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Yutaka HARA
Nuclear Regulation Authority (NRA), Japan
NRA’s Regulatory Perspectives
on Decommissioning of TEPCO
Fukushima Daiichi Nuclear Power Station
September 18, 2017
Approach in NRA’s Regulation of Fukushima Daiichi
Topics -Contaminated water (Stagnant) -Slurry
-Sludge
-Processed water (Stored)-Debris removal
Conclusion
Contents
1
2
Approach in NRA’s Regulation of Fukushima Daiichi (1/2)
Reducing risks rapidly, with minimizing negative effects to the public and environment in the region and radiation exposure to employees
3
Approach in NRA’s Regulation of Fukushima Daiichi (2/2)
Risk oriented ( Prioritize and reduce risks: imminent risk, First)
→ “Mid-term Risk Reduction Map” by NRA (Latest: July 2017)
(http://www.nsr.go.jp/english/library/nraplans_01.html)[English]
Fact based (Obtain vital information inside R/Bs, PCVs, T/Bs etc. )
Safety, Timely (Do now whatever can be done)
Flexibility ( Be prepared for unexpected, maximize use of available
resources, information and knowledge)
4
Figures by TEPCO
Upper permeable layer
trenchSub-drain
Desalination and removal of cesium
Reactor building
Turbine building
Figures by TEPCO ,
edited by NRA
Contaminated water (Stagnant) (1/2)
Inventory:~✕1017 Bq
As of 2011
Regulatory Perspectives
Reduction of leakage risk of contaminated water
accumulated in R/Bs, T/Bs, etc.
Large amount of highly radioactive water is stagnated in R/Bs and T/Bs
5Trend of inventory of contaminated water in R/Bs and T/Bs
Source: TEPCO,Edited by NRA
The amount of contaminated water is decreasing under control:・Unit 1 T/B floor was dried out in August 2017・The work on T/Bs of Units 2&3 is in progress .
App. 5.3✕1013 Bqas of Dec. 2020
inve
nto
ry o
f co
nta
min
ated
wat
er
Inventory of contaminated water in the buildings including condensers and trenchesInventory of contaminated water in condensers
Present
App. 3✕1015 Bq(August 2017)
Inventory:~✕1015 Bq
6
4
2
0
✕1015(Bq)
Contaminated water (Stagnant) (2/2)
6
Slurry
Reducing risks of highly radioactive slurry from ALPS in HICs.
Regulatory Perspectives
Stabilization and immobilization of slurry in HICs need to be
started as soon as possible
Remaining IssuesFigures by TEPCO , edited by NRA
Coastline
Storage of HICs containing slurry
Contents in slurry(Inventory of 90Sr)
Storage amount
FeO(OH)・H2O(App. 1 ×1015Bq)
App. 1000m3
(366 HICs)
CaCO3, Mg(OH)2
(App. 2×1017Bq)App. 4,900m3
(1,888 HICs)
TEPCO has been planning stabilization(dehydration etc. ) and immobilizationof slurry
Inventory:~✕1017 Bq
(July 2017)
ALPS:Advanced Liquid Processing SystemHIC: High Integrity Container
Sludge
7
Preventing release of highly radioactive sludge from
AREVA system by earthquake / tsunami
Removing and transporting sludge generated from
AREVA system (in progress) → Then, stabilization
Sludge
Storage for sludge from AREVA system
Coastline
Schematic diagram of granulated and
solidified storage
3
Regulatory Perspectives
Figures by TEPCO , Edited by NRA
Remaining Issues
<Present>10m above sea level
<Future>Higher place on the site
Storage amount597m3
Basement
Inventory✕1016 Bq
Processed water (Stored) (1/2)
8©Google
9
Discharging the treated water containing tritium to the sea under
the conditions which comply with the regulatory requirements, etc.
ALPS treated water
Cs reduced water
Cs and Sr reduced water
Int. A
Int. B
Treated
Remaining Issues Source: TEPCO, Edited by NRA
TotalApp. 1,000,000m3
(August, 2017)
0.2%
19.5% TreatedWater
80.3%
App. 800,000m3
Inventory:~✕107~12 Bq
Processed water (Stored) (2/2)
・Treated water containing tritium has been increasing, however capacity of tanks is limited
・Harmful rumors could be a concern in the region
10
Debris removal
Regulatory Perspectives
Evaluation of structural integrities of RPVs and PCVs
Collecting more data and information inside RPVs, PCVs and R/Bs
Remaining Issues
Obtaining information on and inside RPVs, PCVs and R/Bs, as
a base of planning and safety evaluation of fuel debris retrieval
and for analysis of the accident.
・Location, physical/chemical forms and other properties of fuel debris・Integrities of buildings, piping, etc.・Dose distribution, etc.
・RPVs and PCVs were damaged (Unidentified leak paths, aging effects, etc. )
Leaking path at Unit 1( November 2013)
Leaking path from a drain pipe
Source: TEPCO ,
Edited by NRA
Rapid fuel debris removal in a safe manner is important Fact findings/Analysis of Fukushima Daiichi accident is also important
Conclusion
TEPCO Fukushima Daiichi site has shifted from
“Emergency Response Stage” to “Planned Action
Stage”.
Some measures, however, are delayed, and still
so many tasks are to be accomplished regarding
contaminated water, radioactive waste and so on.
Field surveys inside RPVs, PCVs and R/Bs are
vitally important for TEPCO and NRA to obtain
information for planning and safety evaluation of fuel
debris retrieval and for analysis of the accident.
11
12
Thank you for your attention
13
Appendix
Nuclear Emergency Response HeadquartersChair: Prime MinisterVice-Chair: Cabinet Secretariat, Minister of Economy, Trade and Industry, Minister of the Environment, Chairman of NRAMember: Ministers
NRATeam for Decommissioning and Contaminated Water
CountermeasuresHead: Minister of Economy,
Trade and Industry
TEPCO
Technical Advice
・Risk identification・Progress management・Financial support
Regulation
Governmental framework for decommissioning of Fukushima Daiichi NPS
115
Participation
In order to communicate existing mid-term risks at TEPCO
Fukushima Daiichi NPS to the public, the NRA published “Mid-
term Risk Reduction Map” in February 2015 (Latest updated
in July 12, 2017)
Mid-term Risk Reduction Map
15
Website of “Mid-term Risk Reduction Map” (English)
To address risk concerns plainly by presenting key priorities for safety identified by the NRA among the various measures taken by TEPCO for decommissioning.
To clearly distinguish completed measures from ongoing and planned ones.
Scientifically providing the greater earthquake/tsunami model (900 gal, 26.3m),and establishing the basic protection plan that corresponds to this model (Dec. 2015)
Measures for Mid-term Risk Reduction at TEPCO’s Fukushima Daiichi NPS (as of July 2017)
Avoiding leakage of contaminated water from tanks etc.
Preventing scattering and leakage of radioactive waste during decommissioning processes
Removing fuel from Spent Fuel Pools (SFPs)
Managing off-site effective dose during decommissioning processes
Site and environmental protection from Earthquake / Tsunami
Enabling a sustainable work environment for decommissioning
Understanding the internal situation of the damaged facilities
Completing construction of Unit 3 R/B cover and completing fuel removal facility
Completing fuel removal operation at Unit 3 SFP
Completing fuel removal operation at Unit 4 SFP (Dec. 2014)
Managing the additional effective dose to 2mSv/year* or less by continuous radiation monitoring and by treating high-radioactive contaminated water etc. (Mar. 2015)
Building the food-service center (Mar. 2015)
Starting operation of incineration plants for miscellaneous radioactive waste e.g. protective clothing (Mar. 2016)
Treating high-radioactive contaminated water in tanks (May. 2015)
Removing high-radioactive contaminated water from the sea-side pipe trenches (Units 2-4) (June. 2015; Unit 2, July. 2015; Unit 3, Dec. 2015; Unit4))
Preventing the outflow of contaminated groundwater into the sea by completing the sea-side underground impermeable wall including sub-drain control systems (Oct. 2015)
Completing removal of tanks lacking concrete foundations and/or dikes (Dec. 2014;H1 Area)
Building the large resting facility(May. 2015)
Managing the additional effective dose to 1mSv/year* or less (Mar. 2016)
Starting operation of incineration plants for felled trees, flammables in rubble, etc.
Managing the increase of the total capacity of water in tanks by restraining the inflow of groundwater into Reactor Buildings(R/Bs) and Turbine Buildings(T/Bs)
Reducing the volume of contaminated water in tanks by discharging the water after necessary treatment to the sea in accordance with the regulatory requirements, etc.
Transferring3 to the stable management of secondary waste from treatment of contaminated water e.g. sledges in the High Integrity Container(HIC)s, etc.
Implementing the site protection measures for Mega-Float (Tanker) following the established plan
Managing a work environment not requiring full-face mask respirators excluding the vicinity of R/Bsetc. (May. 2015)
Directly observing inside of Primary Containment Vessels(PCVs) and Reactor Pressure Vessels(RPVs)
Characterizing nuclides in water passing through the reactors
Completing construction of Unit 1 R/B cover and completing fuel removal facility
Contaminated water Radioactive wasteEffective dose at
the site boundary(estimated value)
Earthquake / TsunamiWork
environment
Examining the inside of the
facilities
Analyzing the contaminated water of the inside of R/Bs, etc.
Preventing the outflow of contaminated water in R/Bs and T/Bs.Accurately controlling the levels of groundwater and contaminated water in R/Bs and T/Bs (Oct. 2015)
Examining the process of accumulation of contaminated water in R/Bs, etc.
12 July, 2017
Spent fuel
Preventing the outflow of contaminated water anticipating the recurrence of the 2011 Tsunami (max 15.5m)
Blocking the openings(Sep.2013; Common Pool, Oct.2014; Unit 1 T/B, Unit 2 T/B, HTI)
[Note]Completed measures:
Measures in progress or in preparation:Measures (Timing TBD):
Issue
Objective
*Estimated value
Preventing scattering of dusts
Preventing scattering of radioactive dusts during decommissioning processes
Removing high-radioactive contaminated water from bolt-joint tanks (May.2015)
Construction of temporary seawall (June 2011)
Starting operation of the 9th storage facility for radioactive waste
Starting operation of Radioactive Material Analysis and Research Facility-1
Starting operation of volume reduction plants (metal, concrete)
Stopping of outside storage (used protective clothing)
Starting operation of large storage plants
Completing construction of Unit 2 R/B cover and completing fuel removal facility
Implementing the countermeasures against scattering of dusts, in light of the scattering incident from Unit 3 (optimization of dispersion of scattering prevention chemicals and installing more dust monitors ) (2013)
Implementing and monitoring of enhanced countermeasures against scattering of dusts
Completing rubble removal operation at Unit 3 SFP(Dec.2016)
Implementing and monitoring of enhanced countermeasures against scattering of dusts
Dismantling of the covering of Unit 2
Completing rubble removal operation at Unit 1 operating rooms and SFP
Completing treatment of contaminated water in R/Bs and T/Bs.
(Provisional Translation)
Starting operation of temporary storage facilities for contaminated soil
Removing (treated) contaminated water from bolt-joint tanks
*Estimated valueCompleting on-site decontamination excluding the vicinity of R/Bs etc. (Sep. 2016)
Treating contaminated water in R/Bs and T/Bs .To reduce the amount of radioactive material to less than half.
2015
2016
2017
2020
(year)
2018
Preventing the outflow of contaminated water anticipating the recurrence of the 2011 Tsunami (max 15.5m)
Blocking the openings (Unit 3 T/B, Process main building ( planned))
Dismantling of the upper part of stack for Units 1 and 2
Stabilizing sludge generated from decontamination device
17
(As of November 2013)
Seaside pipe trench(Unit2)
Seaside pipe trench(Unit3)
T/B (Unit3)
T/B (Unit2)
Highly contaminated stagnant water
Accomplished removal of highly radioactive contaminated water from the seaside pipe trenches (Units 2&3) (July. 2015)
Source: TEPCO, Edited by NRAConcentration(Cs134+Cs137)
Unit 2 ~109 Bq/L
Unit 3 ~108Bq/L
Removal of stagnant water in trenches
Pumping up groundwater from Sub-drain pits
18
Figures by TEPCO
3
Source: TEPCO,Edited by the NRA
Water level difference
⑨Sea-side impermeable wall⑤Land-side impermeable all
Sea Level
Groundwater drain
Well point
Water pumping
⑧Ground improvement by sodium silicate
②trench
④Sub-drain
Desalination through removal of cesium
Reactor building
⑤Land-side impermeable all
Water pumping④Sub-drain
Water pumpin
g
Turbine building
⑥Paved with asphalt ③Groundwater bypass
Groundwater level
Rain
Upper permeable layer
Low-Permeable layer
Pumping well
②Expansion of tank ①Treat by ALPS
Water pumping
Source: TEPCO, Edited by the NRA
( Pumping up app. 500m /day[July])Pumping up groundwater
from Sub-drain pits is the most essential measure
→ The inflow of groundwater to R/Bs and T/Bs has been under control
The water level inside the building shall be lower than the ambient water
Remaining Issues
Figures by TEPCO , edited by the NRA
*
Spent fuel
19
Removing risk of spent fuel pools
Removing spent fuel from Unit 3 steadily (in progress)
Removal method of spent fuel from Unit 2 and Unit 1 (under discussion)
Step of installing Unit 3 fuel removal cover etc.
Storage status of spent fuel pool
Regulatory Perspectives
Present phase
Removal of spent fuel from Unit 4 was completed in 2014
*
Effective dose at site boundary
20
Managing off-site effective dose during decommissioning processes
Trend of the site boundary effective dose(The values exclude the background inside and outside of the site)
Figures by TEPCO
Regulatory Perspectives
Dose due to solid waste etc.
Dose due to sprinkling water
Dose due to liquid waste
Dose due to gas waste
Keeping low level and stable after March 2015
Figures by TEPCO ,
edited by the NRA