ML19210A176

Nonroutine 10-Day Rept 75-07 Re 751113 Unplanned Radiation Release from Coolant Sys Pressurizer Surge Line to C Reactor Coolant Bleed Tank.Caused by Lack of Procedural Guidance.No Tech Specs Limits Exceeded

ML19210A176
Person / Time
Site:	Three Mile Island
Issue date:	11/21/1975
From:	Arnold R METROPOLITAN EDISON CO.
To:
References
75-07, 75-7, GQL-1749, NUDOCS 7910240899
Download: ML19210A176 (4)

Text

{{#Wiki_filter:. ,l NRC 3 .BUTION FOR PART 50 DOCKE - ERIAL (TEMPORARY FORM) 13355 CONTROL NO: . FILE; INCIDENT REPOI'T FILI FROM: Met. Edison ca. DATE OF DOC DATE REC'D LTR TWX RPT OTHER Reading, Pa. 19603 q . c . A ,. . , ,, , a 11-21-75 11-25-75 XX

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XX TU J Ti NRC  : . Isibned SENT LOCAL PDR CLASS UNCLASS FROPINFO INPUT NO CYS REC'D DOCKET NO: XXX 1 50-289 Non-Routine 10-Day Report 75-07 DESCRIPTION: Ltr trans the following: ENCLOSURES: Report of an unplanned release of radioacti-materials occurring on 11-13-75.... (1 cy enc 1 rec'd) o +. PLANT NAME: Three Mile Island Unit 1 OTEN - FOR ACTION /INFORMATION mn 12-2 n BUTLER (L) SCHWENCER (L) ZIEM ANN (L) REG AN (E) W/ Copies W/ Copies W/ Copies W/ Copies CLAR K (L) STOLZ (L) DICKER (E) LEAR (L) W/ Cooies W/ Cocies W/ Cooies W/ Copics PAR R (L) VASSALLO (L) KNIGHTON (E) SPELS W/ Copies W/ Copies W/ Copics / Copies KNIEL (L) PURPLE (L) YOUNGBLOOD (E) RID W/ Copics V// Copies W/ Copics W@opies INTERNAL DISTRIBUTION

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u , ..17_; f M, , , 195Ulatone Docyg( g. , s -e ., METROPOLITAN EDISON COMPANY POST OFFICE LOX 542 READING, PENNSYLVANI A 19603 TELEPHONE 215 - 929-3601

icvember 21, 1975 GQL 17L9 - g Eirectcr of Nuclear Eeacter Regulation S\ '

ff , U.S. :iucLear Regulo cry Cc=nissicn Washingt>n, D.C. 20555 g05#3 g u Dear Sir; 497A 0 Dccket :io. 50- % p Operating License t,. L eo y Ncnrcutine 10-Day Repcrt i,-{, In accordance with Section 6.7.2.a.2 cf the Technical Specificatient for cur Three Mile !sland Nuclear Station Unit 1 and 10 CFE 20.kC5 (a) (2) & (3), enclosed please find :icracutine 10-Day Reper: 75-06 that deals with an unplanned release Of radioactive material which cccurred on Ncvenber 13, 1975 We would like to point cut that no ne=ber of the public and no station or contractor personnel received a radiation dose 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 Specificaticus were exceeded. We trust that this satisfies the reperting requirements referenced above and adequately ansvers any ccccerns you =ay have. Sincerely,

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E.C./Arncid Vice President ECA:JMC:11= File: 20.1.1/7 7 3.12.1 Enclcsure: Nonroutine 10-Day Repcrt 75-07 cc: Mr. J. F. O'Reilly (U.S. :RC-Region 1) Ms. Margaret Reilly (Fa ZE) 13355 1476 159

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                                                                                                                                    ,, . , C_ l1Mh' Cn Ucvember 13, 1975, Eetween the hcurs Of 1633 and 2123 (tvc (2) hcurs and forty-five (k5 minutes))an inaivertant release of radicactive raterial occurred while draining the Reactor Ccclant System frc the pressurizer surge line to the C Reactcr Ccolant Eleed Tank. The reacter ecolant in the pressurizer surge line was at a temperature cf 26Cc? which, when drained to the bleed tank, flashed to steam resulting in an increase in pressure in the bleed tank gas space. The everpressure conditicn caused the over fica lcop seal for the Miscellanecus 'n'aste Stcrage and Peactcr Ccclant Eleed Tanks to partially evacuate and release radicactive gas to the Auxiliary Building sump. This gas then was released to the at=csphere by the Auxiliary Building 'lentilation Exhaust Syster- The release was ncted by Ccntrol Rcce personnel iurin6 rcutine checking cf the Eadiation Mcnitcring System recorders and the transfer of reactor coolant to the bleed tank was terminated. The everficv locp seal was refilled and the release was terminated.

A;;arent Cause of the Occurrence Lack cf procedural guidance is the apparent cause cf the cccurrence in that the precedure restricted draining of the reactor ccciant systern to perieds when the average temperature cf the system was less than 150"F. c Even though the average temperature at the peint of draining was 110 y, the pressurizer surge line temperature was 260cy, Analysis of the Cccurrence For the fclicvine_ reasons it is believed that the unnlanned release cf . radicactive material on the 13th of November did nct endanger either the health cr safety of the public.

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b. Ucne of the maximum permissible concentraticn limits for ncn-radiation verkers as given in 10 CFR 20 were exceeded at the site boundary.

c. Nc individual on site at the time of the release received a radiatien dcse in excess of the limits for radiation verkers specified in 10 CFF 20.

1476 150

Ccrrective Action I:=ediate corrective action as described abcVe was taken to terminate the release. Additionally precedural changes vill te inecrporated to insure that draining of the reacter ecclant system frc= the pressuriner surge line vill be accceplished only when the prcosurizer terperature is less than 15CC F. Failure Data Uct applicable. Release Data Note: In ne case did any member of the public cr any station er centractor perscnnel receive a radiation dose near the applicable limits given in 10 CFR 20. The total release censisted of 6.38 curies cf predcminantly (>99%) Xe-133 based en Radiation Monitering Syste= Strip Chart Recordings and samples of the vent header system. The maximum instantaneous ncble gas release rate during the tvc hour and forty-five minute period was 7.36 x 105 =3/sec which is belev the Technical Srecificatica limit of 1.2 x 105 =3/see.

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The average release rate during the pericd was 2.31 x 103 =3/sec. The 2h hour average concentration in the auxiliary building sump was 3.37h x 10-k pCi/cc (based cn the design air flcw of 500 CFM thrcugh the cubicle), which is reportable under Technical Specification 6.7.2.a.2 and 10 CFR 20. There were no perscnnel exposures involved during the release since there were no personnel in the auxiliary building su=p, (a ner= ally uncccupied area). TA76 161}}