ML20086F080
| ML20086F080 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom, 05000000 |
| Issue date: | 06/06/1977 |
| From: | Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | Case E Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20086F058 | List: |
| References | |
| NUDOCS 8312120485 | |
| Download: ML20086F080 (4) | |
Text
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PHILADELPHIA ELECTRIC COMPANY p7 2301 MARKET STREET
'h P.O. BOX 8699 PHILADELPHIA. PA.19101 IE FILE COPE
<2""**'-'
June 6, 1977 RE:
Docket Nos.
50-277 50-278 Mr. Edson G. Case Acting Director Office of Nuclear Reactor Regulation United States Nuclear Regulatory Commission Washington, D.C.
20555
SUBJECT:
Unique g ort for Plant Iodine and Particulate Release Rate Exceeding Four Percent of the Peach Bottom Atomic Power Station Technical p _cif_ication fi 3.8.C.2 Averaged Over the Se3nd-Calender Quarte /
of 1977
Dear Mr. Case:
This letter is being transmitted in accordance with the unique reporting requirements specified in Technical Specification 3.8.C.3.b, which states that the Director of the Office of Nuclear Reactor Regulation should be informed when the release rate exceeds four percent of Technical Specification 3.8.C.2 when averaged over a calendar quarter. The release rate when averaged over the second quarter of 1977 (April 4 to July 4) exceeded this four percent value on May 6, 1977.
Apparont Cause This release rate was apparently caused by fuel perforations coupled with end of cycle testing, reactor coolant and steam leaks, and a refueling and maintenance outage. The major isotope was I-131.
Releases of particulates with half lives greater than eight days were approximately eleven percent of the total releases.
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8312120485 771005 I
PDR ADOCK 05000277 j
S PDR COPY SENT REGION L
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Mr. Edson G. Case July 6, 1977 Page 2 l
During the first five weeks of the second quarter 92.8 percent of the total activity released was from the Unit 2 building (reactor and turbine) ventilation system exhaust stack. The Unit 3 building ventilation system released accounted for the remaining 7.2
/
percent.
Analysis of Occurrence Analysis of the release data for I-131, indicates that the releases were primarily associated with the Unit 2 end-of-cycle testing program and the subsequent refueling outage. The end-of-cycle testing program entailed a number of reactor shutdowns and startups during the relatively short period of three weeks. It has been our experience that each shutdown causes a spike in the I-131 concentration in the reactor coolant. These spikes vary the I-131 concentrations in the coolant by a factor of ten to one hundred from the normal range.
Because of the higher than normal I-131 concentrations in the coolant, any water or steam leaks which were present during this period resulted in higher than normal iodine release rates. During this period, the standby gas treatment system was in service on the reactor building equipment cell exhcust thereby reducing the amount of I-131 that was released from the Unit 2 huilding ventilation system.
When the Unit 2 refueling outage began on April 27, 1977 the I-131 concengration in the primary coolant was still elevated (1x10-2 to tx10- uCi/ml range). This elevated concentration resulted in higher than normal I-131 releases from coolant leakage. Operations associated with the Unit 2 refueling outage involving draining of reactor coolant from components for maintenance and opening of the a
reactor vessel added to the I-131 release rate from the Unit 2 reactor building.
To minimize the effects of these operations on the I-131 release rate, the reactor building and refueling floor ventilation l
systems were placed on the standby gas treatment system.
Eight of the forty-four milk samples from the radiological monitoring program gathered and analyzed during the first four weeks of May showed detectable levels which were significantly below the reporting requirement level. The concentrations detected were, in fact, just above the limit of minimum detectibility.
Based on this data and data from previous quarters, the releases have caused no safety harerd to the public.
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O Mr. Edson G. Case July 6, 1977 Page 3 j
Corrective Action The I-131 concentrations in the reactor coolant are a result of fuel cladding perforations. During the present Unit 2 refueling
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outage, an extensive fuel sipping program is in progress to identify and remove as much defective fuel as possible.
Removal of the reactor vessel head and any maintenance work which requires lowering of the vessel water level normally increases 1
the release rate of I-131 In an effort to minimize these contributions to the release rate, cleanup of the reactor coolant was performed with both the reactor water cleanup filter demineralizers and the condensate filter demineralizers. Before the reactor head was removed, the complete reactor building and refuel floor ventilation systems were placed on the stanby gas treatment system. These actions dropped the I-131 release rate from 23 percent to 7.4 percent during a time when the release rate would otherwise have increased.
Further, to minimize the I-131 release rate after the lifting of the Unit 2 main turbine hood for maintenance, the open turbine section was covered with plastic and was purged with air that was vented through temporary filtration units. After this air purging was completed, turbine maintenance proceeded without causing an additional increase in the I-131 release rate.
By application dated May 27, 1977, Philadelphia Electric Company proposed an amendment to Section 3.8.C.2 of the Peach Bottom Technical Specifications which contains the I-131 release rate limit. This amendment request is based on the assessment of the meteorologyof the Peach Bottom Site and consequent calculated doses of I-131 by the NRC Staff as detailed in "NRC Staff Report - Evaluation of the Radioactive Waste Treatment Systems Installed at Peach Bottom Atomic Power Station Unit Nos. 2 and 3 with Respect to the Requirements of Appendix I to 10 CFR Part 50," dated April,1977.
The expected acceptance of this amendment will result in raising the current release rate limit for I-131 by a factor of approximately five and will allow more operating flexibility than the present limit which was derived on a very conservative basis prior to the completion of the NRC Staff analysis.
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Mr. Edson G. Case July 6, 1977 Page 4
1 Should you have any questions or require any further information, please do not hesitate to contact us.
Yours truly, l, )'
oney S
rintendent__
t, Generation Division - Nuclear I
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e GJT:bnm cc: Mr. J. P. O'Reilly, NRC Mr. J. G. Davis, NBC l
Mr. W. G. Mcdonald, NRC 1
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