05000311/LER-1990-005, :on 900117,Tech Spec Action Statement 3.0.3 Entered Due to Inoperability of Two High Head ECCS Subsys. Caused by Leak from Welded Pipe Cap on Boron Injection Tank. Pipe-to-cap Socket Welded Joint Repaired

:on 900117,Tech Spec Action Statement 3.0.3 Entered Due to Inoperability of Two High Head ECCS Subsys. Caused by Leak from Welded Pipe Cap on Boron Injection Tank. Pipe-to-cap Socket Welded Joint Repaired

ML20006E454
Person / Time
Site:	Salem
Issue date:	02/15/1990
From:	Miller L, Rupp J Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-005, LER-90-5, NUDOCS 9002230195
Download: ML20006E454 (5)

LER-1990-005, on 900117,Tech Spec Action Statement 3.0.3 Entered Due to Inoperability of Two High Head ECCS Subsys. Caused by Leak from Welded Pipe Cap on Boron Injection Tank. Pipe-to-cap Socket Welded Joint Repaired

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(1)
3111990005R00 - NRC Website

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Public Service Electric and Gas Company P.O. Box 236 Hancocks Bridge, New Jersey 08038 h

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'U. S. Nuclear Regul'atory Commission-Document Control = Desk Washington,' DC 20555-J

Dear' Sir:

f SALEN GENERATING STATION LICENSE NO. DPR-75

' DOCKET.NO..50-311L UNIT NO. 2 LICENSEE: EVENT REPORT 90-005-00.

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.This Licensee' Event-Report is being submitted pursuant to the a

requirements,of the. Code'of Federal Regulations 10CFR

- I 50.73 (a) (2) (i) (B). 'This-report is required within thirty (30)-days 1

ofidiscovery..

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K. Miller General Manager -

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, o e, On January 17, 1990, at 0010 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br />, following the discovery and i

l subsequent isolation of a leak.from a welded pipe cap on the discharge side of No. 2 Boron Injection Tank (BIT), Technical Specification Action Statement 3.0.3 was entered due to the inoperability of two (2) high. head Emergency Core Cooling System subsystems.

The leak was physically located on a portion of the old BIT recirc line which was removed and capped by a design change during the Unit 2 refueling outage in November 1988.

The leak was promptly identified, isolated, and a Unit shutdown was initiated and completed in accordance with Technical Specification requirements.

The affected pipe-to-cap socket weld joint was removed and immediately shipped to Westinghouse for failure analysis.

The joint was repaired and hydrostatically tested with satisfactory results.

The integrity of the remaining joints-associated with the design change was verified by a combination of l

hydrostatic and dye-penetrant testing.

The root cause has been attributed to a defect in the root of the weld.

A crack may have been

(

initiated at this defect during the system hydrostatic test following l

the design change.

High frequency, low amplitude cyclic loading, which is characteristic of the positive displacement pump discharge, caused the crack to propagate through the weld.

Stress corrosion in the area of the defect may have contributed to the crack initiation.

The metallurgical investigation concluded that the normal cyclic loading characteristics of the system would not have initiated a crack in the absence of the weld defect.

Based on the failure analysis-report, testing performed, and subsequent investigations performed by System Engineers, it was determined that this was an isolated case, ge ses

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psw LICENSEE EVENT REPORT (LER) TEXT CONTINUATION 7

L iSalem-Generating Statio'n

. DOCKET NUMBER LER NUMBER PAGE b

Unit 2 5000311 90-005-00 2 of<4 L

ELANT AND SYSTEM IDENTIFICATION:

- Westinghouse

- Pressurized Water Reactor 4

- Energy Industry Identification System (EIIS) codes'are identified in the text as (xxl IDENTIFICATION'OF OCCURRENCE:

TechnicalLSpecification 3.0.3 entry and subsequent Unit. shutdown due toLthe'inoperability of two Emergency Core Cooling System Subsystems Event Date:

1/17/90-Repcrt Date:

2/15/90 This report was initiated by Incident Report No.90-044.

CONDITIONS PRIOR TO OCCURRENCE:

' Mode I - Reactor Power 100% - Unit Load 1155 MWe c

DESCRIPTION'OF OCCURRENCE:

On January 17, 1990, at 0010 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br />, following the discovery.and subsequent isolation of a leak from a welded pipe cap on the discharge L

side of No.-2 Boron Injection Tank (BIT) (BQl, Technical Specification L

Action Statement 3.0.3 was entered due to the inoperability of'two (2) 4 EnergencycCore' Cooling System (ECCS) (BQl subsystems.

During Modes I

'(POWER' OPERATION), II'(STARTUP) and III (HOT STANDBY), Technical Specification 3.5.2 requires two (2) independent ECCS subsystems to be L

operable.

Isolation of the leak eliminated the discharge flowpath' from both centrifugal charging pumps, rendering both high head ECCS subsystems inoperable; hence, entry into Technical Specification Action Statement 3.0.3.

l Technical Specification Action Statement 3.0.3 states:

1 6'

"When a Limiting Condition for Operation is not met except as provided in the associated ACTION requirements, within one hour l

action shall be initiated to place.the unit in a MODE in which the specification ~does not apply by placing it, as applicable, t

in:

L 1.

At'least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, L

2.

'At least HOT SKUTDOWN within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, and 3.

At least COLD SHUTDOWN within the subsequent 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

Where corrective measures are completed that permit operation under the ACTION requirements, the ACTION may be taken in accordance with the specified time limits as measured from the l1 time of failure to meet the Limiting Condition of Operation.

Exceptions to these requirements are stated in the individual L

specifications."

The-sequence of events were as follows:

9

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LICENSEE: EVENT' REPORT (LER) TEXT CONTINUATION i

Salem' Generating Station-DOCKET NUMBER LER-NUMBER PAGE Unit-2 5000311 90-005-00 3 of 4 DESCRIPTION OF OCCURRENCE:

(contfdl J

The sequence of events were as follows:

2222 hours0.0257 days <br />0.617 hours <br />0.00367 weeks <br />8.45471e-4 months <br />, January 16, 1990 - Commenced performing Reactor Coolant System leak rate calculations due to the automatic initiation of

- residual heat removal sump pump runs.

2300 hours0.0266 days <br />0.639 hours <br />0.0038 weeks <br />8.7515e-4 months <br /> - Leak discovered coming from the general area of SJ10 (BIT

- Relief Valve).

Shut SJ4 and SJ5 valves 1(BIT inlet motor operated valves).

Visually verified leakage to stop.

i 0010 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br />, January 17,-19901-After gaining access to the immediate area, identifying the actual source of the leak, and discussing the situation with the System Engineers, immediately declared the cold leg injection line via the BIT inoperable and entered Technical 4

Specification 3.0.3.

- 0030 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br /> - Commenced Unit shutdown to comply with Technical Specification 3.0.3 requirements.

0105. hours - Notified the Nuclear Regulatory Commission of-the initiation of the plant shutdown in accordance with the requirements of 10CFR 50.72 (b) (1) (i) ( A).

0503 hours0.00582 days <br />0.14 hours <br />8.316799e-4 weeks <br />1.913915e-4 months <br /> - Entered Mode II.

0554 hours0.00641 days <br />0.154 hours <br />9.160053e-4 weeks <br />2.10797e-4 months <br /> - Entered Mode III.

1300 hours0.015 days <br />0.361 hours <br />0.00215 weeks <br />4.9465e-4 months <br /> - Entered Mode IV, exited Technical Specification Action Statement 3.0.3, and entered Technical Specification Action Statement 3.5.3.a (applicable in_ Mode IV) which requires the Unit to be in Mode V (COLD SHUTDOWN) in twenty (20) hours due to an inoperable flowpath from the refueling water storage tank.

0808 hours0.00935 days <br />0.224 hours <br />0.00134 weeks <br />3.07444e-4 months <br />, January 18, 1990 - Entered Mode V and terminated Technical Specification Action Statement 3.5.3.a.

APPARENT CAUSE OF OCCURRENCE:

As previously stated, the cause of the Technical Specification 3.0.3 entry and subsequent Unit shutdown was the isolation of the BIT discharge flowpath.

Following metallurgical evaluation of the pipe-to-cap socket weld joint, the root cause has been attributed to a:

defect in the root of the weld.

A crack may have been initiated at this defect during the system hydrostatic test following the design change, which was performed at 1.5 times the design system pressure..

Stress corrosion in the area of the defect may have contributed to the crack initiation.

High frequency, low amplitude cyclic loading, which is characteristic of the positive displacement pump discharge, caused the crack to propagate through the weld, resulting in a system boundary leak path.

DThe leak was physically located on a portion of the BIT to BAST recirculation line (# 1091), a one and one-quarter inch line which

ty' LICENSEE EVENT REPORT (LER) TEXT CONTINUATION

- Salem Generating Statio'n' DOCKET. NUMBER LER NUMBER PAGE

- Unit ~2 5000311-90-005-00 4 of 4

- ANALYSIS OF ' OCCURRENCE:

)

was removed and capped by a design change during.the Unit 2 refueling

)

outage in November 1988.

The metallurgical investigation performed by Westinghouse concluded that the normal cyclic loading characteristics 1

of the system would not have initiated a crack in the absence of the R

weld defect.

Although the exact type of weld defect is indeterminate,-

i examination of the joint revealed proper fitup and analysis-revealed u

the use of proper filler metal (316 stainless steel).

Additionally, a review of records indicate that the welders qualifications are not in question.

Following repairs, a hydrostatic test verified' integrity of the replaced joint plus three (3) other joints installed during the design change (2EC-2187).

The remaining joints installed during the design change were verified to contain no through-wall leaks by dye-penetrant testing.

The weld detect is not common to this type of fillet weld.

No similar defec';s have been reported on either Unit.

Unit i has been in' service for over one fuel cycle with the same design change without incident.

This is considered an isolated case.

The leak was promptly located and isolated, and operations were in-accordance with Technical Specification requirements; therefore, the health or safety of the public was not affected by this event.

However, due to the completion of a plant shutdown which is required by the Technical Specifications, the event is reportable in accordance with the Code of Federal Regulations, 10CFR 50.73 (a) (2) (1) (A).

?

CORRECTIVE ACTION

o The leak was promptly identified, isolated, a Unit shutdown was initiated and completed in accordance with Technical Specification requirements, and the Commission was verbally notified in accordance l

with the requirements of the Code of Federal Regulations.

The l:

affected pipe-to-cap socket weld joint was removed'and immediately L

shipped.to Westinghouse for failure analysis.

Results of the investigation are documented in the " Apparent Cause" and " Analysis of

' Occurrence" sections of this report.

The joint was repaired and hydrostatically tested with satisfactory L

results.

The integrity of the remaining joints associated with the design change was. verified by a combination of hydrostatic and' dye-penetrant testing.

Based on the failure analysis report-by Westinghouse, testing performed, and subsequent investigations performed by System Engineers, which included review of the weld history,. design. change records, system configuration and previous system problems, it was determined that this was an isolated case.

Consequently, no further corrective actions are deemed necessary.

General Manager -

Salem Operations h

JLR:pc L

SORC Mtg.90-014