Actions Taken
by the Nuclear Regulation Authority- Five Years after the Fukushima Daiichi Nuclear Accident
and Lessons Learned -23 March, 2016Shunichi Tanaka

Chairman of Nuclear Regulation Authority

Lessons Learned from the Fukushima Daiichi Nuclear
Accident and New Regulatory Requirements

1

Establishment ofthe Nuclear Regulation Authority (NRA)• The Nuclear Regulation Authority was established in September
2012 in light of the lessons learned from Fukushima Daiichi
Accident as a new independent and transparent organization.

2

Lessons and Countermeasures againstthe Fukushima Daiichi Nuclear Accident
Earthquake
Automatic reactor
shutdown

Loss of off-site power
Prevent prolonged
loss of off-site
power

Emergency DGs started

TsunamiLoss of emergency DGs& DC power
Loss of core cooling system
Core damage

Securement ofplant control
functionsContainment failure
Leak to reactor building
Hydrogen explosion inreactor building* DG： Diesel Generator

Large release of radioactive
materials to environment

Reinforce measuresagainst earthquake &tsunami
Reinforce emergency
power supply & corecooling system
Prevent containment
failure (filter ventingsystem)
Suppress dispersion ofradioactive materials
3

Investigation and verification of Fukushima Daiichi Accident
and New Regulatory Requirements
The NRA obtained knowledge sufficient to establish new regulatory
requirements to prevent a nuclear accident similar to Fukushima Daiichi
Accident, judging from information identified in its investigation into theaccident to date.

Establishment and enforcement ofNew Regulatory Requirements (July 2013)
The NRA is willing to incorporate new findings into its
criteria for safety assessment.
4Outline of New Regulatory Requirements< New Regulatory Requirements >< Pre-existed Regulations >Regulations to prevent a severe
accident (design basis provisions)(Based on a single failure andconfirmed not to lead to damage)Countermeasures for intentional
aircraft crash
Suppression of radioactive
materials dispersal
Prevention of CV failure
Prevention of core damage(Assumptions of multiple failuresof SCCs)[Severe accidentmeasures] NEW

Internal Flooding [New]Natural phenomena(Volcano eruption, tornado,
forest fire) [New]Natural phenomenaFire protection

Reliability
power supply
Fire ofprotection

Reliability of power supply

Reliability of power supply[Counterterrorism]
NEW

Reinforced

Function of other SCCs

Function of other SCCs
Seismic/Tsunami resistance

Seismic/Tsunami resistance* SSC: Structures, Systems and Components

ReinforcedImportant Things in Considering Nuclear Safety
Current

Previous
Baseline

New

Previous
regulations

Regulatory

Requirements
Safetyof Nuclear
原子力発電所の安全性
Power
Plant

Licenseeenhances
continuouslysafety.

Without satisfaction in compliance with the safety regulations,
it is fundamental for licensees to continue the efforts to enhance thesafety, according to characteristics of each power plant.
6New Regulatory Requirements and Conformity Reviews• The NRA established the new regulatory
requirements in 10 months after its inauguration.
• 26 power reactors (16 nuclear power stations)and 20 fuel cycle facilities are under review. Twounits of the Sendai Nuclear Power Station wererestarted.
• Regarding application for extending theoperational period, 3 reactors of 2 nuclear powerstations are under review.
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Safety Regulation andNuclear Emergency Preparedness

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NRA’s view on Nuclear Emergency Preparedness• In nuclear facilities satisfied the New RegulatoryRequirements, the possibility of a severe accident seen in Fukushima Daiichi NPS - is extremely low.
• Apart from safety regulations, it is necessary toestablish Nuclear Emergency Preparedness measuresagainst unexpected nuclear events.

9

IAEA's “Defense in Depth” Concept
Level ofDefense

Objectives

Essential Measures

1

Prevention of abnormal operation and failures2

Control of anticipated abnormal plant
operation, and countermeasures to prevent
evolution towards an accident.

Quality improvement of siting, design,
maintenance and operation, after taking
into account natural phenomena

3Control of accidents within the design basis toprevent the progress to core damage.

Facilities and operating procedures for
accident situations

4

Prevention of the core damage and thecontainment failure for the beyond designbasis accident (severe accident)

Countermeasures and responses for asevere accident

5

Mitigation of the radiological consequences ofsignificant external releases of radioactive
materials

Installation of control/surveillancesystems and equipment

Radiation protection measures(evacuation of residents, etc.).
Development and improvement ofevacuation plans

NRA* Cabinet
Office* Regarding Level 5, NRA has a role to develop the Nuclear Emergency Response Guideline.
10Nuclear Emergency Response Guideline••••Setting up the extents of priority areas in the new Nuclear Emergency Response
Measures and establishment of criteria for assessment of emergency protective
measures for residents
Taking preventive/protective measures before discharging radioactive material
in response to conditions in the facilities
Taking further protective measures after discharge of radioactive material
according to emergency monitoring results
Staving off deterministic effects of radiation exposure and curbing the risks ofprobabilistic effects to the minimum[ Example ]Intensity-6-lower earthquake
in an area near nuclear
facilities

Alert

Preparation of evacuation ofpeople requiring special
help in PAZ

Station Blackout(Loss of all power supply)

Site Area Emergency

Evacuation of people requiring special
help, preparation of evacuation ofother residents in PAZ, andpreparation of sheltering in UPZ

Incapable water injection by emergency
core-cooling systems

General Emergency

Evacuation of residents in PAZ
Sheltering of residents in UPZ11Emergency Monitoring Information• In nuclear emergency, swift responses are necessary
based on secure information.
• Monitoring information should be integrated andassessed by the government and swiftly released to thepublic on the NRA web-site in a way easy-tounderstood.

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Reference information: Simulation results of SPEEDIat the time of the Fukushima Daiichi Nuclear Accident

13

Actions and Responses towards the Decommissioningof the Fukushima Daiichi Nuclear Power Station

14

Measures for Mid-term Risk Reduction at TEPCO’s
Fukushima Daiichi NPS (as of March 2016)15

Reduction of Concentration of Radioactive Materials byTreatment of Highly Contaminated Water

Sep. 2013

May 2015

Source TEPCO, Edited by NRA
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Completion of Removal of Highly Contaminated Water(approx. 10,000 tons)in Seaside Piping Trench

Unit 2 Turbine building
Unit 3 Turbine building

Unit 2 Trench
Unit 3 TrenchHighly contaminated water
has been accumulating
inside the trench.

Port

Source TEPCO, Edited by NRA
17

Prevention of Groundwater Flowing into the Port Area
(Completion of Construction of Seaside Impermeable Wall)

Source TEPCO, Edited by NRA
18

Expansion of Full-Face Mask Unnecessary Area

Full-Face Mask Unnecessary Area

Source TEPCO, Edited by NRA
19

Improvement on Working Environment withEstablishment of the Meal Service Center and the Large Rest House

Large Rest House

20

Challenges: Control of Contaminated Water

Continuous accumulation of storage tanks
for contaminated water

21

Reference information: Tritium Water
Total amount of tritium in contaminated water is 3.4 peta becquerels(at Mar.2014)
in the site of the Fukushima Daiichi Nuclear Power Station.

3.4 peta becquerels = 3,400,000,000,000,000 becquerels
57 milliliters of tritium water

Small glass

Tritium is one of isotopes of hydrogen. It exist in the form of water.
Ordinary water (H2O)

HHydrogen

Tritium water (THO)

HOxygenTH

OxygenTritium(tritiated hydrogen)* Tritium is generated by cosmic rays (protons and neutrons) on the earth. Its amount is about 72 peta
becquerels per year, according to an estimate.

22Challenges: Management of Solid Radioactive Waste
Accumulated radioactive waste(rubble) after the disaster

23

Challenges: Removal of Spent Fuel from Unit 1, 2 and 3
As in the case of Unit 3１２３

４Ｎ

Source TEPCO, Edited by NRA

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Radiation Monitoring in the areas where it is expected that the residents havedifficulties in returning for a long time25

Radiation Monitoring in the areas where it is expected that the residents havedifficulties in returning for a long time
Aircraft Monitoring

Walking Monitoring*Walking monitoring is limited to areas with low radiationand low-height.

The radiation doses have become low even in many areas in the areas where it isexpected that the residents have difficulties in returning for a long time.

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Radiation Monitoring in the areas where it is expected that the residents havedifficulties in returning for a long time• Future review and readjustment of radiation
monitoring
Enhancement of radiation monitoring in
the areas where it is expected that theresidents have difficulties in returning fora long time, etc.
Areas where it is expected thatthe residents have difficulties in
returning for a long time
(Yonomori in Tomioka Town)
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Thank you for your attention.

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