ML19262A254

Nonroutine 10-Day Rept 74-04:on 750821 Unplanned Release of Radioactive Matl Occurred W/Excessive Concentration of Radioactive Matl.Caused by Loss of Reclaimed Boric Acid Tank B Loop Seal Due to Component Failure

ML19262A254
Person / Time
Site:	Three Mile Island
Issue date:	08/28/1975
From:	METROPOLITAN EDISON CO.
To:
Shared Package
ML19262A245	List: ML19262A244 ML19262A248 ML19262A254
References
75-04, 75-4, NUDOCS 7910260589
Download: ML19262A254 (2)

Text

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ENCLOSURE 1 Metropolitan Edison Cocpany Three Mile Island Nuclear Station Unit 1 (TMI-1)

Docket No. 50-289 Operating License No. DPR-50 Nonroutine 10-Dcy Report 75-Oh Report of an Unplanned Radioactive Release of Radioactive Material and Excessive Concentration of Radioactive Material Occurring on August 21, 1975 Descriutien of Occurrence On August 21, 1975, between the hcurs of 0053 and 0231 (one hour and thirty-eight minutes) an inadvertant release of radioactive material occurred due to the loss of the Reclai=ed Boric AcM Tank "B" Loop Seal. The radicactive =aterial was released into the Reclaimed Boric Acid Tank / Concentrated Waste Storage Tank Roc =

and subsequently discharged by the ventilation syste= through the plant vent stack.

Alert level alar =s were received from Vent Stack Exhaust Monitor P3f-A8 (Gasecus Channel) and Auxiliary Building Vent Exhaust Monitor RM-A6 (Gaseous 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 terninated.

One Instru=ent and Control Technician in the vicinity of the Reclaimed Boric Acid Tank Loop Seal at the tire of the release was monitored and found to be slightly contaninated about the face. Subsequent decontamination reduced con-ta=ination to acceptable levels.

Arnarent Cause of the Occurrence Component failure was the apparent cause of the occurrence in that a leak developed at a union fitting in the piping associated with the loop seal sight glass and this in turn caused the loss of the loop seal.

Analysis of Occurrence For the following reasons it is belived that the unplanned release of radioactive caterial 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 Maximu= Permissible Concentration (APC) li=its fer non-radiation workers listed in 10CFR20 were exceeded at the site boundary.

Corrective Action As described above, inmediate corrective action was taken to terminate the release.

Following this, the leaking union fitting in the piping associated with the 1 cop seal sight glass was repaired.

railure Data 1484 230 Union fitting in piping associated with sight glass 'iDL-II-2083 on "B" Reclaimed '

Boric Acid Storage Tank. 7910260

Enclosure I (Continued) Release Data The total release consisted of 8.51 curies of predo=inately Xe-133 (100%).

This value was obtained frc= the chart recordings of Vent Stack Exhaust Monitor RM-A8. The gross gaseous release rate was 1 55 x 10 M 3/sec., which is below the Technical Specification limit of 1.2 x 105 M3 /sec. Analysis of the release data indicates that the 24-hcur average concentration of .cactive material ingheReclaimedBoricAcidTank/ConcentratedWasteStora, fank Room was 3.73 x 10- pCi/ce, which is reportable under 10CFR20.h03(b)(2). .he 24-hour average concentration is based on 8.51 curies of Xe-133 released aver a one hour and thirty-seven minute period with a room air flov of 560 ft / min 3 (measured) .

Personnel Extosure Data (10CFR20.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 / Concentrated Waste Storage Tank Room on an unrelated job. The second individual was an Auxiliary Operator who entered the room to investigate the problem. The third individual was the Shift Supervisor, who also entered the room to investigate the problem. Their stay time in the room was less than one minute. Based on a calculated raxicum concentration of 1.07 x 10-2 pCi/cc and a restricted area MFC of 1 x 10-5 pCi/cc (Xe-133 100%), the al;:ved stay ti=e for these individuals was 1.22 minutes. The TLD's worn by the three individualu were evaluated with

. results showing all Beta exposures to be less than the minimum detectable (k0 MR) and all gan=a exposures less than 25 MR; however, it is believed that the gn==a exposures are due to other =aintenance and inspections during the month rather than to the present rehases. In that much of the exposure can be accounted for by previous assignments and by the fact that Xe-133 exposures show as beta exposures due to the energy and in that no beta was detected, it is believed that no additional significant exposures resulted from the incident.

1484 231

E:iCLCSURE II PERSO it!EL I?IVOLVED (10CFR20.h05(b))

Social Estimate h*rsonnel Security ITo. Birth Date of Extosure Edward G. Lawrence 102-38 h137 1-19 h7 Zero: exposure on TLD accounted for Joseph T. Wilt 191-32-1888 5-30 ho by other activities during that period.

Marshall L. Beers 169-24-0035 1-31-28 1484 232