ML092510359

Email, Request for Additional Information, Exigent License Amendment Request to Revise Technical Specification 3.7.1, Main Steam Safety Valves (Mssvs), for Unit 2 Cycle 15 (TAC ME2176))

ML092510359
Person / Time
Site:	Diablo Canyon
Issue date:	09/08/2009
From:	Wang A Plant Licensing Branch IV
To:	Parker L, Schrader K Pacific Gas & Electric Co
Wang, A B, NRR/DORL/LPLIV, 415-1445
References
TAC ME2176
Download: ML092510359 (2)

Text

From: Wang, Alan Sent: Tuesday, September 08, 2009 2:40 PM To: Parker, Larry M; Schrader, Kenneth Cc: Lent, Susan; Burkhardt, Janet

Subject:

Diablo Canyon Request for Information Regarding MSSV Inoperable (ME2176)

Larry and Ken, By letter dated September 3, 2009, Pacific Gas and Electric Company (PG&E, the licensee),

submitted an one-time emergency license amendment request (LAR) to the Diablo Canyon Power Plant (DCPP), Unit 2 to revise Technical Specification (TS) 3.7.1, Main Steam Safety Valves (MSSVs),

Table 3.7.1-1, Maximum Allowable Power Range Neutron Flux High Setpoint With Inoperable MSSVs.

DCPP, Unit 2 currently has a MSSV inoperable (MS-2-RV-224), and per TS 3.7.1, Required Action A.1 is operating at approximately 80 percent rated thermal power (RTP). The proposed change will allow an increase in the Power Range Neutron Flux High setpoint from 87 percent RTP to 106 percent RTP in Table 3.7.1-1 with MS-2-RV-224 inoperable for the remainder of Cycle 15, which is scheduled to end in October 2009.

The US Nuclear Regulatory Commission (NRC) staff has determined that the following additional information is needed to complete its review of the subject license amendment request for ANO-1. This request was discussed with Ken Scharder of your staff on September 8, 2009, and it was agreed that a response would be provided within 1 day of receipt of this email. If circumstances result in the need to revise the requested response date, please contact me at (301) 415-1445 or via e-mail at Alan.Wang@nrc.gov.

REQUEST FOR ADDITIONAL INFORMATION

1) In the NRC staff's judgment, the integral power achieved during the pre-trip power ascension could be a fairly significant factor affecting the secondary pressure rise.

Therefore, the assertion that initiating the transient at 102-percent power is a conservative treatment of power uncertainty may not be correct.

Discuss why initiating the lost of load/turbine trip (LOL/TT) transient in an overpower condition is conservative relative to secondary pressurization when the transient is assumed to be terminated by an overpower trip. Address (1) whether initiating the transient from a 98-percent power condition would result in a greater secondary pressurization, and (2) why the modeling technique employed is sufficiently conservative to account for this potentially greater pressurization.

2) What is the moderator temperature at end of cycle conditions? Is there any sort of Tcold reduction? What's the actual condition relative to the analysis?

3) The Maximum Allowable Value in TS Table 3.7.1-1 is being changed from 87 percent to 106 percent and as addressed in NRC's letter dated January 8, 2008, (ADAMS accession No. ML073240006) and PG&Es license amendment request dated January 11, 2007, the footnotes to comply with RIS 2006-17 need to be added.

E-mail Properties Mail Envelope Properties (419623E8C7444444BF132DA3AE69EDA21B0A0C0B6B)

Subject:

Diablo Canyon Request for Information Regarding MSSV Inoperable (ME2176)

Sent Date: 9/8/2009 2:39:36 PM Received Date: 9/8/2009 2:39:36 PM From: Wang, Alan Created By: Alan.Wang@nrc.gov Recipients:

LMP1@pge.com (Parker, Larry M)

Tracking Status: None KJSe@pge.com (Schrader, Kenneth)

Tracking Status: None Susan.Lent@nrc.gov (Lent, Susan)

Tracking Status: None Janet.Burkhardt@nrc.gov (Burkhardt, Janet)

Tracking Status: None Post Office:

HQCLSTR02.nrc.gov Files Size Date & Time MESSAGE 11441 9/8/2009 Options Expiration Date:

Priority: olImportanceNormal ReplyRequested: False Return Notification: False Sensitivity: olNormal Recipients received: