ML20058B791
| ML20058B791 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 11/17/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20058B783 | List: |
| References | |
| NUDOCS 9312020220 | |
| Download: ML20058B791 (4) | |
Text
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)t UNITED STATES E
NUCLEAR REGULATORY COMMISSION' I
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WASHINGTON, D.C. 20586-0001
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION j
RELATED TO AMENDMENT NO. 89 TO FACILITY OPERATING LICENSE NO. NPF-38 i
l ENTERGY OPERATIONS. INC.
WATERFORD STEAM ELECTRIC STATION. UNIT 3 i
i DOCKET NO. 50-382
1.0 INTRODUCTION
By application dated August 5,1993, Entergy Operations, Inc. (the licensee),
submitted a request for changes to the Waterford Steam Electric Station, t
Unit 3, Technical Specifications (TSs). The requested changes would modify TS 3.6.2.1 to indicate that the containment spray system may be mode inoperable prior to initiation of shutdown cooling and would modify TS surveillance 4.6.2.1.e to increase the spray nozzle air or smoke test interval from at least once per 5 years to at least one per 10 years.
2.0 EVALUATION t
Mode 4 Operation The containment spray system is one of two containment heat. removal. systems.
The other is the containment cooling system. The containment spray system serves the dual purposes of (1) post-accident containment heat removal and (2) post-accident fission product removal.
Should a loss-of-coolant accident (LOCA) or main steam line break (MSLB) accident occur, the containment spray system condenses the steam released to the containment atmosphere, thereby reducing the containment pressure. The containment spray system also provides an iodine removal function. These safety functions are required by the'TSs to be operable during MODE 1, MODE 2, MODE 3 and MODE 4, except during shutdown cooling operation.
During normal operation, the reactor coolant system (RCS) conditions are i
maintained at 2250 psig and approximately 590*F.
The normal procedure for bringing the plant to cold shutdown involves cooling and depressurizing the 1
RCS to a temperature of $350'F and pressure of $400 psi (i.e., =392 psi). At this point, MODE 4 conditions are met (i.e., RCS temperature <350*F and k,,,
)
<0.99) and shutdown cooling (SDC) operation is' initiated. The TSs provide i
that when this condition (i.e., Mode 4 in shutdown cooling operation) is met, the containment spray systems may be made inoperable. The reason for this TS provision is that during SDC operation, a single spurious actuation of the spray header isolation valve for either containment spray train, would result in diversion of coolant from the RCS into the containment (i.e., a form of 9312O20220 931117 PDR ADOCK 05000382 P
PDR i
. LOCA). The spray header valves at Waterford 3 are of a fail-open design (air is bled off to open them) and thus considered particularly vulnerable to spurious opening.
In consideration of this, Bases 3/4.6.2.1 and 3/4.6.2.2 of the TSs state-i When shutdown cooling is placed in operation, the containment spray system is no longer required OPERABLE in order to allow realignment and isolation of the spray headers. This is necessary to avoid a single failure of the spray header isolation valve causing RCS depressuri-zation and inadvertent spraying of the containment. At the reduced RCS pressure and temperature associated with entry into shutdown cooling, the probability and associated heat loads of a LOCA or MSLB are greatly reduced. The OPERABILITY of the containment cooling system in MODE 4 is sufficient to provide depressurization and cooling capability.
The containment cooling system noted above consists of four fan coolers (two per train) and a ducted distribution system.
Each fan cooler has two banks of cooling coils and a two-speed axial fan enclosed in a casing. Three fan coolers are normally operated at high speed.
Upon initiation of a safety injection signal, all four fan coolers are operated at low speed.
Realignment of the RCS to shutdown cooling is a step-by-step process.
The shutdown procedure involves a period of time during which the containment spray system has been made inoperable, due to the above concern, but SDC is not yet established. During this period, the containment spray systems TS operability requirements are not met. The licensee is therefore required to declare the spray system INOPERABLE, and enter the specified ACTION STATEMENT.
This ACTION STATEMENT involves a required plant shutdown. The licensee must also make certain reports and notifications required by the Emergency Plan, 10 CFR Part 50, and plant administrative procedures, even though the plant is already in the process of being shutdown. The amendment proposed by the licensee would explicitly allow containment spray systems to be made inoperable at any time the RCS temperature is <350*F cnd RCS pressure is also
<400 psi (regardless of whether SDC has been initiated).
The proper shutdown procedure could then be followed without invoking an entry into the ACTION STATEMENT.
i The safety concern is whether the containment is adequately protected from overpressure, and whether 10 CFR Part 100 radiological dose consequence requirements would be met in event of an accident during the transition period of operation. The licensee's application indicates, and the Bases (cited above) state, that the fan coolers are available and have sufficient capacity to provide containment depressurization and cooling, in the event of a LOCA or MSLB at the reduced pressure and temperature conditions of Mode 4.
This is confirmed by staff calculations. At normal RCS temperature and pressure conditions, approximately 36% of the break fluid discharged by a LOCA would flash to steam whereas, at the MODE 4 entry conditions, less than 7% of the l
. 4 break discharge fluid weuld flash to steam.
It can thus be seen that the containment heat challenge is significantly reduced during MODE 4.
Accordingly, the facility is adequately protected.
(It is noted that, with both containment spray subsystems INOPERABLE and subsequent reliance on the containment cooling system as the sole system for containment heat removal, it is not clear from available analyses whether a single failure vulnerability may exist. However, the period of time involved is very short - less than the associated ALLOWED OUTAGE TIME for loss of one train of containment cooling.)
The sole effect of the proposed change is to eliminate a nuisance administra-tive burden. The change has no adverse effect on safety, and is therefore acceptable.
Air or Smoke Test The staff has reviewed the submittal by Entergy Operations, Inc. for the Waterford Steam Electric Station, Unit No. 3 to revise the Surveillance Requirement (SR) 4.6.2.1.e for performing an air or smoke flow test of the Containment Spray System nozzles. The proposed change is to extend the frequency from once every 5 years to once every 10 years. We concur that the proposed TS change is consistent with the Technical Specification Improvement Program as supported in the implemented NUREG-1366 " Improvements to Technical Specification Requirements" and NUREG-1432 " Standard Technical Specifications Combustion Engineering Plants".
Both NUREG-1366 (Item 8.1) and NUREG-1432 (SR 3.6.6B.9) suggest a 10-year interval for spray nozzle testing.
The licensee has also determined that the testing and containment conditions are consistent with the increase in the interval for testing.
Nozzle clogging at other facilities was as the result of coating materials on carbon steel piping.
The piping at Waterford is stainless steel. The last test at Waterford of the spray nozzles was in April 1988, and the nozzles were verified open.
We agree that the plant conditions warrant the extension of the test interval for the Waterford spray nozzles. This TS change is acceptable.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Louisiana State official was notified of the proposed issuance of the amendment. The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATIM
\\
The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes surveillance requirements. The NRC 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
I i
4-proposed finding that the amendment involves no significant hazards considera-i tion and there has been no public comment on such finding (58 FR 48383).
l Accordingly, the amendment meets the eligibility criteria for categorical j
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 amendment.
l 1
5.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the l
public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, i
and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
l Principal Contributor:
W. Long D. Wigginton l
i Date: November 17, 1993 l
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