ML20057A335
| ML20057A335 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 09/02/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20057A334 | List: |
| References | |
| NUDOCS 9309140030 | |
| Download: ML20057A335 (3) | |
Text
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wasmNGTON, D C. MS4m SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NOS.172 AND 153 TO FACILITY OPERATING LICENSE NOS. NPF-4 AND NPF-7 VIRGINIA ELECTRIC AND POWER COMPANY OLD DOMINION ELECTRIC COOPERATIVE NORTH ANNA POWER STATION. UNITS NO 1 AND NO. 2 DOCKET NCS. 50-338 AND 50-339
1.0 INTRODUCTION
Pursuant to 10 CFR 50.90, by letter dated April 8,1993, the Virginia Electric and Power Company (the licensee) proposed changes to the Technical i
Specifications (TS) for the North Anna Power Station, Units 1 and 2.
The changes would separete the containment recirculation spray (RS) subsystems into two containment RS trains.
2.0 PROPOSED TECHNICAL SPECIFICATION CHANGES The current TS 3.6.2.2 describes the RS system as consisting of six separate and independent subsystems and a casing cooling tank. The allowable outage time (A0T) is 7 days for one subsystem.
If more than one of the six subsystems becomes inoperable, then within one hour the inoperable subsystems are required to be restored to an operable status or the unit must be shut down.
TS 3.6.2.2 is being revised to separate the containment RS subsystems into two containment RS trains.
Each train will consist of:
(a) one inside RS subsystem composed of an inside RS pump, associated heat exchanger and flow path, and (b) one outside containment recirculation spray subsystem consisting of l
one outside RS pump, associated heat exchanger and flow path, and a casing cooling pump and a flow path capable of transferring fluid from the casing cooling tank to the suction of the outside RS pump.
l TS 3.6.2.2 Action "a" is being revised to delete the reference to one casing cooling subsystem being inoperable since it is included in the definition of the outside RS subsystem.
9309140030 930902 PDR ADOCK 05000338 P
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TS 3.6.2.2 Action "b" is being revised to address the inoperability of two l
subsystems in one train and reflect an A0T of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
TS 3.6.2.2 Action "c" is being revised to address the inoperability of the l
casing cooling tank and is currently Action "b" of the existing TS.
i 3.0 EVALUATION The containment RS system, in conjunction with the containment quench spray i
system, is designed to limit the post-accident pressure and temperature in the containment to less than the design values and to depressurize the containment to subatmospheric pressure in less than 60 minutes.
l The Final Safety Analysis Report states that the RS system consists of four separate but parallel RS subsystems, each of approximately 50% capacity. Two RS pumps and motors (rated at 3300 gpm) are located inside the containment structure, and two pumps and motors (rated at 3640 gpm) are located outside the containment. Following a loss of coolant accident, water accumulates in the containment sump which provides a suction for the four RS pumps. The water is continuously recirculated through the containment to remove heat from the reactor core and containment atmosphere and radiciodine from the containment atmosphere. The water is cooled when pumped through the RS heat exchanger (one downstream of each pump).
The casing cooling subsystem provides adequate net positive suction head to the outside RS pumps.
l The proposed change separates the containment RS subsystems into two l
containment recirculation trains and defines the trains. No hardware changes 1
are being made for this separation. The accident analysis basis assumes that j
one train of containment RS system fails to operate during a design basis i
accident. A single train of containment RS is capable of supplying 100% of the required containment RS assumed in the accident analysis basis.
TS 3.6.2.2 Action "a" will address the inoperability of one subsystem of containment RS. The change deletes the reference to a separate casing cooling subsystem since the casing cooling subsystem is considered a part of the outside RS subsystem. The remaining three subsystems still provide 150% of the required capacity assumed in the accident an-lysis bases and the seven day i
A0T to restore the subsystem to operable staL _
s retained from the current i
TS.
TS 3.6.2.2 Action "b" will address the inoperability of two subsystems in one train of containment RS. The other operable train of containment RS will still provide 100% of the capacity assumed in the accident analysis bases.
The 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> A0T to restore at least one subsystem to operable status takes i
into account the redundant capacity of the operable train, a reasonable amount of time for repairs, and the low probability of a design basis accident j
occurring during this period.
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3 The changes will not affect the capability of the containment RS system to perform its design function. The system performance will remain bounded by the existing accident analysis basis.
4.0
SUMMARY
The changes will not affect the capability of the containment RS system to perform its design function. Since the containment will continue to meet its design basis acceptance criteria following a design basis accident, the staff finds the licensee's proposed revision to TS 3.6.2.2 to be acceptable.
5.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Virginia State official was notified of the proposed issuance of the amendment. The State official had no comment.
6.0 ENVIRONMENTAL CONSIDERATION
These amendments change a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20.
The NRC staff has determined that the amendments involve 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 these amendments involve no significant hazards consideration and there has been no public comment on such finding (58 FR 28063). Accordingly, these amendments meet the eligibility criteria for categorical exclusion set forth in 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 the amendments.
7.0 CONCLUSION
The Commission 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 eadangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
R. P. Croteau Date: September 2, 1993