Toward the New Nuclear Regulation
New Nuclear Regulatory Organisation
Discussion on basic direction of safety regulation
on severe accidents

Hiroshi YAMAGATA
Director for Safety Standard
Nuclear and Industrial Safety Agency (NISA)
Japanese Government
Side Event by Government of Japan
at 56th IAEA General Conference, Sep 17, 2012

New Nuclear Regulatory Organization
Independence: Separate nuclear regulation function and nuclear promotion function and establish the “Nuclear Regulation
Authority (NRA)”, as an independent commission body affiliated to the MOE. Chairman and Commissioners are appointed by
the Prime Minister after the approval of the National Diet.
Integration: Integrate nuclear regulation functions, namely, nuclear safety, security, safeguards, radiation monitoring andradioisotopes regulation, into the NRA.
Crisis Management: Establish “Nuclear Emergency Preparedness Commission (NEPC)” in a cabinet and implement nuclear
emergency prevention measures in close cooperation with relevant organisations.

Current Organisations

New Organisation
Ministry of the Environment (MOE)

CabinetOfficeAtomic Energy
Commission(AEC)- Nuclear Security
PolicyNuclear Safety
Commission(NSC)

Ministry ofEconomy, Tradeand Industry(METI)

Ministry ofEducation,Culture, Sports,Science andTechnology(MEXT)

Agency for Natural
Resources andEnergy (ANRE)
Nuclear andIndustrial Safety
Agency (NISA)- Nuclear Power Plants
Regulation, etc.

-Nuclear Regulation Authority(NRA)
Commission: Chairman and4 Commissioners

Research Reactors
Regulation
Safeguards *Radiation Monitoring *Radioisotopes Regulation,etc. *Secretariat

Merged into the NRA afternecessary legal arrangements

Double Checking

JNES

JAEA
Nuclear Research, etc. *Independent Administrative Agencies- JNES: Japan Nuclear Energy Safety Organisation- JAEA: Japan Atomic Energy Agency- NIRS: National Institute of Radiological Sciences

NIRS
Radiation Research, etc. *JAEA

JNES

Nuclear Research, etc.

NIRS
Radiation Research, etc.

* Transferred by 1st April 20131The New Commission
Prime Minister Noda decided he would appoint chairman and four commissioners on
September 19th.
They will assume their duties on the same day.

Tanaka Shunichi

Chairman-to-beCommissioners-to-be

Oshima Kenzo

Shimazaki KunihikoNakamura Kayoko

Fuketa Toyoshi

New Nuclear Safety Regulation
Amendment to the Nuclear Regulation Act(1) New regulation against severe accidents•

Legally request severe accident measures to the licensees.

(2) Regulation system based on the latest scientific / technical knowledge•

Apply new technical standards to existing licensed nuclear facilities as a legal obligation(back-fitting).

(3) 40-years operational limit for NPPs•

Legally set the limit for NPP’s operation to 40 years. However the NRA can give
permission to extend operational limit (not longer than 20 years) only once.

(4) Special safety regulation for disaster-experienced NPPs
• e.g. Fukushima Dai-ich NPPAmendment to the Nuclear Emergency Act(1) Provision of the guidance for nuclear emergency preparedness(2) Strengthening nuclear operator disaster prevention drills(3) Reinforcing the Nuclear Emergency Response Headquarters(4) Facilitation of post-accident countermeasures(5) Clarification of mandate of the Prime Minister at nuclear emergency

2

Discussion onbasic direction of safety regulation on
severe accidents in nuclear power plants
byNuclear and Industrial Safety Agency (NISA)

Note: The report summarising the discussion on basic direction of safety regulation on severe accidents
in nuclear power plants by NISA was reported to the Nuclear Safety Commission on August 27,
2012. NISA will carry it on into the new Nuclear Regulatory Authority and hope it could contribute
their discussion.

Lessons Learned from the Fukushima Daiichi NPS Accident
Against conditions and accidents beyond design basis<Accident sequence><Direction of countermeasures>

Earthquake
Shut down

Loss of ExternalPower Supply
Start-up Emergency D/Gand Core cooling system

Prevention of long-term Lossof External Power Supply

Loss ofCommunication,
I&C system
Enhancement of Plant
Controlling & Monitoring
function

TsunamiConsidered: 5.7m
Actual:15.5m
Common Cause Failure

Design Basis revisedby the latest science
Robustness against external
events beyond design basis

Loss of Emergency D/G& DC Battery

Prevention of Core Damage
Loss of Core
Cooling System

Enhancement of Emergency Power
Supply & Core Cooling System

Core Damage
CV Damage
Leakage to building
Hydrogen Explosion

Prevention of damage ofContainment Vessel

Mitigation of release ofRadioactive Material

Large release ofRadioactive Material
to the Environment3

Proposed schematic of new regulation on severe accidents
Objectives ofeach layer of safety(4)

Plant status considered in
the present regulation

Loss of safetyfunctions ofequipments fordesign basis(Multiple failure)

Design basis
accident(single failure)Occurrence offailures /abnormal events

Normaloperation

Measures fordisaster prevention(4-2) Mitigation of
release / diffusion

Measures for mitigationof radioactivity release

ＣＦＦ Prevention of- Large release(4-1) - CV damage

Measures for prevention of CV damage
Mobile RHR, etc.
(SA measure II)
Specific safety facilities

ＬＲＦ

(3-2)

(3) ＣＤＦ(3-1)(2)

Water cannon truck, etc.

(tentative)

Alternative CV spray etc.

Measures for prevention ofcore damage (SA measure I)

Power supply car, etc.

＋Specific safety facilities(tentative)

Tie line to DG of another NPP, etc.

ECCS, etc.

Prevention ofprogress toward
accidents

Detection of abnormal events,
Equipments for shutdown, etc.

Design basis

Large release,
CV damageCore damage

Prevention of humandamage,
Recovery of environment(5)

Prevention ofcore damage

Large release /diffusion

Safety measures

Voluntary efforts by licensee

Plant status

Prevention of(1) failures / abnormalInterlock, etc.

eventsCoverge of present regulation

MarginHazard
level ofexternalevents

External events (natural phenomena,
aircraft crash, terrorism, etc.)

Internal events

Proposed basic direction of measures for external events
Natural phenomena

Aircraft crash
Frequency of accidents（＞10－７）*（≦10－７）*

Hazard level

All equipmentswith safety function

Withstand(external events)

Terrorism
Intentional
Detection

Early detection

Detection

Shutdown・power down

Security order

Delay

Protection,
Isolation

Management

Maintenance of safetyfunction (1)Margin(Notconsidered)(2)

Durability (actual)
Specific safety
facilities

Isolation,
Mitigation(from external events)

Safety function

Recovery,
Mobile(Commonality)(3)•Seismic isolation,•Spatial separation,•Watertight structure,•Diversification (Watercooled + Air cooled)•Robustness•Spatial separation(4)•Recovery•Mobile equipments(* unit: reactor･year)

4

Proposed schematic of examination of measures for severe accidents
Regulatory
requirement

Requirement for
specific safety
facilities against
external events

Representative
reactorAccident sequences which may lead to coredamage against initiating events assumed

Categorized accident sequence groups (CASGs)
A,B,C

PSA results on object plant

DChecking sufficiencyof the sequences

Confirming CASGs(A,B,C,D)

Construction
permitConfirming specific safety
facilities based on PSA
results etc. of the object
plant

Specific
Safetyfacilities

Determination of the important accident
sequences in each CASGs
Determination of convergence scenario
against the important accident sequences

Structural measures(specification, performance)

SpecificSafety
facilities

Non-structural measures(order, procedure)

Safety assessment on validity of convergence scenario,structural and non-structural measures
Approval on;•Construction plan,•Safety provision

Detailed design of structural
measuresCriteria forjudgment

Detail of non-structural
measures

Evaluation forimprovement of safety

Evaluation for improvement of safety

Improvement of safety

Responsibility of licensee’s commitment

CompareSafety
performance
objectives

Thank you5