INSPECTION MANUAL CHAPTER 0609 APPENDIX L

# EXTENSIVE DAMAGE MITIGATION GUIDELINESSIGNIFICANCE 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 licensee’s 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.

# 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 – SecurityRelated Information.

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.

# 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)

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

Attachment 1 – Revision History for IMC 0609 Appendix L

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