ML21311A003

IMC 0609 App L Extensive Damage Mitigation Guidelines Significance Determination Process

ML21311A003
Person / Time
Issue date:	12/07/2021
From:	Matthew Leech NRC/NRR/DRA/APOB
To:
Matthew.Leech@nrc.gov
Shared Package
ML21334A350	List: Inspection Manual Change Notice 21-039, ML21208A134 ML21311A002 ML21311A003
References
CN 21-039
Download: ML21311A003 (5)

Text

NRC INSPECTION MANUAL APOB INSPECTION MANUAL CHAPTER 0609 APPENDIX L EXTENSIVE DAMAGE MITIGATION GUIDELINES SIGNIFICANCE DETERMINATION PROCESS 0609L-01 PURPOSE The purpose of this SDP is to accommodate all potential more than minor inspection findings associated with the development and implementation of guidance and strategies intended to maintain or restore core cooling, containment, and spent fuel pool cooling capabilities under the circumstances associated with loss of large areas of the plant due to explosions or fire as required by 10 CFR 50.155(b)(2).

Each issue entering the SDP must first be screened to determine its documentation threshold (i.e. if more than minor in significance) using Inspection Manual Chapter (IMC) 0612, Appendix B, Issue Screening Directions. Issues screened as minor are not subjected to further SDP screening.

0609L-02 DEFINITIONS Extensive Damage Mitigation Guidelines (EDMG) event - a beyond-design-basis loss of a large area of a reactor plant due to fires or explosions.

Unrecoverable - an unavailable mitigating strategy is unrecoverable if licensee actions could neither reasonably correct nor compensate for the conditions creating the unavailability in time during an EDMG event for the mitigating strategy to achieve its objective. The time limit is the time allowed by NEI 06-12, Revision 2, for establishment of the strategy where applicable, or a reasonable time.

Unavailability - a mitigating strategy is unavailable if its hardware or components are not functional and ready for intended use, or personnel training and procedures are inadequate, as described in the licensee submittal and safety evaluation report (SER) supporting the requirements of individual plants Mitigating Strategies license condition, which were made generically applicable in 10 CFR 50.155(b)(2).

Note: These strategies for each operating reactor licensee were reviewed by the staff who issued a SER to document the commitments to implement these strategies. The site-specific responses delineating each licensees commitment and the SERs are available through the B.5.b Inspection SharePoint Page. These responses are not available to the public due to the highly sensitive nature for plant security contained in these responses. This SharePoint site contains additional useful information including references, correspondence, etc.

Issue Date: 12/07/21 1 0609 App L

0609L-03 GUIDANCE Record the performance deficiency and factually describe known observations associated with the deficiency in Table 1 - SDP Screening Worksheet for EDMG Evaluation of the listed attributes may be informative in determining the significance of the finding. Consider only attributes which relate directly to the significance of the finding and document the basis for the consideration. If Table 1 is used to document a performance deficiency and the factual description of the condition, the table will be properly labeled as Official Use Only -

Security-Related Information.

TABLE 1 - SDP Screening Worksheet for EDMG Inspection Report #

Performance Deficiency (concise statement clearly stating the deficient licensee performance)

Factual Description of Condition (facts about the condition that resulted from the performance deficiency without hypothetical failures included)

Systems/Trains Degraded by Condition or Programmatic Weakness (list the Hardware, Procedures or Training)

Extent of Condition (describe what other strategies are directly affected by the deficiency)

Exposure Time (Period of time the performance deficiency existed; and if opportunity to identify the finding during such period was missed (operating experience, licensees programs such as surveillance testing)

Recovery (The likelihood that the licensees recovery actions would successfully mitigate the performance deficiency)

Cornerstone (For findings that affect core cooling select Mitigating Systems. For ____ Mitigating Systems ____ Barrier Integrity findings that affect the containment or spent fuel pool select Barrier Integrity)

The examples provided for each level of significance in Table 2 - Significance Characterization, serve as guidance in determining the appropriate characterization for findings; however, they are neither exhaustive nor controlling. The characterization of each finding is dependent on the circumstances of the issue defined in Table 1. In addition, these examples do not create new requirements. Each is intended to illustrate the significance that the NRC places on a particular type of finding. Each potential finding must be considered on its own merits to ensure that its significance is characterized at the level best suited to the circumstances using qualitative engineering judgment and regulatory oversight experience in each case. This is necessary because the examples provided are intentionally limited to deter a mechanistic approach or unreasoned conclusion. With this in mind, the entire spectrum of characterizations should be considered with the particular finding placed in context in consideration of its particular circumstances.

Issue Date: 12/07/21 2 0609 App L

TABLE 2 - Significance Characterization GREEN Unrecoverable unavailability of any individual mitigating strategy.

WHITE 1. Unrecoverable unavailability of multiple mitigating strategies such that SFP cooling, injection to RPV, or injection to SGs cannot occur, or

2. Unrecoverable unavailability of on-site, self powered, portable pumping capability, or

3. Substantial inability to perform Command and Control Enhancements.

Examples:

- Unrecoverable unavailability of injection to the reactor vessel or steam generators (concurrent unavailability of low-pressure pumping/depressurization strategies and unavailability of manual operation of RCIC/Isolation Condenser or turbine-driven (or diesel-driven) AFW)

- Unrecoverable unavailability of SFP internal strategy, SFP external fill strategy, AND SFP external spray strategy

- Substantial inability to perform Command and Control Enhancements YELLOW A failure to substantially establish mitigating strategies in one or more of the following overall mitigating strategies areas:

- Firefighting response strategies

- Operations to mitigate reactor core fuel damage including command and control and actions to minimize release

- Operations to mitigate Spent Fuel Pool fuel damage including command and control and actions to minimize release RED In an actual EDMG event, a substantial failure of mitigating strategies to function as intended (i.e., achieve the strategies objectives) in one or more of the following overall mitigating strategies areas:

- Firefighting response strategies

- Operations to mitigate reactor core fuel damage including command and control and actions to minimize release

- Operations to mitigate Spent Fuel Pool fuel damage including command and control and actions to minimize release Issue Date: 12/07/21 3 0609 App L

0609L-04 REFERENCES

1. Power Reactor Security Requirements Rulemaking (74 FR 13925; March 27, 2009)

2. Mitigation of Beyond-Design-Basis Events Rulemaking (84 FR 39684; August 9, 2019)

3. NUREG-0800, Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants: LWR Edition - Severe Accidents, Section 19.4 revision 0, June 2015 (ADAMS Accession No. ML13316B202)

4. NEI 06-12, Revision 2 (ADAMS Accession No. ML070090060)

END Issue Date: 12/07/21 4 0609 App L

Attachment 1 - Revision History for IMC 0609 Appendix L Commitment Accession Description of Change Description of Comment Resolution Tracking Number Training and Closed Number Issue Date Required and Feedback Form Change Notice Completion Accession Number Date (Pre-Decisional, Non-Public Information)

N/A 12/24/09 Researched commitments for 4 years and found none. None N/A CN 09-032 This Appendix to the IMC 0609, Significance Determination Process incorporates the lessons learned from the performance of Temporary Instruction (TI) 2515/171 on Verification of Site Specification Implementation of B.5.b Phase 2 & 3 Mitigation Strategies and provides the framework for determining the significance of B.5.b findings.

N/A ML21311A003 Documented the shift in the current requirements for the N/A None 12/07/21 mitigating strategies to § 50.155(b)(2) and incorporated terminology changes resulting from the Mitigation of CN 21-039 Closed FBF:

Beyond-Design-Basis Events Rulemaking. This occurred on September 9, 2019. Re-named from B.5.b 0609L-2444 to Extensive Damage Mitigation Guidelines (EDMG) to ML21224A307 coincide with the renaming that occurred during the MDBE rulemaking. Definition for EDMG was provided.

Edited the link for the B.5.b Community of Practice site to its new SharePoint location. This addressed open ROP Feedback Form 0609L-2444. Added a new reference section including the Power Reactor Security Requirements Rulemaking, (74 FR 13925; March 27, 2009), and the Mitigation of Beyond-Design-Basis Events Rulemaking, (84 FR 39684; August 9, 2019).

These document the shift in requirements from EA 026 to § 50.54(hh)(2) to § 50.155(b)(2).

Issue Date: 12/07/21 Att1-1 0609 App L