ML19210A228

Nonroutine 10-Day Rept 75-06 Re 750927 Unplanned Radioactive Release.Lifting Relief Valve DH-V-57A Allowed Primary Coolant Leakage to Auxiliary Bldg.Caused by Matl Failure.No Tech Spec Limits Exceeded

ML19210A228
Person / Time
Site:	Three Mile Island
Issue date:	10/07/1975
From:	Creitz W METROPOLITAN EDISON CO.
To:
References
75-06, 75-6, GQL-1586, NUDOCS 7910240940
Download: ML19210A228 (4)

Text

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NRC <STRIBUTION FOR PART SO DOCK- " TTE RI AL

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, CONTROL NO: 10740 FILE: INCIDE:Tr Er?crT vm FROM: Metropolitan Edison Co. DATE OF DOC DATE REC'D LTR TWX RPT OTHER Reading, PA.

W.M. Creitz 10-7-75 10-9-75 XXX TO: ORIG CC OTHER SENT AEC PDR ^^^

NRC 1 Sign'ed 0 SENT LOCAL PDR XXX CLASS UNCLASS PROPINFO INPUT NO CYS REC'D DOCKET NO:

XXX , 1 50-289 DESCRIPTION: '

ENC LOSU.R ES Letter trans the following. . . . Nonroutine i0-Day Report # 75-06, On 9-27-75 Concerning an unplanned release of Radioactive Material due to a Material Failure. .. . .

(1 Copy Er. closure Received)

PLANT NAME: Three Mile Is. land FOR ACTION /INFORMATION SAB 10-14-75 BUTLER (L)

W/ Copies SCHWENCER (L) ZIEMANN (L)

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? OCT9 1975 Directcr of :Iuclear Reactor Regulation _

U.S. !iuclear Regulatory Cec =ission -

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Dear Sir:

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Dceket :Ic. 50-269 Cperating License DFR-50 Tenrcutine IC-Cay Report 75-C6 In acecrdance with Section 6.7.2.A.2 cf the Technical Specifications for our Three Mile Island :iuclear Station Unit 1, enclosed please find

icnrcutine 10-Day Report 75-06 that deals with an unplanned release of radicactive material which occurred on September 27, 1975

'4e vculd like to point cut that no member of the public and no statien or contractor personnel received a radiation dcse in excess of the limits stated in 10 CFR 20 as a result of the release. Further, ncne of the limits given in the Technical Specificaticns were exceeded.

'4e trust that tnis satisfies the repcrting requirements referenced abcve and adequately teisvers any concerns you may have.

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Enclosure:

lonrcutine 10- ay Repcrt 75-06 cc: Mr. J. P. O'Reilly (U.S. :iRC - Regicn 1)

Ms. t:argaret Reilly (PALER) 1476 270

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~'t p-Lescriptice of Occurrence Cn September 27, 1975, between the hcurs cf 1523 and 16C0 (thirty-seven (37) minutes) an inadvertent release cf gasecus radicactive material ccetrred due to the lifting cf relief valve DE-V-57A that resulted in leakage cf pr'. mary ecolant to the 261 feet elevatien of the Auxiliary Euilding. The sub: equent degassing cf the coolant resulted in the gasecus radicactive raterial being released to the at=csphere via the Auxiliary Euilding Ventilation System.

The initial indicatien cf the problem cccurred when at 1535, with the reacter subcritical and eccling devn via the decay heat rencval cperating =cde, an alert-level alar: vas received on the Auxiliary Euilding Ventilation Exhaust Radiaticn Monitor (FM-A6) Gas Channel. Investigation determined the cause to be the lifting of relief valve DE-V-57A which was caused by leakage thrcugh check valve DE-V-lhA. The Decay Heat Re=cval "A" System was secured and the release was ter=inated. Three individuals, cne cperater and tvc Radiaticn Frctection Technicians, received slight contaminaticn due to the spray frc=

the relief valve DE-V-57A, hcvever nose and =cuth swabs indicated nc internal contaninaticn. Subsequent decontamination of the individuals effectively reduced the contaminaticn levels of all personnel invcived.

Apparent Cause of the Cccurrence Material failure was the apparent cause of the occurrence in that check valve DE-V-14A leaked by causing relief valve DE-V-57A to lift at its designed relief point.

Analysis of the Cccurrence For the following reasons it is believed that the release of gasecus radic-active material cn the 27th of September did not endanger either the health cr safety of the public,

a. Ncne of the limits of the TMI-l Technical Specifications were exceeded.

b. None of the maximum permissible concentration limits for ncn-radiation verkers as given in 10 CFR 20 were exceeded at the site boundary.

c. No individual en site at the time of the release received a radiatien dcse in excess of the limits of radiation verkers specified in 10 CFR 20.

Cerrective Actiens }k7b 271 2nnediate corrective action as described abcVe was taken to terninate the release. Additionally, maintenance vill be perferred on check valve CH-V-lhA during a future cutage to prevent a recurrence of the incident.

-s-Failure Eata Previcus Failure Data: None Equipment Identification: DE-V-1kA. Ih inch check valve manufactured by Walverth Ccrp.

Felease Lata NOTE: In co case did any me=ber cf the public cr any statien er centracter perscenel receive a radiatien dcse near the applicable limits given in 10 CFF 20.

A total release acnsisted of .792 curies of predeminantly (>99%) Xe -133 based en Radisticn Menitoring Syste= Strip Chart recordings and sanples of the affected area during the release. The maximum instantaneous noble gas release rate during the thirty-seven t.inute period was 1.88x10 3M'/sec. which is belev the Technical Specification lim.t of 1.2x10 2 M3 /sec. The average release rate during the period was 1.19x103 M3 /sec. The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> average ccncentratien in the affected area was h.85x10-0 pCi/cc (based en a measured air flev of LCCO CFM), which is repcrtable under Specification 6.7.2.A.2. Evaluatien of the TLD's vern by the three individuals showed lov expcsures (< 21 =R em ) . EcVever it is believed that these exposures can be attributed to other verk during the sonth. Negative results en ncse and

=cuth swabs for the three individuals precluded the necessity of whole-bedy counting.

1476 272