Provisionally translated Feb 8,2013 Rev.1

Outline of the New Safety Standards for Light
Water Reactors for Electric Power Generation- Abstract
Ab ttF bFebruary
66, 2013※This Document is based on the consideration by NRA Study Team as of January 31, 2013

1. Pointed out to the safety regulations before Fukushima○Severe accident measures against external events have been left to the operator's
autonomy without careful review. (Investigation report: The National Diet of Japan)
g framework to impose
pretroactive application
ppto existingg nuclear○There was no legal
power plants.
(Investigation report: The National Diet of Japan)
p , the nuclear industry
y lacked the attitude to improve
pthe safetyy againstg○In Japan,uncertain risks by actively introducing knowledge from the international community.
(Investigation report: The National Diet of Japan)○Comprehensive risk assessments of earthquakes, tsunamis, and other external events
such as fire, volcanoes, and landslides which may cause accidents had not been
implementedimplemented.
(Investigation report: The Japanese Government)○Act on the Regulation of Nuclear Source Material, Nuclear Fuel Material and Reactors
and Electric Utility Industry Law are related to the nuclear safety regulations.
regulations
In order to avoid the adverse effect due to dispersion of the office under thejurisdiction or the application of the multiple laws, the law system should be unified.
(Investigation report : The National Diet of Japan)

2. Legal Reform for New Safety Standard(Issued June 2012)○Expand the Purpose
・Assumption of large scale natural disasters, terrorism, and war.
・The purpose is to protect peoples’ lives, health and property, the environment
and national security○ Safety Regulation for Severe Accidents
・Safety regulation for severe accidents by Law
・Comprehensive safety assessments by licensee to be reported to the government andp
disclosed to the public○ Reflection of the latest knowledge to existing NPPs
ywhich imposespretroactive application
pp・Introduction of so called “Back Fit System”
of the new standards to existing NPPs.
○ Unification of the nuclear safety
y regulations
g・Integration of the regulations imposed by the Electric Utility Industry Law to the Act
on the Regulation of Nuclear Source Material, Nuclear Fuel Material and Reactors.
・DeletingD l ti theth termstunrelatedl t d tot safetyf t fromftheth purpose andd licenselipermit
it criteria
it i off
the Act to express the stance for safety explicitly.

3. Process of Fukushima Accident & Countermeasure<Process of accident>
Earthquake
Reactor Shutdown
Loss-of-offsite-power
Prevent prolonged
Loss of Power

Start-up Emergency
DG and ECCS
TsunamiEnforce Instrumentation
and Communication

Assumption:5.7m
Actual:15.5m

Multiple failures and common cause failure

L
Lossoff DG/DC power supplyl<Countermeasures>
Enhance the Tolerability for
Earthquake & Tsunami

Prevent Severe Core Damage
Enhance DG and ECCS

Loss-of-cooling
Loss ofCommunication/
Instrumentation

Core Damage

Preventt CP
Containmentt it
Vessel Failure

Containment Vessel Failure
Hydrogen Explosions in RB
Large Scale Radioactive Release

Reduce Radioactive Release
Mitigate Diffusion

4. Consideration Step
Consideration bythe Study Team

Input from experts to NRA

Comparison with
Global Standard

Input from the Operators
E bli hEstablishment
off Draft
D f Outline
O liHearing from specialists(Only for DB & SA)

Public Comment

Drafting Provision
Public CommentE fEnforcementt (in(i July)J l )CurrentlyCrrentl
at this stage

5 Basic Policy of New Safety Standards
5.
① Exhaustive Defense in Depth Concept
 Prepare multiple layers effective for each intended function
 Secure independence of each layer to achieve intended function without
other layers; that is, no expectation for former layers nor latter layers(Denial of former layers / Denial of latter layers)② Enhancement of Reliability
 Enhance Fire Protection/Countermeasures against Internal Water Flooding Improve Design reliability of Systems Particularly Important to Safety(Avoid dual use of passive components with long time demand)③ Safety Countermeasure for Common Cause Failures by Natural Event Strict Review for Earthquake and Tsunami Evaluation
 Countermeasure for Tsunami inundation/immersion
 Respect for Diversity and Independence(Refrain from too much emphasis on redundancy)

6 Basic Policy of Countermeasures against SA & Terrorism
6.
① Preparepmultiple
p layersy((Countermeasures),), that is“Protection of Severe Core Damage,”“Protection of Containment Vessel Failure”“M“ManageddR
Releaselbby venting”
ti ”“Suppression of Radioactive Materials Diffusion”② IIn addition
dditi tto SA managementt bby portable
t bl equipment,it th
the same as iin
the US, install permanent equipment to improve reliability of SA
managementg((Continuous Improvement)p)③ Enhance Protection measures at Spent Fuel pools④ EEnhancehffunctionti off Emergency
EResponseRF
Facility,
ilit iimprove reliability
li bilitand durability of communication equipment, and enhance function andreliabilityy of instrumentation includingg Spentp
Fuel ppools⑤ Install Specified Safety Facility in preparation for intentional Aircraftattack7. Perspective of the New Safety Standards< Existing Safety Standards>< New Safety Standards>
Preventing Large Scale Radioactive Release

Intentional Airplane Crash
Preventing Containment Vessel Failure

Design Basis Standard
to prevent Severe Core Damage(Only assuming single failure etc.)

Preventing Severe Core Damage((Assumingssu
g multipleu p e malfunction)u c o )

Consideration for Fire

Consideration for Fire

Consideration for Reliability

Reliability of power source
Performance of cooling equipment

CountermeasuresagainstSevere Accident

Consideration for Natural Events

Consideration for Natural EventsConsideration for Reliability

NewEnhancement

y of ppower source
Reliability
Performance of cooling equipment
Performance of other equipment
q p

Performance of other equipment
Tolerability for Earthquake & Tsunami

Tolerability for Earthquake & Tsunami

Enhancement

8. Enhancement of Design Basis Standard
Review Design Basis Standard completely,“Design Basis Standard with No Severe Core Damage assumed”① Tornadoes and Bushfires included as Natural Events to be considered② Enhancement of Fire Protection③ Enhance Reliabilityy of Components
pp
particularly
y importantpto the safetyy(Redundancy of Components with long time demand)④ Enhancing external electricity supplies(Multiple Power line Systems from Separate Substations)⑤ Physical Protection of Heat Removal System(Protection of Seawater Pumps )9. Countermeasures against SA (Severe Core Damage)
Requirements
qfor Countermeasures againstgSevere Core
Damage assuming beyond the Design Basis Accidents.
① Countermeasures for Failure of Reactor Shutdown② Countermeasures for Loss of Cooling Reactor (at high pressure)③ Countermeasures
Ct
f LossforL
off Depressurization
Di ti④ Countermeasures for Loss of Cooling Reactor (at low pressure)⑤ Countermeasures for Loss of Ultimate Heat Sink ((LUHS))⑥ Securing Support Function (Make-up Water, Electricity Sources)

Examples of Countermeasure against Severe Core Damage○ Countermeasures for Loss ofdepressurization (PWR)○Securing Support Function(Common to both PWR and BWR)

Installation of a handle and proceduresfor opening the decompression valve
manually

Installation of alternate power source
equipment (Electric Vehicle, Batteries, etc.)
in case of SBO

A manually-manipulated handle
for the main steam relief valve

Locating Electric Vehicle on a hill

Inside the Vehicle

10. Countermeasures against SA (Containment Vessel Failure)
Requirements for Countermeasures against Containment
Vessel Failure assuming Severe Core Damage.
① Countermeasures for cooling, depressurization and radioactive material
mitigation (CV Spray)② Countermeasures for cooing and depressurization of CV((Filtered Ventingg system)y)③ Countermeasures for cooling melted core fallen to the bottom of CV④ Countermeasures against hydrogen explosions inside CV⑤ Countermeasures against hydrogen explosions at the reactor building, etc.
⑥ Countermeasures
Ct
ffor coolingli off spentt fuelf l storage
tpoolslExamples of Countermeasure against CV Failure (BWR)○ Cooling and depressurization of containment vessel
IInstallt ll FV forf theth exhausth t with
ith reduced
d d radioactive
di timaterials while reducing pressure and temperatureof CV○ Cooling melted core
DeployDl watert iinjection
j ti facilities
f iliti intoi t theth bottomb tt
off
CV for preventing CV failure after core meltdown

Reactor building

Reactor building

C t iContainmentt vessellC t iContainmentt vessell (CV)Pressurevessel

Pressurevessel

Exhaust stack

Permanent waterjfacility
y into theinjection
bottom of CV

Filteri

Suppression pool

Filtered Venting (FV) system

Portable water injection
facility into the bottom ofCV

Suppression pool11. Countermeasures against Intentional Airplane Crash
Specific Safety Facilities to manage Severe Core Damage caused byTerrorism Attack such as Intentional Airplane Crash Accident
Mountain Side
Filtered Containment
Vessel Venting
g SystemySecondary
Control Room
Reactor Building
PowerPSource

CV S
Spray
Pump
CV SprayWaterSource

Melted Core
Cooling Pump

Reactor
Water Injection

CVReactor

CV Lower
Water Injection

Sea Side

Physically Separatede g 100me.g.

※System Layout is one of the example and expressed simplistically12. Countermeasures against Large Scale Release
Requirements for Outdoor Water Spraying Facilities,Facilities
assuming Containment Vessel failure(suppress diffusion of radioactive materials by spraying into reactor building)High Capacity Foam Water Cannon

Source of the Pictures
Left
RightWater Spraying drill
with High Capacity Foam Water Cannon

13.Enhancement of Tolerability
y for Earthquake
q& Tsunami
Strict Review for Earthquake and Tsunami evaluation, especially Tsunami

Strict Criteria for Tsunami

Requirement for Tsunami protection facilities such asWatertight Door based on “Design Basis Tsunami”
exceeding past maximum Tsunami

Expand the scope forhigh seismic resistance

Tsunami Protection Facilities should be the highest“S Class” as same as Pressure Vessel＜Examples of Tsunami Countermeasures (Multiple Protection against Tsunami)＞ Tsunami Protection Wall
(preventing inundation at site) Watertight Door
(preventing immersion of buildings)
WatertightTideDoor Gate

Strict Judging Criteriaof Active Fault

Capable fault should be judged in the light of past
activity after Late Pleistocene (in last 120,000130,000 years ago) , if necessary expanded up toMiddle Pleistocene (400,000 years ago).

Precise Design Basis
Earthquake

Understand underground structure of thesite three-dimensionally

Judging Criteria for“shears or deformation”
added to vibration“S Class” should be built at the Ground without any
evidence of outcrop by active faults<Example of Underground Structure Investigation>
Figure out underground structure by analyzing the geophone data of generated quakes by earthquake simulation vehicle
Boring Hole

GenerateGt quakes
k att
multiple points by moving

Vibration

Vibration

E thEarthquakek SiSimulation
l ti
VehicleVibration

Geophone
Earthquake Simulation Vehicle