ML20076E463
| ML20076E463 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 08/14/1991 |
| From: | Hopkins J Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20076E461 | List: |
| References | |
| NUDOCS 9108200155 | |
| Download: ML20076E463 (3) | |
Text
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00'6 yT UNITED STATES
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NUCLEAR REGULATORY COMMISSION l
.f WASHINGTON. D c. ?W4 SAftTY EVALVATION BY THE OFFICE OF NUCLEAR REACTOR REGULA*:0N 1
RELATED TO AMENDMENT No.159 TO FACILITY OPERATING LICENSE NO. NPF-3 TOLEDO EDISON COMPANY CENTER 10R SERVICE COM9ANY U$
THE CLEVELAND ELECTRIC ILLUM1NAT1f4G_ COMPANY DAVIS-BESSE NUCLEAR POWER STATION, UNIT NO. 1 DOCKET NO 50-346 l
1.0 INTRODUCTION
By letter dated June 4,1991, Toledo Edison Company (the licensee) proposed changes to the Technical Specifications for the Davis-Besse Nuclear Power Station, Unit 1 (DBNPS).
The proposed changes involve Technical Specification (TS) Table 3.3-3, " Safety Features Actuation System Instrumentation," and TS table 4.3 2, " Safety Features Actuation System Instrumentation Surveillance Requirements." The proposed changes would remove operability requirements for decay heat isolation valve interlock i
channels and pressurizer heater interlock channels in Modes 4 (hot shutdown) and 5 (cold shutdown).
2.0 EVALVATION During Modes 4 and 5 operation, the reactor coolant system (RCS) is directly connected to the decay heat removal (DHR) system via isolation valves DH-11 and DH-12.
In these Modes, the low temperature overpressure (LTOP) protection of the RCS is provided by the decay heat removal system relief valve (DH-4849). While the RCS is above the DHR system design pressure, diverse interlocks prevent DHR overpressurization by closing and preventing opening DH-11 and DH-12 when the RCS pressure exceeds the allowable setpoint, l
While in Modes 4 and 5, closure of DH-11 or DH-12 would leave the plant without LTOP protection and would isolate the suction to the DHR pumps.
i To prevent this, TS 3.4.2 requires, in part, that control power be removed from DH-11 and DH-12 after they are opened in Modes 4 and 5.
The licensee has evaluated the various scenarios which could cause a pressure transient while in Modes 4 or 5.
The relief valve, DH-4849, was sized to accommodatt 9100200155 910014 i
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the flow from two High Pressure Injection Pumps, which the licensee
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determined to be the largest overpressure source.
Because DH-11 and DH-12 must remain open in Modes 4 and 5 to provide LTOP protection, valve isolation interlocks are not required. Therefore, the NRC staff finds I
deleting this requirement for Modes 4 and 5 acceptable.
In order to ensure that double valve protection is established between the RCS and the DHR/ Low Pressure injection (LPI) system prior to raising the RCS pressure above the DHR system design pressure, interlock channels with the pressurizer (PZR) heaters have been included.
These interlock channels prevent PZR heater operation if either DH-11 or DH-12 is off its closed seat while the RCS pressure is above the interlock's setpoint.
These t
interlock channels prompt plant operators to properly position the valves and enable the valve isolation interlock prior to raising RCS pressure.
i The PZR heater interlock channels need only be operable in Mode 3 while l
either of the Decay Heat isolation Valves is open. Once both valves are closeu, the valve isolation interlock provides redundant, diverse l
overpressure protection.
When cooling down the plart, the valve isolation interlock prevents opening DH-11 or DH-12 until RCS pressure has been reduced below the allowable setpoint. Once one of the DHR isolation valves is open, the PZR heater interlock channels prevent pressure from being raised until both DH-11 and DH-12 are open placing relief valve DH-4849 in operation.
Therefore, the NRC staff finds that the PZR heater interlock needs only to be operable in Mode 3 while either of the DHR isolation valves is open and deleting the requirement so have this interlock operable in Modes 4 and 5 is acceptable.
Finally, to ensure that the PZR heater interlock is operable when it needs to be, the licensee proposes to remove the waiver of TS 3.0.4 for this interlock.
This results in a requirement to have the interlock operable prior to Mode 3 operation with one DHR isolation valve open. The NRC staff has reviewed this issue and finds it acceptable.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Ohio State official was notified of the proposed issuance of the amendment.
The State official
-had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
This amendment changes a requirement with respect to installation or use of a i
facility component located within the restricted area as defined in 10 CFR Part 20 or changes a surveillance requirement.
The staff has determined that the amendment involves no significant increase in the amounts, and no significant L
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 Connission has previously issued a proposed finding I
that the amendment involves no significant hazards consideration and there has been no public connent on such finding (56 FR 29282).
Accordingly, the amend-ment meets the eligibility criteria for categorical exclusion set forth ir.
l
Pursuant to 10 CFR 51.22(b), no envircnmental impact stetement or environmental assessment nted be prepared in connection with the issuance of the amendment.
5.0 CONCLUSION
The staff has ccncluded, based on the considerations discussed above, that:
not be endangered by operation in the proposed manner, (2) y of the public w (1) there is reasonable assurance that the health and safetsuch activities wi'l be condveted in compliance with the Comliision's regulations, and (3) the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.
principal Contributor: Jon Hopkins, NRR Date:
August 14, 1991
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