ML14128A289

NRR E-mail Capture - FW: Fyi: Watts Bar Unit 2 - Open Items 23 & 26

ML14128A289
Person / Time
Site:	Watts Bar
Issue date:	05/07/2014
From:	Jessie Quichocho Plant Licensing Branch II
To:	Siva Lingam Division of Operating Reactor Licensing
References
Download: ML14128A289 (4)

Text

NRR-PMDAPEm Resource From: Quichocho, Jessie Sent: Wednesday, May 07, 2014 5:23 PM To: Lingam, Siva

Subject:

FW: FYI: Watts Bar Unit 2 - Open Items 23 & 26 Attachments: WATTS BAR UNIT 2 Action Items 23 EEEB Input.docx Fyi Jessie Quichocho, Chief Plant Licensing Branch LPL II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation 301-415-0209 From: Zimmerman, Jacob Sent: Wednesday, May 07, 2014 2:45 PM To: Poole, Justin Cc: Quichocho, Jessie; Matharu, Gurcharan

Subject:

FYI: Watts Bar Unit 2 - Open Items 23 & 26 Justin Attached is the EEEB write-up closing out the Open Items 23 & 26 for Watts Bar Unit 2 licensing review.

If you have any comments or questions, please contact Singh Matharu.

Thanks, Jake Jacob I. Zimmerman, Chief Electrical Engineering Branch Division of Engineering Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission E-mail: Jacob.Zimmerman@nrc.gov l Office: (301) 415-1220 l NRC - One Mission - One Team 1

Hearing Identifier: NRR_PMDA Email Number: 1271 Mail Envelope Properties (2B99C8FC0E9CB14D9BAD822B6E7B17E02C5F3B4FD7)

Subject:

FW: FYI: Watts Bar Unit 2 - Open Items 23 & 26 Sent Date: 5/7/2014 5:23:17 PM Received Date: 5/7/2014 5:23:18 PM From: Quichocho, Jessie Created By: Jessie.Quichocho@nrc.gov Recipients:

"Lingam, Siva" <Siva.Lingam@nrc.gov>

Tracking Status: None Post Office: HQCLSTR02.nrc.gov Files Size Date & Time MESSAGE 908 5/7/2014 5:23:18 PM WATTS BAR UNIT 2 Action Items 23 EEEB Input.docx 25005 Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

Recipients Received:

WATTS BAR UNIT 2 ACTION ITEMS EEEB ITEM #23 Issue: Resolve whether or not TVAs reasoning for not upgrading the MSIV solenoid valves to Category I is a sound reason to the contrary, as specified in 10 CFR 50.49(i). (SSER 22, Section 3.11.2.2.1, pages 3-15)

Detailed

Description:

Main Steam Isolation Valves (MSIVs)

TVA stated that the original WBN Unit 2 MSIVs are qualified to NUREG-0588, Category II. TVA is refurbishing the MSIVs by replacing the missing subcomponents, including the solenoid valves, terminal blocks, and manufacturing wiring, with components of the same make, model, and type as supplied on the original purchase order. With the exception of the solenoid valves, the subcomponents will be qualified to NUREG-0588, Category I requirements. According to TVA, the solenoid valves cannot be upgraded because equivalent subcomponents qualified to NUREG-0588, Category I, requirements are not available. The NRC staff does not consider TVA's justification for not upgrading the MSIV solenoid valves to Category I, as specified in 10 CFR 50.49(1), to be a sound reason. Resolution of this issue is Open Item 23 (Appendix HH).

Resolution: By letter dated April 6, 2011, (ADAMS # ML110980637) TVA response to Request for Additional Information (RAI) stated that the MSIV solenoids would be upgraded to Cat I.

Based on this response, the staff considers this item to be resolved.

EEEB ITEM #26 Issue: For the scenario with an accident in one unit and concurrent shutdown of the second unit without offsite power, TVA stated that Unit 2 pre-operational testing will validate the diesel response to sequencing of loads on the Unit 2 emergency diesel generators (EDGs). The NRC staff will evaluate the status of this issue and will update the status of the EDG load response in a future SSER. (SSER 22, Section 8.1)

Detailed

Description:

By letter dated November 18, 2011, Watts Bar Nuclear Plant, Unit 2 -

Request for Additional Information Regarding Supplemental Safety Evaluation Report, the staff requested additional details on Open item 26. TVA updated its response by letter dated June 7, 2012 (ADAMS # ML12163A048). The questions were related to Emergency Diesel Generator (EDG) rating and loading criteria. Specifically the staff requested TVA to:

a) Explain the variations in the worst-case loading provided in different responses and provide a summary of current calculations depicting DG loading, including procedurally required loads that may be manually connected b) Provide verification or test documents from manufacturer or Appendix B qualified supplier of DG engine and DG generator certifying the 'hot, cold and step load' capabilities.

Resolution: In response to staff questions, TVA stated that the ongoing plant modifications and validation of calculation accuracies through the inspection process had resulted in adjustments to the EDG loading calculations. TVA attached excerpts from calculation #

EDQ00099920080014, Rev. 16 summarizing the results from the last update.

The licensee has evaluated the load carrying capability (steady-state running load) and margin available for the worst case EDG loading for two separate events. As stated in the Final Safety

Analysis Report (FSAR), load carrying capability is based on a 2-hour rating of 4840 kilowatt (kW) from 0 to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> and on a continuous rating of 4400 kW from 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> to the end. Table 1, provided in Attachment 1 to Calculation No. EDQ00099920080014, Rev. 16 depicts worst case EDG loading with available margin when serving loads during a loss of offsite power (LOOP) concurrent with a loss of coolant accident (LOCA). This table indicates that EDG 2B-B has the highest loading of 4,237.20 kilowatt (kW) which is less than the 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> rating of 4840 kW. The maximum steady state running load (2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> to end) is calculated to be 4093.66 kW for EDG 1A-A compared to nominal rating of 4400 kW. The other EDGs have lower loading for this event. to the Calculation provides details on each EDG loading with one unit in LOOP plus LOCA and the second unit in LOOP only. For the case of Unit 1 in LOOP/LOCA event and Unit 2 in a LOOP only condition, the licensee has concluded that EDG 1A-A has the maximum loading of 4220.51 kW for the first two hours and 4093.66 kW for the remaining duration. These loading are below the corresponding nominal and 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> ratings of the EDGs. The other EDGs have lower loading for this event.

For the case of Unit 2 in LOOP/LOCA event and Unit 1 in a LOOP only condition, the licensee has concluded that EDG 2B-B has the maximum loading of 4237.2 kW for the first two hours and EDG 2A-A has 3975.57 kW for steady state operation beyond 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> . These loading are below the corresponding nominal and 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> ratings of the EDGs. The other EDGs have lower loading for this event.

The licensee has also performed a sensitivity analyses for transient loading of the EDGs during motor starts. Based on the details provided in the referenced calculation, the staff finds that the EDGs at WBN units 1 and 2 are adequately rated to support safe shutdown of both units following an accident in one unit coupled with a LOOP at both units.

The licensee has indicated that the hot cold and step load capabilities of the EDGs were reviewed and concurred by MKW Power Systems, Inc., the Appendix B qualified supplier of EDG engine and generator for WBN. The licensee has used the higher rating(s) for motor starting analyses. The staff did not consider the additional spare margin available with these ratings as the nameplate ratings envelope the postulated steady state loadings.

Based on the responses provided by the licensee, staff considers open item #26 to be resolved.

Prepared BY: G. S. Matharu Reviewed By: Roy Mathew