ML20031A608
| ML20031A608 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 09/08/1981 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20031A605 | List: |
| References | |
| NUDOCS 8109240215 | |
| Download: ML20031A608 (4) | |
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UNITED STATES
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NUCLEAR REGULATORY COMMISSION p
WASHINGTON. D. C. 20555
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR P.EGULATION SUPPORTING AMENDMENT N0. 78 TO PROVISIONAL OPERATING LICENSE NO. DPR-21 NORTHEAST NUCLEAR ENERGY COMPANY-MILLSTONE NUCLEAR POWER STATION, UNIT NO. 1 DOCKET N0. 50-245
1.0 INTRODUCTION
By letter dated September 9,1980*, Northeast Nuclear Engineering Company (NNECO) (the licensee) proposed a Te::hnical Specification change to Section 3.1. ~ The proposed change would reduce the maximum reactor protection system response time (i.e.- the time from initiation of any channel trip to de-energization of the scram solenoid) from 100 milliseconds (msec) to 50 msec.
2.0 EVALUATION, During the NRC staff's review of the tiillstone Unit 1 Reload 7 application, it was noted that the safety analyses were performed using a 50 millisecond scram circuit-delay time.
This time to open the sensor contact and the trip actuator is only half the tir= limit of Technical Specification 3.1 which specifies that the RPS delay logic will not exceed 100 milliseconds. As a result of reported discrepangs from other licensees, we had issued earlier NRC IE Circular 80-08.
As stated therein:
"For GE BWRs, we request that you take the..following corrective action promptly after rec.eipt of this Circular:
(1) verify that the actual RPS response time in the most recent test is less than the value specified in the safety analysis, (2) observe the RPS response time value specified in the safety analysis until a Technical Specification change (if necessary) is approved, and (3) take appropriate actions to make Technical Specifications on RPS response time consistent with the RPS response time used in the safety analysis.
If a value less than that currently in the Technical Specifications is proposed, the licensee will be expected to provide the basis J
for that value, including the validity of tests and methods."
NNECo in support of the proposal to reduce the Technical Specification RPS 1
response time requirements from a limit of 100 msec to 50 msec stated that i
" measurements at plants have demonstrated that actual response time is less than 50 msec." NNECo added that 100 msec response' time instead of 50 msec response time results in a-
- Reload 7 application 8109240215 810908 PDR ADOCK OS 45 P
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s Calculated increase in the minimum critical power ratio (MCPR) of.03 o Calculated increase in peak pressure for both the turbine generator trips and mainsteam isolation valve flux s; ram events by about 5 psi.
According to the licensee such calculated increases in the., severity of these limiting transients is not justified because the actual RPS response times are less than 50 msec.
The Technical Specification limit should, therefore, be reduced from 100 msec to 50 msec.
E Amendment No. 73(2) authorized changes to Technical Specification MCPR limits based on 50 msec RPS response times.
However, NNEC0 resumed operation at Millstone Unit 1 after the extended outage constrained bv a self-imposed increase in the Technical Specification MCPR limits of.03 pending completion of our evaluation of the NNEC0 request.
The increased MSCP limit has not necessitated a rbduction in reactor power thus far in. Cycle 8 operation and the delay in completing our evaluation has not penalized reactor power production up to this point.
We explained to NNEC0 representatives that we could not complete our review of the proposed Technical Specification reduction in RPS response time until test measurements were made at Millstone Unit 1 to verify that the limiting response time was less than 50 msec. NNEC0 agreed.to make such measurements.
The Millstone NRC Resident inspectors: 3 reviewed the results of tests performed by NNECO on August 13, 1981, and concluded that all logged times were well within (less than) the 50 msec proposed Technical Specification limit.
On the baiis of these measurements and consistent with similar RPS response time reductions authorized for other nuclear power plants we find the proposed change to Technical Specification 3.1 acceptable.
The self-imposed MCPR restrictions are no longer justified and the new i
Technical Specification limit of 50 msec is in confonnance with the MCPR limits authorized by Amendment No. 73.
3.0 ENVIRONMENTAL CONSIDERATION
We have determined that the amendment does not authorize a change in effluent types or total amounts nor an increase in power level and will not result in any significant environmental impact. Having made this determination, we have further concluded that the amendment involves an action' which is insignificant from the standpoint or environmental impact and pursuant to 10 CFR f 51.5(d)(4),
that an environmental impact statement or negative declaration and environmental impact appraisal need not be prepared in connection with the issuance of this amendment.
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4.0 CONCLUSION
.We have concluded, based upon the considerations discussed above, that: (1) because the amendment does not involve a significant increase in the probability or consequences of accidents previously considered and does not involve a significant decrease in a safety margin, the amendment does not involve a significant hazards consideration, (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (3) such activities will be conducted in compliance with the Commission's regulations and the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.
Date:. September 8, 1981 4
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References:
1.
IE' Circular 80-08, "BWR Technical Specification. Inconsistencies -
-RPS Response Time", dated April:18, 1980.
' 2.-
Amendment No. 73_to Provisional Operating License No. DPR-21 for Millstone Nuclear Power Station Unit 1, dated March 11, 1981.
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