ML20079D670
| ML20079D670 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 07/17/1991 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20079D669 | List: |
| References | |
| NUDOCS 9107230419 | |
| Download: ML20079D670 (3) | |
Text
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION D
RELATED TO AMENDMENT NO.144 TO FACILITY OPERATING LICENSE NO. DPR-46 NEBRASKA PUBLIC POWER DISTRICT COOPER NUCLEAR STATION DOCKET NO. 50-298
1.0 INTRODUCTION
By letter dated July 10, 1991, Nebraska Public Power District (the licensee) submitted a request for changes to the Cooper Nuclear Station, Technical Specifications (TS).
The requested changes would revise the setpoint and time delay values for the Emergency Buses Loss of Voltage Relays of Table 3.2.B (page 3).
The change corrects an error made when the setpoint and time delay values were added to the TS as part of Amendment No. 43.
- 2. 0 EVALUA110N The undervoltage protection for the Cooper Nuclear Station emergency AC buses is provided by two levels of relays.
The first level of relays are the emer-gency buses loss of voltage relays which were included in the original plant design to protect against loss of voltage conditions.
Tne second level of relays were added as a plant modification to improve protection against degraoed voltage conditions and were incorporated into the TS by Amendment No. 43.
The setpoints and time delays for the loss of voltage relays were also added to the TS by Amendment No. 43, During a design basis review by the licensee, an incensistency was discovered associated with the loss of voltage relays' actual setting limits and time delays and those specified in TS Table 3,2.o.
The inconsistency apparently resulted from an error in the set. :g limit wnich was added to the TS by Amendment No. 43.
The actual settings for the loss of voltage relays as installed and calibrated were confirmed to be in agreement with the design basis.
To correct the inconsistency between the design basis and the TS, the licensee requested a temporary waiver of comp 1P nce and this TS amendment.
The relays used for the loss of voltage protection are inverse time relays which have a variable time celay dependant upon the decrease in voltage.
These type of relays are not easily characterized by single setting limit and time delay values which are usually 'ncorporated into the TS.
This, in part, resulted in the error which is being corrected by the proposed TS change.
The proposed amendment changes the TS setting limit and time delay for the loss of voltage relays from "2900 V (+/- 5%); 5 second (+/- 1 second) delay" to "2300 V
(+/- 5%); time delay less than or equal to 5 seconds".
The proposed change in combination with the plant surveillance procedures will ensure that the relays are maintsined in accordence with the voltage-time curve which was justified by the design basis analysis.
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. i Based upon its review, the staff finds the proposed change to the loss of voltage relay setting limit and time delays in 15 Table 3.2.B does maintain the pl%nt within the design basis and is therefore acceptable.
3.0 EMERGENCY CIRCUMSTANCES In the letter dated July 10, 1991, tie licensee requested that this amendment application be treated as an emergency because unless approved, the T5 would require a plant shutdown upon the expiration of a temporary waiver of compliance which covers the period from July 9, 1991, through July 18, 1991.
Regarding the timeliness of the licensee's submittal, the discrepancy between the 15 setpoint value and the existing plant configuration and design basis was discovered on July 9, 1991, by the licensee during a design review program.
Upon discovery, the licensee evaluated the discrepancy, determined operability and prepared a justification for continued operation, requested and received a temporary waiver of compliance from NRR, and requested a T5 change on an emergency basis, Accordingly, pursuant to 10 CFR 50.91(a)(5), the Commission has determined that there are emergency circumstances warranting prompt approval by the Commission.
4,0 FINAL NO SIGNIFICANT HAZARDS CONSIDERATION DETERMjNATION The Commission's regulations in 10 CFR 50.92 state that the Commission may make a final determination that a license amendment involves no significant hazards considerations if operation of_that facility in accordance with the amendment would not:
(1)
Involve a significant increase in the probability or consequences of any accident previously evaluated; or (2) Create the possibility of a new or different kind of accident from any accident previously evaluated; or (3) Involve a significant reduction in a Margin of Safety.
This amendment has been evaluated against the standards in 10 CFR 50.92.
It does not involve a significant. hazards consideration because the changes would not:
1.
Involve a significant increase in the probability or consequences of an accident previously evaluated.
The change involves a correction to setting limit and time delay values which were incorporated into the TS (Amendment No. 43) but which did not correspond to the plant configuration or supporting design basis.
The revised values of 2300 V (+/- 5%) with a delay less than or equal to 5 seconds reflect calibration points on the voltage-time curve which was justified by the plant's design basis.
The amendment incorporates the original design basis settings and does not therefore involve a significant increase in the probability or consequences of any accident previously evaluated.
d 3-s 2.
Create the possibility of a new different kind of accident from any previously evaluated.
The function and operation of the loss of voltage relays are not changed by this proposed amendment.
The TS change corrects an error which was incorporated into the TS as part of Amendment No. 43.
The change does not involve a modification to plant hardware or plant operation and therefore does not create the possibility of a new or different kind of accident from any previously evaluated.
3.
Involve a significant reduction in the margin of safety.
The amemdment corrects an error in the TS and ensures that the loss of voltage relays operate in accordance with the design basis analysis.
The function and performance of the loss of voltage relays are not affected by the change.
In combination with the second level degraded voltage relays, the loss of voltage relays continue to provide protection over the entire range of voltage (normal to zero).
Since the change is consistent with the design basis and continues to ensure loss of voitage protection, no significant reduction in the margin of safety is involved.
- 5. 0 STATE CONSULATION In accordsnce with the Commission's regulations, the Nebraska State official was notified of the proposed issuance of the an,endment.
The State official had no comment.
6.0 ENVIRONMENTAL CONSIDERATION
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 in 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 occupa-tional radiation exposure.
The Commission made a final no significant hazards consideration finding with respect to this amendment.
Accorringly, the amendment meets 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 the amendment.
- 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 endangered by operation in the proposed manner, (2) such l
activities will be conducted in compliance with the Commission's regulations,
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and (3) the issuance of the amendment will not be inimical to the common j
defense and security or to the health and safety of the public.
Principal Contributor:
W.D. Reckley Date: July 17,1991 l
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