ML20027A257
| ML20027A257 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 10/27/1978 |
| From: | CONNECTICUT YANKEE ATOMIC POWER CO. |
| To: | |
| Shared Package | |
| ML20027A256 | List: |
| References | |
| ETS-NR-50-213-7, NUDOCS 7811060107 | |
| Download: ML20027A257 (2) | |
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4 Facility: Haddam Neck Nuclear Facility Report Number:
ETS/NR/50-213/78-10 Report Date: October 27, 1978 Occurrence Date: Third Quarter, 1978 DESCRIPTION OF OCCURRENCE:
The following level of tritium (H-3) activity was observed in the quarterly composite of river water near the discharge area and this exceeded the control station (Middletown) by greater than a factor of ten.
Analysis Confirmation Results Grab Sample Report Date Date (pCi/1)
Discharge Area 7/10,7/17,7/24,7/31,8/8,8/14 10/10 10/18 5,120 300 Middletown 7/10,7/18,7/25,8/1,8/7,8/14 10/10 160 80 (control)
PLANT OPERATING CONDITIONS PRIOR TO OCCURRENCE:
The plant was operating at about 100% power throughout July and August except for power operation at 100 MWe for a few hours on July 30 and a plant trip resulting in approximately a half-day outage on August 20.
During this period the plant was routinely discharging effluents.
CAUSE OF OCCURRENCE:
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The collection of one of the six weekly river water grab samples (the one on 7/31) was coincidental with the station discharge. This along with sampling a few hours af ter upstream tidal river flow, low river flow characteristic of this time of year, and the phenomonon of the plant effluent remaining on the river surface and along the east bank of the river resulted in an un-representative high level of H-3 in a river water grab sample.
CORRECTIVE ACTION:
(1) Status of Corrective Actions Resulting From a Similar Report on November 4, 1977, ETS/NR/50-213/77-6:
a) Analyses of each of the weekly grab samples that make up a quarterly composite was instituted on 10/77 and has continued. These analyses revealed only two instances where the H-3 levels were above background.
The 11/18/77 sample contained 3000 180 pCi/1 and the 7/31/78 sample contained 28,500 1800 pCi/1. The latter resulted in this anomalous measurement report.
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i 4 b)
In order to try to obtain more representative river water samples, the sampling-at other locations was investigated. A location just 4
across the river from the outfall of the canal was chosen as a likely alternate to-the present location. This location was sampled during the fourth quarter of 1977 and first quarter of 1978. The sample taken on 11/18/77 was during a discharge as can be seen by the result of 3000 180 pCi/1 in the sample from the present location.
However the result from this sample was 100 60pci/1 which indicated that here the plant discharges would probably never be seen across the river. Therefore it was decided to continue with the present location and proceed with the evaluation of alternate sampling methods (e.g. automatic sampling).
c) As a result of a recommendation made by the NRC during an audit under-taken in February 1978 and the above investigations, the use of a continuous or short interval composite sampler has been under 3
evaluation. The equipment used at another nuc) gar facility has been-evaluated, but it is ideally limited to conditions which we do not
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have. In an attempt to reach a practical solution and location the f
plans have changed several times. The present solution is to experi-ment with an automatic sampler located near the present grab sample location. This f acility is expected to be operational by December 30, 1978. Composite grab sampling will be continued in parallel.
1 (2) Additional Corrective Actions Resulting from this Report:
Another location for an automatic sampling station will be evaluated.
It would probably be located somewhere downstream in an area where the effluents will be more evenly distributed in the river to give a more realistic assessment of the plant effects.
g (3) Dose Consequence:
A dose calculation (Reg. Guide 1.109 methods) was performed, assuming-an individual could have consumed fish, resident in the river having the tritium concentration as measured. The whole body dose would be f(
0.0025 mrem. There is no drinking water pathway. This is a conservative estimate (high). as the actual river concentration would be lower than that 1
measured by the nonrepresentative sampling. Another more' realistic calculation is to again use the Reg. Guide 1.109 methods, assume that the fish are resident in the canal, and use the measured plant discharges-for this quarter. This results 'in the calculation of 0.009 mrem for the 3rd quarter. Even this is conservative in that the fish do not reside'in the canal 100% of the time.. The more conservative calculation resulting in 0.0025 mrem is an extremely.small fraction (less than 0.0001) of the natural background radiation exposure to this individual during -
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this quarter which ~is about 30 millirem.
Thus the dose consequence of this event is insignificant. The reporting requirement is conservatively designed. Tritium from plant discharges-is rapidly (within a few hours) diluted by the river to below background levels from naturally oc urring tritium.
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