ML20092M992

Application for Amend to License NPF-8,modifying Unit 2 TSs 3/4.4.6 & 3/4.4.7 Re SG Tube Plugging Criteria for Tube Support Plates.Westinghouse Authorizing Use of Proprietary Rept WCAP 12871,Rev 2 Encl

ML20092M992
Person / Time
Site:	Farley
Issue date:	02/20/1992
From:	Woodard J SOUTHERN NUCLEAR OPERATING CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20034D323	List: ML20092M992 ML20092N003 ML20092N028 ML20094J968
References
NUDOCS 9202280275
Download: ML20092M992 (7)

Text

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• Docket tio. 50-364 U. S. iluclear Regulatory Commission ATill: Document Control Desk Washington, DC 20555 Joseph li. f arley 11uclear Plant Unit 2 Steam Generator TubtSynnEt_ Plate Interim Plungina Criteria

Dear Sirs:

By letter dated February 26, 1991, Alabama Power Company submitted a steam generator tube support plate alternate plugging criteria. On flovember 13, 1991, in response to questions and comments from the 11RC Staff, a revised submittal was made simplifying the alternate plugging criteria and including additional pulled tube data. On January 29, 1992, the f1RC Staff indicated to Southern fluclear Operating Company that the amendment would not be approved prior to the upcoming Unit 2 Spring 1992 outage. At that time, the Staff indicated that a more conservative submittal might be approved on a one cycle basis. This letter provides Southern tiuclear's proposed, one cycle, interim plugging criteria for f arley Unit 2. 11RC approval is requested by March 27, 1992.

Southern fluclear proposes that the Unit 2 technical specifications be modified, on an interim basis, to clarify that the percent tube wall degradation criteria currently employed is inappropriate to determine serviceability of tubes with flaw indications at the tube support plate intersections. Rather, the appropriate method for determining serviceability is by a methodology that more reliably assesses structural integrity. As a result of the structural integrity assessment at farley Nuclear Plant, tube indications within the tube support plate with a bobbin coil voltage less than or equal to 1.0 volt will be left in service, furthermore, Southern fluclear will ensure that primary-to-secondary leakage as a result of a steam line break are sufficiently low to ensure the dose at the site boundary is a small fraction of the Part 100 limits. Southern tiuclear further proposes to modify the technical specifications to reduce the total allowable primary-to-secondary operational leakage from any one steam generator from 500 gallons per day to 150 gallons per day. The total allowable primary-to-secondary operational leakage through all steam generators will be reduced from one gallon per minute (1,440 gallons per day) to 450 gallons per day.

The proposed interim criteria is comoosed of two parts. Attachment I contains the proposed interim voltage plugging criteria including a sampling program. Attachment 2 contains the steam line break primary-to-secondary leakage criteria to b9 used with the interim criteria.

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U.S. fluclear Regulatory Commission Page 2 Attachment 3 contains the proposed changed Technical Specification pages in support of the interim plugging criteria.

Attachment 4 provides a significant hazards evaluation for the pror sed interim plugging criteria in accordance with 10 CfR 50.92. The technical justifications supporting the proposed change are provided in Attachment 5 as:

, 1. WCAP-12871, Revision 2 - J.H. f arley Units 1 and 2 SG Tube Plugging Criteria for ODSCC at lube Support Plates (Proprietary).

2. WCAP-12872, Revision 2 - J.H. farley Units 1 and 2 SG Tube Plugging Criteria for ODSCC at Tube Support Plates (flon-Proprietary).

These WCAPs provide the basis for the use of a 3.6 volt alternate plugging criteria for farley Units 1 and 2. Consequently, these WCAPs provide a conservative basis for use of the 1.0 volt interim plugging criteria threshold on a one cycle basis for Unit 2. These WCAPs supersede the Revision 1 WCAPs provided with the flovember 13, 1991 submittal and should be used as updated justification for the alternate plugging criteria.

Attachment 6 provides responses to the issues identified in the Staff's January 29, 1992 letter. Attachment 7 provides the proposed eddy current guidelines for use in the Unit 2 Eighth Refueling Outage, assuming the interim criteria is approved for use.

As the Staff requested, the voltage / burst and voltage / leakage correlations for 3/4 inch tubes are being compiled into a separate WCAP.

Included in that WCAP is one method which could be used to combine the 3/4 inch and 7/8 inch tube data. This methodology is not necessarily the most correct manner to combine the data. Unfortunately, time constraints have precluded further evaluation of the data. This WCAP will be forwarded to the t1RC Staff separately as soon as it is received from Westinghouse.

Also enclosed are a Westinghouse authorization letter, CAW-92-265, accompanying affidavit, Proprietary Information tiotice, and Copyright f40tice. As item 1 contains information proprietary to Westinghouse Electric Corporation, it is supported by an affidavit signed by Westinghouse, the owner of the information. The affidavit sets forth the basis on which the information may be withheld from public disclosure by the Commission and addresses with specificity the considerations listed in paragraph (b)(4) of Section 2.790 of the Commission's regulations.

4 Accordingly, it is respectfully requested that the information which is proprietary to Westinghouse be withheld from public disclosure in j accordance with 10 CFR Section 2.790 of the Commission's regulations.

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U.S. Nuclear Regulatory Commission Page 3 Correspondence with respect to the copyright or proprietary aspects of the items listed above or the supporting Westinghouse Affidavit should reference CAW-92-265 and should be addressed to R. P. DiPlazza, Manager of fluclear Safety Licensing, Westinghouse Electric Corporation, P. O.

Box 355, Pittsburgh, Pennsylvania 15230-0355.

If there are any questions, please advise.

Respectfully submitted, SOUlllERilNKl(AROPERAINGCOMPANY

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. D. Woodard --

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1 Attachment 1 Voltage Plugging Criteria for the l i

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Interim Plugging Criteria ,

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Voltage Plugging Criteria So_uthern Nuclear Operatina Company proposal:

1. A bobbin inspection of 100% of the hot and cold leg steam generator tube support plate intersections will be performed.

2. Flaws within the bounds of the tube support plate with bobbin voltage less than or equal to 1.0 volt will be allowed to remain in service.

3. flaws within the beunds of the tube support plate with a bobbin voltage greater than 1.0 volts will be repaired or plugged except as noted in 4.

4. Flaw indications within the bounds of the tube support plate with a bobbin voltage greater than 1.0 volt but less than or equal to 3.6 volts may remain in service if a rotating pancake coil probe (RPC) inspection does not detect a flaw. Flaw indications with a voltage greater than 3.6 volts will be plugged or repaired.

5, A sample RPC inspection of 100 tube sup) ort plate intersections will be performed. All intersections with a boabin dent voltage exceeding 5 volts will be inspected. Other intersections in the sample population will be based on inspecting intersections with artifact indications and intersections with unusual phase angles. Expansion of the sample plan, if required, will be based on the nature and number of the flaws discovered.

Justification:

WCAP-12871, Revision 2, J.M. Earley Units 1 and 2 SG Tube Plugging Criteria for ODSCC at Tube Support Plates, provides the develo] ment of a 3.6 volt alternate plugging criteria. Use of a 1.0 volt thresiold for a) plication of the current Technical Specification is'more conservative than tie use of the 3.6 volt criteria. Burst pressure for steam generator tubes with flaws within the bounds of the tube support plate will still meet the requirements of Regulatory Guide 1.121.

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Attachment 2 Steam Line Break Leakage Criteria i for the l Interim Plugging Criteria l

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Steam Line Dreak Leakage Criteria igulbern_.Nulcar Operatina Company _ntopnA11 Prior to startup, measures will be taken to limit predicted primary-to-secondary steam generator leakage in the event of a steam line break event to less than l~ gallon per minute.

l Operational primary-to-secondary leakage during normal operation will be limited to 150 gallons per day per steam generator. l duttificationi l The Bases for Technical Specification 3/4.4.7.2 indicates that the acceptance i criteria- for steam line break accident site boundary dose is "a small fraction .

of Part-100 limits", i.e., 30 rem. This acceptance criteria is based on a 1 gallon per minute steam generator primary-to-secondary leak rate. Therefore, ,

predicted total primary-to-secondary steam generator tube leakage will remain within the current licensing basis for Unit 2.

Primary-to-secondary leakage is currently limited to 500 gallons per day per steam generator. The use of a 150 gallons per day is more restrictive, and as ,

a result, provides greater margin of safety than provided by the current Technical - Specifications.  !

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