ML13330B574
| ML13330B574 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 11/05/1991 |
| From: | Rosenblum R SOUTHERN CALIFORNIA EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| REF-GTECI-A-30, REF-GTECI-EL, TASK-A-30, TASK-OR GL-91-06, GL-91-6, NUDOCS 9111080290 | |
| Download: ML13330B574 (13) | |
Text
Southern California Edison Company 23 PARKER STREET IRVINE, CALIFORNIA 92718 R. M. ROSENBLUM TELEPHONE MANAGER OF (714) 454-4505 NUCLEAR REGULATORY AFFAIRS November 5, 1991 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C. 20555 Gentlemen:
Subject:
Docket Nos. 50-206, 50-361, and 50-362 Generic Letter 91-06, "Resolution of Generic Issue A-30, Adequacy of Safety-Related DC Power Supplies" San Onofre Nuclear Generating Station Units 1, 2, and 3 By letter dated April 29, 1991, the NRC issued Generic Letter 91-06, "Resolution of Generic Issue A-30, Adequacy of Safety Related DC Power Supplies."
Included with this Generic Letter is a list of questions regarding the adequacy of Safety Related DC power in operating nuclear power plants.
Generic Letter 91-06 requires licensees to provide a response to these questions by October 28, 1991.
Accordingly, this letter provides Southern California Edison's response to Generic Letter 91-06 for San Onofre Unit 1 (Enclosure I), and San Onofre Units 2 and 3 (Enclosure II).
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S Document Control Desk November 5, 1991 If you have any questions, please contact me.
Very truly yours, By:
R. M. Rosenblum Manager of Nuclear Regulatory Affairs State of California County of Orange On November 5, 1991, before me, Mariane Sanchez
, personally appeared R. M. Rosenblum
, personally known to me (mAR WdxhARxoR o xcdeocne)<to be the person 4l whose name(s) isAar subscribed to the within instrument and acknowledged to me that heA!kekkky executed the same in his/Aiebhedc authorized capacity(ded), and that by hisAhe e4exsignature s)<on the instrument the person(s), or the entity upon behalf of which the person@o acted, executed the instrument.
WITNESS m hand and offi
- 1 seal.
(Seal OFFICIAL SEAL Signatur.
(Seal)
MAXIAESANCHEZ cc:
J. B. Martin, Regional Administrator, NRC Region V George Kalman, NRC Senior Project Manager, San Onofre Unit 1, 2 & 3 J. 0. Bradfute, NRC Project Manager, San Onofre Unit 1, 2 & 3 C. W. Caldwell, NRC Senior Resident Inspector, San Onofre Units 1, 2 & 3
E I
Enclosure I
RESPONSE TO QUESTIONS IN ENCLOSURE 1 OF GENERIC LETTER 91-06 SONGS UNIT 1 Questions The following information is to be provided for each unit at each site:
- 1.
Unit 1
- 2.
- a.
The number of independent redundant divisions of Class 1E or safety related dc power for this plant is 2*.
(Include any separate Class 1E or safety-related dc, suchas any dc dedicated to the diesel generators.)
There is an additional safety-related DC system which powers the safety injection and recirculation valves for one of the three RCS loops.
- b.
The number of functional safety-related divisions of dc power necessary to attain safe shutdown for this unit is 1
- 3.
Does the control room at this unit have the following separate, independently annunciated alarms and indications for each division of dc power?
- a.
alarms
- 1.
Battery disconnect or circuit breaker open?
Yes
- 2.
Battery charger disconnect or circuit breaker open (both input ac and output dc)?
Yes. Battery Charger AC breaker open or disconnect will be alarmed in the control Room by the charger failure alarm.
No.
Battery charger DC breaker open is alarmed indirectly as DC bus undervoltage alarm.
- 3.
dc system ground?
Yes
- 4.
dc bus undervoltage?
Yes
- 5.
dc bus overvoltage?
No. However, DC voltage is read during weekly surveillances and during shiftly rounds by Operators by reading a local voltmeter on the bus.
- 6.
Battery charger failure?
Yes.
1
C
- 7.
Battery discharge?
No. However, this is indirectly annunciated as DC bus undervoltage alarm.
- b.
Indications
- 1.
Battery float charge current?
No. This is accomplished by weekly surveillances.
- 2.
Battery circuit output current?
No. This is indirectly annunciated as DC bus undervoltage alarm. Additionally, the local ammeter is.monitored during shiftly rounds by operations personnel.
- 3.
Battery discharge?
No. However, indirect battery discharge indication is provided by Bus voltage indication.
No for Battery #2. This is indirectly annunciated as DC bus undervoltage alarm.
- 4.
Bus voltage?
Yes for DC bus #1.
No for DC bus #2. This is confirmed during shiftly rounds by Operators by reading the local bus voltmeter.
- c.
Does the unit have written procedures for response to the above alarms and indications?
Yes
- 4.
Does this unit have indication of bypassed and inoperable status of circuit breakers or other devices that can be used to disconnect the battery and battery charger from its dc bus and the battery charger from its ac power source during maintenance or testing?
Yes (See responses to questions 3.a.1, and 3.a.2.). Additionally, this is administratively controlled by Operations by the use of tags and Work Authorization Reauests (WAR's).
- 5.
If the answer to any part of question 3 or 4 is no, then provide information justifying the existing design features of the facility's safety-related dc systems.
The Safety-Related DC power system at San Onofre Unit 1 was evaluated as part of the Systematic Evaluation Program (Topic VIII-3.B). Design details for the Safety-Related DC power systems, as well as the NRC's evaluation, are contained in NUREG-0829, dated December 1986.
(For "no" responses, details regarding alternative monitoring methods are provided with the individual response).
2
- 6.
(1) Have you conducted a review of maintenance and testing activities to minimize the potential for human error causing more than one dc division to be unavailable?
and (2) do plant procedures prohibit maintenance or testing on redundant dc divisions at the same time?
SCE has not conducted a review of maintenance and testing activities as discussed above. SCE does have a policy statement in effect that prevents removing redundant safety-related equipment from service at the same time.
To ensure consistent application of this policy statement, all maintenance and testing activities are controlled by a single group, the Equipment Control group. This group, through use of SCE's computerized Work Authorization Process, ensures that the conflicts identified in this question are avoided.
If the facility Technical Specifications have provisions equivalent to those found in the Westinghouse and Combustion Engineering Standard Technical Specification for maintenance and surveillance, then question 7 may be skipped and a statement to the effect may be inserted here.
Batteries are maintained to IEEE 450-1980 and the Unit 1 Technical Specifications.
(San Onofre Unit 1 does not have Westinghouse Standard Technical Specifications. However, the current Unit 1 battery surveillance Technical Specifications are equivalent to the Westinghouse Standard Technical Specifications for the items below).
- 7.
Are maintenance, surveillance and test procedures regarding station batteries conducted routinely at this plant? Specifically:
- a.
At least once per 7 days are the following verified to be within acceptable limits:
- 1.
Pilot cell electrolyte level?
- 2.
Specific gravity or charging current?
- 3.
- 4.
Total bus voltage on float charge?
- 5.
Physical condition of all cells?
- b.
At least once per 92 days, or within 7 days after a battery discharge, overcharge, or if the pilot cell readings are outside the 7-day surveillance requirements are the following verified to be within acceptable limits:
- 1.
Electrolyte level of each cell?.,
- 2.
The average specific gravity of all cells?
3
- 3.
The specific gravity of each cell?
- 4.
The average electrolyte temperature of a representative number of cells?
- 5.
The float voltage of each cell?
- 6.
Visually inspect or measure resistance of terminals and connectors (including the connectors at the dc bus)?
- c.
At least every 18 months are the following verified:
- 1.
Low resistance of each connection (by test)?
- 2.
Physical condition of the battery?
- 3.
Battery charger capability to deliver rated ampere output to the dc bus?
- 4.
The capability of the battery to deliver its design -duty cycle to the dc bus?
- 5.
Each individual cell voltage is within acceptable limits during the service test?
- d.
At least every 60 months, is capacity of each battery verified by performance of a discharge test?
- e.
At least annually, is the battery capacity verified by performance discharge test, if the battery shows signs of degradation or has reached 85% of the expected service life?
- 8.
Does this plant have operational features such that following loss of one safety-related dc power supply or bus:
- a.
Capability is maintained for ensuring continued and adequate reactor cooling?
Yes
- b.
Reactor coolant system integrity and isolation capability are maintained?
Yes
- c.
Operating procedures, instrumentation (including indicators and annunciators), and control functions are adequate to initiate systems as required to maintain adequate core cooling? Yes 4
- 9.
If the answer to any part of question 6, 7 or 8 is no, then provide your basis for not performing the maintenance, surveillance and test procedures described and/or the bases for not including the operational features cited. *See note below.
- Note:
For questions involving supporting type information (question numbers 5 and 9) instead of developing and supplying the information in response to this letter, you may commit to further evaluate the need for such provisions vulnerabilities (IPE).
If you select this option, you are required to:
(1) So state in response to these questions, and (2) Commit to explicitly address questions 5 and 9 in your IPE submittal per the guidelines outlined in NUREG-1335 (Section 2.1.6, Subitem 7), "Individual Plant Examination: Submittal Guidance."
5
Enclosure II
RESPONSE TO QUESTIONS IN ENCLOSURE 1 OF GENERIC LETTER 91-06 SONGS UNITS 2 and 3 Questions The following information is to be provided for each unit at each site:
- 1.
Units 2 and 3
- 2.
- a.
The number of independent redundant divisions of Class 1E or safety related dc power for this plant is 2 Trains each consisting of 2 subsystems.
(Include any separate Class 1E or safety-related dc, such as any dc dedicated to the diesel generators.)
- b.
The number of functional safety-related divisions of dc power necessary to attain safe shutdown for this unit is 1 Train
- 3.
Does the control room at this unit have the following separate, independently annunciated alarms and indications for each division of dc power?
- a.
alarms
- 1.
Battery disconnect or circuit breaker open?
Yes
- 2.
Battery charger disconnect or circuit breaker open (both input ac and output dc)?
Yes Battery charger trouble is alarmed in the control room. This alarm is initiated by battery charger input breaker open and DC output low amperes which indirectly provides an alarm on opening of the DC output breaker.
- 3.
dc system ground?
Yes
- 4.
dc bus undervoltage?
Yes
- 5.
dc bus overvoltage?
Yes
- 6.
Battery charger failure?
Yes
- 7.
Battery discharge?
No This is indirectly annunciated as DC bus undervoltage alarm.
1
- b.
Indications
- 1.
Battery float charge current?
No. However, this is accomplished during weekly surveillances (a local ammeter is provided).
- 2.
Battery circuit output current?
Yes
- 3.
Battery discharge? Yes.
Indication provided for battery discharge amps.
- 4.
Bus voltage?
Yes
- c.
Does the unit have written procedures for response to the above alarms and indications?
Yes
- 4.
Does this unit have indication of bypassed and inoperable status of circuit breakers or other devices that can be used to disconnect the battery and battery charger from its dc bus and the battery charger from its ac power source during maintenance or testing?
Yes for battery breaker open. Yes for charger breaker (both ac input and dc output).
- 5.
If the.answer to any part of question 3 or 4 is no, then provide information justifying the existing design features of the facility's safety-related dc systems. *See note below.
The Safety-Related DC power system at San Onofre Units 2 and 3 were evaluated during the original licensing of the Units. Design details for the Safety-Related DC power systems, as well as the NRC's evaluation, are contained in NUREG-0712, Section 8.3.2. dated December 1986.
(For "no" responses. details regarding alternative monitoring methods are provided with the individual response).
- 6.
(1) Have you conducted a review of maintenance and testing activities to minimize the potential for human error causing more than one dc division to be unavailable?
and (2) do plant procedures prohibit maintenance or testing on redundant dc divisions at the same time?
SCE has not conducted a review of maintenance and testing activities as discussed above. SCE does have a policy statement in effect that prevents removing redundant safety-related equipment from service at the same time.
To ensure consistent application of this policy statement, all maintenance and testing activities are controlled by a single group, the Equipment Control group.
This group, through use of SCE's computerized Work Authorization Process, ensures that the conflicts identified in this question are avoided.
2
If the facility Technical Specifications have.provisions equivalent to those found in the Westinghouse and Combustion Engineering Standard Technical Specification for maintenance and surveillance, then question 7 may be skipped and a statement to the effect may be inserted here.
Batteries are maintained to IEEE 450-1980 and the Units 2 and 3 Technical Specifications.
(San Onofre Units 2 and 3 have Combustion Engineering Standard Technical Specifications).
- 7.
Are maintenance, surveillance and test procedures regarding station batteries conducted routinely at this plant? Specifically:
- a.
At least once per 7 days are the following verified to be within acceptable limits:
- 1.
Pilot cell electrolyte level?
- 2.
Specific gravity or charging current?
- 3.
- 4.
Total bus voltage on float charge?
- 5.
Physical condition of all cells?
- b.
At least once per 92 days, or within 7 days after a battery discharge, overcharge, or if the pilot cell readings are outside the 7-day surveillance requirements are the following verified to be within acceptable limits:
- 1.
Electrolyte level of each cell?
- 2.
The average specific gravity of all cells?
- 3.
The specific gravity of each cell?
- 4.
The average electrolyte temperature of a representative number of cells?
- 5.
The float voltage of each cell?
- 6.
Visually inspect or measure resistance of terminals and connectors (including the connectors at the dc bus)?
- c.
At least every 18 months are the following verified:
- 1.
Low resistance of each connection (by test)?
- 2.
Physical condition of the battery?
3
- 3.
Battery charger capability to deliver rated ampere output to the dc bus?
- 4.
The capability of the battery to deliver its design duty cycle to the dc bus?
- 5.
Each individual cell voltage is within acceptable limits during the service test?
- d.
At least every 60 months, is capacity of each battery verified by performance of a discharge test?
- e.
At least annually, is the battery capacity verified by performance discharge test, if the battery shows signs of degradation or has reached 85% of the expected service life?
- 8.
Does this plant have operational features such that following loss of one safety-related dc power supply or bus:
- a.
Capability is maintained -for ensuring continued and adequate reactor cooling?
Yes
- b.
Reactor coolant system integrity and isolation capability are maintained?
Yes
- c.
Operating procedures, instrumentation (including indicators and annunciators), and control functions are adequate to initiate systems as required to maintain adequate core cooling? Yes
- 9.
If the answer to any part of question 6, 7 or 8 is no, then provide your basis for not performing the maintenance, surveillance and test procedures described and/or the bases for not including the operational features cited. *See note below.
- Note:
For questions involving supporting type information (question numbers 5 and 9) instead of developing and supplying the information in response to this letter, you may commit to further evaluate the need for.such provisions vulnerabilities (IPE).
If you select this option, you are required to:
(1) So state in response to these questions, and (2) Commit to explicitly address questions 5 and 9 in your IPE submittal per the guidelines outlined in NUREG-1335 (Section 2.1.6, Subitem 7), "Individual Plant Examination:
Submittal Guidance."
4