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Fukushima Response. George Attarian 1/21/2013. Fukushima Response. Timeline: March 11: Event occurred March 18: INPO IER 11-1 issued (April 15) March 23: NRC TI 2515/183 issued (May 13) April 25: INPO IER 11-2 issued (September 20) April 19: NRC TI 2515/184 issued (June 30)

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Fukushima response

Fukushima Response

George Attarian


Fukushima response1
Fukushima Response

  • Timeline:

    • March 11: Event occurred

    • March 18: INPO IER 11-1 issued (April 15)

    • March 23: NRC TI 2515/183 issued (May 13)

    • April 25: INPO IER 11-2 issued (September 20)

    • April 19: NRC TI 2515/184 issued (June 30)

    • May 11: NRC Bulletin 2011-01 issued (July 11)

    • June 8: NEI The Way Forward issued

    • July 12: NRC NTTF issued

    • August 1: INPO IER 11-4 issued (January 28)

    • August 1: INPO Equipment Survey issued (November 4)

Fukushima response2
Fukushima Response

  • Timeline

    • September 1: INPO IER 11-1 Supplement issued (March)

    • September 9: NRC SECY-11-0124 issued, SRM issued October 18

    • October 3: NRC SECY-11-0137 issued, SRM issued November 8

    • December 14: NRC holds first public, issue specific meetings on SECY-11-0137

    • January 18-19:NRC holds second public issue specific meetings and presents draft 50.54(f) letter with enclosures

    • March 9: 50.54(f) letter and enclosures and Orders issued to the Licensee for Tier I NTTF’s

Fukushima response3
Fukushima Response

  • NRC Near Term Task Force (NTTF) Recommendations (12)

    • Clarifying The Regulatory Framework (1)

    • Ensuring Protection (2)

    • Enhancing Mitigation (5)

    • Strengthening Emergency Preparedness (3)

    • Improving the Efficiency of NRC Programs (1)

Fukushima response4
Fukushima Response

  • NTTF Impact

    • NTTF 2.1 Flood and Seismic

      • 50.54(f) letter to licensee

      • New flood analysis beyond design basis

      • Seismic currently following GI 199

    • NTTF 2.3 Walkdowns

      • 50.54(f) letter to licensee

      • Walk down the site for all external design basis events: flood; seismic, other external events

    • NTTF 4.1 SBO

      • Rule making

Fukushima response5
Fukushima Response

  • NTTF Impact

    • NTTF 4.2

      • By order

      • Additional pumps and related equipment

      • FLEX approach

    • NTTF 5.1 Harden Vents

      • By order

      • BWR Mark I & II only

      • Filtration system not in order

    • NTTF 7.1 Spent Fuel Pool Instrumentation

      • By order

      • Level only

      • Primary and backup

      • Control Room or Alternate Shutdown monitoring

      • Qualifications

Fukushima response6
Fukushima Response

  • NTTF Impact

    • NTTF 8 EDMG EOP SAMG integration

      • Rule making

    • NTTF 9.3 Emergency Preparedness Staffing

      • 50.54(f) letter to licensee

      • Extension of the EP Rule

      • Staffing impact to multiple Unit plant sites

      • Communication guidance

Station blackout definition
Station Blackout Definition

  • 10CFR50.2 Definition

  • The complete loss of alternating current (ac) electric power to the essential and nonessential switchgear buses in a nuclear power plant.

  • Station blackout does not include the loss of available buses fed by station batteries through inverters or by alternate ac sources as defined, nor does it assume a concurrent single failure or design basis accident.

Alternate ac sources
Alternate AC Sources

  • An alternating current (ac) power source that is available to and located at or nearby a nuclear power plant and meets the following requirements:

    • Is connectable to but not normally connected to the offsite or onsite emergency ac power systems;

    • Has minimum potential for common mode failure with offsite power or the onsite emergency ac power sources;

    • Is available in a timely manner after the onset of station blackout; and

    • Has sufficient capacity and reliability for operation of all systems required for coping with station blackout and for the time required to bring and maintain the plant in safe shutdown (non-design basis accident)

Current nrc rule
Current NRC Rule

  • 10CFR 50.63 Loss of all alternating current power

  • (a) Requirements. (1) Each light-water-cooled nuclear power plant licensed to operate must be able to withstand for a specified duration and recover from a station blackout as defined in § 50.2. The specified station blackout duration shall be based on the following factors:

  • (i) The redundancy of the onsite emergency ac power sources;

  • (ii) The reliability of the onsite emergency ac power sources;

  • (iii) The expected frequency of loss of offsite power; and

  • (iv) The probable time needed to restore offsite power.

Current nrc rule cont d
Current NRC Rule (cont’d)

  • (2) The reactor core and associated coolant, control, and protection systems, including station batteries and any other necessary support systems, must provide sufficient capacity and capability to ensure that the core is cooled and appropriate containment integrity is maintained in the event of a station blackout for the specified duration.

  • The capability for coping with a station blackout of specified duration shall be determined by an appropriate coping analysis. Licensees are expected to have the baseline assumptions, analyses, and related information used in their coping evaluations available for NRC review.

Regulatory guide 1 155
Regulatory Guide 1.155

  • Reg. Guide 1.155, Station Blackout

  • Specifies a method acceptable to the NRC staff for complying with 10CFR50.63

  • Twenty four pages of detailed guidance

  • EDG Target Reliability Levels

  • Restoration of Offsite Power

  • Ability to Cope with a Station Blackout

  • Quality Assurance Guidance for Non-Safety Systems and Equipment

Numarc 87 00
NUMARC 87-00

  • Guidelines and Methodologies for Implementing the Nuclear Management an Resources Council (NUMARC) Station Blackout Initiatives

  • Three Hundred Pages of Detailed Guidance, Examples, Topical Reports, and Questions & Answers

  • Endorsed by Reg. Guide 1.155 as Acceptable Guidance for Compliance to 10CFR50.63

  • Contains Detail Beyond Reg. Guide 1.155

Typical results
Typical Results

  • Plant Specific SBO Coping Analyses Produced

  • Specifies How Long You Have to Cope Without AC Power

    • Typically 4 or 8 hours

  • Specifies How Coping is Achieved

    • Batteries, alternate ac power, RCS leak rates, water sources, pumps, instrumentation & control, etc.

  • Requires Containment Isolation

  • Typically Addresses Pre- Hurricane Preparations for Coastal Plants

  • Excludes Concurrent Design Basis Events

  • Assumes Restoration of at Least One Source of Offsite or Onsite AC Power is Successful Before the Coping Period Ends

Typical limitations beyond sbo coping
Typical Limitations Beyond SBO Coping

  • Battery Depletion

  • Water Sources Run Out – CST Inventory

  • RCS Inventory Losses - PWR RCP Seal Leakage

  • BWR Suppression Pool Heat-up & Saturation

  • Emergency Lighting Battery Packs Deplete

  • Increasing Manual Actions for Available Personnel as SBO Time Increases

Beyond sbo coping strategies
Beyond SBO Coping Strategies

  • Medium Size Generators to Re-Energize Battery Chargers

  • Emergency Engine Driven Pumps to Replenish Water Sources – CST Make-up

  • Medium Size Generators and Pumps to Restore RCP Seal Injection

  • RCP Shutdown Seal Package Designs to Limit Leakage

  • BWR Hardened Wetwell Venting Systems and Suppression Pool Make-up with Cool Water

  • Helmet Mounted LED Lights for Personnel or Longer Lasting LED Emergency Lights

  • Pre-Plan and Pre-Stage More Emergency Equipment to Make Manual Actions Easier and Train More Personnel to Use it

What is flex
What is FLEX?

  • Response to NRC Mitigating Strategies Order (EA 12-049)

  • Provides a diverse and flexible means to prevent fuel damage while maintaining containment function in beyond design basis external event conditions resulting in an:

    • Extended Loss of AC Power, and

    • Loss of Normal Access to the Ultimate Heat Sink

  • Objective:

    • Establish an essentially indefinite coping capability by relying upon installed equipment, onsite portable equipment, and pre-staged offsite resources

Diverse flexible coping capability flex
Diverse & Flexible Coping Capability (FLEX)








Diverse & Flexible




Increased Defense-in-Depth

SBO Coping


SBO Coping


Prevention of

Fuel Damage

Design Basis

External Events

Design Basis

External Events

Protection of

Plant Equipment


Current plus FLEX

Flex mitigation strategies
FLEX Mitigation Strategies

  • FLEX employs a three phase approach:

    Phase 1 - Initially cope by relying on installed plant equipment,

    Phase 2 - Transition from installed plant equipment to onsite FLEX equipment,

    Phase 3 - Obtain additional capability and redundancy from offsite equipment until power, water, and coolant injection systems are restored or commissioned.

  • Diverse and flexible to enable deployment of the strategies for a range of initiating events and plant conditions

Representative high level example bwr
Representative High-level Example (BWR)

  • Phase 1Initial Coping Capability

    • Use RCIC for RPV makeup from suppression pool

    • Rely on DC Power for key instrumentation and controls

  • Phase 2/3 Extended Coping Capability

    • Charge battery to maintain DC power

    • Use Reliable Hardened Vent for containment heat removal

    • Provide extended RPV makeup with portable pump

Representative high level example pwr
Representative High-level Example (PWR)

  • Phase 1Initial Coping Capability

    • Turbine-driven AFW for SG makeup from Condensate Storage Tank

    • Rely on DC Power for key instrumentation and controls

  • Phase 2/3 Extended Coping Capability

    • Charge battery to maintain DC power

    • Provide extended SG makeup with portable pump

    • Provide RCS makeup with portable pump, as needed

Nrc advance notice of rule making
NRC Advance Notice of Rule Making

  • Rule Making Objectives

    • What specific objectives should the SBO rule be designed to achieve?

    • How should actions taken in the NTTF 4.2 be used?

    • What regulatory approach to SBO mitigation that follows the conceptual approach outlined in NTTF 4.1?

    • How can regulatory action in NTTF 8.0 be best integrated with SBO?

    • How can regulatory action in NTTF 5.1 be best integrated with SBO?

    • How can regulatory action in NTTF 7.1 be best integrated with SBO?

Nrc advance notice of rule making1
NRC Advance Notice of Rule Making

  • Relationship between 10CFR 50.63 and the new SBO rule

    • Keep existing rule and supplement with scenarios that go beyond the existing rule.

    • Integrate existing rule with new requirements into a new rule for SBO.

    • Supersede the existing SBO rule with an enveloping rule.

  • Comments have been submitted, ACRS meeting to be held.

  • Ball in NRC court.