ML20039B949
| ML20039B949 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 12/10/1981 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20039B947 | List: |
| References | |
| NUDOCS 8112280097 | |
| Download: ML20039B949 (3) | |
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UNITED STATES h
- I NUCLEAR REGULATORY COMMISSION j
WASHINGTON D. C. 20555
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%..u f SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 51 TO LICENSE NO. DPR-35 BOSTON EDISON COMPANY DOCKET NO. 50-293 PILGRIM NUCLEAR p0WER STATION UNIT 1
1.0 INTRODUCTION
By letter dated November 4,1981 (BECo.81-257), the Boston Edison Company (licensee) requested relief frome the requirements Of the Technical Specifications (Section 3.7.B.l.c, 3.7.B.1.e, 3.7.B.2.a., and 3.7.B.2.c) regarding the operability requirements for the Standby Gas Treatment System and the Control Room High Efficiency Air Filtration System for the initiation of and during fuel movement in refueling operations.
2.0 BACKGROUND
A recent engineering analysis was performed by Boston Edison in response to Inspection and Enforcement Bulletin 80-11 (Masonry Wall Design). This analysis has revealed the potential failure of 3 walls located in the Turbine Building due to High Energy Pipe Breaks Outside Containment *, Tornado Depressurization or Seismic events. The failure of the walls would impact certain safety systems which are required for refueling mode operations.
These systems are the Standby Gas Treatment System, High Efficiency Control Room Air Filtration System, the Residual Heat Removal System, and the Standby Liquid Control System. Their failure would be caused by the loss of the power cables in a raceway ca the wall. The Licensee has declared the first two of these systems to be inoperable due to this potential failure mode and has developed a corrective design modification to remedy the deficiency.
However, the modifications will not be completed until December 1,1981.
The fuel loading schedule and subsequent plant start-up from the refiieling i
outage would be impacted unless the modifications can be done in parallel with the fuel loading. However the current Technical Specifications do not allow the initiation of loading without full operability of the Standby Gas Treatment System and they also require the operability of the Control Room j
High Efficiency Air Filtration System during fuel handling operations. Each system also possesses Limiting Conditions for Operation, with one train inoperable, which are 'etss than the time needed to complete the sall modifi-cations. Therefore, we licensee has requested relief from the current requirements, on the basis of providing interim compensating measures, for the period of November 4 through November 24, 1981, for fuel loading.
- Wall failure from HELB is not feasible in cold shutdown.
8112280097 811210 PCR ADOCK 05000293 P
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, 3.0 EVALUATION The review of the safety concerns is divided into three areas.
First, it is shown that the probability of an event (Seismic or Tornado) during fuel handling operations is small.
Second, the licensee's compensating measures provide adewate assurance that the system will be available if needed to mitigate the consequences of a fuel handling accident. Third, that the systems are not required to limit offsite doses within those of 10 CFR 100.
The licensee has evaluated the probability of a fuel handling accident in conjunction with a block wall failure. The total probability was determined to be 1.0x10E-5/ refueling. The NRC staff has also conservatively estimated the probability of block wall failure while handling fuel and the estimate is comparable to that of Boston Edison.
The licensee has committed to the following compensating actions while the single train of each of the two systems is declared inoperable:
1.
The Standby Gas Treatment System (Train B) and the Control Room High Efficiency Air Filtration System (Train B) train will be continuously operated during all irradiated fuel handling activities.
Train B of the Standby Gas Treatment System has valve MO-N-ll3 disconnected (ie.
failed) in the open position to ensure system function in the event of a wall failure. These systems will be monitored to assure operability and irradiated fuel handling operations will be terminated if either of the systems (Train B) is found or made to be inoperable.
2.
The RHR system will be restored to full functional status immediately upon failure of the wall. The licensee will have procedures in place prior to el movement which direct actions to restore the functional capability of the RHR system. Subsequent to procedure execution, only a protective feature of one set of RHR pumps will be inoperative with all other shutdown cooling system features fully operable. The failure of this pump protective feature was determined by the licensee to be the only concern during this mode of operations.
3.
A procedure will be in place prior to the start of fuel movement, which requires the immediate termination of fuel handling (moves in progress may be completed) in the event that a Tornado Watch is issued in the area of the plant.
No compensatory actions are necessary for the Standby Liquid Control System _.
since the Licensee has demonstrated that the system will perform its intended function if required.
This system is required during control rod drive testing during loading.
The licensee has evaluated the radiological effects of a fuel handling accident assuming that the SGTS is inoperable.
It has been determined that if the fuel movement takes places more than 120 hours0.00139 days <br />0.0333 hours <br />1.984127e-4 weeks <br />4.566e-5 months <br /> after reactor shutcown, the limits of 10 CFR 100 regarding doses at the site boundary would not be exceeded.
The subject fuel movement will not be initiated prior to 120 hours0.00139 days <br />0.0333 hours <br />1.984127e-4 weeks <br />4.566e-5 months <br /> after reactor shutdown.
l We have determined that the licensee has provided adequate assurance regarding accident mitigation during the period necessary to complete the fuel loading. Therefore, we grant the requested relief from the Technical Specifications 3.7.B.l.c 3.7.B.1.e, 3.7.B.2.a., and 3.7.B.2.c for the period from November 4 through November 24, 1981.
4.0 ENVIRONMENTAL CONSIDERATION
S We have determined that the amendment does not involve a change in effluent types or total amounts nor an increase in power level and will not result in any significant environmental impact. Having made this determination, we have further concluded that the amendment involves an action which is insignificant from the standpoint of environmental impact and pursuant to 10 CFR Section 51.5(d)(4) that an environmental impact statement or negative declaration and environmental impact appraisal need not be prepared in connection with the issuance of the amendment.
5.0 CONCLUSION
S We have concluded, based on the considerations discussed above, that:
(1) because the amendment does not involve a significant increase in the probability or consequences of accidents previously considered and does not involve a significant decraase in a safety margin, the amendment does not involve a significant hazards consideration, (2) there is reasonable assurance that the health and safety of the publ'.c will not be endangered by operation in the proposed manner, and (3) such activities will be conducted in compliance with the Commission's regulations and the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Dated: December 10, 1981 b
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