ML083170492

Validation of Pilgrim Fluence Data for P-T Curves

ML083170492
Person / Time
Site:	Pilgrim
Issue date:	10/31/2008
From:	Bethay S Entergy Nuclear Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML083170492 (2)

Text

Entergy Nuclear Operations, Inc.

Pilgrim Nuclear Power Station 600 Rocky Hill Road Plymouth, MA 02360 October 31, 2008 StephenNuclear Director, J. Bethay Assessment U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001

SUBJECT:

Entergy Nuclear Operations, Inc.

Pilgrim Nuclear Power Station Docket No. 50-293 License No. DPR-35 Validation of Pilgrim Fluence Data for P-T Curves

REFERENCES:

1. Entergy Letter No. 2,07.078, License Renewal Application Commitment 47 Regponse, dated September 12, 2007

2. Entergy Letter No. 2.07.006, Proposed Change to the Applicability of Pilgrim's Pressure-Temperature Curves as described in Technical Specification Figures 3.6.1, 3.6.2, and 3.6.3, Revision 1, dated, dated January 15, 2007 LETTER NUMBER: 2.08.059

Dear Sir or Madam:

In Reference, 1, Entergy provided an action plan- f0or :the benchmarking validation of RAMA fluence calculations for the Pilgrim Nuclear Power Station (PNPS) reactor vessel to'satisfy the commitment made-in Reference 2 for revised Pressure-Temperature (P-T) curves beyond Operating Cycle 18.

Entergy stated in Reference 1, Action Item No. 4,. that it will review data from a similar EPRI sponsored BWR/3 under the Integrated Surveillance, Program (ISP) to determine if it can be used to document an acceptable Regulatory Guide 1.190 Calculated-to-Measured (C/M) bias for a BWR/3 using the RAMA code. Further, in the event Action Item 4 is not successful, Entergy stated that it is working in parallel (Action 5) to remove the existing capsule from the PNPS reactor vessel in the spring 2009 refueling outage for use in developing a new fluence calculation benchmark.

Since the last PNPS reactor vessel fluence evaluation, Entergy contractor TransWare has performed an activation/fluence evaluation for the Monticello nuclear power plant, also a BWR/3 class plant. As a part of the Monticello evaluation, RAMA-calculated activation predictions were compared to measurements for the 3000 ISP: capsule flux wires that were irradiated for 23 cycles (28.2 EFPY). Activation comparisons were performed for four copper, four iron, and four nickel flux wires that resided at various axial elevations in the capsule. The average C/M result for all copper activation measurements is 0.89, for all iron activation measurements is 1.08, and for all nickel activation measurements is 1.13. The resulting average C/M for all measurements in the Monticello capsule is 1.03- +/- 11 (1 a). The comparison results are well within the Reg.

Guide 1.190 guidelines and-confirm that theRAMA-fluence methodology provides an unbiased estimate of the fluence in the Monticello nuclear plant. In addition, the results obtained from the Monticello capsule comparisons using the RAMA Fluence Methodology are consistent with the observed comparisons from other BWRs (including BWR/2s, BWR/4s, and BWR/6s).

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Entergy Nuclear Operations, Inc. Letter Number: 2.08.059 Pilgrim Nuclear Power Station Page 2 Accordingly, Entergy has determined that the Monticello reactor vessel fluence calculation provides an acceptable BWR/3 RAMA benchmark.

Entergy will use Monticello as the benchmark for PNPS RAMA fluence calculations, rerun the model for PNPS, and use the results directly to prepare the revised P-T curves for Operating Cycle 18 and beyond. Consequently, we do not intend to remove the existing capsule from the PNPS reactor vessel during the spring 2009 refueling outage. This information was discussed with the NRC Staff on October 17, 2008.

Based upon the above acceptable approach, Entergy rescinds Action Item 5 specified in Reference 1 to remove the dosimetry capsule from PNPS reactor vessel during the spring 2009 refueling outage.

This letter contains no new commitments.

If you have any questions regarding the subject matter, please contact Joseph R. Lynch at (508)-830-8403.

Sincerely, Stephen J. Bethay Director, Nuclear Safety Assessment cc: Mr. James S. Kim, Project Manager Division of Operating Reactor Licensing Office of Nuclear Reacdor Regulation U. S. Nuclear Regulatory Commission One White Flint North O-8C2 11555 Rockville Pike Rockville, MD 20852 Mr. Samuel J. Collins, Administrator Region I U.S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406 NRC Resident Inspector Pilgrim Nuclear Power Station 2 of 2