Fort Calhoun, Unit 1 - OPPD Response to NRC Request for ... · walkdown checklists (SWC) were Mr. Ashwin Patel and Mr. Jim Carlson. As shown in Attachment 11.2 to EA12-021, Revision

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444 South 1(jh Street Mall Omaha, NE 68102-2247

LlC-14-0049 March 27, 2014

u.s. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001

Fort Calhoun Station, Unit No.1 Renewed Facility Operating License No. DPR-40 NRC Docket No. 50-285

Subject: OPPD Response to NRC Request for Additional Information Regarding Seismic Walkdown at Fort Calhoun Station

Reference: Email from NRC (J. Sebrosky) to OPPD (8. Hansher), "Fort Calhoun Seismic Walkdown Request for Additional Information (MF0126)," dated March 19, 2014 (NRC-14-0023)

This letter is responding to the NRC staff's request for additional information (RAI) regarding the seismic walkdown conducted at Fort Calhoun Station. The Omaha Public Power District's (OPPD) response to the NRC RAI is attached.

This letter contains no new regulatory commitments.

If you should have any questions regarding this submittal or require additional information, please contact Mr. Bill R. Hansher, Supervisor-Nuclear Licensing, at 402-533-6894.

I declare under penalty of perjury that the foregoing is true and correct. Executed on March 27, 2014.

Respectfully,

LoUIs P. CortopaSSi Site Vice President and CNO

LPC/JKG/mle

Attachment: OPPD Response to NRC Request for Additional Information Regarding Seismic Walkdown at Fort Calhoun Station

Employment with Equal Opportunity

LI C-14-0049 Attachment Page 1

OPPD Response to NRC Request for Additional Information

Regarding Seismic Walkdown at Fort Calhoun Station


By letter dated November 27, 2012, (Agencywide Documents Access and Management System (ADAMS) Accession No ML 12340A257) as supplemented by letters dated June 28, 2013, and November 27, 2013 (ADAMS Accession Nos. ML13193A236 and ML 13333A674, respectively) Omaha Public Power District, (the licensee) submitted seismic walkdown information in response to the NRC's March 12, 2012, request for information (ADAMS Accession No. ML12053A340). The March 12, 2012, NRC letter requested licensees to conduct seismic hazard walkdowns to verify current plant configuration with the current licensing basis.

Based on a review of your November 27, 2012, June 28, 2013, and November 27, 2013, submittals, the NRC staff has determined that the following additional information (RAI) is required in order to complete its review. The request for additional information was discussed with Mr. Michael Edwards (OPPD Nuclear Licensing Engineer) on March 18, 2013. It was agreed that a response to these RAls would be provided by March 28, 2013. Should the NRC determine that this RAI is no longer necessary prior to the scheduled date, the request will be withdrawn. If circumstances result in the need to revise the requested response date, please contact me at (301) 415-1132 or via e-mail at [email protected]. The NRC staff has determined that no security-related or proprietary information is contained herein.

Request for Additional Information

1. The staff does not have enough information to verify that there are no items that could lead to rapid drain-down of the Fort Calhoun Station SFP or, if there are drain-down items, that they were sufficiently assessed in accordance with the guidance. The rapid drain-down discussion does not reach a clear conclusion with respect to equipment that could cause a rapid drain down. In particular, the seismic walkdown report does not include a discussion on the evaluation of penetrations within 10 feet above the top of the fuel assemblies. Also, the report does not include a Rapid Drain-Down list as described in the seismic walkdown guidance (page 8-3). It is unclear whether the SFP items that cause rapid drain-down were included as part of the combined seismic walkdown equipment list (SWEL).

OPPD Response

The spent fuel pool (SFP) and SFP cooling system is designed to prevent drainage of the spent fuel pool below the top of stored spent fuel. The top of a fuel assembly in a storage rack is about the same elevation as the bottom of the gate opening which is at elevation 1008' - 6". There are five possible exit paths from the pool. The cooling water makeup line and the cooling water outlet line (with strainer) are both located at elevation 1 034'. The bottom of the fuel transfer gate with the additional plate is at elevation 1009' 8-%". None of these paths is below the top of the spent fuel. The main cooling water supply enters the pool at elevation 1034' and terminates at elevation 1031' - 7". The secondary pool drain line is equipped with a normally locked closed valve (AC-187) at elevation 1011' - 4" to protect the pool from any ruptures of the line downstream of the valve. This line is designed so that a rupture between the valve and the pool wall will not drain the pool below the top of the fuel (Le. , the bottom of the pipe is at elevation 1011' - 0").


Connection

Cooling water makeup

Cooling water outlet

Fuel transfer gate

Main cooling water supply

Secondary pool drain

Elevation

1034'

1034'

1009'-8-W'

1031' - 7"

1011'-4"

There are also two temporary 6" SFP cooling lines that are part of a temporary SFP cooling system. The temporary SFP cooling system is only installed if it is necessary to remove the permanent SFP cooling system from service for maintenance. The suction line is less than 7' below the top of the SFP and the return line is less than 7'-6" below the top of the SFP so these lines do not have the potential to be a significant drainage pathway.

The fuel transfer gate and the secondary pool drain are the only two exit paths at elevations less than ten feet above the stored fuel (i.e., below 1018' - 6"). The secondary pool drain line was not considered for inclusion in the SWEL2 list because it is seismically designed and equipped with a normally locked closed isolation valve. Likewise, the fuel transfer gate is seismically designed and is not considered a rapid drain down pathway. Thus, there are no items that could cause the spent fuel pool to drain rapidly (i.e., within 72 hours after an earthquake).

As described in Section 6.2 of EA12-021, Revision 1 submitted by OPPD letter, LlC-13-0070 dated June 28, 2013 (Adams Accession No. ML13193A236), components were selected in Base List (BL) 2 that are connected to systems associated with the SFP that could cause loss of SFP inventory. None were identified that could cause the spent fuel pool to drain rapidly. Components, rather than piping, were selected because EPRI Technical Report 1025286, "Seismic Walkdown Guidance for Resolution of Fukushima Near-Term Task Force Recommendation 2.3," June 2012 does not encompass piping systems and their associated inline valves (Le., manual valves).

These BL-2 items are listed in Attachment 11.1, page 27 of 30 of OPPD letter, LlC-12-0169 dated November 27,2012 (Adams Accession No. ML12340A254). The portions of the spent fuel pool and spent fuel pool cooling system that must be seismically designed are shown below on the system boundary diagram.


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The components of the SFP and SFP cooling system that were included in the SWEL are shown in the following table.

Equipment I D Description Storage Pool Heat Exchanger (HX)

HCV-478 Component Cooling Water (CCW) Outlet Valve

AC-SA SFP CirculatinQ pump AC-S8 SFP Circulating pump AC-8 SFPHX AC-7 SFP Demineralizer AC-6 SFP Filter


A SFP inventory in excess of ten feet above the stored fuel assemblies is maintained if any of these components are lost.

2. The staff is unable to confirm that the cabinets were opened and inspected. The submittal report, including the seismic walkdown checklists, did not provide any information to confirm that cabinets were opened to view internal lateral anchorages to adjacent cabinets, any internal floor anchorage, and to determine the condition of any internal equipment.

OPPD Response

In OPPD letter, L1C-12-0093 dated July 5,2012 (ADAMS Accession No. ML121910223), OPPD confirmed that EPRI Technical Report 1025286 as endorsed by the NRC would be used to conduct the seismic walkdowns and develop the necessary information for Fort Calhoun Station. Section 3 of EPRI Technical Report 1025286 contains the following statement:

The purpose for preparing lists of equipment to be included on the SWEL is to allow those items to be walked down, as described in Section 4: Seismic Walkdowns and Area Walk-8ys. Of course, to be able to perform the Seismic Walkdowns on these items, it is necessary to have access to them and to be able to view their anchorage.

Section 4 of EPRI Technical Report 1025286 contains the following statement:

Guidance for identifying anchorage that could be degraded, non-conforming, or unanalyzed relies on visual inspections of the anchorage and verification of anchorage configuration.

Therefore, in accordance with the EPRI guidance, electrical cabinets on the SWEL were opened and inspected to view internal anchorage as well any other potentially adverse seismic conditions.

3. The staff cannot verify that any individual involved in performing a given walkdown activity was not a peer reviewer for that same activity. Table 1, Personnel Functions, of the updated seismic walkdown report lists two individuals to have participated in seismic walkdown and peer review activities (one is the peer review team lead). Neither the response to the November 1, 2014 RAI-2b, nor the seismic walkdown report address whether these two individuals reviewed their own work or sufficiently explain how this did not contradict the objective of the peer review efforts.

OPPD Response

As shown in Table 1 of EA12-021, Revision 1 submitted by OPPD letter, L1C-13-0070, the individuals that performed the seismic walkdowns and who also peer reviewed seismic walkdown checklists (SWC) were Mr. Ashwin Patel and Mr. Jim Carlson. As shown in Attachment 11.2 to EA12-021, Revision 1, Mr. Patel prepared SWCs 6,7, and 10 and Mr. Carlson prepared SWCs 8, 9, 11, 13, 14, and 23. As shown in Section 9.2 of EA 12-021, Revision 1, none of these checklists was selected for a peer review. Therefore, no member of the peer review team reviewed their own seismic walkdown activity, and the objective of the peer review efforts described in EPRI Technical Report 1025286 was maintained.