ML13304A366
| ML13304A366 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 09/27/1988 |
| From: | Hickman D Office of Nuclear Reactor Regulation |
| To: | Baskin K, Cotton G San Diego Gas & Electric Co, Southern California Edison Co |
| References | |
| GL-84-015, TAC-61514, TAC-61515 NUDOCS 8810060080 | |
| Download: ML13304A366 (9) | |
Text
R RE oU N IT ED STA T ES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 September 27, 1988 ocket Nos.: 50-361 and 50-362 Mr. Kenneth P. Baskin Mr. Gary D. Cotton Vice President Senior Vice President Southern California Edison Company Engineering and Operations 2244 Walnut Grove Avenue San Diego Gas & Electric Company Post Office Box 800 101 Ash Street Rosemead, California 91770 Post Office Box 1831 San Diego, California 92112 Gentlemen:
SUBJECT:
UNIT-TO-UNIT LOAD TRANSFER SWITCH (PCN-215) AND DEFERRED PORTIONS OF GENERIC LETTER 84-15 RESPONSE (PCN-192) (TAC NOS. 61514 AND 61515)
By letter dated June 13, 1986 you submitted proposed amendments designated as PCN-192 and PCN-215. The proposed change PCN-192 was in response to Generic Letter 84-15 and included a request to increase the diesel generator out-of service time limit from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 7 days with an annual (365 consecutive days) limit of 800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br /> on the combined out-of-service time of the two diesels on each unit. You stated that this request was consistent with Generic Letter 84-15. While the staff had at one time considered this a potential approach, it has not been confirmed that increasing the allowable outage time beyond the present values increases reliability. The current policy is to not allow increases in diesel generator limiting conditions for operation (LCO).
Therefore, this portion of proposed change PCN-192 is hereby denied.
By letter dated April 9, 1987 we issued Amendment 59 to Facility Operating License NPF-10 and Amendment 48 to Facility Operating License NPF-15. These amendments allowed most diesel generator starts for surveillance purposes to be preceded by prelube and other recommended warmup.procedures. We have recently become aware that you have installed modifications to the control logic to perform the diesel generator slow starts. Because of the safety significance of the emergency diesel start circuitry, we require staff review of these modifications. Please provide within 30 days of receipt of this letter, details of the modifications, including schematics of the circuits before and after the modifications, along with your safety evaluation and a written description of the changes.
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Mr.. Kenneth P. Baskin
- 2 Mr. Gary D. Cotton The proposed change PCN-215 to add unit-to-unit transfer switches, along with the change to Technical Specification 3/4.8.1, "AC Sources," proposed in PCN-192, are currently under staff review. We require the additional information described in the enclosure to complete our review. Please provide this information within 90 days of receipt of this letter.
Sincerely, Donald E. Hickman, Project Manager Project Directorate V Division of Reactor Projects - III, IV, V and Special Projects Office of Nuclear Reactor Regulation
Enclosure:
As stated cc: See next page
Mr. Kenneth P. Baskin
- 2 Mr. Gary D. Cotton The proposed change PCN-215 to add unit-to-unit transfer switches, along with the change to Technical Specification 3/4.8.1, "AC Sources," proposed in PCN-192, are currently under staff review. We require the additional information described in the enclosure to complete our review. Please provide this information within 90 days of receipt of this letter.
Sincerely, original signed by Donald E. Hickman, Project Manager Project Directorate V Division of Reactor Projects -
- III, IV, V and Special Projects Office of Nuclear Reactor Regulation
Enclosure:
As stated cc:
See next page DISTRIBUTION:
Docket File NRC & Local PDRs PD5 Reading GMHolahan JLee DEHickman OGC (for infor only)
DHagan EJordan BGrimes TBarnhart (4)
Wanda Jones EButcher ACRS (10)
GPA/PA ARM/LFMB Region V (4)
DR PM RSP/D/PDV SELB PDIV D
an.cw GKnig ton FRosa JCalvo 08/z2/88 08/t/
88 01/1 /88 C847/88
Mr. Kenneth P. Baskin San Onofre Nuclear Generating Southern California Edison Company Station, Units 2 and 3 cc:
Mr. Gary D. Cotton Mr. Hans Kaspar, Executive Director Senior Vice President Marine Review Committeet Inc.
Engineering and Operations 531 Encinitas Boulevard, Suite 105 San Diego Gas & Electric Company Encinitas, California 92024 101 Ash Street Post Office Box 1831 San Diego, California 92112 Mr. Mark Medford Southern California Edison Company Charles R. Kocher, Esq.
2244 Walnut Grove Avenue James A. Beoletto, Esq.
P. 0. Box 800 Southern California Edison Company Rosemead, California 91770 2244 Walnut Grove Avenue P. 0. Box 800 Mr. Robert G. Lacy Rosemead, California 91770 Manager, Nuclear Department San Diego Gas & Electric Company Orrick, Herrington & Sutcliffe P. 0. Box 1831 ATTN:
David R. Pigott, Esq.
San Diego, California 92112 600 Montgomery Street San Francisco, California 94111 Richard J. Wharton, Esq.
University of San Diego School of Alan R. Watts, Esq.
Law Rourke & Woodruff Environmental Law Clinic 701 S. Parker St. No. 7000 San Diego, California 92110 Orange, California 92668-4702 Charles E. McClung, Jr., Esq.
Attorney at Law Mr. S. McClusky 24012 Calle de la Plaza/Suite 330 Bechtel Power Corporation Laguna Hills, California 92653 P. 0. Box 60860, Terminal Annex Los Angeles, California 90060 Regional Administrator, Region V U.S. Nuclear Regulatory Commission Mr. C. B. Brinkman 1450 Maria Lane/Suite 210 Combustion Engineering, Inc.
Walnut Creek, California 94596 7910 Woodmont Avenue, Suite 1310 Bethesda, Maryland 20814 Resident Inspector, San Onofre NPS c/o U. S. Nuclear Regulatory Commission Mr. Dennis F. Kirsh Post Office Box 4329 U.S. Nuclear Regulatory Commission San Clemente, California 92672 Region V 1450 Maria Lane, Suite 210 Mr. Sherwin Harris Walnut Creek, California 94596 Resource Project Manager Public Utilities Department Mr. Dennis M. Smith, Chief City of Riverside Radiological Programs Division City Hall Governor's Office of Emergency Services 3900 Main Street 2800 Meadowview Road Riverside, California 92522 Sacramento, California 95832
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0 oUNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAN ONOFRE UNITS 2 AND 3 DIESEL CROSS-CONNECT MODIFICATION (PCN-215)
REQUEST FOR ADDITIONAL INFORMATION TAC NOS. 61514 AND 51515 By letter dated June 13, 1986 Southern California Edison Company (SCE) requested a change to the Technical Specifications of San Onofre Nuclear Generating Station (SONGS) Units 2 and 3 to allow a diesel generator in one unit to automatically supply the loads of both units in a cross connect configuration. This is PCN-215. In that same letter SCE proposed changes to the SONGS 2 and 3 Technical Specifications in the areas of response to Generic Letter 84-15, diesel fuel oil surveillance requirements, and the offsite power supplies to the 4kV safety buses. This is PCN-192. The staff reviewed PCN-192 and prepared a safety evaluation on a portion of it. The remaining portion was deferred to the review of PCN-215.
On July 9, 1987 SCE briefed the staff on PCN-215 and the deferred portions of PCN-192. During the briefing the staff requested additional information on these modifications. SCE provided this information by letter dated January 14, 1988.
We have reviewed all the additional and previous information supplied by Southern California Edison Company on these items and find that we require additional information to complete our review.
The following questions pertain specifically to the design modification portion of PCN-215:
- 1. Because your estimated diesel generator loading in the cross-connect configuration is so close to the diesel generator loading limits (5057 kW versus 5170 kW at the 2 hr. rating, and 4640 kW versus 4700 kW at the continuous rating), you should provide a detailed power analysis identifying each connected load and the basis for its loading value. The basis for the loading value should be sufficiently detailed to allow an independent reviewer to conclude that the load truly represents the worst case for the shutdown or accident condition analyzed. For example, if the load is a pump motor whose power demand in the analysis is taken directly from the measured value obtained during your capacity test, compare the pump's operating flow and pressure during the test to the required accident or shutdown flow and pressure. If the load has been calculated, provide the values used in the calculation (flow, pressure, efficiency, etc.) and verify that these are the worst case accident or shutdown values. Because the cross-connect operating configuration is the most limiting condition relative to diesel generator loading, this power analysis should be added to the San Onofre 2&3 FSAR. This should then form the basis for any future modifications involving addition or deletion of loads from the diesel generators.
-2
- 2. With regard to the diesel generator load sequence test results you provided in your January 14, 1988 letter:
- a. For the tests in which an additional CCW pump or an additional HPSI pump was started, were all the sequenced pumps operated under full flow conditions or were some operated under mini-flow conditions?
Discuss the impact on the test results if all pumps were not operated at their designed full flow rating.
- b. For the tests in which an additional CCW pump or an additional HPSI pump was started with an AFW pump at 30 secs, was the steady state load up to the 30 sec. point of the load sequence equal to the actual accident load? Discuss the impact on the test results if it was not.
- c. When operating in the cross-connect configuration the loading sequences between Units 2 and 3 may not start simultaneously. There are therefore not any discretely defined intervals between a start of a Unit 2 load and a Unit 3 load. Describe therefore how you intend to demonstrate compliance with the R.G. 1.9 requirements regarding voltage and frequency recovery minimums between load sequencing steps. Discuss the consequences on voltage and frequency recovery and stability during the loading sequence as a result of the indeterminate load sequencing intervals.
- d. The tests you conducted in which an additional CCW pump or an additional HPSI pump was started at the 0 second load sequence step did not actually simulate the worst case starting load for this load step when in the cross-connect configuration. There are a number of other small loads that also may start at this load sequencing step as identified in Table 8.3-1 of the San Onofre 2&3 FSAR. Therefore you should provide an analysis that demonstrates that the diesel generator can satisfactorily start and operate the worst case loads when in the cross connect configuration. The results of this analysis should be verified by a full comprehensive test that.
demonstrates that the diesel generator can start and operate the worst case loads when in the cross-connect figuration. The analysis should include consideration of the voltage drop from the diesel generator to the load terminals.
- 3. Verify that the additional time needed for closing of the bus tie circuit breakers following closing of the diesel generator breaker will not result in a total time to establish power to the safety loads that exceeds that required in your accident analysis.
- 4. With regard to your discussion of compliance with R.G. 1.81 provided in your January 14, 1988 letter:
- a. You have not addressed position c.2.d. This position states that the interaction between each unit's engineered safety feature elec tric circuits should be limited such that any allowable combination
-3 of maintenance and test operations in the units will not preclude the capability to automatically supply power to minimum ESF loads in any unit, assuming a loss of offsite power. Therefore you should develop a matrix of all possible scenarios (including the interaction between units for test and maintenance operations) that could occur after the cross-connect modifications have been implemented, and identify the response of the electrical distribution system to them. With regard to this, in our review we have identified one scenario which may be a problem. With a diesel generator in the test mode operating in parallel with its offsite power supply and the transfer enable switch in AUTO on the opposite unit, if a loss of the offsite power supply should occur on the opposite unit's bus, that bus will be connected to the parallel combination of the diesel generator and offsite supply thru the bus tie breakers. This could result in overloading of the diesel generator. An interlock which originally existed to trip the diesel generator circuit breaker upon initiation of this event is disabled when the transfer enable switch is in AUTO.
Therefore you should ensure that this particular scenario is addressed in your matrix.
- b. In your response addressing position c.2.e you discuss the need for administrative procedures to prevent the control room operator, on the unit with the actual LOCA, from resetting the SIAS signal while the shared diesel generator is carrying LOCA loads. You state that before any plant modification is declared operable, an evaluation of the station's Emergency Operating Instructions (EOIs) and FSAR accident analysis will be performed to ensure that these contain no existing requirements that the SIAS signal be reset for accident mitigation. We require this information before we can approve your modification. Therefore you should conduct your evaluation of the EOls and FSAR on this issue noW and provide-us the results.
- c. You should also respond to the position of c.2.e that coordination between the unit operators should not be necessary in order to meet Regulatory Position 2.c with regard to onsite power capacity. Your response should address the need and coordination required to limit the number of manually energized loads if these can overload the diesel generator, and the need and coordination required to reduce load to less than the overload rating of the diesel generator after two hours if the load fails to automatically come down to within the continuous rating of the machine.
- d. You should also respond to the position of c.2.e that coordination required to meet Regulatory Position 2.d should be minimized. See question 4.a above.
- e. You did not provide a discussion of how the modification complies with position c.2.f. Please provide this information.
- f. You did not provide a discussion of how the modification complies with position c.2.g. Please provide this information.
-4
- 5. Do the diesel generators utilize an automatic synchronizing scheme?
Explain the operation of the synchronizing circuits shown on drawings 30328, 30216, 32328, and 32216. Provide a logic diagram for these circuits if one is available.
- 6. Describe the function of the Unit 2 and Unit 3 SIAS DG START TEST pushbotton. The staff found only one contact going to the diesel generator start circuitry. Are there any others?
- 7. Describe the operation of the "Auto-Manual Control" circuit shown on drawings 30216 and 32216. There are two relays labeled AR/RC and AR/OC in this circuit, however'the contacts of the relays are only labeled AR.
How does one determine which contacts are associated with which relay?
- 8. The contact labeled "SIAX" in the diesel generator circuit breaker trip circuit is shown as normally open on drawing 30328 and as normally closed on drawing 32328, even though the two circuits are identical in every other respect. Please correct this discrepancy.
- 9. Describe the operation of the load sequencer circuits. Is a centralized load sequencing scheme used or are the loads controlled by individual timers at their switchgear?
- 10. Discuss the coordination of the breakers involved when operating in the cross-connect configuration on the diesel generator. Are the tie breakers coordinated with the diesel generator breaker such that on a fault the tie breakers will trip first? Have the changes to maximum and minimum available fault currents been considered?
The following questions pertain specifically to the Technical Specification changes proposed to support PCN-215 and the portions of PCN-192 that were previously deferred.
- 11.
The portion of the Technical Specification changes which removes the requirements to have buses B04/BO6 available when the tie breakers must be available should be retained. These buses provide AC power to the battery chargers which supply the DC buses that provide control power to the tie breakers. The battery chargers and their associated batteries should be considered integral parts of the DC bus power supply. If either the charger or the battery is inoperable their associated DC bus should be considered inoperable.
- 12. The portion of the Technical Specification change which deleted the words "during shutdown" from the requirement to test the offsite power transfers should be retained. Testing these transfers while the plant is operational would create unnecessary transients to the electrical systems.
- 13. The proposed change to Technical Specification Section 4.8.1.1.2a.5 to increase the diesel generator loading to 5170 kW during the monthly periodic surveillance testing should be deleted. The 5170 kW rating is the 110% 2 hr. overloading rating of the diesel generator and, although the maximum estimated worst case load is near this value when operating
-5 in the cross-connect.configuration, periodic operation at this level could be detrimental to the machine. The existing specification should be retained in this area which calls for only testing the machine.to its continuous load rating of 4700 kW.
- 14. It is not clear from the proposed change to Technical Specification Section 4.8.1.1.2d.11 that the override of the test mode by a safety injection signal must be checked separately for an SI signal from Unit 2 and then for an SI signal from Unit 3. The words in parentheses should be changed to read "(separately from each unit with the Unit 2 transfer enable switch in Auto)." A similar change should be made to the Unit 3 technical specification.
- 15. With regard to the additional technical specification requirement in Section 4.8.1.1.2d.6.b), it is not clear that the surveillance must be performed separately for an ESF test signal from Unit 2 and then for an ESF test signal from Unit 3. The requirement should be changed to read "With a simulated loss of offsite power in both units in conjunction with an ESF test signal separately from each unit, and the Unit 2 Transfer Enable Switch in Auto:"
- 16. There is no requirement in your proposed technical specification change to verify the operability of the unit-to-unit transfer enable circuit by simulating only a total loss of offsite power in both units. This surveillance requirement should be added to Section 4.8.1.1.2d.6.
- 17.
We require that a limit be placed on the amount of time a unit may operate with a Transfer Enable Switch in the Auto position. This limit should be 30 days in any one year period for each unit. Please incorporate this requirement into your proposed technical specification changes.