ML20210C418

Final Deficiency Rept 86-16 Re Temp Envelope Requirements on Environ Qualification of Equipment Outside Containment for High Energy Line Breaks.Advance Change Notice ACN-0067 Issued for Const of Insulated Encl to Pressure Transmitters

ML20210C418
Person / Time
Site:	Beaver Valley
Issue date:	01/22/1987
From:	Carey J DUQUESNE LIGHT CO.
To:	Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
2NRC-7-011, 2NRC-7-11, 86-16, NUDOCS 8702090385
Download: ML20210C418 (4)

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M 2NRC-7-011 Beaver Valley No. 2 Unit Project Organization (412) 643-5200 Telecopy (412) 643-5200 Ext.160 S.E.G. Building P.O. Box 328 January 22, 1987 Shippingport, PA 15077 United. States Nuclear Regulatory Coninission Region I 631 Park Avenue King of Prussia, PA 19406 ATTENTION: Dr. Thomas E. Murley Administrator .

SUBJECT:

Beaver Valley Power Station - Unit No. 2 Docket No. 50-412 High Energy Line Break Concerns Outside Containment Potential Significant Deficiency Report 86-16 Gentlemen:

This Potentially Reportable Significant Deficiency Report is being submitted pursuant to the requirenents of 10CFR50.55(e). It is anticipated that no additional reports will be required.

DUQUESNE LIGHT COMPANY

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By

_J. J. Carey Sr. Vice President LMR/ijr NRC/LMR/SDR/8616 Attachnent AR/NAR cc: Mr. P. Tam, Project Manager Mr. J. Beall, NRC Sr. Resident Inspector Ms. A. Asars, NRC Resident Inspector INP0 Records Center NRC Docunent Control Desk pg2988st E86jh2 S

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Attachnent

1. Summary In June 1984, Beaver Valley Unit 2 was notified by Westinghouse of a possible unreviewed safety question concerning the tenperature enve-lope requirenents on the Environnental Qualification of equipnent outside of containnent for High Energy Line Breaks (HELB). Westing-house analyses have shown that the stean generator tube bundle may becone uncovered during a HELB resulting in superheating of the stean exiting fran the stean generator. This effect results in an increase in the tenperature of this stean and may impact the environnental qualification envelopes of safety-related equipment outside contain-ment which may be required to function during a HELB.

?. Im.nediate Action Taken The Westingnouse Owners Group, of which Duquesne Light Company is a menber, formed a High Energy Line Break /Superheated Blowdowns Outside Containnent (HELB/SBOC) Subgroup to provide steanline break mass and energy release data, and the supporting documentation necessary to address the issue of equipnent qualification.

Mr. L. M. Rabenau, Conpliance Engineer, BV-2, notified Mr. D. Limroth e NRC Region I, of this concern on Decenber 24, 1986.

3. Description of Deficiency During the NRC Containnent Systens Branch review of Westinghouse topi-cal report, " Mass and Energy Releases Following a Steanline Rupture,"

WCAP-8822, the staff noted that heat transfer to the stean from the uncovered portion of the stean generator was not properly accounted for. Based on this review, the NRC required Westinghouse to include the stean superheating in their model.

As a result of this modeling change, Westinghouse has revised the main steanline break mass and energy release data. For sone break sizes, locations, and pl ant conditions these releases may produce thennal environnents more severe than pc0Viously prescribed for environnental qualification of safety-related equipnent.

4. Analysis of Safety, Implications

a. Inside Containnent The isapact of tne superheated stean effect on the tenperature responses during HELB inside containnent has been addressed by Westinghouse and it was deter.ained to be negligible.

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b. Outside Containment Main steanline breaks in the main stean valve house and the upper elevation of the Service Building have been analyzed using the revised Westinghouse mass and energy release data.

All safety-related equipment and cables in the affected areas and their safety functions with respect to a main steanline break outside containnent have been identified. For equipnent required to perfonn a safety function for this event, actuation times have been conpared to stean generator tube uncovery time. For all functions except stean line isolation, the safety function is coupleted prior to superheated stean release. Regulatory Guide 1.97 equipment or cable in the area is required to operate after steanline isolation. For equipnent and cable required to perfonn a safety function for other than steanline isolation, the equip-ment's qualification tenperature is being compared with the tenp-erature at the beginning of stean generator tube uncovery. MSLB with superheat will also affect equipment within the BVPS-2 Mech-anical Environnental Qualification (MEQ) Progran.

A thennal lag analysis has also been perfonned on the main stean isolation valves, cabling and associated Cl ass 1E electrical equipnent to determine their actual tenperatures at isolation ,

plus 600 seconds, and up to a maximum time of 1800 seconds.

Additionally, a spurious signal analysis on safety-related equip-ment in the affected areas has been perfonned. This analysis had two objectives; the first was to detennine if a spurious signal could be generated from the high tenperature evident during an HELB; and the second was to detennine if the spurious signal could have detrimental effects on the safety systens.

5. Corrective Action, to Resolve the Deficiency All of the above mentioned analyses have been completed. These analy-ses have been incorporated into Appenaix E of the Equipnent Qualifi-cation Report - Environnental Qualification of Class IE Electrical Equipnent and transmitted to the NRC via letter 2NRC-6-099, dated Septenber 20, 1986. Suppl enental information concerning Appendix E was also transmitted to the NRC via letter 2NRC-6-126, dated Decenber 19, 1986. With the exception of the main stean isolation valve (MSIV) pressure transmitters, all Class 1E equipnent has been shown by analy-ses to perform its function while renaining wi thin its design and qualification paraneter. It was shown that the MSIV pressure trans-mitters are required to be insul ated in order to slow their tenperature response to the accident envirorrnent. Without insulation, the pressure transmi tters rapidly exceed their qualification tenperature. Additional ly, the accuracy for isolation of the MSIVs sharply decreases with increasing tenperature, thereby, potentially impacting the safety analysis. Tne insulation requirenent is documen-ted in SWEC Calculation No. 12241-US(B)-202-1. Advance Change Notice ACN-0067 has been issued for construction of the insulated enclosure for the pressure transmitters.

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l The BVPS-2 Regulatory Guide 1.97' Implenentation Report is currently under review for consistency with the analyses provided in Appendix E mentioned above. Any required revision to this report will De separately _ sub;nitted to the NRC for review.

The effects of MSLB wi th suparheat on the BVPS-2 MEQ Progran is currently under review. BVPS-2 files will be updated to denonstrate that equipnent is qualified for its application for this event.

6. Additional Reports No additional reports are expected, s.

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