ML20198D999

Forwards Responses to 980916 RAI Re Response to GL 97-01, Degradation of Control Rod Drive Mechanism Nozzle & Other Vessel Closure Head Penetrations

ML20198D999
Person / Time
Site:	Vogtle
Issue date:	12/16/1998
From:	Beasley J SOUTHERN NUCLEAR OPERATING CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LCV-1015-D, TAC-M98608, TAC-M98609, NUDOCS 9812230306
Download: ML20198D999 (5)

Text

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• J. Bernie Beasley, Jr., P.E. Southern Nuclear  ;

. V.ce President Operating Company, Inc.

Vogtle Project 40 invemess Center Parkway P.O. Box 1295 Birming.arn Alabama 35201 Tel 205 992.7110 Fax 205.992.0403 SOUTHERNA I December 16, 1998 COMMW l

! Energ to Serve nur World' LCV-1015-D  ;

1 Docket Nos. 50-424 50-425 I

TAC Nos.: M98608 I M98609

]

U.S. Nuclear Regulatory Commission Attn: Document Control Desk I Washington, D.C. 20555-0001 ,

Ladies and Gentlemen:

VOGTLE ELECTRIC GENERATING PLANT RESPONSE TO NRC STAFF REQUEST FOR ADDITIONAL INFORM ATION

'CONCERNING GENERIC LETTER 97-01," DEGRADATION OF CRDM/CEDM NOZZLE AND OTHER VESSEL CLOSURE HEAD PENETRATIONS"  ;

By letter dated September 16,1998, the NRC requested additional information (RAl) regarding the response to Generic Letter 97-01," Degradation of Control Rod Drive Mechanism Nozzle and Other Vessel Closure Head Penetrations", for Vogtle Electric Generating Plant-Units 1&2.

A response was requested 90 days after the receipt of the letter from the NRC.

The EPRI Materials Reliability Project, in cooperation with the PWR Owners groups, is coordinating a generic industry program for the Alloy 600 head penetrations. As part of that program, they have developed a comprehensive industry response to the RAls that were sent to VEGP and other PWRs. On December 11,1998, NEl submitted to the NRC that generic industry response to address the questions in the RAl. SNC's response to the NRC questions raised in the VEGP RAI is provided as part of the generic industry response. As a guide, the attachment provides a restatement of the NRC questions in the VEGP RAI, and the response indicates the appropriate location in the NEl letter that responds to that NRC question.

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If there are any questions concerning our response, please contact L. K. Mathews at (205) 992-7729.

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'.U. S. Nuclear Regulatory Commission Page 2 l

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l JBB/PAH/gmb xc: Southem Nuclear Ooerating Comoany i 1

Mr. J. T. Gasser .

Mr. M. Sheibani- ,

SNC Document Management ]

U. S. Nuclear Regulatory Commission )

Mr. L. A. Reyes, Regional Administrator J Mr. D. H. Jaffe, Senior Project Manager, NRR Mr. J. Zeiler, Senior. Resident Inspector, Vogtle i l

LCV-1015-D v

4 ATTACHMENT RESPONSE TO NRC STAFF REQUEST FOR ADDITIONAL INFORMATION CONCERNING GENERIC LETTER 97-01, " DEGRADATION OF CRDM/CEDM NOZZLE AND OTHER VESSEL CLOSURE HEAD PENETRATIONS" In our response, we restate the question received from the NRC. Our response indicates the location in the NEI letter where the requested information can be located.

L FROM NRC:

1. In WCAP-14901, WEC did not provide any conclusions as to what the probabilistic failure model would lead the WOG to conclude with respect to the assessment of primary water stress-corrosion cracking (PWSCC)in WEC-designed vessel head penetrations.

' With respect to the probabilistic susceptibility model (e.g., probabilistic failure model) provided I in WCAP-14901:

l a. Provide the susceptibility rankings compiled for the WOG member plants for which WCAP-14901 is applicable. In regard to other WOG member plants to which WCAP-14901 is applicable, include the basis for establishing the ranking of your plant relative to the others.

VEGP Response:

l a. See response to Generic Question 4 in Section 1 of Enclosure 5.

FROM NRC:

l b. Describe how the probabilistic failure model in WCAP-14901 for assessing postulated flaws in the VHP nozzles was benchmarked, and provide a list and discussion of the standards the model was benchmarked against.

VEGP Response:

l b. See response to Generic Question 2 in Section I of Enclosure 5. (Westinghouse Model applies.)

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ATTACHMENT (CONTINUED)

RESPONSE TO NRC STAFF REQUEST FOR ADDITIONAL INFORM ATION CONCERNING GENERIC LETTER 97-01, " DEGRADATION OF CRDM/CEDM NO. ZZLE AND OTHER VESSEL CLOSURE HEAD PENETRATIONS" From NRC:-

I c. Provide additional information regarding how the probabilistic failure models in WCAP-14901 will be refined to allow the input of plant-specific inspection data into the model's

. analysis methodology.

VEGP Response:

I c. See response to Generic Question 3 in Section I of Enclosure 5. (Westinghouse Model applies.)

From NRC:

Id. Describe how the variability in product forms, material specifications, and heat treatments used to fabricate each CRDM penetration nozzle at the WOG member utilities are -

addressed in the probabilistic crack initiation and growth models described or referenced in Topical Report WCAP-14901, VEGP Response:

Id. See response to Generic Question 1 in Section 1 of Enclosure 5. (Westinghouse Model applies.)

From NRC:

2. Table 1-2 in WCAP-14901 provides a summary of the key tasks in WEC's VHP nozzle assessment program. The table indicates that the Tasks for (1) Evaluation of PWSCC I

Mitigation Methods, (2) Crack Growth Data and Testing, and (3) Crack initiation Characterization Studies have not been completed and are still in progress. In light of the fact that the probabilistic susceptibility models appear to be dependent, in part, on PWSCC crack initiation and growth estimates, provide your best estimate when t%se tasks will be completed by WEC, and describe how these activities relate to and will be used to update the probabilistic susceptibility assessment of VHP nozzles at your plant. j i

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, , ATTACHMENT (CONTINUED) '

l RESPONSE TO NRC STAFF REQUEST FOR ADDITIONAL INFORMATION l CONCERNING GENERIC LETTER 97-01," DEGRADATION OF CRDM/CEDM  !

N_QZZLE AND OTHER VESSEL CLOLURE HEAD PENETRATIONS" l

l VEGP Response: -

2. See response to Generic Question 5 in Section 1 of Enclosure 5.

From NRC:

3. In the NEl letters of January 29,1998 (Ref.1), and April 1,1998 (Ref. 2), NEl i

mdicated that inspection plans have been developed for the VHP nozzles at the Farley Unit 2 L plant in the year 2002, and at the Diablo Canyon Unit 2 plant in the year 2001, respectively. The '

staff has noted that although you have endorsed the probabilistic susceptibility model described in WCAP-14901, Revision 0, other WOG members have endorsed a probabilistic susceptibility

. model developed by an alternate vendor of choice. The WOG's proposal to inspect the VHP L nozzles at the Farley Unit 2 and the Diablo Canyon Unit 2 plants appears to be based upon a

. composite assessment of the VHP nozzles at all WOG member plants.. Verify that such a l composite ranking assessment has'been applied to the evaluation of VHP nozzles at your plant.

I Ifcomposite rankings of the VHP nozzles at WOG member plants have been obtained from the .

l composite results of the two models, justify why application of the probabilistic' susceptibility -!

L model described in WCAP-14901, Revision 0, would yield the same comparable relative ,

l rankings of the VHP nozzles for your plant as would application of the alternate prcbabilistic l susceptibility model used by the WOG member plants not subscribing to WCAP-14901, Revision 0. Comment on the susceptibility rankings of the VHP nozzles at your plant relative to the susceptibility rankings of the VHP nozzles at the Farley Unit 2 and Diablo Canyon Unit 2 plants.

L .!1 L VEGP Response:

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3. See response to WOG Specific Question 1 of.Section II of Enclosure 5.

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