ML13150A255

NRR E-mail Capture - Monticello Nuclear Generating Plant - Draft Request for Additional Information (Srxb & Evib) in Support of EPU LAR Review

ML13150A255
Person / Time
Site:	Monticello
Issue date:	05/17/2013
From:	Beltz T Plant Licensing Branch III
To:	Fields J Northern States Power Co
Beltz TA
References
TAC MD9990
Download: ML13150A255 (5)

Text

1 NRR-PMDAPEm Resource From:

Beltz, Terry Sent:

Friday, May 17, 2013 7:53 AM To:

'Fields, John S.'

Cc:

Carlson, Robert; Parks, Benjamin; Sydnor, Christopher

Subject:

Monticello Nuclear Generating Plant - Draft Request for Additional Information (SRXB &

EVIB) in Support of EPU LAR Review (TAC No. MD9990)

Attachments:

Monticello - Request for Additional Information (EVIB & SRXB) in Support of EPU LAR Review.docx

Dear Mr. Fields:

By letter dated November 5, 2008, Northern States Power Company, a Minnesota Corporation (NPSM, the licensee), submitted a license amendment request (LAR) for the Monticello Nuclear Generating Plant (MNGP).

The proposed amendment would change the MNGP operating license to increase the maximum authorized power level by approximately 13 percent of the current licensed thermal power. The proposed request for extended power uprate (EPU) represents an increase of approximately 20% above the original licensed thermal power level.

The U.S. Nuclear Regulatory Commission (NRC) staff in the Reactor Systems Branch and Vessel & Internals Integrity Branch of the Office of Nuclear Reactor Regulation has identified areas where additional information is needed to complete its review related to the Monticello EPU LAR. The draft requests for additional information (RAIs) are attached.

You may accept these as formal requests for additional information and respond to the questions within 30 days. Alternatively, you may request to discuss the contents of these RAIs with the NRC staff in a conference call, including any needed changes to the proposed response date.

Please let me know if you have any questions or concerns.

Sincerely, Terry A. Beltz, Senior Project Manager Plant Licensing Branch III-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation (301) 415-3049 Terry.Beltz@nrc.gov

Hearing Identifier:

NRR_PMDA Email Number:

711 Mail Envelope Properties (7E9EA9BB82325E46B07B0F04F99B40D87C56038A45)

Subject:

Monticello Nuclear Generating Plant - Draft Request for Additional Information (SRXB & EVIB) in Support of EPU LAR Review (TAC No. MD9990)

Sent Date:

5/17/2013 7:53:25 AM Received Date:

5/17/2013 7:53:00 AM From:

Beltz, Terry Created By:

Terry.Beltz@nrc.gov Recipients:

"Carlson, Robert" <Robert.Carlson@nrc.gov>

Tracking Status: None "Parks, Benjamin" <Benjamin.Parks@nrc.gov>

Tracking Status: None "Sydnor, Christopher" <Christopher.Sydnor@nrc.gov>

Tracking Status: None

"'Fields, John S.'" <John.Fields@xenuclear.com>

Tracking Status: None Post Office:

HQCLSTR01.nrc.gov Files Size Date & Time MESSAGE 1507 5/17/2013 7:53:00 AM Monticello - Request for Additional Information (EVIB & SRXB) in Support of EPU LAR Review.docx 21145 Options Priority:

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ZZZ

REQUEST FOR ADDITIONAL INFORMATION OFFICE OF NUCLEAR REACTOR REGULATION REACTOR SYSTEMS BRANCH AND VESSEL & INTERNALS INTEGRITY BRANCH IN SUPPORT OF THE LICENSE AMENDMENT REQUEST FOR EXTENDED POWER UPRATE MONTICELLO NUCLEAR GENERATING PLANT, UNIT 1 NORTHERN STATES POWER COMPANY DOCKET NO. 50-263 (TAC NO. MD9990)

1. Section 2.1.2 of the NEDO-33322, Safety Analysis Report for Monticello Constant Pressure Power Uprate, Revision (Rev.) 3, October 2008 (the non-proprietary version of the power uprate safety analysis report (PUSAR)) dispositions the upper shelf energy (USE) for the reactor pressure vessel (RPV) beltline materials by stating that [t]he USE remains bounded by the [Boiling Water Reactor Vessel and Internals Project (BWRVIP)] equivalent margins analysis [EMA], thereby demonstrating compliance with [10 CFR Part 50,] Appendix G.

Section 4.2.1.2 of NUREG-1865, Safety Evaluation Report [SER] Related to the License Renewal of the Monticello Nuclear Generating Plant, October 2006 (ADAMS Accession No. ML063050414)) documents the staffs evaluation of the 54 effective full power year (EFPY)

USE projections for three RPV beltline materials. Table 4.2.1-1 of the SER summarizes the staffs review and acceptance of these USE projections. All three 54 EFPY USE projections were found to be acceptable because they exceed the 50 ft-lbs acceptance criterion specified in 10 CFR Part 50, Appendix G.

Key points from the staffs license renewal evaluation are summarized below:

The staff issued an RAI requesting that the applicant determine the impact of surveillance data on the USE for the limiting RPV beltline plate (Heat No. C2220). In its RAI response, the applicant calculated an adjusted percentage USE decrease of 33.5 percent using the procedures in Position 2.2 of Regulatory Guide (RG) 1.99, Radiation Embrittlement of Reactor Vessel Materials, Rev. 2, May 1988. The 33.5 percent adjusted decrease in USE was found to exceed the BWRVIP EMA acceptance criterion for BWR Type 3 through 6 plate materials. However, a 54 EFPY USE projection of 57.5 ft-lbs was calculated, based on the 33.5 percent adjusted decrease and a transverse unirradiated USE value of 86.5 ft-lbs for the limiting plate, as documented in the SER.

The staff also requested that the applicant provide a direct projection of the 54 EFPY USE for the RPV beltline shielded metal arc welds (SMAWs). The applicant calculated a 54 EFPY USE value of 68 ft-lbs using the procedures in Position 1.2 of RG 1.99, Rev. 2, based on a lower 95/95 confidence unirradiated USE value from the BWRVIP SMAW database, as documented in the SER.

The BWRVIP EMAs are not applicable to RPV nozzles, nozzle-to-shell welds, or other structural discontinuities, due to the effects of stress concentration in these components. Therefore, the staff requested that the applicant provide a direct projection of the 54 EFPY USE for the RPV beltline recirculation inlet nozzle forgings (N2 nozzles).

The applicant calculated a 54 EFPY USE value of 52 ft-lbs using the procedures in Position 1.2 of RG 1.99, Rev. 2, based on a generic unirradiated USE of 60 ft-lbs (lower 95/95 confidence value) for the SA-508, Class 2 forging data set, as documented in the SER.

Please update the 54 EFPY USE projections for the above materials based on the consideration of EPU conditions. In addition, please provide a 54 EFPY USE projection or valid EMA for the N2 nozzle-to-shell beltline welds for EPU conditions. As indicated in part

b. of Question 3 below, USE projections for EPU conditions should account for any credible plant-specific and BWRVIP integrated surveillance program (ISP) surveillance data that result in non-conservative adjustments to the projected percentage decrease in USE at 54 EFPY, based on the procedures in Position 2.2 of RG 1.99, Rev. 2.

2. Describe the current reactor vessel neutron fluence calculations that support EPU operation:

a. Explain whether and how they adhere to the guidance contained in NRC Regulatory Guide 1.190, Calculational and Dosimetry Methods for Determining Pressure Vessel Neutron Fluence, or how they are otherwise acceptable.

b. Reference the methodology used to perform the calculations, if such a document exists.

c. Describe how the EPU core flux is represented in the calculations.

d. Indicate whether the fluence in any location is increased by any conservative augmentation factors, and describe the nature of, and reason for, the augmentation.

e. Provide information to compare the EPU core flux to actual EPU core designs to indicate whether the fluence calculations acceptably represent planned facility operation.

3. List all PUSAR sections that have been superseded by the implementation of more recent RPV neutron fluence calculations and changes to any material properties affecting the neutron embrittlement analyses for the RPV and internals. Explain how the information is superseded. Revised or marked up PUSAR sections may facilitate the review, if there are substantial changes. The assessment should take into consideration the following:

a. The implementation of revised pressure-temperature (P-T) limit curves and associated changes to the adjusted RTNDT calculations (including the neutron fluence, material property inputs, and application of credible BWRVIP ISP data) used for generating the P-T limit curves;

b. Any changes to the upper shelf energy projections or equivalent margins analyses (including the neutron fluence, material property inputs, and application of credible BWRVIP ISP data) that support compliance with the upper shelf energy (USE) requirements of 10 CFR Part 50, Appendix G through 54 effective full power years (EFPY);

c. Any changes to the 54 EFPY circumferential weld and axial weld properties that support RPV circumferential weld examination relief for 54 EFPY; and

d. Any changes that could affect the adequacy of the RPV internals aging management programs under EPU conditions.