ML19329F417
| ML19329F417 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island, Midland  |
| Issue date: | 12/24/1975 |
| From: | Ziemann D Office of Nuclear Reactor Regulation |
| To: | Gove P ECIMPCA, MINNESOTA, STATE OF |
| Shared Package | |
| ML19329F414 | List: |
| References | |
| NUDOCS 8006270463 | |
| Download: ML19329F417 (2) | |
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UNn CD tTATES NUCLEAR REGULATORY CO'aMISW
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December 24, 1975 o.-
Docket N.>. 50-282 Mr. Peter L. Cove Executive Director Min.csota Pollution Control Agency 1935 West County Road - B2 Roc ville, Minnesota 5'5113
Dear Mr. Gove:
This is in response to your letter dated December 1,1975 in which you expreosed concern over the release of radioactive belogens and particulates at the Prairie Island Unit 1 facility duri.ng the May 11, 1975 through August 10, 1975 interval. Your letter was received on December 10, 1975 and has been referred to me.
y On June 26, 1975, reactor co$lant leakage from No. 12 reactor coolant pump seal injection system was detected. The plant uas brought to a shutdoun condition and the containment air was processed through i
particulate and charcoal filters to minimize the release of radio-I active effluents and to permit personnel entry into containment.
l Inspection revealed the presence of a crack in the seal injection i
piping. Further inspection also revealed a crack in a 3/4 pipe in the residual heat removal system.
The total co=bined reactor coolant leakage rate into the containment was approximately 2.5 gallons per minute.
The net result of this leaka;;u was to increase the airborne halogen and cobalt-58 activi.ty within containment above that normally present without piping defects.
Consequently, the release of radio-I active halogens and cobalt-58 was characterized as abnormal only in the context that it was higher than the normal release experienced at this facility. The total radioactivity with half lives greater than eight days released during the thirteen week interval was 0.0107 cura.. The dose associated with this release at the nearest occup ed residence was less than 1/100,000 of the requirements of 10 C M 20 and is extremely low. This ralesse did not violate the Prair b Island Unit 1 Technical Specifications and further verifies the. effectiveness of the air cleanup. The Northern States Power l
Company has repaired the defective piping and will install pressure pulse suppreasors in the seal injection piping to minimize recurrence l
of the piping failure.
A pipe-hanger has also been installed in the residual heat removal systect to reduce vibration of the 3/4 inch line. While defects such as described above do occur occasionally, they should not be characterized as routine and any associated main-tenance.and purging should be classified as extra-ordinary r ther than routine in view of their infrequent occurrence.
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Mr. Peter L. Cove 2-D' ember 24, 1975 You are correct in stating that the Northern States Power Company exceeded the thirty day interval allowed to notify the Nuclear Regulatory Commission of such an occurrence. The delay in notifying our staff was apparently due to a breakdoun in communications within the Northern States Power Company. However, when the appropriate facility personnel recognized that this was a reportable occurrence they promptly notified our staff of this occurrence as described in their November 14, 1975 report.
Our office of Inspection and Enforeccent vill shortl) visit the Prairie Island Unit I site to review this matter and to determine if any additional enforcement action will be required.
I believe that it is important to state that the current requirenents as stated in the Prairie Island Technical Specifications are substantially = ore conservati re than what would be permitted by our present guidelines in regard to the release o radioactive gaseous effluents. !!hile we are continuing to require stringent control of release of radioactive materials, we also consider provisions for operational flexibility. This must flexibility, compatible with considerations of the public health and safety, assures that the public is provided with a dependable source of power under unusual operating conditions that may temporarily result in releases higher than the design objective but less than the limits specified in 10 CFR 20.
Sincerely,
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b; e, Dennis L. Ziemann, Chief Operating Reactors Branch 92 Division of Reactor Licensing e
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