Regulatory Changes for Nuclear Power Plants in Japan Changes for Nuclear Power Plants in Japan ... NISA : Nuclear and ... Use of mobile equipment as a base and further enhancement

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  • Regulatory Changes for Nuclear Power Plants

    in Japan

    Tomoho Yamada Secretariat of Nuclear Regulatory Authority

    June 28, 2013 Technical Meeting on Technology Assessment of Embarking Countries

  • NRA

    Organization

    1

  • NRA Safety Fundamentals

    Principle 2: Role of government

    An effective legal and governmental framework for safety, including an independent regulatory body, must be established and sustained.

    The regulatory body must:

    Have adequate legal authority, technical and managerial competence, and human and financial resources to fulfil its responsibilities;

    Be effectively independent of the licensee and of any other body, so that it is free from any undue pressure from interested parties;

    JAPAN IRRS Report S1 Suggestion:

    NISA is effectively independent from ANRE, in correspondence with the GS-R-1. This situation could be reflected in the legislation more clearly in future.

    2

  • NRA Reform of Nuclear Regulatory Organizations (NRA was established in September 2012)

    Independence

    Clear separation of Regulation from Promotion

    An independent Commission

    Integration

    All nuclear regulatory functions integrated in NRA

    safety, security, safeguards

    radiation monitoring

    Radio Isotope

    3

  • NRA

    METI

    NISA

    Commercial

    facilities

    MEXT

    Research

    reactors,

    Radio Isotope

    Safeguards,

    Monitoring

    Integration and Independence

    AEC : Atomic Energy Commission

    METI : Ministry of Economy, Trade and Industry

    MEXT : Ministry of Education, Culture, Sports, Science and Technology

    MOE : Ministry of the Environment

    NISA : Nuclear and Industrial Safety Agency (abolished)

    NSC : Nuclear Safety Commission (abolished)

    NSC

    AEC

    Security

    double Check

    MOE

    NRA

    Safety,

    Security,

    Safeguards,

    etc.

    MOE AEC

    METI

    MEXT

    4

  • NRA NRAs Core Values and Principles

    (Mission Statement)

    5

    Independence

    Independent decision-making based on scientific and technological information, free from any outside pressure or bias

    Effectiveness

    Achieve genuinely effective regulations rather than formalities

    Openness and Transparency

    Open and transparent organization: avoid self-isolation, self-righteousness

    High Ethics

    High ethical standards, sense of mission, rightful pride;

    Swift and effective emergency response.

  • NRA

    Regulatory Requirements

    6

  • NRA

    Release of large amount of radioactive materials to environment

    Progression of Fukushima-Daiichi Accident and Countermeasures

    Core damage

    Hydrogen explosion in reactor building

    Loss of communication & instrumentation

    functions

    Enhancement of plant monitoring and

    control functions

    Emergency DGs / core cooling systems started

    Reactor shutdown

    Prevention of prolonged loss

    of off-site power

    Earthquake

    Tsunami

    Suppression of release and dispersion of

    radioactive materials

    Prevention of containment failure

    Prevention of core damage

    Enhancement of emergency power supply and core

    cooling

    Enhancement of robustness against

    earthquake and tsunami

    DG Diesel Generator

    Design basis height: 5.7m Inundation height: 15.5m

    7

  • NRA Basic Policy of New Regulatory Requirements

    1) Thorough Application of Defense-in-Depth Concept Prepare multiple effective measures (multi-layered protective

    measures) and, for each layer, achieve the objective only in that layer regardless of the measures in the other layers.

    Assume the preceding layer be breached (denial of preceding layer) .

    2) Elimination of Common Cause Failure Fire protection Reinforcement of SSCs important to safety (elimination of shared use

    of passive components, if relied on for a long time).

    3) More Stringent Assessment and Enhanced Protective Measures Against Extreme Natural Hazards More stringent approach for assessment of earthquake and tsunami,

    introduction of measures against tsunami inundation. Due consideration of diversity and independence (shift of emphasis

    from redundancy centered).

    4) Performance based Requirements

    8

  • NRA Structure of New Regulatory Requirements

    Prevention of Core Damage Multiple Failures

    Seismic/Tsunami Resistance

    Natural Phenomena

    Present

    Reliability of Power Supply

    Function of other SCCs

    Ultimate Heat Sink

    Fire

    Seismic/Tsunami Resistance

    Ultimate Heat Sink

    Fire

    Function of other SCCs

    Reliability

    Natural Phenomena

    Prevention of Containment Failure

    Suppression of release of Radioactive Materials

    Measures against Intentional Aircraft Crash

    Reliability Reliability of Power Supply

    New

    Rein

    force

    d

    Measu

    res b

    eyond D

    BA

    NEW

    Rein

    force

    d 9

  • NRA

    1) Comprehensive consideration of natural hazards such as volcano, tornado and forest fire in addition to earthquake and tsunami, etc.

    2) Reinforce fire protection measures

    3) Enhance reliability of SSCs important to safety (Redundancy of passive component such as piping, if relied on for a long time)

    4) Reinforce the reliability of off-site power supply (connect to different substations by multiple transmission lines)

    5) Protect systems for Ultimate Heat Sink (Protection of seawater pumps, etc.)

    6) Legally require measures against Severe Accident and Terrorism

    Strengthening the Requirements

    10

  • NRA

    Nuclear Power Station

    Sub Station A Sub Station B

    Sub Station C

    Nuclear Power Station

    Sub Station A Sub Station B

    Sub Station D Sub Station E

    11

    Reinforcement of Off-Site Power Supply (connection to different substations through multiple lines)

  • NRA

    seawater pumps

    wall

    12

    Protection of Systems for Ultimate Heat Sink

    (Protection of seawater pumps, etc.)

  • NRA

    1) Preparation of multi-layered protective measures for prevention of core damage,

    maintaining containment integrity, controlled release by venting, and

    suppression of release / dispersion of radioactive materials

    2) Use of mobile equipment as a base and further enhancement of reliability by

    combined use with permanently installed systems / equipment as Continuous

    improvement

    3) Enhancement of protective measures for Spent Fuel Pool

    (Water level measurement, Alternative water supply, Spray)

    4) Enhancement of command communication and instrumentation (Reinforced

    seismic-resistance of on-site emergency response center, improved reliability /

    durability of communication system, enhanced instrumentation including SFP )

    5) Introduction of Specialized Safety Facility against intentional aircraft crash

    Basic Policy of New Requirements

    Against Severe Accident and Terrorism

    13

  • NRA Requirements to Prevent Core Damage

    Accidents including the followings:

    1) ATWS

    2) Loss of reactor cooling function (at high pressure)

    3) Loss of reactor depressurization function

    4) Loss of reactor cooling function (at low pressure)

    5) Loss of UHS System

    6) Loss of support function (makeup water, power supply)

    7) Others identified by IPE and IPEEE

    Measures to Prevent Core Damage assuming situations more severe than Design Basis Accidents

    14

  • NRA

    Example: Alterative UHS System

    PWR Through main steam relief valves to the

    atmosphere Sea water injection to RHR-S

    BWR Filtered venting system Mobile RHR

    re

    acto

    r b

    uild

    ing

    sea

    pump RHR

    15

    Measures against Loss of UHS System

  • NRA

    Example: Batteries(8hours without load shedding + 16hours with load shedding) Alternative onsite AC power for 7 days External Support by the 6th day

    Batteries

    hours

    Onsite AC

    External Support

    8 24 144 168

    Alternative onsite AC power (Power Vehicle) 16

    Measures against Loss of Electric Power

    (Station Blackout)

  • NRA

    1) Cooling and depressurization of CV, reduction of release of radioactive materials (e.g., CV spray

    2) Heat removal from CV and depressurization of CV

    e.g., Filtered venting

    3) Cooling of molten core at the bottom of CV and inside RPV (e.g., water injection)

    4) Prevention of Direct Containment Heating (DHC) (e.g., depressurization of RPV)

    5) Prevention of hydrogen explosion inside CV (e.g., igniter)

    Requirements to Prevent Containment Failure

    Measures to Prevent Containment Failure after Core Damage

    17

  • NRA

    Filtered Venting system

    Alternative mobile equipment

    Stack

    Reactor building

    Containment

    RPV

    Permanently installed system

    Filter

    18

    1) CV spray to cool and depressurize CV, and reduce release of radioactive materials

    2) Filtered venting to reduce the pressure and temperature inside CV in addition to reducing radioactive materials while exhausting

    3) Water injection system into lower part of CV to prevent C