ML020170495

RAI - Application for Amendments to Facility Operating Licensees

ML020170495
Person / Time
Site:	Vogtle
Issue date:	01/17/2002
From:	Assa R NRC/NRR/DLPM
To:	Beasley J Southern Nuclear Operating Co
Assa R,NRR/DLPM,415-1391
References
TAC MB3568, TAC MB3569
Download: ML020170495 (4)

Text

January 17, 2002 Mr. J. B. Beasley, Jr.

Vice President Southern Nuclear Operating Company, Inc.

Post Office Box 1295 Birmingham, Alabama 35201-1295

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION RE: APPLICATION FOR AMENDMENTS TO FACILITY OPERATING LICENSEES, VOGTLE ELECTRIC GENERATING PLANT, UNITS 1 AND 2 (TAC NOS. MB3568 AND MB3569)

Dear Mr. Beasley:

The Nuclear Regulatory Commission is reviewing your amendment request dated October 17, 2001, in which you proposed changes to Vogtle Unit 1 and Unit 2 Technical Specification Table 3.3.1-1, Reactor Trip Instrumentation. These changes would clamp the over temperature T (OTT) function during cooldown events to a value 3- lower than the reference temperature for the associated loop. This clamp will limit the OTT trip setpoint increase during cooldown events, thereby increasing the clad stress margin. In addition, you proposed to use this increased clad stress margin to allow relaxation of the reduced relaxed axial offset control (RAOC) band to limits which do not account for cycle-to-cycle fuel management variations.

The staff has determined that, in order to complete its review, a detailed technical justification is needed to show that the proposed clamp will provide the required clad stress margin to allow relaxation of the RAOC band to the limits proposed in the licensing amendment request. In addition, the staff is requesting you to show that the effects of relaxation of the RAOC band have been considered for plant transients and accidents for which the axial flux difference (AFD) is an initial condition. Based on these considerations, the staff requests the following information in order to continue with its review:

1) Identify the clad stress criteria used as the basis for determining the allowable values of the AFD. Include a reference to the NRC approved methodologies used in performing the analyses that serve as the basis for justifying the proposed changes.

2) Submit a quantitative technical justification demonstrating that the proposed OTT clamp value will result in the required clad stress margin necessary to allow relaxation of the RAOC band to the proposed limits.

3) Demonstrate that with the proposed RAOC band the clad stress criteria identified in question number (1) continues to be met for all transients and accidents for which the AFD is an initial condition. In addition, identify any transients or accidents which will have a reduced safety margin resulting from the proposed changes.

4) Provide justification for the non-conservative change in the trip setpoint reduction value when AFD > +10 percent. Include a discussion of the effects of the change in this value from 2.7 percent rated thermal power (RTP) to the less conservative 1.95 percent RTP on transients and accidents which result in a top-skewed AFD.

5) Provide a discussion, including references to NRC approval, explaining the technical considerations which resulted in the current AFD limits for Vogtle.

I discussed these questions with Mr. Jim Bailey, Vogtle Licensing Manager, and he estimated that your answers will be submitted by January 31, 2002.

Sincerely,

/RA/

Ramin Assa, Project Manager, Section 1 Project Directorate II Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos. 50-424 and 50-425 cc: See next page

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