ULNRC-06076, Response to Request for Information Regarding Near-Term Task Force Recommendation 2.3 Flooding - Review of Available Physical Margin (APM) Assessments

Response to Request for Information Regarding Near-Term Task Force Recommendation 2.3 Flooding - Review of Available Physical Margin (APM) Assessments

ML14031A319
Person / Time
Site:	Callaway
Issue date:	01/31/2014
From:	Reasoner C Ameren Missouri, Union Electric Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
ULNRC-06076
Download: ML14031A319 (7)

Text

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'ilWAmeren MISSOURI January 31, 2014 ULNRC-06076 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Ladies and Gentlemen:

10 CFR 50.54(+/-)

DOCKET NUMBER 50-483 CALLAWAY PLANT UNIT 1 UNION ELECTRIC CO.

FACILITY OPERATING LICENSE NPF-30 Cleve Reasoner Vice President Engineering Ameren Missouri Callaway Energy Center T 573.676.8241 F 573.676.4056 RESPONSE TO REQUEST FOR INFORMATION REGARDING NEAR-TERM TASK FORCE RECOMMENDATION 2.3, FLOODING -REVIEW OF AVAILABLE PHYSICAL MARGIN (APM) ASSESSMENTS

References:

1. NRC Letter, "Request for Information Pursuant to Title 10 of the Code of Federal Regulations 50.54(+/-) Regarding Recommendations 2.1, 2.3, and 9.3, ofthe Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident," dated March 12, 2012 (Accession No. ML12073A348)

2. NRC Letter to Nuclear Energy Institute, "Endorsement of Nuclear Energy Institute (NEI) 12-07, "Guidelines for Performing Verification Walkdowns of Plant Flood Protection Features,"

dated May 31,2012 (Accession No. ML12144A142)

3. ULNRC-05934, "Ameren Missouri 180-day Flooding Walkdown Response to NRC Letter, Request for Information Pursuant to Title 10 of the Code of Federal Regulations 50.54(+/-)

Regarding Recommendations 2.1, 2.3, and 9.3, ofthe Near-term Task Force Review of Insights From the Fukushima Dai-ichi Accident," dated November 27, 2012 (Accession No. ML12333A165)

4. NRC Letter, "Request for Additional Information Associated with Near-Term Task Force Recommendation 2.3, Flooding Walkdowns," dated December 23, 2013 (Accession No. ML13325A891)

Junction CC & Hwy 0 PO Box 620, MC CA-460 Fulton, MD 65251 AmerenMissouri.com STARS* Alliance

ULNRC-06076 January 31,2014 Page2 On March 12, 2012, the NRC staff issued Reference 1 requesting information pursuant to 1 0 CFR 50.54(t). In Enclosure 4 of Reference 1, the NRC staff requested that licensees perform flood protection walkdowns associated with Near-Term Task Force Recommendation 2.3 for Flooding, and report the results to the NRC. By Reference 2, the NRC endorsed Nuclear Energy Institute (NEI) 12-07 as providing acceptable guidelines for performing walkdowns of plant flood protection features.

By Reference 3, Ameren Missouri submitted a final report for Callaway Plant in response to the Reference 1 request for information.

Following the NRC staffs initial review of the walkdown reports, regulatory site audits were conducted at a sample of plants. Based on the walkdown report reviews and site audits, the staff identified additional information necessary to allow them to complete their assessments. The NRC observed that several licensees did not always determine and document Available Physical Margin (APM) in a consistent manner that met the expected interpretation ofNEI 12-07. Reference 4 transmitted an NRC request for addition information (RAI) regarding the determination and documentation of APM. Ameren Missouri's response to the Reference 4 RAI for Callaway Plant is attached to this letter.

This letter does not contain new commitments.

If there are any questions regarding this submittal, please contact Scott Maglio, Regulatory Affairs Manager, at 573-676-8719.

I declare under penalty of perjury that the foregoing is true and correct Sincerely, Executed on: -----------------

Cleveland Reasoner Vice President, Engineering Enclosure

ULNRC-06076 January 31,2014 Page 3 cc:

Mr. Marc L. Dapas Regional Administrator U.S. Nuclear Regulatory Commission Region IV 1600 East Lamar Boulevard Arlington, TX 76011-4511 Senior Resident Inspector Callaway Resident Office U.S. Nuclear Regulatory Commission 8201 NRC Road Steedman, MO 65077 Mr. Fred Lyon Project Manager, Callaway Plant Office ofNuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop 0-8B 1 Washington, DC 20555-2738 Mr. Eric Leeds Director, Office of Nuclear Reator Regulation U.S. Nuclear Regulatory Commission Mail Stop 0-13H16M Washington, DC 20555-0001 Mr. Jack Davis Director, Mitigation Strategies Directorate Office ofNuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555-0001

ULNRC-06076 January 31,2014 Page4 Index and send hardcopy to QA File A160.0761 Hardcopy:

Certrec Corporation 4150 International Plaza Suite 820 Fort Worth, TX 76109 (Certrec receives ALL attachments as long as they are non-safeguards and may be publicly disclosed.)

Electronic distribution for the following can be made via Responses and Reports ULNRC Distribution:

F. M. Diya C. 0. Reasoner III L. H. Graessle D. W. Neterer S. A. Maglio T. B. Elwood J. T. Patterson J. L. Fortman S. J. Meyer Corporate Communications NSRB Secretary STARS Regulatory Affairs Mr. John O'Neill (Pillsbury Winthrop Shaw Pittman LLP)

Missouri Public Service Commission

Enclosure to ULNRC-06076 Page 1 of3 Ameren Missouri Response to Request for Additional Information Regarding Flooding Walkdown APM Assessments The specific information requests as stated in Reference 4 are presented in italics below, followed by the corresponding Ameren Missouri response. A list of references is provided at the end of this enclosure.

Please provide the following:

1. Confirmation that the process for evaluating APMwas reviewed; Response - Ameren Missouri confirms that it has reviewed the process for evaluating APM.

2. Confirmation that the AP M process is now or was always consistent with the guidance in NEI 12-07 and discussed in this RAJ; Response - Ameren Missouri confirms that the APM evaluation process was, and remains, consistent with the guidance in NEI 12-07 (Reference 2) and discussion in the Reference 4 RAI.

3. If changes are necessary, a general description of any process changes to establish this consistency; Response-No changes are necessary to establish consistency with the guidance in NEI 12-07 and discussion in the Reference 4 RAI.

4. [First Part] As a result of the audits and subsequent interactions with industry during public meetings, NRC staff recognized that evaluation of APMfor seals (e.g., flood doors, penetrations, flood gates, etc.) was challenging for some licensees. Generally, licensees were expected to use either Approach A or Approach B (described below) to determine the APMfor seals:

a) If seal pressure ratings were known, the seal ratings were used to determine AP M (similar to example 2 in Section 3.13 ofNEI 12-07). A numerical value for APM was documented No further action was performed if the APM value was greater than the pre-established small-margin threshold value. If the AP M value was small, an assessment of "significant consequences" was performed and the guidance in NEI 12-07 Section 5.8 was followed b) If the seal pressure rating was not known, the AP M for seals in a flood barrier is assumed to be greater than the pre-established small-margin threshold value if the following conditions were met: (1) the APMfor the barrier in which the seal is located is greater than the small-margin threshold value and there is evidence that the seals were designed/procured, installed, and controlled as flooding seals in accordance with the flooding licensing basis. Note that in order to determine that the seal has been controlled as a flooding seal, it was only necessary to determine that the seal configuration has been governed by the plant's design control process since installation. In this case, the APMfor the seal could have been documented as "not small".

Enclosure to ULNRC-06076 Page 2 of3 As part of the RAJ response, state if either Approach A or Approach B was used as part of the initial walkdowns or as part of actions taken in response to this RAJ No additional actions are necessary if either Approach A or B was used.

Response - Ameren Missouri inspected penetrations in below-grade exterior walls of safety related buildings as part of the flood protection walkdowns. As detailed below, the determination of APM is not required for Callaway Plant by NEI 12-07.

Details-The flood protection features that are within the scope of the NEI 12-07 walkdowns are those features credited for protection and mitigation from external flood events in a plant's current licensing basis (CLB). This is explicitly stated in several sections ofNEI 12-07 (e.g., Section 4.1.1). As stated in NEI 12-07 Section 3.13, APM describes the flood margin available for applicable flood protection features. Based on the stated scope of NEI 12-07, the "applicable flood protection features" for which APM determinations are required are those credited in the plant's CLB.

The CLB for Callaway Plant is that the plant is a "Dry Site" as defined in Regulatory Guide 1.102 (Reference 5). This is documented in the Callaway Plant Final Safety Analysis Report (FSAR), Section 1.8, regarding conformance to NRC Regulatory Guides. The Flooding Walkdown Report transmitted by Reference 3 noted the Probable Maximum Precipitation (PMP) is the bounding Probable Maximum Flood (PMF) event for Callaway Plant. As stated in FSAR Section 3.4.1.1.1 regarding external flood events, seismic Category I structures are not protected above grade for flooding because there are no above-grade floods at the structure locations. Exterior and access openings to all Seismic Category I structures are located above the design basis flood level. Safety-related systems located below grade are protected from groundwater in-leakage by a combination of a waterproofing system for the structures and the location of safety-related systems in watertight compartments. Below-grade flood protection features are designed, installed and controlled in accordance with the plant's configuration control processes. An exceedingly conservative calculation of ground water in-leakage around four 36" diameter Essential Service Water pipes through 48" diameter penetrations with failed boot seals located 13.5' below grade without implementing any mitigating actions resulted in 158 days of continuous seepage prior to impacting safety related equipment (CAR 200906746). This calculation is considered bounding for other below-grade penetrations. Flood protection measures are not provided for Callaway Plant since they are not required.

Ameren Missouri documented APM for certain flood protection features. APM values were determined based on the feature's height above the design basis ground water elevation. The approach used was consistent with the definition of APM in NEI 12-07 section 3.13 which states:

"The APM for each applicable flood protection feature is the difference between licensing basis flood height and the flood height at which water could affect an sse important to safety."

The APM values were determined to be "not small."

Enclosure to ULNRC-06076 Page 3 of3

4. [Second Part] If neither Approach A orB was used to determine the AP M values for seals (either as part of the walkdowns or as part of actions taken in response to this RAJ),

then perform the following two actions:

Enter the condition into the CAP (note: it is acceptable to utilize a single CAP entry to capture this issue for multiple seals). CAP disposition of "undetermined" APMvaluesfor seals should consider the guidance provided in NEI 12-07, Section 5. 8. The CAP disposition should confirm all seals can perform their intended safety function against floods up to the current licensing basis flood height. Disposition may occur as part of the Integrated Assessment. If an Integrated Assessment is not performed, determine whether there are significant consequences associated with exceeding the capacity of the seals and take interim action(s), if necessary, via the CAP processes. These actions do not need to be complete prior to the RAJ response.

Report the AP Mas "undetermined" and provide the CAP reference in the RAJ response.

Response - As described above, determination of APM values for Callaway is not required by NEI 12-07. However, the APM evaluations that Ameren Missouri did perform were consistent with the definition of APM in NEI 12-07. Ameren Missouri therefore considers that no condition adverse to quality exists with respect to the processes used to determine and document APM values for plant flood protection features, and that a Corrective Action Program entry is not required.

References

1)

NRC Letter, "Request for Information Pursuant to Title 10 of the Code ofFederal Regulations 50.54(f) Regarding Recommendations 2.1, 2.3, and 9.3, ofthe Near-Term Task Force Review of Insights from the Fukushima Dai-Ichi Accident," dated March 12, 2012 (Accession No. ML12073A348)

2)

NRC Letter to Nuclear Energy Institute, "Endorsement ofNuclear Energy Institute (NEI) 12-07, Guidelines for Performing Verification Walkdowns of Plant Flood Protection Features,"

dated May 31, 2012 (Accession No. ML12144A142)

3)

ULNRC-05934, "Ameren Missouri 180-day Flooding Walkdown Response to NRC Letter, Request for Information Pursuant to Title 10 of the Code of Federal Regulations 50.54(f)

Regarding Recommendations 2.1, 2.3, and 9.3, of the Near-term Task Force Review of Insights From the Fukushima Dai-Ichi Accident," dated November 27,2012 (Accession No. ML12333A165)

4)

NRC Letter, "Request for Additional Information Associated with Near-Term Task Force Recommendation 2.3, Flooding Walkdowns," dated December 23, 2013 (Accession No. ML13325A891)

5)

NRC Regulatory Guide 1.1 02, "Flood Protection for Nuclear Power Plants," Revision 1, September 1976.