NLS2014011, Response to Nuclear Regulatory Commission'S Request for Information Associated with Near-Term Task Force Recommendation 2.3, Flooding Walkdowns

Response to Nuclear Regulatory Commission'S Request for Information Associated with Near-Term Task Force Recommendation 2.3, Flooding Walkdowns

ML14035A220
Person / Time
Site:	Cooper
Issue date:	01/31/2014
From:	Higginbotham K Nebraska Public Power District (NPPD)
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NLS2014011
Download: ML14035A220 (5)

Text

N Nebraska Public Power District NLS2014011 Always there when you need us January 31, 2014 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk 11555 Rockville Pike Rockville, MD 20852

Subject:

Nebraska Public Power District's Response to Nuclear Regulatory Commission's Request for Information Associated with Near-Term Task Force Recommendation 2.3, Flooding Walkdowns Cooper Nuclear Station, Docket No. 50-298, DPR-46

References:

1. Nuclear Regulatory Commission Letter, Request for InformationPursuantto Title 10 of the Code of FederalRegulations 50.54(f) Regarding Recommendations 2.1, 2.3, and 9.3, of the Near-Term Task Force Review of Insightsfrom the Fukushima Dai-Ichi Accident, dated March 12, 2012 (Accession No. ML12053A340)

2. Nuclear Regulatory Commission Letter to Nuclear Energy Institute, Endorsement of Nuclear Energy Institute (NE1) 12-07, "Guidelinesfor Performing Verification Walkdowns of Plant Flood Protection Features,"

dated May 31, 2012 (Accession No. ML12144A142)

3. Nebraska Public Power District Letter to Nuclear Regulatory Commission, Flooding Walkdown Report - Nebraska Public Power District'sResponse to Nuclear Regulatory Commission Request for Information Pursuantto 10 CFR 50.540l Regarding the FloodingAspects of Recommendation 2.3 of the Near-Term Task Force Review of Insightsfrom the Fukushima Dai-ichiAccident, dated November 27, 2012 (NLS2012124)

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

Dear Sir or Madam:

On March 12, 2012, the Nuclear Regulatory Commission (NRC) issued Reference 1 requesting information pursuant to Title 10 of the Code of Federal Regulations 50.54(f). Enclosure 4 of Reference 1 contains specific Requested Information associated with Near-Term Task Force Recommendation 2.3 for Flooding. Per Reference 2, the NRC endorsed Nuclear Energy Institute (NEI) 12-07, "Guidelines for Performing Verification Walkdowns of Plant Flood Protection Features," dated May 31, 2012. By Reference 3, Nebraska Public Power District (NPPD) submitted the final report in response to the request for information.

COOPER NUCLEAR STATION /d b P.O. Box 98 / Brownville, NE 68321-0098 Telephone: (402) 825-3811 / Fax: (402) 825-5211 www.nppd.com

NLS2014011 Page 2 of 2 One of the requirements of NEI 12-07 is to identify the available physical margin associated with each applicable flood protection feature, determine if the margin provided is small, and evaluate any small margins that have potentially significant consequences through the corrective action process. The results of this effort were to be maintained on site for future NRC audits.

Following the NRC's initial review of the walkdown reports, regulatory site audits were conducted at a sampling of plants. Based on the walkdown report reviews and site audits, the NRC identified additional information necessary to allow the staff to complete its assessments.

Accordingly, by Reference 4, the NRC has issued a request for additional information (RAI). The RAI questions and NPPD's responses are provided in the Attachment.

This letter contains no new regulatory commitments and no revision to existing regulatory commitments. Should you have any questions regarding this submittal, please contact David Van Der Kamp, Licensing Manager, at (402) 825-2904.

I declare under penalty of perjury that the foregoing is true and correct.

Executed on: i/Z///!

Sincerely, Kenneth Higginboth General Manager of lant Operations

/bk

Attachment:

Response to Request for Additional Information Associated with Near-Term Task Force Recommendation 2.3, Flooding Walkdowns cc: Regional Administrator, w/attachment USNRC - Region IV Director, w/attachment USNRC - Office of Nuclear Reactor Regulation Cooper Project Manager, w/attachment USNRC - NRR Project Directorate IV-I Senior Resident Inspector, w/attachment USNRC - CNS NPG Distribution, w/attachment CNS Records, w/attachment

NLS201401 1 Attachment Page 1 of3 Attachment Response to Request for Additional Information Associated with Near-Term Task Force Recommendation 2.3, Flooding Walkdowns Cooper Nuclear Station, Docket No. 50-298, DPR-46 On March 12, 2012, the Nuclear Regulatory Commission (NRC) issued a letter requesting information per 10 CFR 50.54(f). The request for information letter contained specific requested actions, requested information and required responses associated with Recommendation 2.3 for flooding walkdowns. By letter on May 31, 2012, the NRC endorsed Nuclear Energy Institute (NEI) 12-07 as providing acceptable guidelines for performing walkdowns of plant flood protection features. Nebraska Public Power District (NPPD) submitted a final walkdown report for Cooper Nuclear Station (CNS) in response to the request for information on November 27, 2012.

Following the NRC's initial review of the walkdown reports, regulatory site audits were conducted at a sampling of plants. Based on the walkdown report reviews and site audits, the NRC identified additional information necessary to allow the staff to complete its 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 of NEI 12-07.

On December 23, 2013, the NRC transmitted a request for additional information (RAI) regarding the determination and documentation of APM. Below are the NRC's RAI questions and NPPD's responses.

NRC Request:

Pleaseprovide the following:

1. Confirmationthat the processfor evaluatingAPM was reviewed; NPPD Response: NPPD confirms that it has completed a review of the process used at CNS to evaluate APM.

2. Confirmationthat the APM process is now or was always consistent with the guidance in NEI 12-07 and discussed in this RAI; NPPD Response: NPPD confirms the original walkdown effort was consistent with the guidance provided in NEI 12-07. A numerical value for a small APM was not initially established.

NLS2014011 Attachment Page 2 of 3

3. If changes are necessary, a generaldescriptionof any process changes to establish this consistency; NPPD Response: No changes were necessary as the original walkdown effort followed the guidance provided in NEI 12-07. While a numerical value for small APM was not established, judgment was used to determine if a feature had to be entered into CNS' Corrective Action Program (CAP). In response to this RAI, an engineering report, ER-14-001, was developed to determine a numerical value for small APM. This report concluded that features with one foot or more APM were determined to be not small. Features with less than one foot APM were entered into the CAP. In the case of building walls, the walkdown team judged that excess margin was available. As such, walls were not entered into the CAP, although the walkdown sheets state that the APM is zero.

4. As a result of the audits and subsequent interactionswith industry duringpublic meetings, NRC staff recognized that evaluation of APMfor seals (e.g., flood doors,penetrations,flood gates, etc.) was challengingfor some licensees. Generally, licensees were expected to use either Approach A or Approach B (describedbelow) to determine the APMfor seals:

a) If sealpressure ratings were known, the seal ratings were used to determine APM (similarto example 2 in Section 3.13 of NEI 12-07). A numerical valuefor APM was documented. No further action was performed if the APM value was greater than the pre-establishedsmall-margin thresholdvalue. If the APM value was small, an assessment of "significantconsequences" was performed and the guidance in NEI 12-07 Section 5.8 was followed.

b) If the sealpressure rating was not known, the APMfor seals in a flood barrieris assumed to be greaterthan the pre-establishedsmall-margin threshold value if the following conditions were met: (1) the APMfor the barrierin which the seal is located is greaterthan the small-margin threshold value and there is evidence that the seals were designed/procured,installed,and controlled asflooding seals in accordancewith the flooding licensingbasis. 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 configurationhas been governed by the plant's design controlprocess since installation.In this case, the APM for the seal could have been documented as "not small".

As part of the RAI response, state ifeither Approach A or Approach B was used as partof the initial walkdowns or as part of actions taken in response to this RAI. No additionalactions are necessary if either Approach A or B was used.

If neither Approach A or B was used to determine the APM values for seals (either as part of the walkdowns or as part of actions taken in response to this RAI), 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"APM valuesfor seals should consider the guidance provided in NEI 12-0 7, Section 5.8. The

NLS2014011 Attachment Page 3 of 3 CAP disposition should confirm all seals can perform their intended safety function againstfloods up to the current licensing basisflood height.Disposition may occur as part of the IntegratedAssessment. If an IntegratedAssessment is not performed, determine whether there are significant consequences associatedwith 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 RAI response.

• Report the APM as "undetermined"and provide the CAP reference in the RAI response.

NPPD Response: Approach "A" was used to determine APM for seals as part of the original walkdowns. As such, no additional actions are necessary.