ML20126F658
| ML20126F658 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 12/23/1992 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20126F657 | List: |
| References | |
| NUDOCS 9212310043 | |
| Download: ML20126F658 (3) | |
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l SAFETY EVALUATION BY THE OFFICE OF NVCLEAR REACTOR REGULATION 1'
RELATED TO AMENDMENT NO. 73 TO FACILITY OPERATING LICENSE NO. NPF-49 FORTHEAST NUCLEAR ENERGY COMPANY. ET AL.
t MILLSTONE NUCLEAR POWER STATION. UNIT NO. 3 DOCKET NO. 50-423 1.0 INTRODUCTI@
By letter dated October 22, 1992, the Northeast Nuclear Energy Company (NNECO, the licensee), submitted a request for changes to the_ Millstone Nuclear Power Station, Unit No. 3 Technical Specifications (TS).- The requested changes would extend the surveillance requirement frequency for the Millstone Unit No. 3 emergency diesel generators (EDGs) by allowing a one-time extension to the current 18-month surveillance plus the additional 25% allowed by TS 4.0.2..
This change will allow the EDGs-to be inspected in accordance with the procedures prepared in conjunction with its manufacturer's recommendations: for this class of. standby service' _ The inspection is currently scheduled to be performed no later than December 25, 1992.
The proposed change will defer the.
inspection until the 1993 (fourth) refueling outage, but not beyond September _30, 1993.
2.0 EVALUATION The surveillance requirements contained in the existing TS-are designed to.
assure.that the quality of equipment and com)onents is maintained.
NNECO has-determined the total time of the EDG11nopera)ility during this inspection.
would-be in excess of the current 72-hour TS limit and.as such would prefer to perform the inspection in an extended outage.
-In-the absence of the proposed revision, an unscheduled shutdown of the plant would be necessary to meet the current EDG TS surveillance' schedule. 'The.
-previous EDG inspection of. Train;"A" was completed on. March'4,-1991.
Train "B" wa's last' inspected on February 8,1991.. As a result of an unusually long:
maintenance' outage during 1991,--involving work on the service water _ system and-erosion / corrosion-related repairs, NNECO has. rescheduled Millstone Unit: No.
3's refueling. outage from November-1992 to approximately September 1993.-
Increasing the interval between refueling outages:will cause' Millstone Unit-No. 3 to exceed the 18-month surveillance, plus the additional 25Lallowance:
allowed by. TS 4.0.2.
The licensee notes that. the proposed change does _not.-
alter or change any of the_other surveillances required'per TS 4.8.1.1.2.g..
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' 4 The staff has reviewed the surveillance test data for both Hillstone Unit No.
3 EDGs.
There were no failures in the last 100 valid starts indicating high reliability for this period.
A review of the start time data indicates that there is no observable trend toward increasing start times.
In the period between December 1991 and September 1992, the start time trend data for the EDG Train "A" indicates 16 subsequent starts with start times remaining well below the ll-second time limit (maximum time recorded was approximately 8.5 seconds).
The same data for the EDG Train "B" indicates 26 subsequent starts i
with start times remaining below the ll-second time limit (maximum time recorded was approximately 9.7 seconds).
Since the last surveillance inspection, the diesel engines logged the following number of hours:
EDG Train "A" - 108 hours0.00125 days <br />0.03 hours <br />1.785714e-4 weeks <br />4.1094e-5 months <br />, EDG Train "B" - 103 hours0.00119 days <br />0.0286 hours <br />1.703042e-4 weeks <br />3.91915e-5 months <br />. This total operating time for both engines is considered low, and therefore significant wear of the parts is not expected.
The EDG manufacturer-accepted a 6-month extension in the surveillance inspection time interval in 1987 stating that an additional 60 to 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> of diesel operation should pose no problem.
The additional operating hours during the proposed 9-month extension of the surveillance interval are expected to be in this order and, therefore, not likely to have an impact on engine performance.
Additional information about the engine condition is available from lube oil analyses performed monthly.
Samples are taken at two locations:
the rocker arm area, and the engine sump.
Lube oil is tested for water content which is an indication of an internal engine leak.
Various metal par _ticle contents are monitored, which provide an indication of excessive parts wear or bearing problems.
Review of the lube oil analysis results since June 1991 do not indicate any abnormal readings except high water content in the January 1992 diesel Train "A" rocker arm oil sample.
The presence of water was later attributed to a leak in an injector cooling line.
The problem was corrected by replacing the injection nozzles.
In addition to the plant-specific test data discussed above, the staff has also reviewed the prototype qualification test data of these diesel engines.
The starting reliability of the EDGs was confirmed during repeated start and load acceptance tests.
In these tests, the engine had to start up and accelerate to rated speed and voltage within 10 seconds of initiation of start, run for 5 minutes, then shut down for cooling down to " keep warm" L
temperatures.
The load acceptance reliability test consisted of 200 start and load cycles.
This series required the engine to start and accelerate to rated speed and voltage within 10 seconds and accept 100%-load within 25 seconds-from initiation of the start signal. A minimum of-200 starts-had to be made L
from standby to " keep warm" conditions.
Then, 30 starts had to be made at hot-equilibrium temperature conditions. The engine performed very satisfactorily I
during this test series and did not fail to start in any of an actual 230 l
cycles.
These tests prove the. engine's capability for taking the repeated thermal shock imposed by the start and load acceptance program..
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, -. i The plant-specific surveillance test data and the prototype qualification test data discussed above satisfy the staff that the EDGs are reliable.
The additional operational hours which would be imposed on the EDGs as a result of the proposed deferment of the EDG inspection until the 1993 (fourth) refueling outage, are not likely to have any significant impact on the EDG performance or reliability.
The staff has concluded, based on the considerations discussed above, that the proposed changes to the TS are acceptable.
3.0 STATE CONSULTATION
4 In accordance with the Commission's regulations, the Connecticut State official was notified of the proposed issuance of the amendment.
Th-State official had no comments.
1 4.0 ENVIRONMENTAL CONSIDERATIOy Pursuant to 10 CFR 51.21, 51.32, and 51.35, an environmental assessment and finding of no significant impact have been prepared and published in the-Federal Reaister on December 23, 1992, (57 FR 61100). Acccrdingly, based upon the. environmental assessment, the staff has determined that the issuance of the amendment will not have a significant effcct on the quality of the human-environment.
5.0 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 o' the public.
Principal Contributor:
J. Rajan Date:
December 23, 1992 l
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