ML20138D880
| ML20138D880 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 12/06/1985 |
| From: | Nauman D SOUTH CAROLINA ELECTRIC & GAS CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20138D886 | List: |
| References | |
| RTR-REGGD-01.108, RTR-REGGD-1.108 NUDOCS 8512130318 | |
| Download: ML20138D880 (2) | |
Text
V Sot.th Carolina Electric & Gas Company Dan A. Naumari P.O. Box 764 Vee President Coturnbia. SC 29218 Nuclear Operations (803) 743-3513 SCE&G sema December 6, 1985 Mr. Harold R. Denton, Direc tor Of fice of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, DC 20555
Subject:
Virgil C. Summer Nuclear Station Docket No. 50/395 Operating License No. NPF-12 Diesel Generator Testing
Dear Mr. Denton:
In a letter from Mr. O. W. Dixon, Jr., to Mr. H. R. Denton dated June 10, 1985, South Carolina Electric and Gas Company (SCE6G) requested changes to the Virgil C. Summer Nuclear Station Technical Specifications which were intended to reduce the number and severity of starts of the diesel generators, thereby decreasing engine wear and increasing reliability.
In recent discussions with the NRC Staf f, additional justification for these changes was requested. This letter is being supplied in response to that request for information.
Surveillance requirement 4.8.1.1.2.a requires testing of the diesel generators on a frequency specified in Table 4.8-1 (normally once a month). Surveillance 4.8.1.1.2.a.3 is also required to be perforced upon entry into specific action statements involving degraded A.C. sources.
In the current Technical Specifications and in the June 10, 1985 submittal, the requirement for the diesel generators to load and run for an entire 60 minutes was not part of the s tarting surveillance but was instead a separate line item. SCE6G proposes, based on further investigation, that these items be combined as shown on the attached Technical Specification page 3/4 8-3.
Combining these line itens and requiring a 60 minute run after starting is expected to help minimize thermal transients on the generators and thereby increase their overall reliability.
Surveillance requirements 4.8.1.1.1.b and 4.8.1.1.2.e have been requested to be changed from the current testing frequency of once every 18 months with a 25%
grace period to once per refueling. SCE6G's second refueling outage commenced in October of this year, and in this third fuel cycle SCE6G will go to an 18 month fuel cycle scheme. Therefore, refueling shutdowns will now normally occur on approximately 18 month intervals. Changing the surveillance requirement to read once per refueling helps to ensure that if a fuel cycle is extended beyond 18 months, a forced shutdown to perform surveillance is not required. Other similar testing required on a monthly and bi-annual basis (surveillance requirements 4.8.1.1.2.a and 4.8.1.1.2.d) is adequate to ensure that proper diesel reliability is maintained. Significant deviations from an 18 month cycle are not expected and should only occur if the plant is shutdown in mid-cycle for an extended period of time. Howeve r, significant mid-cycle shutdowns should not occur on a regular basia and could only be expected to occur in rare instances.
Therefore, SCE6G considers the revision to Technical Specifications to be justified based on the low probability that the period of time between re fueling outages will be significantly greater than the currently allowed 18 months.
8512130318 851206 PDR ADOCK 05000395 P
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Mr. Harold R. Denton Diesel Generator Testing December 6,1985 Page 2 In surveillance requirements 4.8.1.1.2.a, d, and e, loading of the diesel generator to specified limits is required. SCE&G has proposed that these limits be revised to indicate bands of acceptable loading in order to avoid overloading the engine. These bands take into account the potential for in s t rumen t inaccuracies and meter reading errors.
For the monthly, bi-annual, and longer portion of the re fueling load run tests, SCE&G has proposed a band of 3900-4100 kW.
SCE&G's position is that these surveillance tests should require the diesel generators to be adequately eFETCised and should verify their operability, or degradations can be identified and corrected to ensure that the engines can perform if required. Consequently, obtaining an indicated value within the specified band of loading would be adequate assurance that the diesel generators are performing acceptably.
For the two hour portion of the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> refueling load run, a band of 4600-4700 kW is given along with the indicated target value of 4676 kW.
This band of operation completely encompasses the design basis accident load, and while operation at an indicated value near the higher end of the band could lead to slight overloading of the diesel generators, the relative infrequency of doing so (one per refueling) is justified in order to ensure testing at the design basis loading conditions. However, SCE&G is also proposing to remove the requirement to perform this two hour test at the beginning of the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> run and allow it to be performed at any time during the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period. This proposal is in accordance with the requirements of Regulatory Guide 1.108, item C.2.a(3), which states that test ing shou ld, " demons trate full-load carrying capability for an interval of not less than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, of which 22 hours2.546296e-4 days <br />0.00611 hours <br />3.637566e-5 weeks <br />8.371e-6 months <br /> should be at a load equivalent to the continuous rating of the diesel generator and 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> at a load equivalent to the 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> rating of the diesel generator."
Surveillance requirement 4.8.1.1.2.e.2 (see attached Technical Specification pages) requires a load rejection test of greater than or equal to the maximum single load placed on the diesel generators. As listed in the Virgil C. Summer Nuclear Station Final Safety Analysis Report, Table 8.3-3, ( Channel A), the largest load is 729 kW and is associated with the charging pump. Accordingly, the Technical Specifications r: ruld be changed to re flec t this load.
In the proposed attached Surveillance requirements, item 4.8.1.2.e.3 requires verification of the diesel generators' capability to reject a load of 4250 kW without tripping. The June 10, 1985 submittal did not include this test requirement; however, upon further evaluation SCE&G proposes this requiremen t continue to remain in the Technical Specifications as shown on page 3/4 8-4.
While this test does submit the diesel generators to an additional stress, performing the test at the required testing frequency of one per refueling is not expected to adversely af fect the generators overall performance and reliab ility.
Current Surveillance item 4.8.1.1.2.e.5 requires starting of the diesel engines on an ESF signal and af ter 5 minutes of stand-by operation, simulat ing loss of offsite power to verify correct load shedding followed by proper load s equenc ing. The June 10, 1985 submittal included the start on the ESF signal h
Mr. Harold R. Denton Diesel Generator Testing December 6, 1985 Page 3 (4.8.1.1.e.4), but did not require the following loss of of fsite power in that item. While a separate verification for proper starting and loading in the event of loss of of fsite power concurrent with as ESF signal is included in the June 10, 1985 submittal, SCE6G finds limited merit in the additional requirenent to simulate loss of of fsite power after the diesel generators have been started via the ESF signal alone. Therefore this requirement is being added to the proposed Technical Specification as shown on page 3/4 8-5.
In the June 10, 1985 submittal SCE&G requested an additional clarifying note be added to Specification 3.8.1.2 to indicate that the ESF Load Sequencer may be de-energized in modes 5 and 6.
The solid state protection system, which the automatic signals that start the diesel go through at the plant, is not required to be operable in modes 5 and 6.
The re for e, to be consistent with the other solid state protection Technical Specifications (see Table 3.3-3, " Engineered Safety Feature Actuation System Instrumentation," items 1 and 7), this note is necessary to provide clarification for the determination of the diesel generators' operability in modes 5 and 6.
To clarify the basis for the surveillance and reporting requirements of the Technical Specifications, SCE6G proposes the bases and section 4.8.1.2 be revised as indicated on the attached Technical Specification pages. This wording takes into account the NRC Staf f evaluation of the surveillance requirements of the diesel generators and encompasses the necessary reporting identified in Regulatory Guide 1.108.
The additional Technical Specification changes included in this letter have been reviewed and approved by both the Plant Safety Review Committee and the Nuclear Safety Review Committee.
If you should have any additional questions, please advise.
Vqry tr 1 yours, i
\\ ).
au n 4
AMM: DAN:tdh c:
V. C. Summer C. L. Ligon (NSRC)
T. C. Nichols, Jr./0. W. Dixon, Jr.
K. E. Nodland E. H. Crews, Jr.
R. A. S t ou gh E. C. Roberts G. Perc ival W. A. Willians, Jr.
R. L. Prevatte J. Nelson Crace J. B. Knotts, Jr.
Group Managers H. G. Shealy O. S. Bradham NPCF C. A. Price File
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