ML19291B686

Nonroutine 7-Day Environ Rept 75-02:on 750730,measured Level of Radioactive Matl Exceeded Ten Times Control Station Value.Caused by Low Jul River Flow Rate W/Increase in Sedimentation.Normal Sampling to Continue

ML19291B686
Person / Time
Site:	Three Mile Island
Issue date:	10/17/1975
From:	Arnold R METROPOLITAN EDISON CO.
To:
Shared Package
ML19291B685	List: ML19291B684 ML19291B686
References
NUDOCS 7911110163
Download: ML19291B686 (1)

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ENCLOSURE Metropolitan Edison Company (Met-Ed)

Three* Mile Island Nuclear Station Unit 1 (TMI-1)

Docket No. 50-289 Operating License No. DPR-50 Nonroutine T-Day Environmental Report 75-02 Report of an Anomalous Measured Level of Radioactive Material Description of Measured Level As reported to Met-Ed on October 10,1975 (by the consultant (RMC) laboratory),

the concentration of Co-58 in the semi-annual river bottom sediment samples collected on July 30, 1975 exceeded ten (10) times the control station value.

The control station, (TM-AQS-1A2) located approximately 0.5 miles north of TMI-l discharge, had concentrations of Co-58 of less than the Minimum Detectable Level (MDL) of <0.20 pCi/ gram. The concentration of Co-58 at TM-AQS-11A1, 0.2 miles and TM-AQS-9B2 at 1.h miles downstream of the TMI-l discharge equaled 0.hTO pCi/ gram and 0.3h0 pCi/ gram respectively.

Possible Cause Discharges of the Liquid Waste Evaporator Condensate Tanks are made from 'IMI-l on an irregular basis based on unit operating conditions as described in the Final Safety Analysis Report. It is thought that the unusually low river flow rates during July may have caused the sedimentation rate to increase significantly.

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

a. The estimated total body dose associated with this measured value from the only significant dose pathway (shoreline deposition) is less than 0.2 = rem per year to the maximum hypothetical individual.

b. The level of Co-58 activity in the river water at the nearest downstream source of public drinking water was below minimum detectable levels.

c. None of the TMI-l Technical Specifications were exceeded.

d. The event resulted from normal unit operations as described in the TMI-l Final Safety Analysis Report.

e. The level of Co-58 activity detected in the river sediment is a very lov level of activity and is expected to have little or no mvironmental impact.

Corrective Actions Due to the scouring effect of the floeding associated with Hurricane Eloise it is thought that an increased sampling effort would be non-productive. Sempling vill continue in accordance with TMI-l Environmental Technical Specifications. The next sediment sampling period vill be October 1975 7911110$3