or
two inputs connected to COIS. These are voltage level inputs with two
levels, i.e. at 0 volt for 48 volts dc. Voltage level inputs are normally
taken across the indicating lamps corresponding to the valve. When
the indicating lamp is ‘ON’ indicating valve “Fully open” or “fully
closed”, the input to COIS is +48V DC, otherwise it is zero. If there
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
45
are tow inputs corresponding to a valve, the COIS will sense both the
inputs and derive the status as follows:
“Fully open” input “Fully Closed” Input Status
48 V 0 V Fully open
0 V 48 V Fully closed
0 V 0 V In intermediate
position
48 V 48 V INST. FAILURE
The COIS will show the actual status in the Mimics appropriately. It
will also log the change of status on the printer accordingly.
For valves having single input to COIS, the status will be either
“Fully open” or Not Fully open” (“Not Fully Closed”).
If there is a change in status the new status will be logged on to the
printer. It may be noted that the “Intermediate” status and “Instrument
failure” status are taken as new status only if it has remained so for
two successive scans. The “Instrument failure” status is treated as an
alarm and would be annunciated on the ACRT.
1.4 Interface to Various other Computer Based Systems
The COIS will also provide Ethernet LAN interface for connecting
the following computer systems. The COIS will receive data from
them as required as per the approved protocol. The data will be
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
46
available for all the functions described in this design manual except
for alarm function:
a) RADAS
b) Electrical SCADA (EDAS).
c) PLC
d) DRS
e) DPHS
f) CTM
g) PDCS etc.
1.5 General Features:
1. The COIS will be user friendly and the operator will be able to get
the desired information in desired formats on the various UCRT’s in
an interactive manner. Menu driven CRT based dialogue with the
system will be designed. Various menus/indexes/lists of UCRT’s
functions, BG’s, History groups and graphic trend groups etc. will be
displayed on the UCRT on operator’s demand. ‘Help’ facility will be
available at all phases of dialogue. Data retrieval procedures will be
quick and easy. No UCRT will have a blank screen at any time. If no
display is demanded, it will be showing the main menu, so that
operator can quickly select the display of his choice.
2. Process data base will contain flags for each Analog input to
indicate whether any Low Alarm Limit/High Alarm Limit is
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
47
applicable or not. Software for Alarm processing and various displays
etc. will not call for entry of artificial low/high alarm limit e.g. lower
than lower end of span/higher than higher end of span etc. as this
causes confusion and inconvenience to the operator while studying the
printouts/displays.
4. Microprocessor based and standalone type I/O subsystems are
used. Analog inputs cards are designed for automatic calibration at
regular intervals under software control using precision reference
sources for 25% and 75% scale. Hence, software offset correction is
provided for any drift due too temperature or time.
5. A facility for enabling/disabling “low” alarms in bulk for certain
points with a single command will be provided. These low alarms
mostly correspond to the failure of the sensors.
1.6 Resolution of Values in Numeric/Plot/Bar Graph Form
Resolution of Values (i.e. data such as current value of a process variable, alarm
point, etc.) will in various cases be as follows or better:
Sr.
No.
Type of output Resolution
1 Numeric form 0.1%
2 Graphic Display/Mimic/Bar
Graph/Plot
0.2% or
better
Numerical resolution will be limited to 0.1 to 0.2% of full span. The
operator will not require a better resolution than this and it will
waste the useful area of the screen. Hence numerical displays like
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
48
21.3245 for a process range of 0-100C will be avoided and an
approximated value 21.3 will be displayed.
1.7 Response Time
Expected response times are described as follows:
1. Initial Display Lag : It is defined as the Maximum Time taken
for the first complete display (static + dynamic parts) to appear on
the display after the operator’s common will not be more than 2
seconds.
2. Time Stamp Lag : It is defined as the maximum time
difference between the real time of a field event occurrence and the
time stamp (Time stamp will be done as soon as the scanning is
done) will in principle be same as the sampling interval.
3. Display Lag : It is defined as the maximum time difference
between time stamping of an event and it being displayed will not be
more than 1 second.
4. Sampling interval : It is defined as the maximum time between
the two consecutive scanning of the inputs
5. Print Lag : It is defined as maximum time difference between
the commencement of the demanded printout and the operator’s
commands and will not be more than 10 seconds.
1.8 Data Storage/Retrieval and Off-line Computer System
1.8.1 Data Storage
The following on-line data will be recorded on the magnetic disk for
last 32 hours:
a) History data
b) Static data base
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
49
c) Changes done in static data base
d) Five sets of DNM data & ECCS Test Data
e) Alarm logging
f) Snapshot of current values of all the points at every shift and as
demanded by the operator.
g) Data and time of recording the data.
This data for the last 24 hours, on default, will be dumped on to the
magnetic tape one in a day at a fixed time, which will be adjustable
on system starting time.
Typically, one tape will be used for a day and previous one month’s
data will be stored (i.e. 31 tapes will be available). Before dumping
the data, system will check, if the tape on the drive is of that day’s
tape. If not, it will ask the operator to insert new tape for dumping
the data.
1.8.2 Data Retrieval
Provision will be made to retrieve the data from the disk (current 24
hours) or from any previously recorded magnetic tape and store it on
a PC (MS-DOS) compatible floppy. Facility will be provided to
select any type of data and in any range (time, usi, etc.).
1.8.3 Off-line computer system
Off-line computer system will comprise of a standard PC-AT and a
printer. It will be possible to read the data recorded on floppies by
the on-line system .The software would also include standard
package like DBASE IV.
1.9 Input Power Supply to the Equipment and Effect of Power
Failure.
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
50
Two independent sources of single phase, A.C. power supply of the
following specifications will be available in the station.
Voltage
RMS Value : 240 Volts + 10%
Steady state variation : + 10%
Transient variation : 0% (for 200m secs)
Frequency
Frequency : 50 Hz
Steady state variations : + 1%
Transient variation : + 5%
During transient variations (upto 200m sec) the COIS will continue
to operate without malfunctioning.
An input a.c. power interruption (total outage) lasting 30
milliseconds or less will not affect the working of the COIS in
anyway.
For all 240V AC loads, both sources of main supply will be
connected through contractors such that failure of any main power
supply will not affect operation of any subsystem. Wherever
duplicated D.C. power supplies are used, separate a.c. main source
will be given to the two D.C. power supplies will be connected to
the load through isolation diodes.
1.9.1 Seismic specification
1. The I/O subsystem equipment will operate satisfactorily during
and after the vibration tests at the following peak accelerations when
subjected to a sinusoidal acceleration for 30 seconds at each
frequency in the given range.
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
51
Peak acceleration I the horizontal axes and vertical axis: 3.5g from 1
Hz to 33 Hz.
1.10 Master Clock Time
Real time clock of the COIS Unit-1 will be used as the master clock
for synchronizing time of various computer systems of the plant.
The COIS will provide a potential free change over contact to each
of the computer based systems for time synchronization with 0.5
second status change at 10.00 hours every day (Normal status will
be resumed at 10:00:00 hours). The contact status change will be
sensed by each of the computer based systems and the time will be
set to 10:00:00 hrs.
1.11 Reliability and Availability
The meantime between failures (MTBF) of the system excluding the
printers, plotters and CRT’s will be 4000 hours or more with an
availability of 99.9% or better. MTBF and availability figures for the
printers/plotters and CRT’s will be 2000 hours and 99%
respectively. The meantime to detect a fault (MTTD) plus the mean
time to detect a fault (MTTD) plus the mean time to repair (MTTR)
will not exceed 1 hour. In order to achieve the high availability
figures, a master and hot standby computer redundancy is employed.
In case of a computer going faulty, its load will be automatically
switched over to the other computer. Displays/printouts active
before the failure of computer, become active automatically without
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
52
operator’s intervention after switching over pertaining to History
will not be lost due to such switchover. To keep the MTTD+MTTR
under one hour, ‘hot repairs’ concept is used.
SUBMITTED BY: - UMESH KUMAR MEHAR RAJASTHAN INSTITUTE OF ENGINEERING & TECHNOLOGY,CHITTORGARH
53
Recommended