ML13193A175

Request for Additional Information Regarding Revision to Pressure and Temperature Limit Curves and Exemption Request for Initial Reference Temperature Values

ML13193A175
Person / Time
Site:	Three Mile Island
Issue date:	07/22/2013
From:	Peter Bamford Plant Licensing Branch 1
To:	Pacilio M Exelon Nuclear
Bamford P
References
TAC MF0425, TAC MF0426
Download: ML13193A175 (5)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 July 22, 2013 Mr. Michael J. Pacilio President and Chief Nuclear Officer Exelon Nuclear 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

THREE MILE ISLAND NUCLEAR STATION, UNIT 1 - REQUEST FOR ADDITIONAL INFORMATION REGARDING PROPOSED REVISION TO PRESSURE AND TEMPERATURE LIMIT CURVES AND EXEMPTION REQUEST FOR INITIAL REFERENCE TEMPERATURE VALUES (TAC NOS. MF0425 AND MF0426)

Dear Mr. Pacilio:

By letter dated December 14,2012 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML12353A319), supplemented by letter dated January 31,2013 (ADAMS Accession No. ML13032A312), Exelon Generation Company, LLC (Exelon) submitted a license amendment request (LAR) for Three Mile Island Nuclear Station, Unit 1 (TMI-1). The LAR relates to a proposed revision to the pressure and temperature limit curves and low temperature overpressure protection limits contained in the TMI-1 Technical Specifications. In the submittal dated December 14, 2013, in addition to the LAR, Exelon also submitted an exemption request relating to the use of alternate initial reference temperature values for Linde 60 welds used in fabricating the TMI-1 reactor vessel.

The Nuclear Regulatory Commission staff has been reviewing the submittal, and has determined that additional information is needed to complete its review. The specific questions are found in the enclosed request for additional information (RAI). The questions were sent via electronic transmission on July 11, 2013, to Mr. Thomas Loomis, of your staff. The draft questions were sent to ensure that the questions were understandable, the regulatory basis was clear, and to determine if the information requested was previously docketed. The questions were discussed with your staff on July 17, 2013, and it was agreed that a response to this RAI would be provided by August 16, 2013.

M. Pacilio - 2 Please contact me at 301-415-2833, if you have any questions.

Sincerely, tP~

Peter Bamford, Project Manager Plant Licensing Branch 1-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-289

Enclosure:

Request for Additional Information cc: Distribution via Listserv

REQUEST FOR ADDITIONAL INFORMATION THREE MILE ISLAND NUCLEAR STATION, UNIT 1 PROPOSED REVISION TO PRESSURE AND TEMPERATURE LIMIT CURVES AND EXEMPTION REQUEST FOR INITIAL REFERENCE TEMPERATURE VALUES DOCKET NO. 50-289 By letter dated December 14,2012 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML12353A319), Exelon Generation Company, LLC (Exelon, the licensee), submitted a license amendment request (LAR) for Three Mile Island Nuclear Station, Unit 1 (TMI-1). The LAR relates to a proposed revision to the pressure and temperature (P-T) limit curves and low temperature overpressure protection limits contained in the TMI-1 Technical Specifications (TS). In addition to the LAR, Exelon also submitted an exemption request relating to the use of alternate initial reference temperature (RT NOT) values for Linde 80 welds used in fabricating the TMI-1 reactor vessel (RV). In order for the Nuclear Regulatory Commission (NRC) staff to complete its review of the LAR and exemption request, a response to the following request for additional information (RAI) is requested.

RA11:

Issue: Section 4.6 of Attachment 4, AREVA Document No. ANP-3102, "Three-Mile Island, Unit 1 Appendix G Pressure-Temperature Limits at 50.2 EFPY [Effective Full-Power Years] with MUR [Measurement Uncertainty Recapture Uprate]," describes the reactor coolant temperature time histories used in the calculations of the revised P-T limits, as specified below:

The following input temperate-time histories are considered:

Normal Ramp Heatup, 50 °F/hr. [degrees Fahrenheit per hour]

Normal Step Heatup, 50 °F/hr.

Normal Ramp Cooldown, 100 °F/hr to 225 OF then 30 °F/hr to 70°F.

Normal Step Cooldown, 100 °F/hr to 225 of then 30 °F/hr to 70°F.

Note 2 to Figure 3.1-2 in the proposed TS markup, Attachment 2, shows the cooldown ramp history as follows:

T > 255°F 100 °F/hr or 15°F 19 min. Steps T > 255°F 30°F/hr or 15°F 1 30 min. Steps Request: Explain this discrepancy, or revise the submittal to make the text consistent, either 255°F or 225°F, with the actual cooldown history that was used. Also, please clarify whether is considered revision 1 or 2, because the attachment listing does not appear to match the attached document.

Enclosure

-2 RA12:

Background:

P-T limit calculations for ferritic reactor coolant pressure boundary (RCPB) components that are not RV beltline shell materials, may define curves that are more limiting than those calculated for the RV beltline shell materials. This may be due to the following factors:

1. Some ferritic RCPB components that are not RV beltline shell materials, such as nozzles, penetrations, and other discontinuities, are complex geometry components that exhibit significantly higher stress intensities than those for the RV beltline region.

These higher stresses can potentially result in more restrictive P-T limits, even if the RTNOT for these components is not as high as that of RV beltline materials that have simpler geometries.

2. Ferritic RCPB components that are not RV beltline shell materials may have material properties, in particular initial RTNDT values, which may define more restrictive P-T limits that those for the RV beltline shell materials.

Issue: In Attachment 4 to the submittal dated December 14,2012, the licensee submitted information indicates that the beltline weld P-T curves are more conservative (limiting) than the P-T curves for the inlet and outlet nozzles. Attachment 4 also provided all of the inputs (per NRC Generic Letter 92-01) for evaluating the properties at the end of extended life for the beltline materials (chemistry and initial RTNOT and upper shelf Charpy energy, as well as neutron fluence) used to generate the limiting beltline weld P-T curves. Attachment 4, Section 4.7 indicates that P-T curves for the inlet and outlet nozzles were based on an assumed RT NOT of 60°F for the limiting nozzle, but does not provide any justification for this assumption. TMI-1 Updated Final Safety Analysis Report, Table 4.3-3, provides Charpy impact data for the nozzles, but no copper content. Neutron fluence values for the nozzle forgings are not included in any of the attachments to the submittal dated December 14,2012 Request: The NRC staff requests that the licensee provide the inputs for evaluating the properties at the end of extended life for the inlet and outlet nozzles - chemistry and initial unirradiated RT NDT, unirradiated upper shelf Charpy energy, and fluence.

M. Pacilio -2 Please contact me at 301-415-2833, if you have any questions.

Sincerely, Iral Peter Bamford, Project Manager Plant Licensing Branch 1-2 Division of Operating Reactor licensing Office of Nuclear Reactor Regulation Docket No. 50-289

Enclosure:

Request for Additional Information cc: Distribution via Listserv DISTRIBUTION:

PUBLIC RidsNrrPMThreeMilelsland Resource LPLI-2 RtF RidsAcrsAcnw MailCTR Resource RidsNrrLAABaxter Resource RidsNrrDeEvib Resource RidsRgn1 MailCenter Resource RidsNrrDorlDpr Resource RidsNrrDorlLpl1-2 Resouce PPurtscher. NRR CFairbanks. NRR ADAMS Accession Number' ML13193A175

• via memo **via email OFFICE LPL1-21PM LPL1-2/LA EVIB/BC* LPLI-2/BC NAME PBamford ABaxter SRosenberg* VRodriguez (JLamb for)

DATE 07/18/2013 07/22112013 07/02/2013 07/22/2013 OFFICIAL RECORD COpy