ML20206D099
| ML20206D099 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 11/14/1988 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20206D091 | List: |
| References | |
| NUDOCS 8811160536 | |
| Download: ML20206D099 (3) | |
Text
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING ANENONENT NO.
49 TO FACILITY OPERATING LICENSE NO. NPF-29 HISSISSIPPI POWER & LIGHT COMPANY SYSTEM EhERGY RESOURCES, INC.
SOUTH HISSISSIPPI ELECTRIC POWER ASSOCIATION GRAND GULF NUCLEAR STATION, UNIT 1 R ET NO. 50-416 O
1.0 INTRODUCTION
By letter dated June 21, 1988, System Energy Resources, Inc. (the licensee), requested an amendment to Facility Operating License No.
Unit 1.
The proposed amendment NPF-29fortheGrandGulfNuclearStation[TS)bymodifyingTable4.3.6-1, would change the Technical Specification "Control Rod Block Instrumentation Surveillance Requirements," and assceiated notes to Table 4.3.6-1 to delete the requirement for daily channel functional tests of the rod pattern control system setpoints during pcwer operation. Additionally, the applicable operational ccndi-tions for the high power setpoint in Table 3.3.6 1, "Control Rod Block Instrumentation," and Table 4.3.6-1 would be changed from Operational Condition 1 (power operation) and 2 (startup) to Operational Cendition 1 with thermal power greater than the low power setpoint.
The licensee requested these changes to reduce manpower required for surveillance tests and to reduce control room distractions associated with these tests. The same TS changes were approved on May 10, 1988 for the River Bend Station, Unit 1, a BWR-6 reactor like Grand Gulf Nuclear Station, Unit 1.
The purpose of these surveillance requirements is to demonstrate the operability of the low power setpoint (LPSP) and the high power setpoint (HPSP) of the rod pattern control system (RPCS). The LPSP initiates RPCS Interlocks below 201 power and rod withdrawal limiter (RWL) interlocks above 20% power. The function of the RPCS is to limit the individual rod worths to ensure the peak enthalpy of 280 cal /g will not be exceeded in the event of a control rod drop accident. As shown by analysis, this is
-' not a concern at reactor power greater than 20% power; and, therefore, the RPCS does not place any pattern restrictions on control rod moverent above the LPSP. The purpose of the RWL is to prevent fuel damage in the event of erroneous rod withdrawal from locations of high power density during power operation above the LPSP.
The HPSP provides the RWL with an interlock to enforce limitations on control rod motion at greater than 701 power. For the range of power level from the LPSP to the HPSP, rod 8811160536 891114 PDR ADOCK 05000416 P
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2 motion is limited to two feet; and above the HPSP, roo motion is limited to one foot.
The RPCS is demonstrated operable by verifying that the rod pattern controller functions when thermal power is less than the LPSP by selecting and attempting to move an inhibited control rod.
The RPCS is also demonstrated operable by verifying that the RWL functions when thermal power is greater than or equal to the LPSP by selecting and attempting to move a restricted control rod in excess of the allowable distance.
The Technical Specifications presently require the channel function test to be performed within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> prior to control roo movement and daily as power is increased above the LPSP and HPSP or decreased below the HPSP. Another channel functional test is performed prior to startup and a third is required at least once per 31 days while operation continues above the LPSP.
The proposed TS changes would delete the daily tests while retaining the test prior to startup and the monthly tests.
2.0 EVALUATION The licensee's June 21, 1988 letter requesting deletion of the requirement for daily functional tests of the LPSP and the HPSP for the rod control system provided the following information in support of the proposed changes.
1.
These functional tests are performed on the LPSP and HPSP Rosemount trip units identical to trip units located throughout the plant which receive channel function tests monthly per their aprilicable Technical Specification surveillance requirements.
These LPSP and HPSP trip units are subjected to a 30 fold it. crease in surveillance test frequency as compared to identical trip units in, for instance, the reactor protection system (Technical Specification 3.4.3.1) without an identified corresponding increase in rd iability.
The channel functional tests performed since corr 4rercial operation l, 2.
approximately 735 for each channel (greater than 2900 total tests were reviewed with no identified as-fcund setpoints excteding Technical Specification limits. Additionally, as-found trip setpoints were reviewed for drift and were found to show negligible drif t over a three month period between channel calibrations.
This performance data confirms the reliability of these trip units and supports the change to their functional testing frequency of once per 31 days.
3.
Since the HPSP is not required to function until 70% power, it is appropriate to change the HPSP applicability to Operational Condition 1 with thermal power greater than the LPP (20%). With these changes, the liPSP surveillance tests will have to be current prior to operation at or above the HPSP.
3 The NRC staff has reviewed the licensee's submittal.
Because of the demonstrated reliability of the Rosemount trip units used in the rod pattern control system, and the negligible drift of the setpoints during a three month period, the staff concludes that deletion of the daily channel functional tests of the low power setpoints (LPSP) and of the.
high power setpoints (HPSP) will not adversely affect the safety of the p1dnt ard, therefore, is acceptable. Because the HPSP is not required to function at power levels below the HPSP (70*.), the change of its opera-tional condition applicability to power levels greater than the LPSP (20%)
eliminates a requirement that serves no purpose and is acceptable.
3.0 ENVIRONMENTAL CONSIDERATION
This amendment changes a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes to the surveillance requirements. The staff has determined that the amer.iment involves no significant increase in the amounts, and no significant t..ange in the types, of any effluents that may be released off site; and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that thi: amendment involves no significant hazards consideration and there has been no public comment on such finding. Accordingly, this amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assess-ment need be prepared in connection with the issuance of this amendment.
4.0 CONCLlJSION The Comission made a proposed determination that this amendment involves no significant hazards consideration, which was published in the Federal Register (53 FR 30137) on August *0, 1988, and consulted with the State of Mississippi.
No public coments or ree.uests for nearing were received, and the State of Mississippi did not have any comments.
The staff has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the p(ublic will not be enAngered by operation in the proposed manner, and2) such activities w regulations ano the issuance of this amendment will not be inimical to the comon defense and the security, or to the health and safety of the public.
Principal Contributor:
Lester L. Kintr.er, Project Direct rate 11-1 Dated:
November 14, d88