ML20056F776
| ML20056F776 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 08/16/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20056F775 | List: |
| References | |
| NUDOCS 9308310046 | |
| Download: ML20056F776 (4) | |
Text
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k UNITED STATES e*I i (sj j
NUCLEAR REGULATORY COMMISSION l
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,e WASHINGTON. D C. 20555-0001
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION t
EfLATED TO AMENDMENT NO 108 TO FACILITY 0?ERATING LICENSE NO. NPF-29 l
ENTERGY OPERATIONS. INC.. ET AL.
GRAND GULF NUCLEAR STATION. UNIT 1 DOCKET NO. 50-416 i
1.0 INTRODUCTION
By letter dated May 20, 1993, as supplemented by letter dated July 15, 1993, I
Entergy Operations, Inc. (the licensee), submitted a request for changes to the Grand Gulf Nuclear Station, Unit 1 (GGNS) Technical Specifications (TS).
The proposed change would remove from the TS the operability requirements for the auto-test feature of the load shedding and sequencing (LSS) system, and would increase the allowed outage time (A0T) in the TS for an inoperable LSS system from 8 to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. As discussed below, the NRC staff has reviewed the proposed changes and finds them acceptable.
The July 15, 1993 letter provided clarifying information that did not change the initial proposed no significant hazards consideration determination.
2.0 BACKGROUND
t In August 1991, problems with the auto-test feature of the GGNS Division II LSS system resulted in discretionary enforcement action by the NRC staff.
Specifically, a temporary waiver of compliance was granted allowing continued operation with the auto-test function inoperable from August 15, 1991 through August 31, 1991. The waiver was granted primarily on the basis that auto-test feature is not essential for the LSS system to perform its safety function.
By letter dated May 20, 1993, the licensee requested approval of a TS change l
to Surveillance Requirements 4.8.3.1.2 and 4.8.3.2.2 to remove operability 4
requirements for the auto-test feature of the LSS syste:n.
In its May 20, 1993 letter the licensee also requested approval of TS charge to ACTION statement a.3 of Technical Specification 3.8.3.1 to increase the A0T for an inoperable LSS system from 8 to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. After discussions with the NRC staff, the licensee, by letter dated July 15, 1993, modified its previous request and proposed changing the A0T for an inoperable LSS system from 8 to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
3.0 EVALUATION v
The LSS system is utilized during a Loss-of-Coolant-Accident (LOCA) and/or bus undervoltage (BUS) condition to disconnect (shed) and connect, automatically r
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in sequence, loads on the Class IE buses. The LSS system at GGNS consists of two solid state LSS panels, one for each division. These panels contain separate sequencers with both manual and automatic test capability. All system logic and timing functions utilize solid state circuits, with buffering relays used for input and output. Section 8.3-8 of the GGNS updated final safety analysis report (UFSAR) states that the timing sequence for the loss of r
coolant accident (LOCA) loads is the same whether the safety buses are energized from offsite or onsite (emergency diesel generator) power.
TS Surveillance Requirements 4.8.3.1.2.a (operating) and 4.8.3.2.2.a (shutdown) require that the LSS panels be demonstrated operable at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> by determining that the auto-test system is operating and is not indicating a faulted condition.
If the auto-test feature indicates a faulted condition, the current TS requires that the plant be shut down even though the LSS system may be capable of performing its specified safety function. The licensee states that based on the LSS system design and their experience with the system, many of the faults identified on the LSS panel do not represent a failure of the functional capabilities of the LSS system, but rather malfunctions of the auto-test feature itself.
The auto-test system is a non-safety-related feature of the LSS system that monitors the LSS circuit operation once every 1.5 seconds and is utilized as a diagnostic tool in identifying LSS system malfunctions.
If a fault is i
detected, the logic displays the step number of the failed test on the LSS control panel, interrupts the auto-test, thereby blocking it from further operation, and actuates a control room annunciator alerting the control room operator that the auto-test has detected an apparent fault in the logic. The LSS system control panel is used in conjunction with manual tests to identify the source of the fault. The auto-test is also terminated upon receipt of a valid LSS actuation signal. The licensee states that they will not disconnect the auto-test feature but rather continue to utilize it to monitor the LSS i
system's ability to perform its intended safety function.
Prior experience has shown that failure of the auto-test does not affect the ability of the LSS system to perform its safety function.
The licensee performs Surveillance Requirement 4.8.1.1.2.d.4.a.2 at least once per 18 months, during shutdown, by simulating a loss of offsite power and verifying the diesel generator starts on auto-start signal, energize; the emergency buses with permanently connected loads within 10 seconds, energizes the auto-connected shutdown loads through the load sequencer and operates for greater than or equal to 5 minutes. This is consistent with the improved GE BWR-6 Standard Technical Specifications, NUREG-1434, Revision 0 (STS).
Moreover, the licensee is retaining the Surveillance Requirements 4.8.3.1.2 and 4.8.3.2.2 which require performing a manual LSS logic test at least once per 31 days by simulating real panel inputs utilizing test switches on the
. e control panel, and verifying response within the design criteria to the following test inputs:
a)
LOCA b)
Bus undervoltage c)
Bus undervoltage followed by LOCA d)
LOCA followed by bus undervoltage This exceeds the requirements given in the STS.
Based on the above, the change to remove the auto-test feature from the TS is, therefore, acceptable.
In its P.ay 20, 1993 submittal, the licensee proposed a change to ACTION statement a.3 of Technical Specification 3.8.3.1 to increase the allowed outage time (A0T) for an inoperable LSS panel from 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The
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licensee states that since the LSS panel comprises an intricate electronic system, the proposed 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> A0T would allow the LSS panel vendor to be contacted and utilized in troubleshooting LSS system problems. The NRC staff review of the licensee's submittal indicated that this change was not consistent with the STS, which requires the restoration of an inoperable automatic load sequencer to operable status within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
The 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> restoration time for the load sequencer is also consistent with ACTION statement c. of TS 3.8.1.1.
This ACTION statement requires that with one offsite circuit and diesel generator 11 or 12 inoperable, at least one of the inoperable ac sources must be restored to operable status within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
When one of the inoperable ac power sources specified in ACTION statement c.
t of TS 3.8.1.1 is restored within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, the sequencer will be required to automatically sequence the safety loads to the safety bus. Therefore, licensee was advised that its request to increase the A0T for an inoperable LSS system from 8 to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> was unacceptable. As a result, the licensee submitted a letter dated July 15, 1993, in which it revised its proposed TS change to increase the A0T for an inoperable LSS system from 8 to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
Based on the discussion given above, the NRC staff finds the 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> A0T to be acceptable.
In summary, on the basis of the above evaluation, the NRC staff has concluded i
that the licensee has provided adequate justification to remove operability requirements for the auto-test feature of the load shedding and sequencing system from TS Surveillance Requirement 4.8.3.1.2 and 4.8.3.2.2.
Operating experience demonstrates that the failure of the auto-test will not affect the
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ability of the LSS system to perform its safety function. The 31 day manual LSS logic test which is retained in Surveillance Requirement 4.8.3.1.2 and 4.8.3.2.2 in conjunction with 18-month surveillance performed per TS 4.8.1.1.2.d.4.a.2 provide a comprehensive test of the LSS system logic.
Therefore, removing the LC0 for the auto-test feature is acceptable. The proposed change to increase the allowed outage time for an inoperable load shedding and sequencing system from 8 to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> in ACTION statement a.3 of i
TS 3.8.3.1 is consistent with the STS and is, therefore, acceptable.
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4.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Mississippi State official was notified of the proposed issuance of the amendment. The State official had no comments.
5.0 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 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 occupational radiation exposure. The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (58 FR 34076). Accordingly, the 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 assessment need be prepared in connection with the issuance of the amendment.
6.0 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 activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
N. Trehan Date: August 16, 1993