ML18100A498

LER 89-031-02:on 931019,TS Action Statement Entered Due to Oxygen Concentration of 2.3% by Volume in Number 11 Wdgt. Caused by Equipment Failure.Transmitter & Flow Control Valve Recalibrated & Valve Lineup inspected.W/930722 Ltr

ML18100A498
Person / Time
Site:	Salem
Issue date:	07/19/1993
From:	POLLACK M J, VONDRA C A Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-89-031, LER-89-31, NUDOCS 9308020237
Download: ML18100A498 (6)

Text

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Public Service Electric and Gas Company P.O. Box 236 Hancocks Bridge, New Jersey 08038 Salem Generating Station 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 July 22, 1993 LICENSEE EVENT REPORT 89-031-02; SUPPLEMENT This Supplemental Licensee Event Report is being submitted pursuant to Code of Federal Regulations 10CFR50.73.

The Apparent cause of and Corrective Action sections have been modified based upon completed investigations.

MJP:pc Distribution -or-1" ,......!*'

• . t .. ll "1 9308020237 I

DR ADOCK 05000272 PDR The power is in your hands. 95-2189 REV 7-92 NRC FORM366 I (6-89) U.S. NUCLEAR REGULATORY COMMISSION APPROVED OMB NO. 3150-0104 LICENSEE EVENT REPORT (LER) EXPIRES

4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS AND REPORTS MANAGEMENT BRANCH (P*530), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (3150-0104), OFFICE OF MANAGEMENT AND BUDGET, WASHINGTON, DC 20503. FACILITY NAME (1) 'DOCKET NUMBER (2) PAliE 131 0 I 5 I 0 I 0 I 0 I 2 17 I 2 1 I OF Ol5 Salem Generating Station -Unit 1 TITLE (4)

• 02 Concentration Greater Than 2% for More Than 48 Hours. EVENT DATE (5) LER NUMBER (6) REPORT DATE 17) OTHER FACILITIES INVOLVED IB) MONTH DAY YEAR YEAR ff:

MONTH DAY YEAR FACILITY NAMES DOCKET NUMBERISl i I o i I 9 9 3 s I 9 -o b ! i -o I 2 al 7 i I 9 9 I 3 OPERATING MODE (9) l THIS REPORT IS SUBMITTED PURSUANT TO THE OF 10 CFR §: (Ch*ck on* or mor* of th* following)

(11) 20.402lb) 20.405lc) 50.73(oH2lliv) 73.71(b) ---20.4061oH1 )II) 50.311cH11 50.73loH211v) 73.71lc) ---20.405(oH1 )Iii) 50.361c)l2) 50.73loH2JlvliJ OTHER (Specify in Abstr*ct >--below and in Text, NRC Form POWER I LEVEL . -1101 110 I 0 --20.405(oH1 HllU x 50.73loH2HiJ 60.73(oH2llviiiJIA) 366AJ --20.40610111 Hlv) &0.73loH2HiiJ 50.73loH2HviliJIBI

--20.406(oJl1 JM 50.731oH2JliiiJ 50.73loJl2llx)

LICENSEE CONTACT FOR THIS LER 1121 NAME TELEPHONE NUMBER AREA CODE M. J. Pollack -LER Coordinator 6 I 019 3 1319 1**-15111613 CAUSE SYSTEM COMPONENT B WI EV I I I I I I I COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13) MANUFAC* TUR ER Mil I 210 I I I y I I I I I I I I MANUFAC* TUR ER I I I I I I SUPPLEMENTAL REPORT EXPECTED (14) MONTH DAY YEAR n YES (If Y6S, comp/et* EXPECTED SUBMISSION DA TE) ABSTRACT (Limit to 1400 spaces, i.tJ., 11pproximately fiftBan single-space typewritten lines) 118) EXPECTED SUBMISSION DATE 1151 I I Oxygen concentration within the Waste Gas Holdup system was greater than 2% for more than 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> between 10/17/89 and 10/19/89 and between 6/3/90 and 6/6/90 contrary to the requirements of Technical Specification Action Statement 3.11.2.5.a.

The maximum oxygen concentration observed in any Waste Gas Decay Tank (WGDT) during the October 1989 event was 3.2% (in 11 WGDT) and 3.0% during the June 1990 event (also in 11 WGDT). No WGDT contained a concentration of oxygen above the 2% limit for more than approximately 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />. Efforts to reduce the oxygen concentration were immediately implemented upon identification of the high concentrations in the WGDT's. It has been concluded that oxygen is entering the Waste Gas Holdup System via the eves Holdup Tanks. samples of No. 13 eves Holdup Tank cover gas had oxygen concentrations as high as 3.5% on 10/2B/89.

Samples of the other tank cover gas sources, taken 11/12/89 through 11/14/89, (other than 11 eves Holdup Tank) to the Waste Gas Holdup System indicated concentrations of less than 0.1%. The apparent cause of these events is equipment failure. The eves Holdup Tank Inlet Valve 1BR78 was allowing leakage into the eves tank. Valve repair was completed during the tenth refueling outage in July 1992. Upon completion of the valve repair, oxygen levels in the WGDT's consistently remained below 2%, and less than 1% for better than 75% of the time in the following nine (9) months. NRC Form 366 16-89) I LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station Unit 1 DOCKET NUMBER 5000272 PLANT AND SYSTEM IDENTIFICATION:

Westinghouse

-Pressurized Water Reactor LER NUMBER 89-031-02 PAGE 2 of 5 Energy Industry Identification system (EIIS) codes are identified in the text as {xx} IDENTIFICATION OF OCCURRENCE:

Waste Gas Holdup System Oxygen Concentration Greater Than 2% For More Than 48 Hours Contrary to Technical Specification Action Statement 3.11.2.5.a Event Date(s): 10/19/89 and 6/05/90 Report Date: 7/19/93 This report supplements LER 272/89-031-01.

The Apparent Cause of Occurrence Section has been revised to address results of subsequent investigation (committed to in the. original LER). The original and first supplement LERs-were initiated based on Incident Reports89-632, 89-635,89-638, and 90-366.

• CONDITIONS PRIOR TO OCCURRENCE:

October 19, 1989 event: Mode 1, Rx. Power 100% Unit Load 1152 MWe June 3, 1990 event: Mode 5 (Cold Shutdown);

Rx Startup in progress DESCRIPTION OF OCCURRENCE:

Oxygen concentration within the Waste Gas Holdup System {WE} was greater than 2% for more than 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />, contrary to the requirements of Technical Specification Action Statement 3.11.2.5.a.

On October 17, 1989, at 0900 hours0.0104 days <br />0.25 hours <br />0.00149 weeks <br />3.4245e-4 months <br />, Technical Specification Action statement 3.11.2.5.a was entered due to an oxygen concentration of 2.6% by volume in the No. 11 Waste Gas Decay Tank (WGDT). Oxygen levels in the other three (3) WGDTs also exceeded 2% at various times through October 19, 1989, at 2140 hours0.0248 days <br />0.594 hours <br />0.00354 weeks <br />8.1427e-4 months <br />; when, the oxygen concentration in all the WGDTs was verified to be less than 2%. At this time the Action Statement was exited. The maximum oxygen concentration observed in any tank was 3.2%, (in No. 11 WGDT). No WGDT contained a concentration of oxygen above the 2% limit for more than approximately 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />. On June 3, 1990 at 0001 hours1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />, Technical Specification Action Statement 3.11.2.5.a was again entered due to an oxygen concentration of 2.3% by volume in the No. 11 WGDT. Oxygen levels in the other three (3) WGDTs also exceeded 2% at various times through June 6, 1990 at 1315 hours0.0152 days <br />0.365 hours <br />0.00217 weeks <br />5.003575e-4 months <br />; when, the oxygen concentration in all the WGDTs was verified to be less than 2%. At this time the Action Statement was exited. The maximum oxygen concentration observed in any tank LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station Unit 1 DESCRIPTION OF OCCURRENCE:

DOCKET NUMBER 5000272 (cont'd) was 3.0% (in No. 11 WGDT). LER NUMBER 89-031-02 PAGE 3 of 5 Efforts to reduce the oxygen concentration were immediately implemented upon identification of the high concentrations in the WGDT's. These methods included:

1. discharge of the Waste Gas Holdup Tanks, at pressure greater than 60 psi, via the plant vent (by procedure);

2. dilution of Waste Gas Holdup Tanks (if the tank pressure is less than 60 psi) with gas from other WGDTs if the oxygen concentration in those tanks is < 2% by volume; 3. nitrogen purge of the Waste Gas Holdup Tanks and eves Holdup Tanks; and 4. fill and vent of the eves Holdup Tanks Technical 3.11.2.5.

states: "The concentration of oxygen in the waste gas holdup system shall be limited to less than or equal to 2% by volume. APPLICABILITY:

At all times. ACTION: a. With the concentration of oxygen in the waste gas holdup system greater than 2% by volume but less than or equal 4% by volume, reduce the oxygen concentration to the above limits within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. b. With the concentration of oxygen in the waste gas holdup system greater than 4% by volume, immediately suspend all additions of waste gases to the system and reduce the concentration of oxygen to less than or equal to 2% by volume without delay." After these events, administrative controls,were implemented to mitigate the possibility of recurrence of the waste Gas System oxygen concentration exceeding 2% for greater than 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. These controls include oxygen concentration monitoring of the inservice WGDT tank via routine shift rounds. Operators record observed concentration on the Radioactive Waste Data Sheet (Operations Directive procedure OD-36) and the Primary Plant Data Sheet (procedure OD-26). If an administrative limit of 1% was observed, the Nuclear Shift Supervisor is notified to enable early initiation of mitigating action. Also, precautions were added to the Reactor Coolant Draindown procedure and to procedure IOP-6, "Hot standby to Cold Shutdown", to avoid undue LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station Unit 1 DESCRIPTION OF OCCURRENCE:

DOCKET NUMBER 5000272 (cont'd) LER NUMBER 89-031-02 PAGE 4 of 5 oxygen buildup in the eves Holdup tanks. These procedural controls continue to date. APPARENT CAUSE OF OCCURRENCE:

The apparent cause of these events is equipment failure. The eves Holdup Tank Inlet Valve 1BR78 was allowing leakage into the eves tank. Valve repair was completed during the tenth refueling outage in July 1992. Upon completion of repairs, oxygen levels in the WGDT's consistently remained below 2%, and less than 1% for better than 75% of the time in the following nine (9) months. Oxygen was entering the Waste Gas Holdup System via the eves Holdup Tanks. Samples of No. 13 eves Holdup Tank cover gas had oxygen concentrations as high as 3.5% (on October 28, 1989). Samples of the other tank cover gas sources (other than No. 11 eves Holdup Tank) to the Waste Gas Holdup System indicated concentrations of less than 0.1%. When these samples were between November 12, 1989 and November 14, 1989, the waste Gas Holdup system was still indicating higher than expected concentrations of oxygen although not above 2%. ANALYSIS OF OCCURRENCE:

The Waste Gas Holdup System is designed to provide controlled handling and disposal of radioactive gaseous wastes generated during routine plant operation.

It will minimize exposure to plant personnel and to the general public as required by the Code of Federal Regulations.

The concern for oxygen within the Waste Gas Holdup System is due to the presence of hydrogen gas within the system. In sufficient quantity, hydrogen in the presence of oxygen can be explosive.

The Technical Specification level of not greater than 2% oxygen is conservatively low, ensuring that this explosive hazard is not Monitoring of the oxygen concentration in accordance with Technical Specif icati6ns ensures that if the oxygen concentration does increase above the 2% limitation expeditious corrective action can be taken to lower the level back below 2%. As discussed in the Description of Occurrence section, this action was taken, therefore, this event did not affect the health or safety of the public. There are several direct pathways for oxygen to enter the WGDTs. These direct pathways include cover gas from eves Holdup Tanks, the Volume Control Tank (VCT), the Spent Resin Storage Storage Tank (SRST), Reactor Coolant Drain Tank (RCDT) and the Pressurizer Relief Tank (PRT) . As discussed above, investigation has shown the oxygen was entering the Waste Gas Holdup System from the eves Holdup Tanks. Historically, oxygen levels of greater than 2% by volume within the Waste Gas Holdup system is attributed to refueling/maintenance outage activities (i.e, reference LERs 272/87-019-01, 272/86-009-00, and LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station Unit 1 ANALYSIS OF OCCURRENCE:

DOCKET NUMBER 5000272 (cont'd) LER NUMBER 89-031-02 PAGE 5 of 5 272/89-016-00).

However, the Unit has been in operation for several months. Therefore, this event cannot be attributed to such activity.

Investigation of the October 1989 event has included a review of a similar high oxygen event in September 1989 which did not result in an LER. The source of the oxygen at that time was also found to be the CVCS Holdup Tank. The 1WG36 valve (Gas Decay Tank To Holdup Tank Regulating Valve) was found stuck in the closed position.

When the Waste Gas Compressor drew upon the eves Holdup Tank cover gas, a vacuum formed within the tank(s) and the respective vacuum breaker opened allowing air into the tank. The 1WG36 valve was stroked and was shown to be operable.

If the oxygen concentration in the Waste Gas Holdup System exceeds 2%, it can normally be purged/diluted from the system within the 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> Technical Specification time limit. However, as stated in the Description of Occurrence Section, the level could not be reduced within the Technical Specification.

Action Statement 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> time frame. Therefore, since Technical Specification Action statement 3.11.2.5.a was not complied with, this event is reportable in accordance with the Code of Federal Regulations lOCFR 50.73(a) (2) (i) (B). CORRECTIVE ACTION: As discussed in the Description of Occurrence section, the oxygen concentration was lowered to below the 2% limit after each time it was identified.

A detailed investigation to identify the source of high oxygen was initiated following each event which included:

transmitter and flow control valve recalibration; valve lineup inspections; maintenance of numerous valves and instruments, snooping of valves and lines which .co.uld possibly provide inleakage to the WG System; and testing the Waste Gas Analyzer.

These testing, maintenance and inspection activities were generally unsuccessful in identifying the source of oxygen in the WG System. The 1BR78 valve received corrective maintenance during the tenth refueling outage. As discussed in the Apparent Cause of Occurrence section, this work resulted in the elimination of the oxygen problem in the WG System. General Manager -Salem Operations MJP:pc SORC Mtg.93-069