ML20073B933
| ML20073B933 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 09/16/1994 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20073B924 | List: |
| References | |
| NUDOCS 9409230034 | |
| Download: ML20073B933 (6) | |
Text
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E UNITED STATES 5
i NUCLEAR REGULATORY COMMISSION
(..,...,/
WASHINGTON. D.C. 2055!W001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 98 TO FACILITY OPERATING LICENSE NO. NPF-38 ENTERGY OPERATIONS. INC.
WATERFORD STEAM ELECTRIC STATION. UNIT 3 DOCKET NO. 50-382
1.0 INTRODUCTION
By application dated September 9, 1994, Entergy Operations, Inc. (the licensee), submitted an emergency request for changes to the Waterford Steam Electric Station, Unit 3, Technical Specifications (TSs).
The requested changes would add a footnote to the Surveillance Requirement for TS 3/4.8.1 Electrical Power Systems A.C. Sources, specifically 4.8.1.1.2 d, to allow testing and analysis of train AB components in lieu of prescribed integrated tests.
This change will remain in effect until startup following refuel 7.
On September 9,1994, the licensee submitted another letter which modified the request for enforcement discretion related to this amendment request; however, the proposed change to the technical specifications remained unaffected. On September 16, 1994, the licensee amended the original request by removing the last sentence in the proposed surveillance requirement to conduct further tests.
2.0 EVALUATIOJ In addition to Train A and Train B 4160 Vac emergency diesel generator-backed busses, the plant's electrical distribution system also has a 4160 Vac bus designated as AB which can be connected to either Train A or Train B 4160 Vac bus and provides power for an extra (third-of-a-kind) high pressure safety injection pump, component cooling water pump, and essential services chiller.
These extra components serve as complete rep'on which train 4160 Vac Bus AB is lacements for the corresponding components in Train A or Train B (depending connected) during periods of maintenance or required surveillance on those components. When in use, these extra components are controlled by the load shedding / sequencing circuitry for the component it is replacing.
Also, in addition to the Train A and Train B 480 Vac busses, the plant has a 480 Vac bus designated as AB which can be connected to either Train A or Train B bus and provides power for an extra safety-related charging pump and a non-safety-related motor-driven fire pump and serves as an alternate backup power source for the p1hnt monitoring computer static uninterruptible power supply.
The uninterruptible power supply is shed on a loss of power as well as the motor-driven fire pump (if it is in use).
The extra charging pump, when in h
p
l l
' use, would be shed and reconnected to the bus by the control circuitry associated with the replaced component in the same train as to which Bus AB is connected.
This 480 Vac bus also supplies power to one safety-related motor control j
center (MCC 3AB311) and two non-safety-related motor control centers (MCC l
3AB312 and 3AB313). MCC 3AB311 is permanently connected (not shed) to the 480 i
Vac bus and provides power to third-of-a-kind support equipment, some non-safety-related loads, and two battery chargers. On a loss of power to MCC 3AB311, the control circuitry for the feeders to the two battery chargers is designed to shed the chargers and subsequently auto-connect them back to MCC j
3AB311. MCC 3AB312 and MCC 3AB313 are also shed on loss of power.
j Current Technical Specifications 4.8.1.1.2.d.3a & 3b require that each emergency diesel generator (EDG) be verified operable every 18 months by performing an integrated test simulating a loss-of-offsite power condition.
1 Technical Specifications 4.8.1.1.2.d.5a & Sb require that each EDG be verified operable every 18 months by performing an integrated test simulating a loss-of-offsite power in conjunction with a safety injection actuation signal.
These tests demonstrate the as-designed operation of the onsite emergency power system and verify that required actions such as load-shedding and reconnection of required loads are performed in the proper sequence for the associated scenario.
On September 7, 1994, the licensee discovered that, due to inadequate plant operating procedures, the integrated tests required by the above mentioned Technical Specifications never encompassed the load-shedding and reconnection of the components powered by 4160 Vac Bus AB and 480 Vac Bus AB.
The licensee i
declared the Train B EDG inoperable (Train AB loads were aligned to Train B) and entered a 72-hour limiting condition for operation. On September 9, 1994, the licensee requested discretionary enforcement and an emergency change to the Technical Specifications to allow the plant to continue operation until startup following refuel 7 (September 1995). The staff verbally granted the enforcement discretion on September 9, 1994, and formally documented that action in a letter dated September 13, 1994, stating that the enforcement discretion would expire on September 17, 1994.
The proposed emergency change to the Technical Specificatbns would allow some testing and analysis of the load-shedding /reconnection of the components l
powered from the two AB busses to establish EDG/ system operability in lieu of integrated testing.
This is necessary since a full integrated test cannot be performed without a plant shutdown.
Specifically the following footnote will i
be added to Technical Specifications 4.8.1.1.2.d.3a, 3b, Sa, and 5b:
]
1 Until startup following Refuel 7 in lieu of the prescribed integrated i
tests (i.e., actual demonstration of shedding, connection, and loading of
{
loads) testing and analysis that shows the capability of the diesel
{
generator to perform these functions will be considered acceptable for t
train AB A.C. ESF busses. This provision will apply to the associated train AB ESF loads with the exception of Motor Control Center 3AB311-5 i
m_________________________.__________
- that has been verified acceptable via analysis.
The testing will include any series of sequential, overlapping, or total steps so that the entire connection and loading sequence is verified.
4 The staff held further discussions with the licensee on September 13-14, 1994, regarding the proposed additional testing and last sentence of the above
)
proposed footnote. The licensee originally proposed to perform one-time testing so that the entire connection and loading sequence is verified for the third-of-a-kind components (component cooling water pump AB, essential services chiller AB, high pressure safety injection pump AB, and charging pump AB) prior to their being declared operable (rendered inoperable as compensatory action associated with N0ED No. 94-6-017). The staff was concerned that testing involving the use of numerous jumpers and components that had been verified to operate in other previous tests or events would cause undue risk to the plant's safety.
In response to that con ern, the licensee agreed to limit testing for the third-of-a-kind components to only that required to ensure operability of load-shed/reconnectior circuitry which could not be verified to be operable from previous tests or events. This approach will also be used for a load-shed test on the alternate feed to the uninterruptible power supply.
This agreement is documented in the licensee's letter dated September 16, 1994.
On this basis, the last sentence of the proposed surveillance requirement has been deleted.
The staff finds the proposed Technical Specification change, as revised, to be acceptable based on the following:
1.
When transferring the AB 480 Vac bus this year, a " dead bus" transfer was utilized.
The nonessential components on the bus that were operating (all components except the uninterruptible power supply and motor-driven fire pump) did trip and did require manual reconnection as designed.
In 1990 unplanned events, all nonessential components on the AB 480 Vac bus (except the uninterruptible power supply) were verified to have tripped on a loss of power.
2.
The tripping and subsequent automatic reloading of the two battery chargers on MCC 3AB311 was confirmed on the dead-bus transfer of the AB 480 Vac bus. Although the proper trip /reconnection times were not obtained, this should not impact the dynamic loading of the EDG since the battery chargers only constitute 2.5% of the total EDG load.
3.
Steady-state and dynamic loading calculations were reviewed by the licensee. The calculations showed that the EDG loading remains acceptable even with the extra loads from MCC 3AB311.
In addition, these extra loads were successfully carried by each EDG during the unplanned loss-of-power events in 1990.
4.
The licensee performed an analysis that determined an EDG would be loaded to slightly less than its continuous rating if MCC 3AB312 and MCC 3AB313 failed to shed.
If both those MCC's and the motor-driven l
. fire pump (if running on a loss of system pressure during a fire) were not shed, the EDG load would increase to just above the continuous rating, but below the 2-hour rating.
5.
The plant monitoring computer static uninterruptible power supply is not normally stoplied from the AB 480 Vac bus and therefore its tripping and manual reconnection would not be expected to occur.
6.
The licensee agrees to the removal of the last sentence of the proposed surveillance requirement. Only that testing that can be done safely and that will provide additional assurance of operability will be pursued.
7.
The licensee has committed to limited use of the third-of-a-kind components only when they are needed to replace a corresponding component in Train A or Train B during their surveillance or maintenance.
(The use (althoegh limited) of the third-of-a-kind components provides the plant with the opportunity to perform additional maintenance while the plant is at power and added redundancy which may lead to increased reliability and availability.)
3.0 EMERGENCY CIRCUMSTANCES The Commission's regulations in 10 CFR 50.91 contain provisions for issuance of amendments with less than a 30-day comment period if emergency circumstances are determined to exist.
Emergency situations involve those cases in which failure to act in a timely way results in the derating or shutdown of a nuclear power plant or prevents either resumption of operation or increase in power output up to the plant's licensed power level.
Under emergency circumstances, the Commission may issue a license amendment involving no significant hazards consideration without prior notice and opportunity for a hearing or for public comment.
In such a situation, the Commission publishes a notice of issuance under 10 CFR 2.106, providing for opportunity for a hearing and for public consent after issuance.
For emergency circumstances, the licensee is required to explain the reason for the condition and why it could not be avoided. This requirement is intended to prevent the abuse of the special provisions of 10 CFR 50.91(a)(6).
On September 7, 1994, the emergency train B was declared inoperable.
The licensee has provided information that shows that the train B emergency diesel generator is capable of performing its safety function, even though these tests do not meet the specific surveillance requirements of TS 4.8.1.1.2.d.
The licensee has also performed analyses that show that the total load on the diesel would not exceed the diesel's 2-hour rating (worst case). Additional tests to be performed will provide added assurance that the train AB cam,nnnants may be used until startup following refuel 7.
This information was
e d
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discussed with the staff on September 9, 1994, and is presented in the licensee's letter dated September 9,1994, as supplemented by letter dated September 16, 1994.
The licensee has cooperated fully with the staff in their request, and has provided all the information necessary to fully understand the basis for operability assurance from past testing and analysis. This operability assurance is an acceptable temporary alternative to the surveillance requirement for integrated testing. Without the requested amendment and the enforcement discretion, the plant would have to be shut down. Shutting the plant down at this time to perform an integrated test with the AB train aligned to either the A or B train would expose the plant to unwarranted plant transients. The licensee has made a good faith effort to examine the AB train system and test requirements and to examine the history of individual testing and analyW of loads that might be placed on the A or B diesel. The licensee promptly adarmed the NRC of the need for the emergency amendment and did not abuse the emergency problems.
Consequently, there are emergency circumstances present that warrant issuance of the amendment pursuant to 10 CFR 50.91(a)(5).
4.0 NO SIGNIFICANT HAZARDS CONSIDERATION 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 consideration if the operation of the facility in accordance with the i
amendment would not:
(1)
Involve a significant increase in the probability or consequences of an accident previously evaluated; or j
(2) Create the possibility of a new or different kind of accident from any accident previously evaluated; or I
(3)
Involve a significant reduction in a margin of safety.
Providing a reasonable assurance of operability of the train AB aligned to either the A or B train based on train AB operating events and analysis of the emergency diesel generator loads is an acceptable alternative to the surveillance requirements of integrated testing required at shutdown during refueling. This acceptance is temporary until the preferred testing can be performed during a time when plant transients are less likely to occur. The emergency diesel generator is expected to perform as designed, should it be i
called upon, and the compensatory measures and additional testing planned will provide added assurance that no unforeseen problems exists. Therefore, the i
proposed change involves no significant increase in the probability or
)
consequences of an accident previously evaluated.
i The acceptance of alternative testing and analysis for operability assurance in lieu of the required integrated testing will result in the diesel generators performing their intended function if called upon. The loads that i
e
- may not shed in an emergency on the AB train are within the capability of the A or B diesel and no adverse conditions on the diesel or emergency train are expected.
Therefore, the proposed change will not create the possibility of a new or different kind of accident from any accident previously evaluated.
The operational tests and design of the system, with the sequencer on the train A or B portion of the circuit, combined with the analysis of the loads that will not separate, provides the margin of safety that is very near that which is provided by the integrated test when performed in accordance with the surveillance requirements.
In the worst case, the loads that will not separate if the emergency system is called upon would cause the diesel to experience a load of 4476.1 KW which is slightly above the continuous rating of the diesel at 4400 KW, but below the 2-hour rating of 4840 KW. Therefore, the proposed change will not involve a significant reduction in a margin of safety.
Based upon the above considerations, the staff concludes that the amendment meets the criteria of 10 CFR 50.92. Therefore, the staff has made a final determination that the proposed amendment does not involve significant hazards considerations.
5.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Louisiana State official was notified of the proposed issuance of the amendment. The State official had no comnients.
6.0 ENVIRONMENTAL CONSIDERATION
The amendment 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 effluent that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.
The Commission has made a final no significant hazards consideration determination with respect to this amendment. 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.
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 activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the commor defense and security or to the health and safety of the public.
Principal Contributors:
F. Burrows D. Wigginton Date:
September 16, 1994 i