ML12132A313

Ngp - Draft Request for Clarification of February 21, 2012 RAI Response Concerning Diesel Fuel Oil LAR

ML12132A313
Person / Time
Site:	Prairie Island
Issue date:	05/08/2012
From:	Thomas Wengert Plant Licensing Branch III
To:	Vincent D Northern States Power Co, Xcel Energy
Wengert T
References
TAC ME6849, TAC ME6850
Download: ML12132A313 (2)

Text

From: Wengert, Thomas Sent: Tuesday, May 08, 2012 12:30 PM To: Vincent, Dale M.

Subject:

Prairie Island NGP - DRAFT Request for Clarification of February 21, 2012 RAI Response Concerning Diesel Fuel Oil LAR (TAC Nos. ME6849 and ME6850)

By letter dated February 21, 2012 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML12054A057), Northern States Power Company, a Minnesota corporation, doing business as Xcel Energy (NSPM or the licensee) submitted a response to the NRCs request for additional information (RAI) concerning the August 11, 2011 Diesel Fuel Oil license amendment request (ADAMS Accession No. ML112240140) for the Prairie Island Nuclear Generating Plant (PINGP), Units 1 and 2. The NRC staff has reviewed these RAI responses and needs additional clarification of three responses to complete its review, as stated below. Please review this draft request for clarification and let me know if NSPM would like to have a clarifying conference call to discuss these questions.

Tom Wengert Project Manager - Prairie Island NGP NRR/DORL/LPLIII-1 (301) 415-4037 DRAFT REQUEST FOR ADDITIONAL INFORMATION RAI EEEB-7 The NSPM response to RAI EEEB-1a delineates the flow paths that are available from the each of the storage tanks to the day tank of each diesel engine. Technical Specification (TS) surveillance requirement (SR) 3.8.1.5 requires verification of capability of the fuel oil transfer system to transfer fuel oil from the storage tank to the day tank. Validate that current plant procedures verify operability of each of the paths delineated in the NSPM response to comply with TS requirements.

RAI EEEB-8 The NSPM response to RAI EEEB-4a states that Section 8.4 of the PINGP Updated Safety Analysis Report (USAR) defines the design basis worst case accident from the emergency diesel generator (EDG) loading perspective as a large break loss of coolant accident (LBLOCA) concurrent with a loss of offsite power (LOOP). NSPM further states that the basis for EDG load reduction within the first hour of EDG operation during this event is associated with the drain-down of the refueling water storage tank (RWST) and the subsequent transfer to the recirculation mode.

The NRC staff notes that the LOOP/LBLOCA event may result in the most severe short term loading of the EDG and may be used to determine the kilowatt rating of the EDG. However, it may not be the most conservative loading from a fuel oil consumption perspective, when some pumps may operate for longer durations depending on the type of break or event. USAR Table 14.7-4 (Unit 2) provides the time durations for RWST low level alarm actuation for various break sizes. According to this Table, the RWST low level is not reached for a 1.5 inch break size and it takes approximately 5467 seconds to reach the low level alarm point following a 2 inch break.

Validate that the calculation of record for fuel oil consumption evaluated events related to different size breaks for LOCA and steam line breaks inside containment for a bounding case.

RAI EEEB-9 The licensees response to RAI EPTB 1a and 1b states that fuel oil consumption rates were determined based on manufacturers testing and pre-operational testing records. The test records provide the consumption rates (in units of pounds / [brake horsepower

• hours] for the Unit 1 EDGs or (in units of grams I [kilowatt

• hours]) for the Unit 2 EDGs at various loading conditions. Provide details on the power factor values that were used in the testing program and how the EDG fuel oil consumption calculations accounted for the reactive power required by accident-mitigating equipment.