ML19290A402

Environ Event Rept 76-8/40:on 760219,flow Recorder FR-123 Would Not Close Discharge Valve WDG-V47 from Waste Gas Decay Tank on High Flow.Caused by Procedure/Personnel Error. Release Terminated & FR-123 Removed from Svc & Calibrated

ML19290A402
Person / Time
Site:	Three Mile Island
Issue date:	02/26/1976
From:	Arnold R METROPOLITAN EDISON CO.
To:
References
GQL-0289, GQL-289, NUDOCS 7911060640
Download: ML19290A402 (4)

Text

NRC FOpv *195

• U.S. NUCLE AR REGULATORY COM' "SION DOCKET NUMBER (2 76,1 50-289 NRd DISTRIBUTION FOR PART 50 DOCKET MATERI AL "Y$"IRb '

FROM DATE OF OOCUMENT TO J P. O'Reilly Metropolitan Edison Co 2-26-76 Reading, Pa. 19603 ^ '

• R. C. Arnold 3-3 Yd' PROP INPUT FORM NUMBER OF COPllIS RECEtVED bTTE R ONOTORIZED "M IGIN A L Q U NC LASSIF I E D OCOPY l Signed _

CESCRIPTION ENCLOSU RE Ltr furnishing Envrio Event 76-8/40 on 2-19-76 on which Flow Recorder ,

would not have closed discharge valve WDG-V47 from the Waste Gas Decay Tank on high flow.....

PLANT NAME: Three Mile Island #1 1556 289 SAFETY FOR ACTION /INFORMATION ENVIRO  ?-P ~/4 KM ASSIGNED AD : .

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' f *f d i, D Mr. J. P. O'Reilly, Director . ,

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U.S. Nuclear Regulatory Commission .

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Dear Mr. O'Reilly:

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Operating License DPR-50 Docket No. 50-289 In accordance with the Environmental Technical Specifications for Three Mile Island Nuclear Station Unit 1, we are reporting the following reportable occurrence:

(1) Report Number: ER 76-8/40 (2a) Report Date: February 26, 1976 (2b) Event Date: February 19, 1976 (3) Facility: Three Mile Island Nuclear Station Unit 1 (h) Identification of Occurrence:

Flow Recorder (FR-123) would not have closed discharge valve WDG-Vhi from the Waste Gas Decay Tan % on high flev vhich ccustitutes a violation of the Environmental Technical Specifications , paragraph 2.3.2. A.h (5) Conditiens Prior to Occurrence:

Power: Core 1005 Elec. 8h8 Kie 1556 290 RC Flow: 138.5 x 106 lbs./hr.

RC Pressure: 2155 psig RC Temp.: 579CF PRZR Level: 220 inches 20S <,

PRZR Temp.- 655 F

(c) Description of Occurrence:

In preparation for a Waste Gas Decay Tank release, the system was lined up for operation in accordance with the operating procedure. At approximately 2110 hours0.0244 days <br />0.586 hours <br />0.00349 weeks <br />8.02855e-4 months <br />, while operating the manual loader to supply air for opening of WDG-VkT (Discharge Valve for Waste Gas Tanks), the operator observed no indication of flow on Flow Recorder (FR-123). The operator increased the air supply to the valve until indication showed the valve was fully open.

He then decreased FR-123 setpoint to 3 CFM which did not actuate the interlock for closing WDG-V47 The operator i==ediately took corrective action by securing WDG-VhT at approxi=ately 2120 hours0.0245 days <br />0.589 hours <br />0.00351 weeks <br />8.0666e-4 months <br /> which terminated the release. A decrease in tank pressure indicated that a gas release was in progress during this time without flow indication on a high flow interlock.

(T) Designation of the Apparent Cause of Occurrence:

The cause of the occurrence has been determined to be procedure / personnel in that the test switch for the recorder was in the test position. In this position the recorder will not respond to its normal input signal from the transmitter.

The surveillance procedure for checking of interlocks associated with WDG-Vh7 includes a specific step to return the " Test-Normal" switch to the Normal position upon cocpletion of test. However, the procedure for release of Waste Gas Decay Tanks does not require verification of the switch position to insure it is in the " Normal" position prior to start of release.

(8) Analysis of Occurrence:

During the release of gaseous vaste with the flow recorder (FR-123) and its associated alarm interlock inoperable, no Technical Specification release rate or concentration limits were exceeded. Based on the Auxiliary and Fuel Handling Building Ventilation Exhaust Radiation Monitor (RM-A8), the release rate from the stack was 4.h x 102 m3/sec. which is below the Technical Specification release rate limit of 1.2 x 105 =?: c.

Radiation Monitor (RM-AT) which monitors g1seous vaste directly fror the tanks alarms at 2 x 10h CPM. The highest indication reached during the release was 3 5 x 103 CPM. Additionally, a release rate of h.h x 102 m3/sec., plus a tank concentration of 2.23 x 10-2 pCi/cc (99 9% Xe-133) and a normal ventilation flow of 120,000 CFM indicates that the release rate from the tank was approximately 10 CFM. However, had the release from the tank been higher, relative to Technical Specification limits, a high alarm on RM-A8 (G) set to alarm at 75% of, the Technical Specification limit, or RM-AT (G), set at 4 x 10 CPM, 4

vould have independently closed WDG-VhT through interlocks terminating the release.

(9) Corrective Action:

Immediate: The immediate ccrrective action was terrination of the release.

In addition, FR-123 was recoved from service and a ecmplete calibration of the recorder was performed. Upon placing FR-123 back in service, the test switch was returned to the nor al position and an interlock test conducted. The calibration and test pros ed to be satisfactory.

1556 291

Long Term: The procedure for Release of Cas Decay Tanks will be revised to include verification of the test normal switch position prior to a release.

(10) Failure Data:

Not Applicable (11) Similar Occurrences:

None Sincerely, Signed - R. C. Arnold R. C. Arnold Vice President RCA:JJM:ilm cc: Director of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commissica Washington, D.C. 20555 1556 292

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