ML20199L887

Safety Evaluation Supporting Amend 110 to License DPR-21

ML20199L887
Person / Time
Site:	Millstone
Issue date:	04/04/1986
From:	Office of Nuclear Reactor Regulation
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ML20199L878	List: ML20199L873 ML20199L882 ML20199L887
References
NUDOCS 8604100467
Download: ML20199L887 (4)

Text

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION 4

SUPPORTING AMENDMENT NO.110 TO PROVISIONAL OPERATING LICENSE NO. DPR-21 l

NORTHEAST NUCLEAR ENERGY COMPANY MILLSTONE NUCLEAR POWER STATION, UNIT NO. I 1

DOCKET NO. 50-245

1.0 INTRODUCTION

4 By letter dated October 30, 1985, Northeast Nuclear Energy Company (the licensee) requested an amendment to the technical specifications for Facility Operating License No. DPR-21. The amendment would change the wording in technical specifications sections 3.10, 4.10, Table 3.1.1 and Bases 3.1 where control rods are required to be inserted and either electrically ofh ydrauli-cally disarmed rather than both electrically and hydraulically disarmed.

2.0 BACKGROUND

AND DISCUSSION There are three disarming methods to ensure that the control rods remain fully inserted during the times when the plant is shutdown for refueling.

1. _ Hydraulically disarming each control rod by closing its respective insert and withdraw line valves at the hydraulic control unit (HCU). This method hydraulically locks the control rod in place even if a movement comand is given.

2. Electrically disarwing each control rod by pulling the amphenol connectors (solenoids) from the Reactor Manual Control System (RMCS) at the HCU.

This method prevents any movement consnand from the RMCS reaching that particular control rod.

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3. Electrically disarming the RMCS by pulling the rod drive-in bus and rod drive-out and settle bus fuses in the RMCS. This prevents any movement command from being generated in the RMCS and sent to the individual control rods. This method electrically disarms all control rods at once.

The existing Millstone 1 technical specification requires:

When the reactor modes switch is in REFUEL or SHUTDOWN and fuel is in the reactor vessel, no trip functions are required to be operable provided that all control rods are fully inserted, valved out and electrically disarmed. Thereafter, daily surveillance shall be perfonned to verify that all control rods remain valved out and electrically disanned.

The licensee proposed the wording change as follows:

When the reactor mode switch is in REFUEL or SHUTDOWN and fuel is in the reactor vessel, no trip functions are required to be operable provided that all control rods are fully inserted, and either electrically or hydraulically disarmed. Thereafter, daily surveillance shall be performed to verify that all control rods remain valved out or electrically disarmed.

The licensee stated that the proposed change will decrease the probability of an error and improve the availability of eqJipment or improve the system performance for the following reasons:

1. By not requiring that the control rods be always hydraulically disarmed, manual cycling of 290 insert and withdraw valves can be precluded. Thus a valving error could be prevented which, while not a safety concern (the affected rod (s) would remain fully inserted), could cause delays in start-up and lost time due to trouble-shooting the system to find the problem. This chance of error can be avoided if the plant configuration is such that electrical disarming is feasible.

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2. Not always requiring hydraulic disarming also allows the use of control rod drive pumps as a make-up source of water to the reactor. This source is not available if all rods are hydraulically disarmed and the return line is not available due to maintenance on feedwater lines or check valves.

3.0 EVALUATION The proposed change involves a modest relaxation in the operability require-ment of the existing technical specifications, but is within acceptable .

criteria as defined in the standard technical specifications that have been approved by the staff. NUREG-0123 " Standard Technical Specifications for General Electric Boiling Water Reactor," section 3.1.3.1 on limiting condition for operation of the reactivity control systems permits the control rod associated directional control valves to be disarmed electrically or.hydrauli-cally. The staff concludes that this proposed change is consistent with the current version of standard technical specifications. The changes on pages 3/4 1-19, 3/4 1-4, 3/4 1-1, B 3/4 1-3, and B 3/4 10-1 are acceptable.

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4.0 ENVIRONMENTAL CONSIDERATION

The amendment involves a change to a requirement with respect to the installation or use of a facility component located within the restricted area, as defined in 10 CFR Part 20, and changes to the surveillance requirements. The staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that this amendment involves no significant hazards consideration and there has been no public comment on such finding. Accordingly, this amenament meets the eligibility criteria for categorical exclusion set forth in e _ _ _ _ _ _ . _

10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of this amendment.

5.0 CONCLUSION

S The staff finds that proposed changes in the technical specifications, as described above, are acceptable and has concluded, based on the considerations discussed above, that: (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (2) such activities will be conducted in compliance with the Commission's regulations and the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.

6.0 ACKNOWLEDGEMENT Principal Contributor: H. Li Dated: April 4,1986 I

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