ML19274D559

LER 78-056/04T-0 on 781221:oyster Samples Showed AG-110m at 81 Plus or Minus 11% Pci/Kg & Background Location Ag-110m at Less than 7 Pci/Kg.More Sensitive Technique Has Reduced MDL Value from 40 Pci/Kg,But New Background Value Is Exceeded

ML19274D559
Person / Time
Site:	Calvert Cliffs
Issue date:	01/04/1979
From:	Eherts R BALTIMORE GAS & ELECTRIC CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19274D558	List: ML19274D557 ML19274D559
References
LER-78-056-04T, LER-78-56-4T, NUDOCS 7902130106
Download: ML19274D559 (3)

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7 8 60 61 COCKET NUMB E R EV ENT DATE '5 EVENT OESCRIPTION AND PROB ABLE CONSEQUENCES h o iO l 0vster samoles collected on 12/5/78 from the Camo Canoy location and analyzed l ioi3 i as reauired .,y Section 3.2, Accendix B, Environmental Technical Specification, l 0 4 ;showed Ag-110m at 81 1 11% oCi/kg. Backcround location showed Ag-110m at less I o is [7 pCi/kg. Based on the observed levels, average individual deses to the GI l C is l Tract and khole Body are very small fractions of the allowable doses to l l 017 l Dembers of the general public (40CFR Part 190) and are of no consequence to ]

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33 J4 37 40 41 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS i lo lThe introduction of a more sensitive technioue has reduced the'1DL value for I

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LICENSEE EVENT REPORT 78-56/4T DOCKET N0. 50-317 REPORT DATE 01/04/79 EVENT DATE 12/21/78 ATTACHMENT EVENT DESCRIPTION AND PROBABLE CONSEQUENCES: (CONT)

The oyster samples were collected on December 5,1978 from the Camo Canoy sampling location and analyzed for gamma-emitting radionuclides as required by Section 3.2 Appendix B Environmental Technical Speci-fications. The results of the analyses showed the presence of Ag-110m at 81 + 11% pCi/K g (wet) . The oyster samoles collected on the same date from the Kenwood Beach sampling location (the backoround location) showed Ag-110m atd 7 pCi/Kg (wet) .

Based on the observed levels of Ag-110m during 1978, for an average individual consuming 50 grams of oysters per day the doses to the GI Tract and Whole body are estimated att 3 x 10-2 mrem / year and s 4x10-5 mren respectively. These are very small fractions of the allowable 25 mrem / year (GI Tract) and 25 mrem / year (Whole Body) doses to members of the general oublic, (40 CFR Part 190 Environmental Radiation Pro-tection Standards for Nuclear Power Ocerations) and are considered to be of no consequence to the health and safety of the public.

CAUSE DESCRIPTION AND CORRECTIVE ACTION: (CONT)

The measurable level of Ag-110m in oysters was first detected in samples collected from the Camp Canoy sampling location in June 1977.

Subseouently, samples collected in 1977 from the same location also showed measurable levels of Ag-li0m as did the samoles collected in January and February 1978. These findings were recorted to the NRC as reouired.

The oyster samnles collected from the Camp Canoy location from March through September 1978 showed an apparent decrease in Ag-110m concen-tra ti ons . These concentrations ranced from 310 + 10% to 160 + 15%

nCi/kg (wet). The observed decrease may in large cart be due to decuration even though the effluent releases from the plant during the period of interest contained small quantities of Ao-llom.

Beginning with the fourth quarter of 1978 oyster samoles are no lancer sent to Radiation Management Corroration (RMC) in Philadelchia for carina analyses. These analyses are done by the Chenical Engineering and Test Section of our Electric Test Departrent, using a 10% Ge(Li) with a Nuclear Data System 6600. The samole size and the count time are selected to reet the recuired detection capabilities for a number of radionuclides includinc Ir-Mb-95. As a result of this exercise, the MCL value for

CAUSE DESCRIPTION AND CCRRECTIVE ACTION: (CONT)

Ag-ilon is calculated at abouti7 pCi/Kg (wet), which is substantially lower than the crevious average D' value of abouti40 pCi/Kg (wet).

On the assumotion that this new f4DL <alue of 7 constitutes the back-ground value, the level of Aa-110m observed in December 1973 Cann rancy samples exceeded the background value by over a factor of 10. However it does show a continuation of the general trend of decreasing Ag-110m activity in oysters at this location.