ML20031F614
| ML20031F614 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 10/02/1981 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20031F608 | List: |
| References | |
| NUDOCS 8110200219 | |
| Download: ML20031F614 (2) | |
Text
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UNITED STATES
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NUCLEAR REGULATORY COMMISSION p
WASHINGTON. D. C. 20555
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SAFETY EVALUATION BY THE'0FFICE'0F' NUCLEAR REACTOR' REGULATION SUPPORTING AMENDMENT NO. 49 TO~ LICENSE NO. DPR-35 BOSTON EDISON COMPANY DOCKET NO. 50-293 PILGRIM ~ NUCLEAR POWER STATION' UNIT 1
1.0 INTRODUCTION
By letter dated September 22, 1981 the Boston Edison Company has proposed a change in the Technical Specifications of the Pilgrim Nuclear Power Station, Unit 1,.to permit removal of the central control cell (central control rod plus the 4 bundles surrounding it) prior to the start of spiral unloading *.
This will permit mounting of equipment necessary for an inspection of the Core Spray Sparger which Boston Edison has committed to perform at this refueling outage.
The considerations of this change involve both those of ALARA criteria (10 CFR 20.1.(c)) and degradation of shutdown margin.
2.0 EVALUATION T'he licensee has proposed to do the inspection with the core installed.
Since the only reason for performing the inspection prior to core removal is a schedular concern, ALARA considerations were raised by NRC staff.
The licensee has prepared the equipment and procedures for the inspection such that it will be performed from the refueling bridge with the reactor vessel and refueling cavity flooded.
This method minimizes the exposure of workers.
In fact, there is a negligible difference in the total exposure obtained by doing the inspection with the core installed and doing the inspection with the core removed.** We, therefore, find that the licensee has adequately considered the ALARA criteria of 10 CFR 20.1(c).
The NRC staff has reviewed the proposed change regarding adequa'cy.of shutdown margin.
The safety concern involved in this change is that the shutdown margin may be reduced.
Boston Edison has referenced a previously submitted document entitled " Pilgrim 1 Multiple Contro.lled Cell Removal" dated November 1979.
This document reports a study which was conducted by Boston Edisori to evaluate the effect of removing
- A complete unloading of the coreis planned for the upcoming reload.
- Reference BECo letter No.81-228, (Oct.1,1981)
D110200219 811002 PDR ADOCK 05000293 P
2 various controlled cells from the Pilgrim Reactor.
From 1 to 16 cells were removed ir.cluding the central cell and cells at various distances from core center.
In all cases the reactivity of the core decreased with the amount cf decrease per cell removed being maximum at core center and minimum near the core edge.
With respect to the central cell, a staff study dated July 18, 1979 also showed that removal of the central cell results in a decrease in core reactivity.
The Boston Edison study was performed with the CASMO-PDQ7 code package which is a widely used calculation technique.. It was qualified for the calculations by comparison with critical experiment data and with critical states of the Pilgrim reactor.
We, therefore, tonclude that the shutdown margin of the Pilgrim reactor udll not be reduced by the removal of the central controlled cell and that the proposed Technical Specification change is acceptable.
3.0 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 amendmert.
4.0 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 con-sidered and does not involve a significant decrease in a safety margin, the amendment does not involve a significant hazards con-sideration, (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (3) such activities will be conducted in com-pliance with the Commission's regulations and the issuance of the amendment will not be inimical to the common defense and security 4
or to the health and safety of the public..
Dated: October 2,1981 9
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