ML20140D071
| ML20140D071 | |
| Person / Time | |
|---|---|
| Site: | 07109073 |
| Issue date: | 02/28/1986 |
| From: | Lempges T NIAGARA MOHAWK POWER CORP. |
| To: | Jennifer Davis NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| 26556, NMP-16434, NUDOCS 8603250571 | |
| Download: ML20140D071 (3) | |
Text
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USNRC 2-L Office of Nuclear Material Safety and Safeguards I
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Mr. John G. Davis, Director
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Washington, DC 20555 Dear Mr. Davis.
On January 14, 1986 Niagara Mohawk Power Corporation sent a shipment of radioactive waste to the Barnwell site.in South Carolina.
Upon arrival at the burial site, it was discovered that contamination in excess of 10 CFR 71.87(i)(2) was present on the exterior surface of the cask. The cause of this contamination has been attributed to the use of the cask. While this event, described in more detail below, does.not strictly meet the reporting requirements of 10 CFR 71.95, this report is being sub-mitted voluntarily since Niagara Mohawk believes the NRC should be made aware of this event.
Niagara Mohawk shipped a cask of reactor components '(velocity limiters and control rod blade sections) from our Nine Mile Point Unit I Facility. The cask used was the NuPac OH-142 (USA /9073/A), which was leased to Waste Chem, Inc. The cask was immersed in the spent fuel pool and loaded underwater. Since the cask was bottom loaded, the lower impact limiter and cover remained on the refuel floor. The cask body, primary lid, and upper impact limiter were lowered into the fuel pool. The lifting point for this cask is the cover, to which the ' upper impact limiter is an integral part. -The upper impact limiter and primary lid were not removed while at the station. The accessible surfaces of the cask were deconned to less than 100 dpm per 100cm2 On arrival at the Barnwell Site a brown streak was present running from the upper impact limiter to the lower impact limiter on the side of the cask at the 5 o' clock position (assuming 12 o' clock was the front of the cask towards the tractor).
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- Chem-Nuclear took three (3) smears of 100cm2 each along the stain. The smears averaged 25,020 dpm/100cm2 Niagara Mohawk was advised by telephone on 1/20/86.
The Supervisor Radwaste Operations went to the Barnwell site on 1/21/86. The stain was observed. The cask was then off loaded. The next day, 1/22/86, the upper impact limiter / lid was removed. A brown spot was observed on the cask body j
and the corresponding area of the impact limiter at the 5 o' clock position above the contamination. The same type of spot was observed at the 11 o' clock position.
These areas were determined not to have excessive contamination. A considerable amount of scoring was observed both on the impact limiter and upper cask body.
The i
area over the contamination was more intensely scored than other areas.
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d Page NMP-16434 It appears that the source of the contamination was the gasket, which according to NuPac is of the open cell type. Chem-Nuclear observed that water came out of the gasket when compressed.
It was the consensus of representatives of Niagara Mohawk, Chem-Nuclear and the State of South Carolina that the contaminated water came out of the gasket and ran down the side of the cask during transit.
Apparently the current cask de. sign does not lend itself to pool submersion since it would be necessary to remove the lid of the loaded cask to decon the gasket area.
In the case of this shipment, the liner radiation reading was 70 R/hr. Since the impact limiter is attached to the cask lid, there is virtually no way to decon the area between the impact limiter and the cask body. The representatives of Chem-Nuclear and the State of South Carolina concurred with this assessment and are looking to NuPac to take corrective actions.
It is our understanding that-NuPac plans to refurbish this cask for non-immersion applications.
Niagara Mohawk was unaware of the potential for water entrapme'nt in the gasket.
In the future we will perform a more intensive evaluation.,of cask design prior to usage in fuel pool immersion applications. ' This appears to be the only way to preclude future potential contamination problems.
4 Very truly-yours, Niagara Mohawk Power Corporation WA Thomas E. Lempges Vice President Nuclear Generation TcL/tg 1
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