ML19210A171

Nonroutine 10-Day Rept 75-04 Re Unplanned Radiation Release Due to Loss of Reclaimed Boric Acid Tank B Loop Seal. Radiation Discharged from Tank Room Through Ventilation Sys

ML19210A171
Person / Time
Site:	Three Mile Island
Issue date:	08/28/1975
From:	METROPOLITAN EDISON CO.
To:
Shared Package
ML19210A170	List: ML19210A169 ML19210A171 ML19210A174
References
75-04, 75-4, NUDOCS 7910240894
Download: ML19210A171 (3)

Text

ENCLCSURE 1

, Metropolitan Edison Cc=pany Three Mile Island Nuclear Statien Unit 1 (TMI-1)

Docket No. 50-289 Operating License No. DPR-50 Ncnroutine 10-Day Report 75-Ch Report of an Unplanned Radicactive Release of Radicactive Material and Excessive Concentratica of Radioactive Material Occurring en August 21, 1975 Descriptien of Occurrence On August 21, 1975, between the hours of 0053 and 0231 (one hour and thirty-eight =inutes) an inadvertant release of radioactive =aterial cecurred due to the loss of the Reclaimed Boric Acid Tank "B" Loop Seal. The radicactive material was released into the Reclaimed Boric Acid Tank /Cencentrated Waste Storage Tank Roc =

and subsequently discharged by the ventilation system through the plant vent stack.

Alert level alarms were received frc= Vent Stack EMaaust Monitor RM-A9 (Gasecus Channel) and Auxiliary Building Vent Exhaust Menitor RM-A6 (Gasecus Channel). Plant operations personnel proceeded to locate the cause of the release, the Reclaimed Boric Acid Tank Loop Seal was re-established, and the release was ter=inated.

One Instrument and Centrol Technician in the vicinity of the Reclaimed Boric Acid Tank Loop Seal at the time of the release was =enitored and found to be slightly contaminated about the face. Subsequent decentamination reduced cen-tamination to acceptable levels.

Apparent Cause of the Cecurrence Cc=nonent failure was the apparent cause of the cecurrence in that a leak developed at a union fitting in the piping associated with the leep seal sight glass and this in turn caused the loss of the loop seal.

Analysis of Occurrence For the folleving reasons it is belived that the unplanned release of radioactive material en the 21st of August did not endanger either the health or safety of the public:

a. None of the limits in the TMI-l Technical Specifications were exceeded.

b. None of the Maximum Permissible Concentration (MPC) limits for ncn-radiation workers listed in 10CFR20 were exceeded at the site beundary.

Corrective Action As described above, i==ediate corrective action was taken to terminate the release.

Folleving this, the leaking union fitting in the piping associated with the lecp seal sight glass was repaired.

Failure Data )47b l44 Union fitting in piping assceiated with sight glass WDL-LI-2083 en "B" Reclaimed Boric Acid Stcra6e Tank.

7910240 [

Enclosure I (Continued) .

Release Data The total release consisted of 8.51 curies of predecinately Xe-133 (100%).

This value was obtained frc= the chart recordirgs of Vent Stack Exhaust Mcnitor RM-A6. The gross gaseous release rate was 1.55 x 10 M 3/sec., which is belev the Technical Specification limit of 1.2 x 105 M 3 /sec. Analysis of the release data indicates that the 2h-hour average concentration of radicactive material in +Nhe Reclaimed Boric Acid Tank /Cencentrated '4aste Sterage Tank Rect was 3.73 x 10- pCi/ce, which is reportable under 10CFR20.h03(b)(2). The 2h-hour average concentration is based on 8.51 curies of Xe-133 released over a one hour and thirty-seven minute period with a roc = air flow of 560 ft /=in 3 (=easured) .

Persennel Exposure Data (ICCFR20.h05)

Station personnel involved in the incident included three individuals who were in the area during the release. The first individual was an instrument and Control Technician who was working in the Reclaimed Boric Acid Tank /Cencentrated

'4aste Storage Tank Roc = on an unrelated job. The second individual was an Auxiliary Operator who entered the rec = to investigate the pro' .em. The third individual was the Shift Supervisor, who also entered the roc = to investigate the problem. Their stay time in the roc = vas less than one minute. Based en a calculated =aximum concentration of 197 x 10-2 Ci/cc and a restricted area MPC of 1 x 10-5 pCi/cc (Xe-133 100%), the alleved stay time for these individuals was 1.22 minutes. The TLD's vorn by the three individuals were evaluated with results showing all Beta exposures to be less than the mini =u= detectable (h0 PR) and all ga==a exposures less than 25 MR; hcvever, it is believed that the ga-a exposures are due to other maintenance and inspections during the =cnth rather than to the present releases. In that much of the exposure can be acccunted for by previous assignments and by the fact that Xe-133 exposures shev as beta exposures due to the energy and in that no beta was detected, it is believed that no additional significant exposures resulted frc= the incident.

\416 \0

O ENCLCSUPE II PERS0!iNEL I:IVOLVED (10CFE20.h05(b))

Social Estimate Personnel Security No. Birth tate of Ex esu*e Edward G. Lawrence 102-38 h137 1-19 h7 Zero: exposure en TLD acccur.ted for Joseph T. Wilt 191-32-1883 5-30 ho by other activities during that peried.

Marshall L. Beers 169-2h-0035 1-31-28 1476 146