Current status of NPP I&C in the United Kingdom

Current status of NPP I&C in the United Kingdom T P SmythAMEC, Knutsford, Cheshire, UK22nd Meeting of the Technical Working Group on Nuclear Power Plant Instrumentation and Control, 20-22 May 2009, Vienna

TWG-NPPIC, May 2009, Vienna: UK status

Current status of NPP I&C in the United Kingdom

Nuclear Power Plants in the UK Status of I&C at nuclear plantsReactor Protection SystemsData Processing SystemsRefuelling machines Status of regulatory environment affecting I&C Recommendations


Nuclear Power Plants in the UK (1)


Nuclear Power Plants in the UK (2)Electricity sources19% nuclear36% gas38% coalNeed to plan for energy replacement7 plants will close in next 9 years14 reactors7359 MWe13% of electricity sourcesNorth Sea oil and gas will be limited in futureNew buildGeneric Design Assessment (AP1000, EPR)Target completion of GDAs June 2011Sites identifiedhttp://www.hse.gov.uk/newreactors/


AGR : Reactor Protection Systems (1)Neoprene insulation degradationMagnox Oldbury power stationDegradation with agePerishingSweatingHygroscopicBecomes conductive - resistance < 1 MStray currents in sensitive circuitsThermocouple amplifiers


AGR : Reactor Protection Systems (2)Neoprene insulation degradation


AGR : Reactor Protection Systems (3)Neoprene insulation degradation


AGR : Reactor Protection Systems (4)Neoprene insulation degradationSurvey of all safety equipmentPresence of neopreneState of neopreneCircuit functionReplacement equipment at older stationsObsolescent anywayRepairs at newer stationsHeysham 2 / Torness6 years work, 1 more year to finalise all equipmentPrioritised by susceptibility


AGR : Reactor Protection Systems (5)Neutron Flux measurement systemsAGR detectors located in core at 8 locationsHigh temperaturesDetector sparesWide range detector integral cableManufacturing spares re-establishing production processesCurrently a batch of 10 in progressElectronic unitsNeopreneRepairs at Heysham 2 / TornessReplacement at other stations


AGR : Data Processing SystemsSafety claims on equipmentSome reactor control functionsSome alarmsHinkley Point BNew DPS installed (1999)Dungeness BNew DPS being installedControl / equipment protection functions segregated Ready for works testingOther AGR'sStabilization of equipment Adequate spares provision / hardware support.Improved air conditioningHeysham 2: specification phase


AGR : Refuelling MachinesOnline refuellingStringent safety requirementsEquipment obsolescenceKey focus at presentHeysham 2 / TornessReplacement of Reypac controllers with Siemens S7I/O replaced, emulates original equipmentReypac controller replacementSoftware reverse engineered and portedSafety functions partitionedSuccessful implementation, scope of replacement expanded.Safety standardsModern standards considered when replacing equipment


Regulatory Environment (1)Standards hierarchyNII SAPs and TAGs (http://www.hse.gov.uk/nuclear)IAEA standardsIEC standardsIEC 61226Modern standards reviewsDesign, Operation and MaintenancePart of Periodic Safety ReviewsPSA based assessmentTarget 10-7 / yearLimit of reliability claims for software based systemsAssume 1 demand / year10-4/demandRequire diverse protection to make up 10-3/demand


Regulatory Environment (2)Application to Sizewell BPrimary Protection SystemFour channels, 2 out of 4 trippingSoftware basedProduction excellenceIEC 60880Independent confidence buildingExtensive testingIndependent code safety assessmentSecondary Protection SystemFour channels, 2 out of 4 trippingProtection for frequent faultsLaddic magnetic amplifiersDiverse technology


Regulatory Environment (3)New buildIn general, same regulatory requirements as Sizewell BDiversity requirements in reactor protection systemsPossibly less onerous protection system targetsPassively safe systems will make fewer demandsSmart InstrumentsRegulator considering application to nuclear facilitiesAssessment of evidencePlant owner collaborationShared qualification and licensing assessmentsSIL1No fieldbus


RecommendationsIAEA topicsEstimating and extending life of I&C equipment to address ageing and obsolescenceSupporting the evaluation, acceptance and licensing of digital I&C systemLessons learned from I&C project implementation and guidance for modernisation and new plant project


Documents

Current status of NPP I&C in the United Kingdom