ML18100A851

LER 93-020-00:on 931223,RCS Accumulator Upper Range Level Indication Inaccuracies Affecting Units 1 & 2 Identified. Caused by Use of Incorrect Original Scaling Factors. Accumulators on Both Units Correctly rescaled.W/940121 Ltr

ML18100A851
Person / Time
Site:	Salem
Issue date:	01/21/1994
From:	Pastva M, Vondra C Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-93-020, LER-93-20, NUDOCS 9402030337
Download: ML18100A851 (6)

Text

e OPS~G Public Service Electric and Gas Company P.O. Box 236 Hancocks Bridge, New Jersey 08038 Salem Generating Station January 21, 1994

u. s. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555

Dear Sir:

SALEM GENERATING STATION LICENSE NO. DPR-70 DOCKET NO. 50-272 UNIT NO. 1 LICENSEE EVENT REPORT 93-020-00 This Licensee Event Report is being submitted pursuant to the

• requirements of Code of Federal Regulation 10CFR50.73{a) (2) (i) (B).

Issuance of this report is required within thirty (30) days of event discovery.

ely yours, MJPJ:pc Distribution 9402030337 940121 PDR ADOCK 05000272 S PDR The paver is in your hands.

95-2189 RL

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSIO (6-891 .. APPROVEO OMB NO. 3150*0104 EXP IRES: 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS. FORWARD LICENSEE EVENT REPORT ILER) COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS AND REPORTS MANAGEMENT BRANCH IP-5301, U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (3150-0104), OFFICE OF MANAGEMENT AND BUDGET, WASHINGTON, DC 20503.

DOCKET NUMBER 121 I PAGE 131 I

FACILITY NAME (1) 8alem r..,n.,,..at-inl1' Station - Unit 1 TITLE 141 0 I 5 I 0 I 0 I 0 I 217 12 1 OF I 0 I5 I~~~ a~cumulator Uuuer ,Range Level Indication Inaccuracies Affecting Both Salem Units.

EVENT DATE (5) LER NUMBER (61 REPORT DATE 171 OTHER FACILITIES INVOLVED IBI MONTH DAY YEAR YEAR :tt SE~~~~~~AL !\f ~t~~~~ MONTH DAY YEAR FACILITY NAMES DOCKET NUMBERISI Salem Unit 2 1 I2 213 9 3 913 - ol 2 lo - olo ol 1 211 9 I4 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE RcQUIREMENTS OF 10 CFR §: (Chock ono or mor* of rhe following} (11)

MODE IBI 5 20.402(b)

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SUPPLEMENTAL REPORT EXPECTED (14) MONTH DAY YEAR EXPECTED

~NO SUBMISSION DATE 1151 j YES !If v*s. compl*t* EXPECTED SUBMISSION DATE}

I I I ABSTRACT (Limit to 1400 spaces, i.t1.* *PProxim*tely fiftt1t1n 1inglt1*l/>>Ct1 typt1wrirtt1n Unt11) '16)

Since initial startup of the Units, the upper Technical Specification limit of 6,500 gallons for borated water volume in each Reactor Coolant System (RCS) accumulator may have been exceeded. Discovery occurred on 12/23/93 while investigating problems with implementing revised Unit 1 RCS accumulator level scaling factors. This event occurred due to calibrations of six Unit 1 and seven Unit 2 level transmitters for the RCS accumulators using incorrect original scaling factors. Use of the original scaling resulted in inaccuracies: The effect of these inaccuracies was conservative for the low level alarm and indication and nonconservative for the high level alarm and indication. Westinghouse assessment shows this event does not involve a significant safety concern. The root cause is Design, Manufacturing, Construction/

Installation. Methodology for the original scaling did not adequately consider elevation differences between the accumulators' upper sensing bellows and taps. The accumulators on both Units have been correctly rescaled. Controlled scaling for the RCS accumulators level transmitters has been issued. Design drawings will be updated to reflect the as-built configurations of the RCS Accumulator level taps and sensing bellows, as depicted in plant surveys. Appropriate E&PB personnel have been made aware of the importance of reviewing existing plant scaling informa~ion as part of the verification of new scaling calculations.

• NRC Form 366 (6-89)

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272 93-020-00 2 of 5 PLANT AND SYSTEM IDENTIFICATION:

Westinghouse - Pressurized Water Reactor Energy Industry Identification System (EIIS) codes are identified in the text as {xx}

IDENTIFICATION OF OCCURRENCE:

Reactor Coolant System Accumulator Upper Range Level Indication Inaccuracies Affecting Both Salem Units '

Event Date: 12/23/93 Report Date: 1/21/94 This report was initiated by Incident Report Nos.93-525 and 93-526.

CONDITIONS PRIOR TO OCCURRENCE:

Salem Unit 1: 11th Refueling outage in progress Salem Unit 2: Mode 5, due to a forced Unit outage.

DESCRIPTION OF OCCURRENCE:

Since initial startup of the Units, the upper limit of 6,500 gallons for borated water volume in each Reactor Coolant System (RCS) {AB}

accumulator, as specified by Technical Specification (TS) 3.5.1, may have been exceeded due to incorrect calibrations of six Unit 1 and seven Unit 2 level transmitters for the accumulators. Event discovery occurred while investigating problems with implementing revised RCS accumulator level scaling factors on Unit 1.

ANALYSIS OF OCCURRENCE:

Operability of RCS accumulators ensures a sufficient volume of borated water will be injected into the reactor core in the event RCS pressure decreases below the pressure of the accumulators. RCS accumulator level indication consists of two channels for each of the four accumulators per Unit. TS 3.5.1 specifies an accumulator contained volume of between 6,223 and 6,500 gallons of borated water.

In December 1992, Engineering & Plant Betterment (E&PB) reverified the original scaling for the RCS accumulators' level sensors. This was done using design drawings which show the level sensors' taps and sensing bellows on the same elevation. The reverified scaling

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272 93-020-00 3 of 5 ANALYSIS OF OCCURRENCE: cont'd) differed from the original plant scaling and appropriate procedure changes were made to reflect the new scali~g. In late November 1993, during the Unit 1 11th refueling/maintenance outage, when an attempt was made to use the new scaling, the Unit accumulators' level indication channels differed by more than 3%. E&PB was then notified by the Maintenance Department that the upper and lower sensing bellows are not located at the same elevations as the tank taps.

Further investigation determined that six of the Unit 1 and seven of the Unit 2 RCS accumulators' level upper sensing bellows are located below their respective level sensing taps which contradicts design drawings. Following this discovery, the RCS accumulators of both Units were correctly rescaled prior to restart of each Unit.

The original scaling was determined using plant survey documents, which showed actual elevations of the sensing bellows and taps.

However, the significance of elevation differences between the accumulators' upper sensing bellows and taps were not adequately considered during development of the original scaling. This resulted in inaccuracies, which affected both the low and high level TS alarms and indications. While the effect of these inaccuracies was conservative for the low level alarm and indication, it was nonconservative for the high level alarm and indication. The following lists the nonconservative inaccuracies of the high level indication and alarm for both Units:

(Unit 1)

Accumulator Transmitter ~

0 Inaccuracy 11 1LT934A 2.63%

11 1LT935A 3.48%

12 1LT934B 1.31%

12 1LT935B 0%

13 1LT934C 1.31%

13 1LT935C 1.31%

14 1LT934D 5.~5%

14 1LT935D 0%

~

.,

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272 93-020-00 4 of 5 ANALYSIS OF OCCURRENCE: cont'd)

(Unit 2)

Accumulator Transmitter 9'-

0 Inaccuracy 21 2LT934A 3.44%

21 2LT935A 0.48%

22 2LT934B 3.019%

22 2LT935B 0.342%

23 2LT934C 1.12%

23 2LT935C 0

• 9'-

0 24 2~T934D 0.835%

24 2LT935D 1. 68%

Design drawings do not reflect the actual field installation of the accumulators' level sensing bellows. This contributed to the error in the scaling performed in December 1992. The existing instrument configuration is such that the sensing bellows are located slightly below the instrument taps.

APPARENT CAUSE OF OCCURRENCE:

The root cause of this event is Design, Manufacturing,.

Construction/Installation, per NUREG-1022. This occurred prior to initial startup of the Units when methodology used for the original scaling did not adequately consider the elevation differences between the accumulators' upper sensing bellows and taps.

PREVIOUS OCCURRENCES:

Review of documentation shows this event is an isolated occurrence.

SAFETY SIGNIFICANCE:

This event did not affect the health and safety of the public. It is conservatively assumed to be reportable pursuant to the requirements of 10CFR50.73(a) (2) (i) (B), as an event involving any operation or condition prohibited by the plant Technical Specifications. The NRC was conservatively notified of this event in accordance with

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272 93-020-00 5 of 5 SAFETY SIGNIFICANCE: (cont'd) 10CFR50.72(b) (2) (i). Subsequent assessment by Westinghouse shows this issue does not involve a significant safety concern as originally reported. This assessment used the 5.25% maximum discrepancy in RCS accumulator upper level indication with respect to the LOCA analyses for each Salem Unit. In addition, it assumed the level discrepancy applied to all accumulators on each Unit.

CORRECTIVE ACTION:

The accumulators on both Units were correctly rescaled.

Controlled scaling for the RCS accumulators level transmitters have been issued. The as-built survey documents have been incorporated into the controlled RCS accumulator level scaling calibrations.

Applicable design drawings will be updated to reflect the as-built configurations of the RCS Accumulator level taps and sensing bellows, as depicted in the plant surveys.

Appropriate E&PB personnel have.been made aware of the importance of reviewing existing plant scaling information as part of the verification of new scaling calculations.

The importance of evaluating the impact of changes made to the plant will be reenforced with E&PB and Techn~Depar~~personnel.

~,; ~~

General anager -

Salem Operations MJPJ:pc SORC Mtg. 94-06