ML110540712

E-mail, Request for Additional Information, Nrr/Dra/Apla Review, Amendment Request for Extended Power Uprate to Increase the Maximum Reactor Core Power Operating Limit from 3898 to 4408 Mwt

ML110540712
Person / Time
Site:	Grand Gulf
Issue date:	02/23/2011
From:	Wang A Plant Licensing Branch IV
To:	Burford J, Millar D Entergy Operations
Wang, A B, NRR/DORL/LPLIV, 415-1445
References
TAC ME4679
Download: ML110540712 (2)

Text

From:

Wang, Alan Sent:

Wednesday, February 23, 2011 4:33 PM To:

'Jerry Burford'; MILLAR, DANA Cc:

Lent, Susan; Burkhardt, Janet

Subject:

GG EPU Probabilistic Risk Assessment Licensing Branch Request for Additional Information (ME4679)

Jerry and Dana, By letter dated September 8, 2010 (Agencywide Documents Access and Management System, Accession No. ML1002660403), Entergy Operations, Inc. (Entergy, the licensee), submitted a request to amend the Facility Operating License No. NPF-29 for Grand Gulf Nuclear Station, Unit 1 (GGNS). The licensee proposed a license amendment request (LAR) for an extended power uprate (EPU) to increase the maximum reactor core power operating limit from 3898 megawatts thermal (MWt) to 4408 MWt.

The U.S. Nuclear Regulatory Commission (NRC) staff has determined that the following additional information is needed for the NRC staff to complete our review of this amendment.

This request for additional information (RAI) was discussed with Mr. Jerry Burford of your staff on February 23, 2011, and it was agreed that a response would be provided within 30 days of receipt of this E-mail. 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.

The following RAIs are related to the Probabilistic Risk Assessment Licensing Branch of the Division of Risk Assessment portion of the LAR review.

1. Many of the evaluations used to determine success criteria for different systems used the modular accident analysis program (MAAP) software. The submittal states that a file was used that contain workarounds for the latest MAAP Part 21 errors that have been identified for MAAP versions 4.0.6 and 4.0.7. MAAP5 is the latest version of MAAP and includes numerous upgrades to the code. Please justify how any inadequacies related to the applicable software version impacts the timings and success criteria evaluation listed in Attachment 13, Appendix E.

2. The submittal states in Attachment 13 page 5:

The GGNS PRA Human Reliability Analysis utilizes two methods to calculate the human error probabilities (HEP): HCR/ORE correlation and the Caused-Based approach. The Cause-Based method is not affected by allowable operation action time. The method used is determined by choosing the highest probability from the two methods.

Table 4.1-11 lists HEPs that have significant reduction in allowable operator action times and were calculated using the cause-based approach. By using the cause-based approach, decreases in allowable operation action time did not change the HEP probability. Since the delta risk assessment for EPU is highly sensitive to HEP due to decreased operator response time, please explain the applicability of using a methodology that is not sensitive to operator response times. For those HEPs evaluated

by the cause based approach that have a decrease in operator action time post-EPU, please confirm that the HCR/ORE correlation method produced a less conservative result.

3. The submittal states in Attachment 13 Page 100:

The fire PRA model was rerun for this EPU risk assessment using the same changes incorporated into the internal events PRA with the knowledge that the results would not necessarily reflect the most up to date model of the Grand Gulf plant.

Please explain in more detail why the results would not reflect the most up to date model of the GGNS. Identify any modeling discrepancies that would significantly alter the three percent change in fire core damage frequency (CDF).

4. The submittal states in Attachment 13 Page 102:

EPU equipment replacements are judged to be installed using anchorages that are similar to the existing equipment anchorages.

Please confirm that EPU equipment replacements will be installed using anchorages that are seismically acceptable for the particular equipment.