ML20138R706
| ML20138R706 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 11/01/1985 |
| From: | NRC |
| To: | |
| Shared Package | |
| ML20138R703 | List: |
| References | |
| TAC-56473, TAC-56474, TAC-56476, TAC-56477, TAC-56873, TAC-56874, NUDOCS 8511180788 | |
| Download: ML20138R706 (4) | |
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~g NUCLEAR REGULATORY COMMISSION n
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W ASHINGTON, D. C. 20555
\\*...J SAFETY EVALUATION REPORT RELATED TO AMENDMENT NO. 47 TO FACILITY OPERATING LICENSE NPF-9 1
AND TO AMENDMENT NO. 28 TO FACILITY OPERATING LICENSE NPF-17 DUKE POWER COMPANY MCGUIRE NUCLEAR STATION, UNITS 1 AND 2 l
INTRODUCTION By letters dated November 12, 1984, and January 30, 1985, the licensee proposed amendments to License Nos. NPF-9 and NPF-17 which would change the action state-ments for the limiting condition for operation and the surveillance require-ments for Technical Specifications 3/4.5.1, Cold Leg Injection Accumulators, and 3/4.5.1.2, Upper Head Injection Accumulator System (UHI).
For the Cold Leg Injection Accumulator, these amendments replace the require-ment to be in hot shutdown (specified in the action statement when one accunu-lator is inoperable for reasons other than a closed isolation valve) with a requirement to reduce pressurizer pressure to less than 1000 psig. The requirement to be in hot standby within "I hour and in HOT SHUTDOWN within the following 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />" (specified in the action statement when one accumulator is inoperable due to the isolation valve being closed) is changed to require that the reactor be in hot standby within "6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and that pressurizer pressure be reduced to less than 1000 psig within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />." Surveillance i
requirement 4.5.1.1.1.d. which requires periodic testing of the automatic opening feature of the accumulator isolation valves, is deleted.
For the UHI, these amendments replace the requirement to be in hot shutdown (specified in ACTION (a) which applies whan the UHI is inoperable for reasons i
other than a closed isolation valve) with a requirement to reduce pressurizer 1
pressure to less than 1900 psig. The requirement to be in " HOT STANDBY within I hour and be in HOT SHUTDOWN within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />" (specified in ACTION i
(b) which applies when the UHI is inoperable due to a closed isolation valve) is changed to require that the reactor be in "at least HOT STANDBY within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and reduce pressurizer pressure to less than 1900 psig within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />." Surveillance Specification 4.5.1.2.c(1) is clarified to more accurately reflect the type of testing used to verify automatic closure of each UHI accumulator isolation valve (i.e., to reflect use of "an actual i
or simulated water level signal") and to clarify that "if actual water level is used, then the accumulator should be at atmospheric pressure."
EVALUATION 1
Cold Leg Injection Accumulator Technical Specification 3.5.1.1 requires each cold leg injection accumulator to 0511180700 851101 DR ADOCK 05000369 p
2 be operable with the isolation valve open when pressurizer pressure is above 1000 psig. The existing Specification 3.5.1.1 allows I hour to place the reactor in hot standby when accumulator inoperability is due to a closed isolation valve, but allows 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> when accumulator inoperability is not due to a closed isolation valve. This is inconsistent because the potential causes for accumulator inoperability other than a closed accumulator isolation valve (e.g., total loss of nitrogen gas pressure) have a safety significance comparable to that of a closed accumulator isolation valve. The I hour require-ment is unnecessarily conservative since the inoperability of the accumulators for up to 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> was previously determined to pose negligible adverse safety consequences. Accordingly, the staff finds that the change from I hour to 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> to be in hot standby when inoperability is due to a closed isolation valve is equally acceptable, i
Thr other change to Specificatin 3.5.1.1 by these amendments requires that pressurizer pressure be lowered below 1000 psig within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> instead of placing the reactor in hot shutdown.
Plant operating procedures require that the accumulators be isolated below a reactor coolant system pressure of 1000 psi zation (g in order to prevent inadvertent injection during planned depressuri-i.e., shutdown).
In support of these operating procedures, licensee's analysis of a large break LOCA during a plant cooldown has previously demon-strated (see Supplement 2 to SER, Section 6.3.4) that adequate protection is provided without the cold leg injection accumulators if reactor coolant system pressure at the time of the accident was at or below 1000 psig. Thus, because accumulators serve no safety function below 1000 psig, the staff finds that the change has no adverse impact on safety and is acceptable.
The accumulator isolation valves must be open for the accumulators to accomplish their safety (injection) function. The design of the control circuit for the motor-operated accumulator isolation valve as accepted by the staff in SER Section 7.3.3 protected against inadvertent closure of the valve by an automatic opening feature. Although the valve is normally open when RCS pressure is above 1000 psig, it receives a safety injection signal to override any bypass feature and cause automatic opening should the valve be closed.
In accordance with 4
the licensee's request, these amendments delete Surveillance Specification 4.5.1.1.1.d which requires periodic testing of the automatic opening feature of the accumulator isolation valves because changes in operating procedures negate the need for (and function of) such a feature (and hence the need for its testing). The licensee's operating procedure for unit startup requires that the valves be opened before exceeding 1000 psig, and that after opening, power to the valve operators is to be disconnected by removal of the breaker from the circuit. Hence, the possibility of inadvertent closure is eliminated by removal of the power source at all times except for those brief periods during planned startups and shutdowns when a deliberate change in valve position is required. The possibility of prolonged operation following inadvertent failure to open the isolation valve during repressurization of
)
the reactor coolant system in accordance with the licensee's startup procedures is eliminated by Surveillance Specification 4.5.1.1.la(2) which is not changed by these amendments and which requires verification at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> that each accumulator isolation valve is open. The staff finds that elimination
3 of the periodic test requirement where the function to be tested is no longer relied upon, and where the 12-hour surveillance requirement is retained, does not have a significant adverse effect on safety and is acceptable.
Upper Head Injection System Technical Specification 3.5.1.2 requires each UHI to be operable with the isolation valves open when pressurizer pressure is above 1900 psig (i.e.,
for Modes 1, 2, and 3, but for Mode 3 only above 1900 psig). Prior to these amendments, the existing Specification 3.5.1.2 allowed I hour to place the reactor in hot standby when UHI was inoperable due to a closed isolation valve (i.e., for ACTION (b)), but allowed 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> when UHI inoperability was not due to a closed isolation valve (i.e., for ACTION (a)).
This was inconsistent because the potential causes for UHI inoperability other than a closed isolation valve (e.g., total loss of the gas-bearing accumulator pressure) have a safety significance comparable to that of a closed isolation valve. The I hour requirement was unnecessarily conservative since the inoperability of UHI for up to 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> was previously detennined to pose negligible adverse safety consequences.
Therefore, the staff finds that the change from 1 to 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> to be in hot standby when UHI inoperability is due to a closed isolation valve is also acceptable.
The other changes to ACTION (a) and ACTION (b) implemented by these ar.iendments permit the pressurizer pressure to be reduced below 1900 psig in operational Mode 3 (hot standby) instead of placing the reactor in hot shutdown. For ACTION (b), this change introduces an additional conservatism in that the change requires that this pressure reduction be achieved within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, whereas the previous ACTION (b) provided a total period of 13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br /> for the plant to be in hot shutdown. Plant operating procedures require that the UHI isolation valves be closed below a reactor ecolant system pressure of 1900 psig in order to prevent inadvertent injection during planned depressurization (i.e., shutdown).
In support of these operating procedures, licensee's analysis of a large break LOCA during a plant cooldown has pre-viously demonstrated (see Supplement 2 to SER, Section 6.3.4) that adequate protection is provided without UHI injection if reactor coolant system pressure at the time of the accident was at or below 1900 psig. Thus, because UHI serves no safety function below 1900 psig, the staff finds that the change does not adversely affect safety and is acceptable.
The previous Surveillance Specification 4.5.1.2.c required that each UHI accumulator isolation valve be periodically verified to close automatically when the water level was 76.2523.3 inches above the bottom inside edge of the water filled accumulator with atmospheric pressure in the accumulator.
The specification required clarification because in its previous form it could be interpreted to mean that the actual tank water level was to be reduced to the setpoint in order to verify that each accumulator isolation valve closes. Such a limited interpretation was not intended; use of simulated signals to test safety systems in which an instrument reaching a setpoint actuates a device is an industry-wide practice which is also acceptable to the Commission as evidenced by its acceptance for other safety related systems involved with water level (e.g., high pressurizer water level and low steam
. generator water level). These amendments, therefore, modify Surveillance Specification 4.5.1.2.C to clarify that simulated signals may be used to verify automatic accumulator isolation valve closure. This change is administrative and has no adverse safety implications.
ENVIRONMENTAL CONSIDERATION These amendments involve changes in use of facility ecmponents located within the restricted area as defined in 10 CFR Part 20 and changes in surveillance requirements. The staff has determined that the amendments involve no signi-ficant 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. Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR Section 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 these amendments.
CONCLUSION The Comission made proposed determinations that the amendments involve no significant hazards consideration which were published in the Federal Register (50 FR 37078 and 37079) on September 11, 1985, and consulted with the state of North Carolina. No public comments were received, and the state of North Carolina did not have any coments.
We have concluded, based on the considerations discussed above, that:
(11 there is reasonable assurance that the health and safety of the will not be endangered by operation in the proposed manner, and (2) public such activities will be conducted in compliance with the Commission's regu-lations, and the issuance of these amendments will not be inimical to the comon defense and security or to the health and safety of the public.
Principal Contributors:
D. S. Hood, Licensing Branch No. 4 DL W. Jensen, Reactor Systems Branch, DSI R. Jones, Reactor Systems Branch, OSI Dated:
November 1, 1985
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