ML20005B225

Responds to Generic Ltr 81-04 Re Commitments for Implementation of NUREG-0313.Inservice Insp Exams Performed on Stainless Steel Piping Sys Revealed No Evidence of Intergranular Stress Corrosion Cracking

ML20005B225
Person / Time
Site:	Cooper
Issue date:	07/01/1981
From:	Pilant J NEBRASKA PUBLIC POWER DISTRICT
To:	Eisenhut D Office of Nuclear Reactor Regulation
References
RTR-NUREG-0313, RTR-NUREG-313, TASK-A-42, TASK-OR GL-81-03, GL-81-3, GL-81-4, LQA8100214, TAC-46657, NUDOCS 8107060482
Download: ML20005B225 (3)

Text

60-1 98 GENcHAL oFFICc P. o. Box 499, COLUMBUS, NEBRASKA 68601 ic Power Distr. t H Nebraska Publ. ____

ic retemoNe non se+ s61 LQA8100214 July 1, 1981 Mr. Darrell G. Eisenhut, Director Division of Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555 Subj ect: Implementation of NUREG-0313, Revision 1

" Technical Report on Material Selection and Processing Guidelines for BWR Coolant Pressure Boundary Piping"

Reference:

1) Generic Letter 81-04 dated February 26, 1981

2) Letter T. A. Ippolito to J. M. Pilant Dated July 20, 1979

3) Letter J. M. Pilant to T. A. Ippolito Dated August 7, 1979

Dear Mr. Eisenhut:

This letter is in response to Reference 1, which transmitted the subject NUREG to all BWR licensees. Nebraska Public Power District's commitments for the implementation of NUREG-0313, Revision 1, for Cooper Nuclear Station are provided below.

Background

Cooper Nuclear Station has performed Inservice Inspection (ISI) in accordance with the ASME Boiler and Pressure Vessel Code,Section XI since 1974 and has completed two-thirds of its first ten year inspection program. In addition, an augmented ISI program of approximately 285 stainless steel welds has been performed by the General Electric Company using advanced ultrasonic examination techniques in the last six years.

None of these examinations have revealed any indications of Intergranular Stress Corrosion Cracking (IGSCC).

Based on guidance from the Nuclear Regulatory Commission (NRC), Cooper Nuclear Station capped the Control Rod Drive (CRD) return line in 1978.

This work was not the result of any IGSCC.

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Nebraska Public Power District has been active in the BWR Owners Group 8 and has a full understanding of IGSCC technology, contingency plans for repairs and possible remedies.

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e I Mr. Dirrell G. Eiesnhut July 1, 1981 Page 2 Focused Inservice Inspection Nebraska Public Power District is conducting a review of all stainless steel piping classified as Class 1 or Class 2 for inservice inspection to identify any materials which do not conform to the guidelines of NUREG-0313. This review includes the calculation of the Stress Rule Index for all welds. From this review, the District will focus the Cooper Nuclear Station ISI program on any welds which may have a re-duced resistance to IGSCC. This review should be conpleted by November 1, 1981.

Leak Detection Current leakage detection commitments as contained in Cooper Naclear Station Technical Specifications provide for evaluation of unidentified leakage and the monitoring of the sump level and air sampling system on a once-per-day (minimum) frequency. Following the issuance of IE Bulletin 79-08, a request for additional information was received, Reference 2, specifically requesting a description of "other instru-mentation which the operator might have to determine changes in reactor coolant inventory, e.g. drywell high pressure, radioactivity levels, suppression pool high temperature, containment sump pump operation, etc."

Nebraska Public Power District's response, Reference 3, included the following items which could assist the operator in determining changes in coolant inventory:

a. Drywell equipment and floor drain sump flow recorders,

b. Drywell equipment sump temperature indicator,

c. Three suppression pool water level indicators and one recorder.

d. Three primary containment and one wetwell pressure indicators.

e. Primary containment internal temperature and wetwell pool temperature.

f. Drywell process radiation monitor.

The District feels that these leakage detection requirements and available instrumentation provide adequate leakage detection due to IGSCC.

Summary Cooper Nuclear Station has been performing IS1 examinations of austenitic stainless steel piping systems since 1974 and has discovered no evidence of IGSCC. Nebraska Public Power District is conducting an IGSCC suscep-tibility evaluation of all Class 1 and 2 stainless steel piping and will

e lir. Darrall G. Eistnhut July 1, 1981 Page 3

- focus the Cooper Nuclear Station ISI program accordingly. Based on these facts and the leakage detection requirements and instrumentation 4

currently in place, the District does not plan to replace any stainless steel piping in the foreseeable future, nor do we feel it uppropriate to propose changes to the Cooper Nuclear Station Technical Specifications at this time.

Should you have any further questions regarding this issue, please contact me.

Sincerely, MA.

JayJ'N. Pilant Director of Licensing and Quality Assurance JMP:KCW:cmk-I

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