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