ML092230023
| ML092230023 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood  |
| Issue date: | 08/06/2009 |
| From: | David M Plant Licensing Branch III |
| To: | Schofield L, Simpson P Exelon Generation Co |
| marshall david 415-1547 | |
| References | |
| TAC ME1613, TAC ME1614, TAC ME1615, TAC ME1616 | |
| Download: ML092230023 (2) | |
Text
From:
David, Marshall Sent:
Thursday, August 06, 2009 4:04 PM To:
patrick.simpson@exeloncorp.com; Lisa.Schofield@exeloncorp.com Cc:
Campbell, Stephen; Gavrilas, Mirela; Karwoski, Kenneth; Murphy, Emmett; Johnson, Andrew
Subject:
BRAIDWOOD & BYRON REQUEST FOR ADDITIONAL INFORMATION RELATED TO STEAM GENERATOR PERMANENT ALTERNATE REPAIR CRITERIA (TAC NOS.
ME1613 - ME1616)
Categories:
Red Category Pat, Lisa, As discussed, below is our second RAI for the SG PARC amendment request. I will be placing a copy of this e-mail into ADAMS.
Marshall REQUEST FOR ADDITIONAL INFORMATION BRAIDWOOD STATION, UNITS 1 AND 2 AND BYRON STATION, UNIT NOS. 1 AND 2 DOCKET NOS. STN 50-456, STN 50-457 STN 50-454, AND STN 50-455 The Nuclear Regulatory Commission (NRC) staff is continuing its review of Exelon Generation Company, LLCs (the licensees) license amendment request (LAR) dated June 24, 2009 (Agencywide Documents Access and Management System (ADAMS) Package No.
ML091770543), to revise the technical specifications (TSs) of Byron Station (Byron) Unit Nos. 1 and 2 and Braidwood (Braidwood) Station Units 1 and 2. The request proposed changes to the inspection scope and repair requirements of TS 5.5.9, Steam Generator (SG) Program and to the reporting requirements of TS 5.6.9, Steam Generator (SG) Tube Inspection Report. The proposed changes would establish permanent alternate repair criteria for portions of the SG tubes within the tubesheet.
In order to complete its review, the NRC staff requests the additional information, below.
Questions 1 through 3 refer to certain questions in the NRC staffs previous request for additional information (RAI) dated July 20, 2009 (ADAMS Accession No. ML091960327).
Questions 1 through 3, below, refer to Westinghouse document, WCAP-17072-P, Rev. 0, H*:
Alternate Repair Criteria for the Tubesheet Expansion Region in Steam Generators with Hydraulically Expanded Tubes (Model D5), which was submitted with the June 24, 2009, LAR.
The NRC staff requests that your responses to the questions, below, along with your response to the NRC staffs July 20, 2009, RAI be provided on August 18, 2009, in lieu of the previously-requested date of August 7, 2009.
- 1. In addition to the information requested in the NRC staffs previous RAI, Question 4, please address the following questions:
- a. Clarify the nature of the finite element model (slice model versus axisymmetric SG assembly model) used to generate the specific information in Tables 6-1, 2, and 3 (and accompanying graph entitled Elliptical Hole Factors) of Reference 6-15. What loads were applied? How was the eccentricity produced in the model? (By modeling the eccentricity as part of the geometry? By applying an axisymmetric pressure the inside of the bore?) Explain why this model is not scalable to lower temperatures.
- b. Provide a table showing the maximum eccentricities (maximum diameter minus minimum diameter) from the 3-dimensional finite element analysis for normal operating and steam line break (SLB), for Model D5.
- c. In Figure 6-70, add a plot for the original relationship between reductions in contact pressure and eccentricity as given in Reference 6-15 in the graph accompanying Table 6-3. Explain why this original relationship remains conservative in light of the new relationship. Explain the reasons for the differences between the curves.
- d. When establishing whether contact pressure increases when going from normal operating to SLB conditions, how can a valid and conservative comparison be made if the normal operating case is based on the original delta contact pressure versus eccentricity curve and the SLB case is based on the new curve?
- 2. In addition to the information requested in the NRC staffs previous RAI, Question 21, include a discussion of the SLB and whether it continues to be less limiting, from maximum H* perspective, than three times normal operating pressure.
- 3. In addition to the information requested in the NRC staffs previous RAI, Question 23, address the feedwater line break (FLB) heatup transient in the Updated Final Safety Analysis Report, as this design-basis accident is part of the licensing basis. Please provide a rationale to justify basing the leakage factor on the SLB, or commit to a leakage factor based on the FLB heatup transient.
- 4. During the review of the June 24, 2009, LAR, it was noticed that a regulatory commitment regarding use of the leakage factor had been stated on page 13 of Attachment 1, but had been left off the list of regulatory commitments in Attachment 6, and did not specifically mention establishment of an administrative operational leakage limit. Since the final leakage factor may change based on the FLB analysis (Question 3, above), the proper factor will need to be used in the regulatory commitment, see below:
For the Condition Monitoring assessment, the component of leakage from the prior cycle from below the H* distance will be multiplied by a factor of X.XX and added to the total leakage from any other source and compared to the allowable accident induced leakage limit. For the Operational Assessment, the difference between the allowable accident induced leakage and the accident induced leakage from sources other than the tubesheet expansion region will be divided by X.XX and compared to the observed operational leakage. An administrative operational leakage limit will be established to not exceed the calculated value.
E-mail Properties Mail Envelope Properties (01BD2A1885C88F45A12CB413DEF03410ABAFE81B5B)
Subject:
BRAIDWOOD & BYRON REQUEST FOR ADDITIONAL INFORMATION RELATED TO STEAM GENERATOR PERMANENT ALTERNATE REPAIR CRITERIA (TAC NOS. ME1613 - ME1616)
Sent Date: 8/6/2009 4:03:35 PM Received Date: 8/6/2009 4:03:35 PM From: David, Marshall Created By: Marshall.David@nrc.gov Recipients:
patrick.simpson@exeloncorp.com (patrick.simpson@exeloncorp.com)
Tracking Status: None Lisa.Schofield@exeloncorp.com (Lisa.Schofield@exeloncorp.com)
Tracking Status: None Stephen.Campbell@nrc.gov (Campbell, Stephen)
Tracking Status: None Mirela.Gavrilas@nrc.gov (Gavrilas, Mirela)
Tracking Status: None Kenneth.Karwoski@nrc.gov (Karwoski, Kenneth)
Tracking Status: None Emmett.Murphy@nrc.gov (Murphy, Emmett)
Tracking Status: None Andrew.Johnson@nrc.gov (Johnson, Andrew)
Tracking Status: None Post Office:
HQCLSTR01.nrc.gov Files Size Date & Time MESSAGE 28541 8/6/2009 Options Expiration Date:
Priority: olImportanceNormal ReplyRequested: False Return Notification: False Sensitivity: olNormal Recipients received: