ML103540184

10/08/10 Summary of Telephone Conference Call Held Btw the Usnrc and PSEG Nuclear, LLC, Concerning Questions Pertaining to the Salem Nuclear Generating Station, Units 1 and 2, License Renewal Application

ML103540184
Person / Time
Site:	Salem
Issue date:	01/07/2011
From:	Brady B M License Renewal Projects Branch 1
To:	Public Service Enterprise Group
BRADY B, NRR/DLR/RPB1, 415-2981
References
Download: ML103540184 (8)

Text

\.t.p.fI REG(J.;:,V UNITED STATES NUCLEAR REGULATORY COMMISSION

.... ('l WASHINGTON, D.C. 20555-0001 0 <fl 0.,. Ii; v;;... January 7, 2011 -"" ****-t<

PSEG Nuclear, LLC Salem Nuclear Generating Station, Units 1 and 2

SUMMARY

OF TELEPHONE CONFERENCE CALL HELD ON OCTOBER 8,2010, BETWEEN THE U.S. NUCLEAR REGULATORY COMMISSION AND PSEG NUCLEAR, LLC, CONCERNING QUESTIONS PERTAINING TO THE SALEM NUCLEAR GENERATING STATION, UNITS 1 AND 2, LICENSE RENEWAL APPLICATION The U.S. Nuclear Regulatory Commission (NRC or the staff) and representatives of PSEG Nuclear, LLC (the applicant), and Exelon held a telephone conference call on October 8,2010, to discuss and clarify the staffs questions concerning the Salem Nuclear Generating Station, Units 1 and 2, license renewal application.

The telephone conference call was useful in clarifying the intent of the staff's questions.

Enclosure 1 provides a listing of the participants, Enclosure 2 contains a brief summary of the discussion and status of the items, and Enclosure 3 contains the staffs draft request for additional information and the applicant's questions for clarification.

The applicant had an opportunity to comment on this summary.

Bennett M. Brady, Project Manager Projects Branch 1 Division of License Renewal Office of Nuclear Reactor Regulation Docket Nos. 50-272 and 50-311

Enclosures:

1. List of Participants

2. Summary of meeting discussion

3. Draft RAJ and questions for clarification cc w/encls: Distribution via Listserv TELEPHONE CONFERENCE SALEM NUCLEAR GENERATING STATION, UNITS 1 AND LICENSE RENEWAL LIST OF October PARTICIPANTS AFFILIATIONS Bennett Brady U.S. Nuclear Regulatory Commission (NRC) Louise Lund NRC Allen Hiser NRC Gary Stevens NRC OnYee NRC Ching Ng NRC Christopher Wilson Exelon Sam Speer Exelon ENCLOSURE

SUMMARY

OF MEETING ON QUESTIONS ON SALEM NUCLEAR GENERATING STATION. UNITS 1 AND LICENSE RENEWAL OCTOBER 8, The U.S. Nuclear Regulatory Commission (NRC or the staff) and representatives of PSEG Nuclear, LLC held a telephone conference call on October 8, 2010, to discuss and clarify the NRC's request for additional information (RAI) related to the WESTEMSTM software that is used for monitoring and analyzing metal fatigue. Discussion:

Prior to the meeting, the staff had provided the applicant with their draft RAI as shown in Enclosure

3. The applicant provided the NRC staff with their questions for clarification on the draft RAI as shown in Enclosure

3. During the meeting, the staff and applicant agreed that the NRC needed more information on the background and chorology of Salem Nuclear Generating Station's metal fatigue analyses and the use ofWESTEMSTM for monitoring and analyzing metal fatigue. The meeting agreed that the NRC would revise their RAI and provide it to the applicant for further discussion.

ENCLOSURE

Background:

Section 4.3.4.2 of the Salem License Renewal Application (LRA) credits the WESTEMS code for evaluation of fatigue for the pressurizer and surge line locations.

For example, Section A.3.1.1 of the Salem LRA identifies WESTEMS as a part of the Metal Fatigue of Reactor Pressure Boundary program. Issue: The staff has identified concerns regarding the results determined by the WESTEMS program as a part of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) fatigue evaluation process. For example, Westinghouse's response to U.S. Nuclear Regulatory Commission (NRC) questions regarding the AP1000 Technical Report (see Agencywide Documents Accession and Management System (ADAMS) Accession Number ML 102300072, dated August 13, 2010) describe the ability of users to modify intermediate data (peak and valley stresses/times) used in the analyses.

In addition, a response provided on August 20, 2010, (ADAMS Accession Number ML 102350440) describes different approaches for summation of moment stress terms. These items can have significant impacts on calculated fatigue cumUlative usage factor (CUF). The potential impact for modifications such as these formed the basis for the staff's conclusions in Regulatory Issue Summary (RIS) 2008-30, "Fatigue Analysis of Nuclear Power Plant Components," dated December 16, 2008, where it was noted that simplification of the analysis requires a great deal of judgment by the analyst to ensure that the simplification still provides a conservative result. The staff recognizes that WESTEMS has been developed under a formal Quality Assurance Program with supporting Technical Bases; however, it is difficult to ascertain the accuracy or conservatism of a component-specific application of WESTEMS given that a variety of analyst judgments may still be applied to the software outputs by the user on a case-specific basis. Request: The staff requests that Salem provide a benchmarking evaluation of the component-specific application of the Salem pressurizer and surge line locations monitored in WESTEMS using the same input parameters and assumptions as those used in the current licensing basis (CLB) analysis of record performed for each location in accordance with the ASME Code,Section III. The intent of this benchmarking evaluation is to confirm that the results of the WESTEMS model are acceptable and conservative compared to the CLB analysis of record for each of the monitored locations.

Provide a summary of the benchrnarking evaluation that includes the following information: A comparison of the calculated stresses and CUF for each location using the WESTEMS system for each transient pair that contributes to the CUF to the same results from the CLB analysis of record. Describe the differences in the results between the WESTEMS evaluation and the CLB analysis of record for each location, and provide a justification for acceptability of the differences.

ENCLOSURE 3

Clarification Questions on Salem WESTEMS Ž RAJ Background Information:

As discussed in Salem LRA Section 4.3.4.2, the pressurizer surge line piping and nozzles were previously evaluated for the effects of thermal stratification and plant-specific transients.

In a later evaluation, a plant-specific WESTEMSTM model was developed for the pressurizer

[lower head] and surge line to evaluate the effects of pressurizer insurge and outsurge transients.

The first evaluation was documented in WCAP-12913 (non-proprietary) and WCAP-12914 (proprietary), and submitted to the NRC in PSE&G Letter NLR-91 083, dated May 15, 1991. This evaluation used four software codes, including ANSYS, but not WESTEMSTM, to conduct the ASME Code Section III, NB-3200, 1986 edition, evaluation.

The second evaluation is documented in WCAP-16194, and looked specifically at the Pressurizer lower head and surge nozzle. This evaluation used WESTEMSTM, Version 4.2, which conducted the evaluation in accordance with ASME Code Section III, NB-3200, 1989 edition. This evaluation was not submitted to the NRC, or referenced in the CLB. However, it is the current design basis for the pressurizer lower head and surge nozzle. Specific Questions for Clarification to Respond: The Request is to provide a summary of a benchmarking evaluation.

Is the benchmarking being requested specifically for the stress and fatigue models used to calculate fatigue usage for the Salem pressurizer and surge line locations in the WESTEMSTM online monitoring system, i.e., the lower head, surge nozzle region that were evaluated in WCAP-16194?

Or does the benchmark consider the WESTEMSTM models used in the Salem Environmentally-Assisted Fatigue (EAF) calculations for the pressurizer nozzle and surge line hot leg nozzle locations? As contained in the supporting calculations for the Salem LRA, the WESTEMS Ž monitoring models for the pressurizer surge nozzle and surge line hot leg nozzle locations were bench marked against ANSYS with respect to the stress responses

[calculated stresses indicated in your first bullet] generated by WESTEMSTM for transient loadings.

The models are then used in the monitoring system to calculate fatigue usage automatically from all stress peaks and valleys identified in the operating history for each location, according to the ASME Code Section III methodology.

In the monitoring role, there is no user post-processing of peaks and valleys or reanalysis of fatigue usage. Therefore, the concern regarding application of analyst judgments noted in the RAI Issue description is not applicable for WESTEMSTM monitoring models. The analyst{s) did edit peaks during the preparation of the Salem EAF calculations, and the final peaks used in the calculations were documented and verified.

-3 Also, the concern noted in the RAllssue description with respect to summation of moments is only applicable to the WESTEMSTM NB-3600 analysis module, which is not used in WESTEMSTM monitoring, or in the Salem EAF calculations.

In addition, the subject of RIS 2008-30 was fatigue evaluation using simplified single component stress models, which is not employed in WESTEMSTM monitoring or EAF calculation models, and is therefore not applicable.

The WESTEMSTM models and fatigue calculations evaluate all components of stress according to NB-3200. In light of these points, are the existing benchmarks performed for the models and documented in the Salem EAF calculations sufficient to satisfy the component specific benchmarking requested?

If so, Salem will use these to provide the requested benchmark comparison. As is the case with most stress and fatigue analyses in the industry, the CLB analyses of record may have been done in a more conservative manner than may be performed in later analyses.

As long as the later analyses are performed in accordance with the ASME Code, it is not required that their results are conservative with respect to the earlier CLB analyses.

In light of this, it is not clear why the request states that the benchmark should intend to show that the WESTEMSTM results are conservative compared to the CLB analysis of record. Depending upon the location(s) of interest to the Staff, the CLB analysis of record was performed using either a combination of four software codes (WCAP-12913), or with an earlier version of WESTEMSTM (WCAP-16194).

If the benchmark is with the earlier version of WESTEMS TM, then the requested benchmarking would be trivial. Salem is requesting the Staff to consider the existing benchmarking in the component model calculations as sufficient for your review on this issue.

January 7, 2011 LICENSEE:

PSEG Nuclear, LLC FACILITY:

Salem Nuclear Generating Station, Units 1 and 2

SUMMARY

OF TELEPHONE CONFERENCE CALL HELD ON OCTOBER 8,2010, BETWEEN THE U.S. NUCLEAR REGULATORY COMMISSION AND PSEG NUCLEAR, LLC, CONCERNING QUESTIONS PERTAINING TO THE SALEM NUCLEAR GENERATING STATION, UNITS 1 AND 2, LICENSE RENEWAL APPLICATION The U.S. Nuclear Regulatory Commission (NRC or the staff) and representatives of PSEG Nuclear, LLC (the applicant), and Exelon held a telephone conference call on October 8, 2010, to discuss and clarify the staff's questions concerning the Salem Nuclear Generating Station, Units 1 and 2, license renewal application.

The telephone conference call was useful in clarifying the intent of the staff's questions.

Enclosure 1 provides a listing of the participants, Enclosure 2 contains a brief summary of the discussion and status of the items, and Enclosure 3 contains the staff's draft request for additional information and the applicant's questions for clarification.

The applicant had an opportunity to comment on this summary. IRA! Bennett M. Brady, Project Manager Projects Branch 1 Division of License Renewal Office of Nuclear Reactor Regulation Docket Nos. 50-272 and 50-311

Enclosures:

1. List of Participants

2. Summary of meeting discussion

3. Draft RAI and questions for clarification cc w/encls: Distribution via Listserv DISTRIBUTION:

See next page ADAMS Accession Number: ML 103540184 OFFICE LA: DLR PM: DLR/RPB1 BC: DLRlRPB1 PM: DLRlRPB1 NAME IKing BBrady BPham BBrady DATE 12/30/2010 01/05/2011 . -01/06/2011

.. 01/07/2011 ,

• OFFICIAL RECORD Memorandum to PSEG Nuclear, LLC from Bennett M. Brady dated January 07,2011

SUMMARY

OF TELEPHONE CONFERENCE CALL HELD ON OCTOBER 8,2010, BETWEEN THE U.S. NUCLEAR REGULATORY COMMISSION AND PSEG NUCLEAR, LLC, CONCERNING QUESTIONS PERTAINING TO THE SALEM NUCLEAR GENERATION STATION, UNITS 1 AND 2, LICENSE RENEWAL APPLICATION DISTRIBUTION:

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