ML19291B699

Nonroutine 30-Day Environ Rept 75-03:on 750802-30,measured Radioactive Matl Level Exceeded Four Times Control Station Value.Caused by Sampling During Abnormally Low River Water Flow.Normal Sampling to Continue

ML19291B699
Person / Time
Site:	Three Mile Island
Issue date:	11/21/1975
From:	Arnold R METROPOLITAN EDISON CO.
To:
Shared Package
ML19291B697	List: ML19291B696 ML19291B699
References
NUDOCS 7911110172
Download: ML19291B699 (2)

Text

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ENCL 0SURE Metropolitan Edison Cc=pany Thr'ee Mile Island Nuclear Station Unit 1 (TMI-1)

Docket No. 50-289 Operating License No. DTR-50 Nonroutine 30-Day Environ = ental Report 75-03 Report on an Anocalous Measured Level of Radicactivity Description of Measured Level A tenth.1/ composite of weekly grab samples of surface river water collected at a locat$ sn about 0 5 miles downstraam frem the TMI-l river discharge had a Co-60 concentration of 2.h ! 0.h x 10-9 pCi and an I-131 concentration of 3.2 0.6 x pCi 1 10-9 'ml as reported to Met-Ed by its consultants on October 7,1975. This value is greater than four times the Mini =um Detectable Levels (MDL) for Co-60 and I-131 which are 5 x 10-10 pCi and 7 x 10-10 uCi respectively.

ml =1 In the absence of any previous positive data these MDL values are referred to as the control station values. It is extremely difficult to estimate background levels of gn--n emitting radionuclides in surface water. These difficulties co=e about since the sensitivity of g'- a spectrographic analyses (the analytical method of choice) is such that results are, and have been, typically below the detection limit. As such this detection limit (MDL), is the only possible Control Station Value to use.

A strict reading of the TMI-l Environ = ental Technical Specifications thus requires us to inform you of these measured levels.

Possible Cause Discharges are made from the TMI-l Liquid Waste Evaporator Condensate Tanks on an irregular schedule based on unit operating conditions. Weekly grab samples for the radiological environ = ental monitoring pregram are taken on a regular basis. It is believed that the grab sa ples which were composited to for:

this sample vere taken during periods of abnormally low river vater flow.

Analysis of Measured Level It is believed that neither the health nor safety of the public was threatened by the occurrence represented by this sample in that :

a. The level of Co-60 activity was less than 1/10,000th of the Maximum Per=issible Concentration Level given in 10CFR20 for members cf the public,

b. The level of. I-131 activity was about 1/100 th of the Maximu= Per=issible Concentration Level given in 1CCFR20 for rembers of the public.

c. Assuming (censervatively) the river water centained 46 pCi/l of I-131 for the 11 day conth of August, any individual drinking 1.2 liters per day at the nearest downstream water source would have a total integrated thyroid dose due to the I-131 of 0.0032 mrem.

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d. The level of activity for these isotopes at the nearest devnstrean source cf continuous public use was determined to be less than the MDL.

e.  : o Technical Specification Limits were exceeded,

f. The etent resulted from ner=al unit operations as described in the TMI-1 Final Safety Analysis Report.

Corrective Action The discharge of effluents frc= the Waste Evaporater Condensate Tank is a ner=al process associated with unit operations and is described in the Final Safety Analysis Report. Met-Ed vill centinue to sanple in accordance with Environ: ental Technical Specifications, Table 3.

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