ML20211D406

Forwards RAI Re Info on Plant,Unit 1 Pressurized Thermal Shock Evaluation.Rai Requested within 60 Days of Ltr Date

ML20211D406
Person / Time
Site:	Prairie Island
Issue date:	09/18/1997
From:	Wetzel B NRC (Affiliation Not Assigned)
To:	Richard Anderson NORTHERN STATES POWER CO.
References
TAC-M97850, NUDOCS 9709290126
Download: ML20211D406 (4)

Text

. 'o l September 18, 1997 Mr. Roger 0. Anderson, Director-Licensing and Management Issues Northern States Power Company 414 Nicollet Mall Minneapolis, Minnesota 55401

SUBJECT:

REQUEST FOR ADDITIONAL-lNFORMATION ON THE PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNIT 1 PRESSURIZED THERMAL SH0CK EVALVATION (TAC N0 M97850)

Dear Mr. Anderson:

By letter dated January 15, 1997. Northern States Power Con a ny provided an analysis of a reactor vessel surveillance capsule and a pressurized thermal shock (PTS) evaluation for Prairie Island Nuclear Generating Plant Unit 1.

This submittal-was superseded in its entirety by letter dated May 13, 1997.

The staff recuires some additional information to complete our review of your submittal. Our request for additional information (RAl) is enclosed.

Please provide your response to the staff's RAI within 60 days of the date of this letter in order to support the staff's review schedule, If you have any

-questions regarding the content of the RAI, please contact me at (301) 415 1355.

Sincerely.

ORIGINAL SIGNED BY Beth A. Wetzel, Senior Project Manager Project Directorate 111-1 Division of Reactor Projects - lil/IV Office of Nuclear Reactor Regulation Docket Nos. 50-282, 50 306

Enclosure:

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Mr. Roger O. Anderson, Director Prairie Island Nuclear Generating Northem States Power Company Plant cc:

J. E. Silberg, Esquire Site Licensing Shaw, Pittman, Potts and Trowbridge Prairie Island Nuclear Gererating 23r0 N Street, N. W. Plant Washington DC 20037 Northem States Power Company 1717 Wakonade Drive East

Plant Manager Welch, Minnesota 55089 Prairie Island Nuclear Generating Plant Tribal Council Northem States Power Company Prairie Island Indian Community 1717 Wakonade Drive East ATTN

Environmental Department Welch, Minnesota 55089 5636 Sturgeon Lake Road Welch, Minnesota 55089 Adonis A. Neblett Assistant Attomey General Office of the Attomey General 455 Minnesota Street Suite 900 St. Paul, Minnesota 55101-2127 U.S. Nuclear Regulatory Commitsion Rosident inspector's Office 1719 Walconade Drive East Welch, Minnesota 55089-9642 Regional Administrator, Region 111 U.S. Nuclear Regulatory Commission 801 Warrenville Road Lisle, Illinois 60532-4351 Mr. Jeff Cole, Auditor / Treasurer Goodhue County Courthouse Box 408 Red Wing, Minnesota 55066-0408 Kris Sanda, Commissioner Department of Public Service 121 Seventh Place East Suite 200 '

St. Paul, Minnesots 55101-2145 November 1990

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!' - REQUEST FOR ADDITIONAL INFORMATION l

PRAIRIE ISLAND UNIT 1

1. It-was stated that the shift in RT was less than the two-siama allowancerequ:redbyRegulatoryG9ude(RG)1.99("RadiationDamageto Reactor Vessei Materials ), Revision 2, for all of the materials except intermediate shell forging C (tangential orientation) and the weld metal. Discuss the significance of underpredicting the shift in RT ,

particularly with respect to the ability to conservatively project Die adjusted reference temperature given credible or noncredible surveillance data.

2. Discus: the significance of the decrease in USE [ upper-shelf energy) being greater than predicted for the correlation monitor material.

3. The predicted 30 ft-lb transition temperature shift listed in Table 5-12 of WCAP-14779 (" Analysis of Capsule S from Northern States Power Company.

Prairie Island Unit 1 Reactor Vessel Radiation Surveillance Program").

Revision 1, for capsule R is incorrect. The correct value should be 97.8, Please verify.

4. In Appendix D of WCAP-14779, an evaluation of the credibility of the surveillance data was provided. In this evaluation, the ratio procedure described in Position 2.1 of RG 1.99, Revision 2, was not used and the y-intercept for the best-fit line was not set to zero as RG 1.99 indicates it should. Furthermore, when credibility was evaluated.-the scatter was compared to a value of 34 *F for base metal and 56 *F for weld metal.

Provide an updated credibility analysis that (a) addresses the need to perform the ratio procedure (i.e., if the copper and nickel content of the surveillance weld differs from the vessel weld (refer to question 6), evaluate the credibility of the data using the ratio 3rocedure): (b) has a y-intercept value of zero (i.e., the best fit line las a shift of zero when the fluence factor is zero); and (c) compares the scatter of the best fit line to a value of 17 'F for base metal and 20 *F for weld metal.

5. Clarify the statement on page D-6 of WCAP-14779 regarding the plot of correlation monitor material which states that the " data has been shifted such that the mean value is at zero and the two-sigma bound at 45 *F."

6. The Prairie Island 1 surveillance weld was fabricated from the same wire (weld heat) as the vessel intermediate to lower shell circumferential weld (Wire UM 40. Heat Number 1752: Flux UM 89. Lot 1230). [ Note that Table 4-5 of WCAP-14779 Revision 1 appears to incorrectly refer to the weld wire as UM 89 since other documentation refers to the weld wire as UM 40.] With respect to the best-estimate chemistry for the vessel and surveillance weld, please respond to the following:

ENCLOSURE

a. Were any chemistry results obtained from the analyses of weld metal qualification test samples or from weld dropout specimens .

for heat-number 17527

b. In a letter dated November 24, 1993, the estimates for copper and nickel for the vessel weld (i.e., 0.14% and 0.17%, respectively) were reported as being determined from a weld fabricated from two weld heats (i.e., weld heats 1752 and 3049) and that 0.14% copper and 0.17% nickel represented the highest and most conservative values of these elements that could possibly exist in the weld.

Why were two different weld heats (i.e., weld heats 1752 and 3049) evaluated during the determination of the best-estimate chemistry for the vessel weld?-

c. In a letter dated October 31 - 1977 (Table 2 for Prairie Island 2),

it was indicated that weld Wire VM 40, Heat Number 1752: Flux UM 89. Lot 1263 contained 0.14% cop)er and 0.14% nickel. Why was this data point not considered in tie determination of the best-estimate chemistry listed in Table 4-5 of WCAP-14779 Revision 1?

d. Was copper-coated filler wire used in the fabrication of the vessel and/or surveillance weld?

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