ML18101B141

LER 95-012-00:during Nov 1995,TDAFWP Encl Not Matching as- Built Conditions of 761211.Caused by Inadequate Verification of as-build Design Deficiency Calculations.Helb Calculations reviewed.W/951218 Ltr

ML18101B141
Person / Time
Site:	Salem
Issue date:	12/18/1995
From:	Gregory Cranston, Warren C Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-95-012-01, LER-95-12-1, LR-N95231, NUDOCS 9512270322
Download: ML18101B141 (5)

Text

PS~G Public Service Electric and Gas Company P.O. Box 236 Hancocks Bridge, New Jersey 08038-0236 Nuclear Business Unit DEC 18 1995 LR-N95231 U. S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 Gentlemen:

LICENSEE EVENT REPORT 272/95-012-000 SALEM GENERATING STATION - UNIT 1 FACILITY OPERATING LICENSE NO. DPR-70 DOCKET NO. 50-272 This Licensee Event Report entitled "Adequacy of Turbine Driven Auxiliary Feed Water Pump Enclosures" is being submitted pursuant to the requirements of the Code of Federal Regulations 10CFR50.73(a) (1).

Sincerely, .

-l-2 <? tl2ui..__

Clad. Warren General Manager -

Salem Operations SORC Mtg.95-149

.Attachment JHA/tcp C Distribution LER File Or*~.-. n , ...

9512270322 951218

• PDR ADOCK 05000272 S PDR 95*2168 REV. 6/94

Attachment A PSE&G Commitments for LER 272/95-012-000 The following items represent PSE&G commitments made to the Nuclear Regulatory Commission related to LER 272/95-012-000. The commitments are' as follows:

Design change alternatives are under consideration to eliminate the potential for overpressurization of the TDAFP enclosure. The design change will be described in the LER supplement and will be implemented prior to restart of the units.

Other HELB calculations involving similar plant configurations will be reviewed to verify the correctness of the input assumptions. A schedule for completion of this review will be provided in the supplement to this LER'.

Any additional corrective actions identified as a result of the dontinuing investigation into this occurence will be provided in the supplement.

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150-0104 14-95) EXPIRES 04/30/98 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITTi 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 INDUSTflY. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE (See reverse for required number of INFORMATION AND RECORDS MANAGEMENT BRANCH IT-6 F33),

U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC digits/characters for each block) 20555-0001, AND TO THE PAPERWORK REDUCTION PROJECT FACILITY NAME 111 DOCKET NUMB9' 121 PAGE 131 Salem Generating Station - Unit 1 05000272 1 OF 3 TITLE 141 Adequacy of Turbine Driven Auxiliary Feed Water Pump Enclosures 171 I

EVENT DATE 151 LER NUMBER 161 REPORT DATE OTHER FACILITIES INVOLVED 181 MONTH DAY YEAR YEAR I SEQUENTIAL NUMBER REVISION NUMBER MONTH DAY YEAR FACILITY NAME Salem Generating Station - Unit 2 FACILITY NAME DOCKET NUMBER 05000311 12 11 76 95 -- 012 -- 000 12 18 95 DOCKET NUMBER I

I I*

OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: !Check one or more) 1111 MODE 191 20.2201 (b) 20.2203(a)(2Jlv) 50.731a)(2)(i) 50.73(aJl2)(viiiJ 20.2203(aJl1 I 20.2203(a)(3Jlil x 50.73(a)(2)(ii) 50.73(a)(2)(x)

I POWER LEVEL 1101 I0 I 20.2203(a)l2)(i) 20.2203(a)(3Jliil 50. 7 3 (a)(2)(iii) 73.71 20 .2203 (a)(2)(ii) 20.2203(a)(4) 50.73(a)(2lli"'.I OTHER 20.2203(a)(2)(iii) 50.36(c)(l I 50.73(a)(2)(v) Specify in Abstract below or in NRC 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 Are. Code)

Greg Cranston, Manager - Nuclear Engineering, 609 - 339 - 1955 Mee anical

• • • 1m-* l'!'l'F. nw1 J,T'NF. 'Ii' "'l'D F.lH~H -* *m - * 'N .. ~n *1* li'l TT.TTRF. r'l~R~'D Tl l'lfln T'tJ 'l'HTA 'DF.Pni>rri , , ":l \

REPORTABLE REPORTABLE CAUSE SYSTEM COMPONENT MANUFACTURER CAUSE SYSTEM COMPONENT MANUFACTURER TONPRDS TO NPRDS X IYES (If yes, SUPPLEMENTAL REPORT EXPECTED (141 complete EXPECTED SUBMISSION DATE).

I 'NO EXPECTED SUBMISSION DATE 1151 MONTH 02 DAY 15 YEAR 96 ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (161 In early November 1995 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 detailed analysis is being performed to determine the extent of the potential overpressurization and the affect on the structural integrity of the TDAFP enclosure. The cause of this occurrence is attributed to inadequate verification of assumptions in the calculations performed to evaluate previously identified as-built design deficiencies and inaccurate design drawings. Corrective actions include a review of other HELB calculation assumptions and evaluation of design changes to eliminate the potential TDAFP enclosure overpressure.

This condition is being reported in accordance with 10CFR50.73(a) (2) (ii) .

A four hour 10CFR50.72 notification was made on November 16, 1995.

NRC FORM 366 14-95)

NRC FORM 366A (4-95)

• LICENSEE EVENT REPORT (LER)

• U.S. NUCLEAR REGULATORY COMMISSION TEXT CONTINUATION FACILITY NAME 111 DOCKET LER NUMBER 161 PAGE 131 YEAR I SEQUENTIAL NUMBER I REVISION NUMBER Salem Generating Station - Unit 1 05000272 2 OF 3 95 -- 012 -- 000 TEXT (If mor8 spac8 is rtJquirtJd, ustJ additional copies of NRC Form 366AJ (171 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: Defueled, o % Reactor Power Unit 2: Mode 5, o % Reactor Power DESCRIPTION OF OCCURRENCE -

In early November 1995 it was discovered that assumptions in the HE~B analysis for the turbine driven auxiliary feed water pump (TDAFP) {BA/P}

enclosure did not match as-built conditions and could potentially al1ow 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 implicitly assumed that the ABS 6 damper opened instantaneously when the pressure in the enclosure reached the setpoint.

Significant 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 implicitly assumed that the damper full open position provided 100 percent of the damper opening for pressure relief. In the full open position the damper is actually open only 45 degrees, limiting the area available to less than 100 percent. It has been determined that with these delays and the less than fully open damper, the peak pressure in the enclosure following a steam line break may exceed the design pressure of the TDAFP enclosure.

A detailed analysis is being performed to determine the extent of the potential overpressurization and the affect on the structural integrity of the TDAFP enclosure throughout the postulated HELB event.

NRC FORM 366A 14-95)

NRC FORM 366A (4-95)

• LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION

• U.S. NUCLEAR REGULATORY COMMISSION FACILITY NAME 111 DOCKET LER NUMBER 161 PAGE 131 YEAR I SEQUENTIAL NUMBER I REVISION NUMBER Salem Generating Station - Unit 1 05000272 3 OF 3 95 -- 012 -- 000 TEXT (If more space is required, use additional copies of NRC Form 366A) 117)

SAFETY SIGNIFICANCE While the detailed analysis to determine the affect on the integrity of the TDAFP enclosure is not yet complete, 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.

The supplement to this LER will provide a more detailed safety significance based on the results of the on-going structural analysis.

APPARENT CAUSE OF OCCURRENCE The cause of this occurrence is attributed to inadequate verification of the unstated 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. A contributing factor is that one of the design drawings erroneously shows the ABS6 damper as normally open.

PRIOR SIMILAR OCCURRENCES Two prior similar occurrences involving unverified calculation assumptions 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 Design change alternatives are under consideration to eliminate the potential for overpressurization of the TDAFP enclosure. The design change will be described in the LER supplement and will be implemented prior to restart of the units. -

Other HELB calculations involving similar plant configurations will be reviewed to verify the correctness of the input assumptions. A schedule for completion of this review will be provided in the supplement to this LER.

Any additional corrective actions identified as a result of the continuing investigation into this occurrence will be provided in the supplement.

NRC FORM 366A (4-951