ML18102B568

LER 95-012-02:on 761211,adequacy of Turbine Driven Auxiliary FW Pump Encls Occurred.Caused by Inadequate Verification of Assumptions in Calculations Performed to Evaluate Previously Identified.Calculation Assumptions reviewed.W/970829 Ltr

ML18102B568
Person / Time
Site:	Salem
Issue date:	08/29/1997
From:	Garchow D, Enrique Villar Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-95-012, LER-95-12, LR-N970564, NUDOCS 9709100126
Download: ML18102B568 (5)

Text

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e PS~G Public Service Electric and Gas Company P.O. Box 236 Hancocks Bridge, New Jersey 08038-0236 Nuclear Business Unit AUG 2 9 1997 LR-N970564 U. S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 Gentlemen:

LER 272/95-012-002 SALEM GENERATING STATION - UNIT 1 AND 2 FACILITY OPERATING LICENSE NOS. DPR-70 AND DPR 75 DOCKET NO. 50-272 AND 50-311 This Supplemental Licensee Event Report entitled "Adequacy of Turbine Driven Auxiliary Feed Water Pump Enclosure" is being submitted pursuant to the requirements of the Code of Federal Regulations 10CFR50. 73 (a) (2) (i).

Sincerely, at/2#/

David F. Garchow  : i General Manager -

Salem Operations

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Attachment EHV ,

'J C Distribution LER File 3.7 9709100126 970829 PDR ADOCK 05000311 \IUll\ U\11 U\\\ \\1\1\\1\11\\11Ull1\\1 S PDR .&&588&

95-2168 REV. 6/94

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NRC FORM 366 e

U.S. NUCLEAR REGULATORY COMMISSION e

APPROVED BY OMB NO. 3150-0104 (4-95) EXPIRES 04/30/98 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS MANDATORY INFORMATION COLLECTION REQUEST: 50.0 HRS.

REPORTED LESSONS LEARNED ARE INCORPORATED INTO THE LICENSEE EVENT REPORT (LER) LICENSING PROCESS AND FED BACK TO INDUSTRY.

COMMENTS REGARDING BURDEN ESTIMATE TO THE INFORMATION FORWARD AND RECORDS MANAGEMENT BRANCH (T-6 F33J, U.S. NUCLEAR (See reverse for required number of REGULATORY COMMISSION, WASHINGTON, DC 20 55-0001, AND TO THE PAPERWORK REDUCTION PROJECT ~3150-0104), OFFICE OF digits/characters for each block) MANAGEMENT AND BUDGET, WASHINGTON, C 20503.

FACILITY NAME (1) DOut\t: 1 NUMBER (2) PAGE(3)

Salem Generating Station Unit 1 05000 1 OF4 TITLE(4)

Adequacy of Turbine Driven Auxiliary Feed Water Pump Enclosures EVENT DATE (5) LER NUMBER (6) REPORT DATE (7) OTHER FACILITIES INVOLVED (8)

FACILITY NAME MONTH DAY YEAR YEAR I SEQUENTIAL I REVISION MONTH DAY YEAR NUMBER NUMBER Salem Generating Station-Unit 2 05000311 12 11 76 95 - 012 - 02 08 29 97 FACILITY NAME DOCKET NUMBER 05000 Ut -*" ,1 . . . THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check one or more) (11)

MODE (9) 20.2201(b) 20.2203(a)(2)(v) 50. 73(a)(2)(i) 50. 73(a)(2)(viii)

POWER 0 20.2203(a)(1) 20.2203(a)(3)(i) x 50. 73(a)(2)(ii) 50. 73(a)(2)(x)

LEVEL(10) 20.2203(a)(2)(i) 20.2203(a)(3)(ii) 50. 73(a)(2)(iii) 73.71 20.2203(a)(2)(ii) 20.2203(a)(4) 50. 73(a)(2)(iv) OTHER 20.2203(a)(2)(iii) 50.36(c)(1) 50. 73(a)(2)(v) Spec~in Abstract below or in C Form 366A 20.2203(a)(2)(iv) 50.36(c)(2) 50. 73(a)(2)(vii)

LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER (Include Area Code) .

E. H. Villar , Licensing Engineer 609- 339 -1989 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLE CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLE TONPRDS TONPRDS SUPPLEMENTAL REPORT EXPECTED (14) EXPECTED MONTH DAY YEAR IYES SUBMISSION (If yes, complete EXPECTED SUBMISSION DATE). XINO DATE(15)

ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (16)

In early November 1995, during an evaluation of a condition adverse to quality report, it was discovered that assumptions in the High Energy Line Break (HELB) analysis for the turbine driven auxiliary feed water pump (TDAFP) enclosure did not match as-built conditions and could allow pressure in the enclosure to exceed the enclosure design pressure during a HELB. A structural analysis of the TDAFP enclosure has shown that it would not be operable during a HELB due to overpressurization. The cause of this occurrence is attributed to inadequate verification of assumptions in the calculations performed to evaluate previously identified as-built design deficiencies. Corrective actions include a review of other HELB calculation assumptions and completion of a design change to eliminate the TDAFP overpressure.

This condition is being reported in accordance with 10CFRS0.73(a) (2) (ii) . A four hour 10CFR50.72 notification was made on November 16, 1995.

NRC FORM 366 (4-95)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (4-95)

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LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

YEAR I SEQUENTIAL NUMBER I REVISION NUMBER 2 OF 4 Salem Generating Station - Unit 1 05000272 95 - 012 - 02 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)

PLANT AND SYSTEM IDENTIFICATION Westinghouse - Pressurized Water Reactor Auxiliary Feedwater System (AF) {BA}*

Auxiliary Building Ventilation System (ABS) {VF}

• Energy Industry Identification System (EIIS) codes and component function identifier codes appear in the text as {SS/CCC}.

IDENTIFICATION OF OCCURRENCE Event Date: Unit 1: December 11, 1976 (Initial Plant Criticality)

Unit 2: August 2, 1980 (Initial Plant Criticality)

Date Determined to be Reportable: November 16, 1995 CONDITIONS PRIOR TO OCCURRENCE Unit 1: De fueled, 0 % Reactor Power Unit 2: Mode 5, 0 % Reactor Power There were no structures, components, or systems that were inoperable at the start of the event that contributed to the event.

DESCRIPTION OF OCCURRENCE In early November 1995, during an evaluation of a condition adverse to quality report, it was discovered that assumptions in the HELB analysis for the turbine driven auxiliary feed water pump (TDAFP) {BA/P} enclosure did not match as-built conditions and could allow pressure in the enclosure to exceed the enclosure design pressure during a HELB.

The ABS 6 damper {VF/DMP} is located in the wall separating the TDAFP enclosure and the adjacent pipe chase. The ABS 6 damper automatically opens to protect the TDAFP enclosure from overpressurization during a HELB in the enclosure. The HELB analysis performed for a steam line break in the TDAFP enclosure assumed that the ABS 6 damper opened instantaneously when the pressure in the enclosure reached the setpoint.

NRC FORM 366A (4-95)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (4-95)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

YEAR I SEQUENTIAL NUMBER IREVISION NUMBER 3 OF 4 Salem Generating Station - Unit 1 05000272 95 - 012 02 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)

DESCRIPTION OF OCCURRENCE (cont'd)

Delays actually exist between the pressure reaching the setpoint and the initiation of the opening stroke of ABS 6 damper, and the damper reaching the full open position. The analysis also assumed that the damper full open position provided 100 percent of the damper opening for pressure relief. In the full open position the damper opening area is actually less than 100 percent.

It has been determined that with these delays and the less than full open damper opening, the peak pressure in the enclosure following a steam line break will exceed the design pressure of the TDAFP enclosure and result in the enclosure becoming inoperable.

The TDAFW pump enclosure could have also been affected via the floor drains within the enclosure. The floor drains share a common header with drains outside the enclosure, and some of these areas contain high energy lines.

Since these floor drains are not isolated by sumps, traps or plugs, the TDAFW pump enclosure could have been adversely affected from a break outside the enclosure. Additionally, if the ABS 6 damper were to fail in the open position, a break in the pipe alley could have also overpressurized the enclosure and adversely affected the room temperature, such that the instrumentation could have been operated outside its environmental qualifications.

SAFETY SIGNIFICANCE An assumed failure of the TDAFP enclosure resulting from overpressurization due to a steam line break would allow steam to escape to surrounding areas.

The escaping steam has the potential to render equipment in the area, including the motor driven auxiliary feed water pumps, inoperable.

APPARENT CAUSE OF OCCURRENCE The cause of this occurrence is attributed to inadequate verification of assumptions in the calculations performed to evaluate previously identified as-built design deficiencies. During that evaluation, the primary focus was on the deficiencies being evaluated and the input assumptions were not questioned.

NRC FORM 366A (4-95)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (4-95)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

YEAR I SEQUENTIAL NUMBER I REVISION NUMBER 4 OF 4 Salem Generating Station - Unit 1 05000272 95 -- 012 02 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)

PRIOR SIMILAR OCCURRENCES Two prior similar occurrences have been identified within the past five years. The first, as reported in LER 272/91-036-01, concerned incorrect input assumptions in the steam line break analyses. The second, as reported in LER 272/95-027-00, concerned inaccurate assumptions in dose calculations.

Corrective actions taken in response to these events could not have prevented the event reported here.

CORRECTIVE ACTIONS

1. The HELB analyses for all spaces that contain air operated backdraft isolation dampers have been checked to ensure that no other overpressurization possibilities exist.

2. A modification that will eliminate overpressurization of the TDAFP enclosure in the event of a HELB will be completed prior to entry into Mode 2.

3. Details of this LER will be reviewed with Nuclear Engineering Department personnel to reinforce the importance of verifying that input assumptions are correct.

4. The design modification described in corrective action 2 above has been completed for Salem Unit 2. The modifications replaced the ABS 6 damper with a blow-out panel, and sealed the floor drains in the turbine enclosure and pipe alley, thus eliminating the cross communication paths.

5. A similar modification is being performed in Salem Unit 1 and will be completed prior to restart of Unit 1.

6. A review of the floor drain system has been initiated to identify any other potential communication issues associated with the floor drain system. Any identified deficiencies will be dispositioned in accordance with the corrective action program.

NRC FORM 366A (4-95)