ML18152A170
| ML18152A170 | |
| Person / Time | |
|---|---|
| Site: | Surry, North Anna  |
| Issue date: | 10/28/1991 |
| From: | Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| REF-GTECI-A-30, REF-GTECI-EL, TASK-A-30, TASK-OR 91-280, GL-91-06, GL-91-6, NUDOCS 9111060229 | |
| Download: ML18152A170 (32) | |
Text
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e VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 October 28, 1991 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555 Gentlemen:
VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION UNITS 1 AND 2 NORTH ANNA POWER STATION UNITS 1 AND 2 RESPONSE TO GENERIC LETTER 91-06 RESOLUTION OF GENERIC ISSUE A-30 Serial No.
NL&P/RMN Docket Nos.
License Nos.
ADEQUACY OF SAFETY RELATED DC POWER SUPPLIES91-280 50-280 50-281 50-338 50-339 DPR-32 DPR-37 NPF-4 NPF-7 We have received your April 29, 1991 letter requesting information on our safety related DC power supplies. The information is provided in the attachments. Separate attachments are provided for each system at each station. In addition to the main DC power supplies, both North Anna and Surry power stations have separate DC power supplies associated with the emergency diesel generators. Surry also has DC power supplies associated with the diesel driven service water pumps.
If you have any questions or require additional information, please contact us.
Very truly yours, 1 01 CCt
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w: L. Stewart Senior Vice President - Nuclear Attachment A: Surry Station DC System Attachment B: Surry Emergency Diesel Generator DC System Attachment C: Surry Diesel Service Water Pump DC System Attachment D: North Anna Station DC System Attachment E: North Anna Station Emergency Diesel Generator DC System 9111060229 9110?0
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cc:
U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, N.W.
Suite 2900 Atlanta, Georgia 30323 Mr. M. S. Lesser NRC Senior Resident Inspector North Anna Power Station Mr. M. W. Branch NRC Senior Resident Inspector Surry Power Station e
Attachment A SURRY - STATION DC SYSTEM The following responses are applicable to the station batteries of both units at Surry.
Question 1 Unit Response: Unit 1 or Unit 2.
Question 2
- a. The number of independent redundant divisions of Class 1 E or safety-related DC power for this plant is
. (Include any separate Class 1 E or safety-related DC, such as any DC dedicated to the diesel generators.)
Response: Two (Batteries A and B). This excludes the EOG and Service Water Diesel systems which are discussed in Attachments Band C.
- b. The number of functional safety-related divisions of DC power necessary to attain safe shutdown for this unit is Response: One.
Question 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?
Response: N/A. The battery is directly connected to the DC bus, with no disconnect or circuit breaker. As such, the battery can only be disconnected while testing or performing maintenance. Both of these are procedurally controlled. A low voltage on any of these buses will be alarmed in the control room.
Response: Yes. Although the battery charger AC input breaker "open" and DC output breaker "open" conditions are not alarmed directly, if either is opened, the Battery Charger Failure Alarm will actuate.
- 3. DC system ground?
Response: No. There is no ground detection alarm, however, ground detection lights are provided at the Main Control Board.
- 4. DC bus undervoltage?
Response: Yes.
- 5. DC bus overvoltage?
Response: Yes.
- 6. Battery charger failure?
Response: Yes
- 7. Battery discharge?
Response: No. There is no "battery discharge" alarm, however, there are other annunciations in the Control Room (charger failure, breaker status, battery voltage, etc.) which would alert Operators that the batteries are being discharged.
- b. Indications
- 1. Battery float charge current?
Response: No.
Instead of battery float charge current indication in the Control Room, which would be an indicator of "battery state of charge", battery parameters (cell specific gravity and cell voltage) are measured and reviewed weekly to ensure proper performance.
- 2. Battery circuit output current?
Response: No. Battery output current indication is not provided, however, conditions which would result in battery output current (i.e. charger breaker open and charger failure conditior:,s) are annunciated in the Control Room and would alert Operators that the batteries are supplying current. The discharge current can be measured quickly (using a hand-held meter) if required.
- 3. Battery discharge?
Response: No. See justification above for 3.a. 7 and 3.b.2.
- 4. Bus voltage?
Response: Yes.
Attachment A Page 2 of 6
- c. Does the unit have written procedures for response to the above alarms and indications?
Response
Yes, annunciator response procedures are provided for each annunciator window.
Question 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?
Response: Yes, there are indications and/or alarms for the following devices which when opened would result in disconnection of power to/from the battery charger:
- a. Motor Control Center breaker to battery charger.
- b. Battery charger AC input breaker.
- c. Battery charger DC output breaker.
The alarm received in the Control Room would be Battery Charger Failure.
Procedures are written such that after battery maintenance or testing is performed, the chargers are returned to service.
Question 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.
Response: Justifications for negative responses are provided in the discussion given above.
Question 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?
Response: (1) Yes. Procedures are written to minimize human error which would cause more than one DC division to be unavailable.
(2) Yes.
Procedures allow maintenance and testing on only one DC division at a time.
Question 7 Are maintenance, surveillance and test procedures regarding station batteries conducted routinely at this plant? Specifically:
Attachment A Page 3 of 6
- a. At least once per 7 days are the following verified to be within acceptable limits:
- 1. Pilot cell electrolyte level?
Response: Yes.
- 2. Specific gravity or charging current?
Response: Yes. Specific gravity is checked.
- 3. Float voltage?
Response: Yes.
- 4. Total bus voltage on float charge?
R~sponse: Yes.
- 5. Physical condition of the cells?
Response: Yes.
- 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?
Response: Yes.*
- 2. The average specific gravity of each cell?
Response: Yes.*
- 3. The specific gravity of each cell?
Response: Yes.*
- 4. The average electrolyte temperature of a representative number of cells?
Response: Yes.*
- This check is performed during quarterly PTs (Periodic Tests). If the pilot cells are outside of the 7 day surveillance requirements, corrective actions, which are listed in the weekly PT are taken.
Attachment A Page 4 of 6
- 5. The float voltage of each cell?
Response: Yes.*
- 6. Visually inspect or measure resistance of terminals and connectors (including the connectors at the DC bus)?
Response: Yes.* All cell posts and connectors are visually inspected as part of the weekly PT. Cable connections/ terminations at the battery terminals are also checked, but terminations within the DC switchboards are not necessarily checked quarterly.
- c. At leas( every 18 months are the following verified:
- 1. Low resistance of each connection (by test)?
Response: Yes.
- 2. Physical condition of the battery?
Response: Yes.
- 3. Battery charger capability to deliver rated ampere output to the DC bus?
Response: No, Surry does not have a formal test specifically for the station battery chargers. Instead the battery chargers are used to recharge the batteries following service and capacity tests. Battery chargers operate at their rated output for more than an hour. This is done every refueling outage (18 months) and is considered sufficient to verify charger operability.
- 4. The capability of the battery to deliver its design duty cycle to the DC bus?
Response: Yes.
- 5. Each individual cell voltage is within acceptable limits during the service test?
Response: Yes.
- d. At least every 60 months, is the capacity of each battery verified by performance of a discharge test?
- This check is performed during quarterly PTs (Periodic Tests). If the pilot cells are outside of the 7 day surveillance requirements, corrective actions, which are listed in the weekly PT are taken.
Attachment A Page 5 of 6
Response: Yes.
- 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?
Response: No, this testing is not performed annually. If the battery shows signs of degradation or has reached 90% of its rated capacity as determined by the capacity test performed every five years, battery capability is subsequently verified by the performance of a capacity test every refueling outage (18 months). This prevents battery removal from service for this testing during unit power operation.
Although our frequency for this testing is longer, the parameters checked for the weekly and quarterly PTs would serve as an indicator of battery capability.
Question 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?
Response: Yes.
- b. Reactor coolant system integrity and isolation capability are maintained?
Response: Yes.
- c. Operating procedures, instrumentation (including indicators and annunciators), and control functions are adequate to indicate systems as required to maintain adequate core cooling?
Response: Yes.
Question 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.
Response: Justifications for negative responses to question 7 have been provided above.
_)
Attachment A Page 6 of 6
Attachment B SURRY - EMERGENCY DIESEL GENERATOR DC SYSTEM The following responses are applicable to the Surry emergency diesel generator batteries. Surry has a total of three EDGs for two units (there is one "swing" EDG).
Question 1 Unit Response: Unit 1 or Unit 2.
Question 2
- a. The number of independent redundant divisions of Class 1 E or safety-related DC power for this plant is
. (Include any separate Class 1 E or safety-related DC, such as any DC dedicated to the diesel generators.)
Response: Two (Batteries H and J. The J battery is associated with the swing diesel.)
- b. The number of functional safety-related divisions of DC power necessary to attain safe shutdown for this unit is Response: One.
Question 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?
Response: N/A. The battery is directly connected to the DC bus, with no disconnect or circuit breaker. As such, the battery can only be disconnected while testing or performing maintenance. Both of these are procedurally controlled.
Response: Yes,although the Motor Control Center AC breaker to battery charger "open" and battery charger DC output breaker "open" are not alarmed directly, if either is opened, a Battery Low Voltage alarm will actuate in the Control Room.
e
- 3. DC system ground?
Response: No.
- 4. DC bus undervoltage?
Response: Yes.
- 5. DC bus overvoltage?
Response: Yes.
- 6. Battery charger failure?
Response: No.
- 7. Battery discharge?
Response: No.
- b. Indications
- 1. Battery float charge current?
Response: No, however, indication of battery charger current is available locally at the charger.
- 2. Battery circuit output current?
Response: No.
- 3. Battery discharge?
Response: No.
- 4. Bus voltage?
Response: No, however, there is bus voltage indication in the emergency switchgear room.
- c. Does the unit have written procedures for response to the above alarms and indications?
Response
Yes, annunciator response procedures are providea-for each annunciator window.
Attachment B Page 2 of 6
Question 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?
Response: No.
Question 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.
Response
EOG batteries may deteriorate with time, but precipitous failure is extremely unlikely. The frequency of the surveillance and testing performed ensure that the chargers are in service and will provide an indication of a ~ell becoming unserviceable long before it fails.
The EOG batteries are of the ironclad-tubular design, which according to Exide are capable of 1200 cycles at 80% discharge.
Question 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?
Response: (1) Yes. Procedures are written to minimize human error which would cause more than one DC division to be unavailable. (2) Yes. Procedures prohibit maintenance and testing on redundant DC divisions at the same time.
Question 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?
Response: Yes.
- 2. Specific gravity or charging current?
Response: Yes. Specific gravity is checked.
Attachment B Page 3 of 6
e e
- 3. Float voltage?
Response: Yes.
- 4. Total bus voltage on float charge?
Response: Yes.
- 5. Physical condition of the cells?
Response: Yes.
- 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 ce/1?
Response: Yes.*
- 2. The average specific gravity of each cell?
Response: Yes.*
- 3. The specific gravity of each cell?.
Response: Yes.*
- 4. The average electrolyte temperature of a representative number of cells?
Response: Yes.*
- 5. The float voltage of each cell?
Response: Yes.*
- 6. Visually inspect or measure resistance of terminals and connectors (including the connectors at the DC bus)?
Response: Yes.* All cell posts and connectors are visually inspected as part of the weekly PT.
- This check is performed during quarterly PTs (Periodic Tests). If the pilot cells are outside of the 7 day surveillance requirements, corrective actions, which are listed in the weekly PT are taken.
Attachment B Page 4 of 6
- c. At least every 1 B months are the following verified:
- 1. Low resistance of each connection (by test)?
Response: Yes.
- 2. Physical condition of the battery?
Response: Yes.
- 3. Battery charger capability to deliver rated ampere output to the DC bus?
Response
No, A formal test of the EDG battery chargers is not performed at refueling. Charger output current and voltage (which verifies charger operability) are measured and reviewed as part of the weekly PT. All PTs which require disconnection of the chargers from the batteries ensure that the chargers are returned to service following testing.
- 4. The capability of the battery to deliver its design duty cycle to the DC bus?
Response: Yes. Battery capability is verified every 18 months. The EDG battery test performed during refueling outages uses a constant resistance load (instead of a design duty cycle) to verify EDG battery capacity.
- 5. Each individual cell voltage is within acceptable limits during the service test?
Response: Yes.
- d. At least every 60 months, is the capacity of each battery verified by performance of a discharge test?
Response: Yes.
- 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?
Response: No, this testing is not performed annually. If the battery shows signs of degradation or has reached 90% of its rated capacity as determined by the capacity test performed every five years, battery capability is subsequently verified by the performance of a capacity test every refueling outage (18 months). This prevents battery removal from service for this testing during unit power operation. Although our frequency for this testing is longer, the parameters checked for the weekly and quarterly PTs would serve as an indicator of battery capability.
Attachment B Page 5 of 6
1
Question 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?
Response: Yes.
- b. Reactor coolant system integrity and isolation capability are maintained?
Response: Yes.
- c. Operating procedures, instrumentation (including indicators and annunciators), and control functions are adequate to indicate systems as required to maintain adequate core cooling?
Response: Yes.
Question 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.
Response: Justifications for negative responses to question 7 have been provided above.
Attachment B Page 6 of 6
l Attachment C SURRY - SERVICE WATER PUMP DIESEL DC SYSTEM The following responses are applicable to the Surry Service Water pump diesel batteries. Surry has three diesel-powered Service Water pumps.
Question 1 Unit Response: Unit 1 or Unit 2.
Question 2
- a. The number of independent redundant divisions of Class 1 E or safety-related DC power for this plant is
. {Include any separate Class 1 E or safety-related DC, such as any DC dedicated to the diesel generators.)
Response: Three.
Each Service Water pump diesel has a dedicated 24 VDC system.
- b. The number of functional safety-related divisions of DC power necessary to attain safe shutdown for this unit is Response: Two.
Question 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?
Response: N/A. The battery is directly connected to the DC bus, with no disconnect or circuit breaker. As such, the battery can only be disconnected while testing or performing maintenance. Both of these are procedurally controlled.
Response: No.
- 3. DC system ground?
Response: No.
---~
- 4. DC bus undervoltage?
Response: No.
- 5. DC bus overvoltage?
Response: No.
- 6. Battery charger failure?
Response: No.
- 7. Battery discharge?
Response: No.
- b. Indications
- 1. Battery float charge current?
Response: No. There is, however, local charger current indication at the chargers.
- 2. Battery circuit output current?
Response: No.
- 3. Battery discharge?
Response: No.
- 4. Bus voltage?
Response: No. There is, however, local bus voltage indication at the chargers.
- c. Does the unit have written procedures for response to the above alarms and indications?
Response: No. There are no response procedures since there are no alarms or indications in the control room for the Service Water pump diesel batteries..
Question 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?
Response: No.
Attachment C Page 2 of 6
Question 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.
Response: The following applies to questions 3a, 3b and 4 above.
Although Surry does not have the listed alarms and indications for the Service Water pump diesels, there are several Periodic Tests (PTs) and Preventive Maintenance Procedures (PMs) which verify operability of these batteries.
A weekly PM is performed to verify pilot cell parameters.
The PT which verifies diesel pump operability (including battery and charger and the associated safety related diesel driven alternator) is performed monthly.
Precipitous failure of these batteries is extremely unlikely. The fact that these batteries are replaced annually further reduces the likelihood of battery unavailability.
Also, all procedures which require disconnection of the charger from the battery have steps which ensure that the chargers are returned to service following testing.
Question 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?
Response: (1) Yes. Procedures are written to minimize human error which would cause more than one DC division to be unavailable. (2) Yes. Procedures prohibit maintenance and testing on redundant DC divisions at the same time.
Question 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?
Response: Yes.
- 2. Specific gravity or charging current?
Response: Yes. Specific gravity is checked.
- 3. Float voltage?
Response: Yes. Battery voltage (for each battery) is verified to be within acceptable limits with the charger disconnected.
Attachment C Page 3 of 6
- 4. Total bus voltage on float charge?
Response
Yes.
Bus voltage is verified to be within acceptable limits with the charger disconnected, which is a more limiting condition.
- 5. Physical condition of the cells?
Response: Yes.
- 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?
Response: Yes.*
- 2. The average specific gravity of each cell?
Response: Yes.*
- 3. The specific gravity of each cell?
Response: Yes.*
- 4. The average electrolyte temperature of a representative number of cells?
Response: Yes.*
- 5. The float voltage of each cell?
Response: Yes.* The float voltage for each battery is verified.
- 6. Visually inspect or measure resistance of terminals and connectors (including the connectors at the DC bus)?
Response: Yes.* Terminals and connectors are visually inspected.
- c. At least every 18 months are the following verified:
- 1. Low resistance of each connection (by test)?
Response: No, low resistance of connections is not verified by test but is ensured as the battery connections are disassembled and cleaned quarterly. Also, SW pump diesel operability is verified monthly.
In addition, SW pump diesel batteries are replaced annually, which supersedes the requirement for low resistance checks every 18 months.
- This check is performed during the quarterly PTs (Periodic Tests).
Attachment C Page 4 of 6
- 2. Physical condition of the battery?
Response: Yes. It is checked quarterly.
- 3. Battery charger capability to deliver rated ampere output to the DC bus?
Response
No, A formal test of the SW pump diesel battery chargers is not performed. There is a weekly PM which ensures that the chargers are energized and operable. There is also a monthly PT which verifies operability of the SW pump diesels (including its DC system). The requirements of the PM and PT are considered sufficient in verifying charger operability.
- 4. The capability of the battery to deliver its design duty cycle to the DC bus?
Response: N/A. In lieu of performing tests on the SW pump diesel batteries every 18 months, these batteries are replaced annually.
- 5. Each individual cell voltage is within acceptable limits during the service test?
Response: N/A. Testing is not performed due to battery replacement frequency.
- d. At least every 60 months, is the capacity of each battery verified by performance of a discharge test?
Response: N/A. Testing is not performed due to battery replacement frequency.
- 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?
Response: N/A.. Testing is not performed due to battery replacement frequency.
Question 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?
Response: Yes.
- b. Reactor coolant system integrity and isolation capability are maintained?
Response: Yes.
Attachment C Page 5 of 6
- c. Operating procedures, instrumentation (including indicators and annunciators), and control functions are adequate to indicate systems as required to maintain adequate core cooling?
Response: Yes.
Question 9 If the answer to anypart 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.
Response: Justifications for negative responses to question 7 have been provided above.
Attachment C Page 6 of 6
Attachment D NORTH ANNA - STATION DC SYSTEM The following responses are applicable to the station batteries of both units at North Anna.
Question 1 Unit Response: Unit 1 or Unit 2.
Question 2
- a. The number of independent redundant divisions of Class 1 E or safety-related DC power for this plant is
. {Include any separate Class 1 E or safety-related DC, such as any DC dedicated to the diesel generators.)
Response: Four.
- b. The number of functional safety-related divisions of DC power necessary to attain safe shutdown for this unit is Response: Two.
Question 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?
Response: N/A. The battery is directly connected to the DC bus, with no disconnect or circuit breaker. As such, the battery can only be disconnected while testing or performing maintenance. Both of these are procedurally controlled. A low voltage on any of these buses will be alarmed in the control room.
Response: Yes. Battery charger AC input breaker "open" and DC output breaker "open" conditions are alarmed.
- 3. DC system ground?
Response: Yes.
- 4. DC bus undervoltage?
Response: Yes.
- 5. DC bus overvoltage?
Response: Yes.
- 6. Battery charger failure?
Response: Yes
- 7. Battery discharge?
Response: No. There is no "battery discharge" alarm, however, there are other annunciations in the Control Room (charger failure, breaker status, battery voltage, etc.) which would alert Operators that the batteries are being discharged.
- b. Indications
- 1. Battery float charge current?
Response: No.
Instead of battery float charge current indication in the Control Room, which would be an indicator of "battery state of charge", battery parameters (cell specific gravity and cell voltage) are measured and reviewed weekly to ensure proper performance. Also, battery float current indication is provided locally at the chargers.
- 2. Battery circuit output current? _
Response: No. Battery output current indication is not provided, however, conditions which would result in battery output current (i.e. charger breaker open and charger failure conditions) are annunciated in the Control Room and would alert Operators that the batteries are supplying current. The discharge current can be measured quickly (using a hand-held meter) if required.
- 3. Battery discharge?
Response: No. See justification above for 3.a. 7 and 3.b.2.
- 4. Bus voltage?
Response: Yes.
Attachment D Page 2 of 6
- c. Does the unit have written procedures for response to the above alarms and indications?
Response
Yes, annunciator response procedures are provided for each annunciator window.
Question 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?
Response: Yes, there are indications and/or alarms for the following devices which when opened would result in disconnection of power to/from the battery charger:
- a. Motor Control Center breaker to battery charger.
- b. Battery charger AC input breaker.
- c. Battery charger DC output breaker.
- d. DC distribution panel breaker from battery charger.
Disconnection of battery equipment during maintenance or testing is controlled by approved procedures.
Question 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.
Response: Justifications for negative responses are provided in the discussion given above.
Question 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?
Response: (1) Yes. Procedures are written to minimize human error which would cause more than one DC division to be unavailable.
(2) Yes.
Procedures allow maintenance and testing on only one DC division at a time; Question 7 Are maintenance, surveillance and test procedures regarding station batteries conducted routinely at this plant? Specifically:
Attachment D Page 3 of 6
- a. At least once per 7 days are the following verified to be within acceptable limits:
- 1. Pilot cell electrolyte level?
Response: Yes.
- 2. Specific gravity or charging current?
Response: Yes.
- 3. Float voltage?
Response: Yes.
- 4. Total bus voltage on float charge?
Response: Yes.
- 5. Physical condition of the cells?
Response: Yes.
- 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?
Response: Yes.
- 2. The average specific gravity of each cell?
Response: Yes.
- 3. The specific gravity of each cell?
Response: Yes.
- 4. The average electrolyte temperature of a representative number of cells?
Response: Yes.
- 5. The float voltage of each cell?
,Response: Yes.
Attachment D Page 4 of 6
- 6. Visually inspect or measure resistance of terminals and connectors (including the connectors at the DC bus)?
Response: Yes.
- c. At least every 18 months are the following verified:
- 1. Low resistance of each connection (by test)?
Response: Yes.
- 2. Physical condition of the battery?
Response: Yes.
- 3. Battery charger capability to deliver rated ampere output to the DC bus?
Response: Yes.
- 4. The capability of the battery to deliver its design duty cycle to the DC bus?
Response: Yes.
- 5. Each individual cell voltage is within acceptable limits during the service test?
Response: Yes.
- d. At least every 60 months, is the capacity of each battery verified by performance of a discharge test?
Response: Yes.
- 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?
Response: No, this testing is performed every 18 months, rather than annually, to better fit our refueling cycle. This prevents battery removal from service for this testing during unit power operation. Although our frequency for this testing is longer, the parameters checked for the weekly and quarterly PTs would serve as an indicator of battery capability.
Question 8 Does this plant have operational features such that following loss of one safety related DC power supply or bus:
Attachment D Page 5 of 6
e
- a. Capability is maintained for ensuring continued and adequate reactor cooling?
Response: Yes.
- b. Reactor coolant system integrity and isolation capability are maintained?
Response: Yes.
- c. Operating procedures, instrumentation (including indicators and annunciators), and control functions are adequate to indicate systems as required to maintain adequate core cooling?
Response: Yes.
Question 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.
Response: Justifications for negative response to question 7.e is provided above.
Attachment D Page 6 of 6
Attachment E NORTH ANNA - EMERGENCY DIESEL GENERATOR DC SYSTEM The following responses are applicable to the North Anna emergency diesel generator batteries. North Anna has two EDGs per unit.
Question 1 Unit Response: Unit 1 or Unit 2.
Question 2
- a. The number of independent redundant divisions of Class 1 E or safety-related DC power for this plant is
. (Include any separate Class 1 E or safety-related DC, such as any DC dedicated to the diesel generators.)
Response: Two.
- b. The number of functional safety-related divisions of DC power necessary to attain safe shutdown for this unit is Response: One.
Question 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?
Response: N/A. The battery is directly connected to the DC bus, with no disconnect or circuit breaker. As such, the battery can only be disconnected while testing or performing maintenance. Both of these are procedurally controlled.
Response: An "EOG Trouble" alarm will annunciate if the EDG's battery charger AC input breaker is open. The charger output voltage and the EOG control circuit power are checked three times daily. Also, an annunciator will sound if an EOG DC bus voltage is low.
- 3. DC system ground?
Response: No. There is no ground detection alarm in the control room, however, ground detection lights at the chargers are checked every 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.
- 4. DC bus undervoltage?
Response: Yes.
- 5. DC bus overvoltage?
Response: Yes.
- 6. Battery charger failure?
Response: Yes.
- 7. Battery discharge?
Response: No. There is no "battery discharge" alarm, however, there are other alarms and indications available (Battery charger AC input breaker "open," battery voltage etc.) which would alert the operators of an EOG battery discharge.
- b. Indications
- 1. Battery float charge current?
Response: No. Instead of battery float current indication in the control room, which would be an indicator of "battery state of charge," battery parameters (cell specific gravity and cell voltage) are measured and reviewed weekly to ensure proper performance. Battery float charge current can be measured locally with a clamp-on ammeter. Also, battery charger current indication is provided locally at the chargers.
- 2. Battery circuit output current?
Response: No. Battery circuit output current indication is not provided, but other alarms and indications are available (battery charger AC input breaker "open," battery voltage, etc.) which would alert the operators of an EOG battery discharge.
- 3. Battery discharge?
Response: No. See justifications above for 3.a.7 and 3.b.2.
- 4. Bus voltage?
Response: Yes.
Attachment E Page 2 of 6
- c. Does the unit have written procedures for response to the above alarms and indications?
Response
Yes, annunciator response procedures are provided for each annunciator window.
Question 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?
Response: There is an "EDG Trouble" annunciation in the control room if the EDG's battery charger AC input breaker is open, or if either the charger or the battery is disconnected from the EDG bus.
Disconnection of battery equipment during maintenance or testing is controlled by approved procedures.
Question 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.
Response: Justifications for negative responses are provided in the discussion given above.
Question 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?
Response: (1) Yes. Procedures are written to minimize human error which would cause more than one DC division to be unavailable. (2) Yes. Procedures prohibit maintenance and testing on redundant DC divisions at the same time.
Question 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?
Response: Yes.
Attachment E Page 3 of 6
.e
- 2. Specific gravity or charging current?
Response: Yes.
- 3. Float voltage?
Response: Yes.
- 4. Total bus voltage on float charge?
Response: Yes.
- 5. Physical condition of the cells?
Response: Yes.
- 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?
Response: Yes.
- 2. The average specific gravity of each cell?
Response: Yes.
- 3. The specific gravity of each cell?
Response: Yes:
- 4. The average electrolyte temperature of a representative number of cells?.
Response: Yes.
- 5. The float voltage of each cell?
Response: Yes.
- 6. Visually inspect or measure resistance of terminals and connectors (including the connectors at the DC bus)?
Response: Yes.
- c. At least every 18 months are the following verified:
Attachment E Page 4 of 6
..r e
- 1. Low resistance of each connection (by test)?
Response: Yes.
- 2. Physical condition of the battery?
Response: Yes.
- 3. Battery charger capability to deliver rated ampere output to the DC bus?
Response: Yes.
- 4. The capability of the battery to deliver its design duty cycle to the DC bus?
Response: Yes.
- 5. Each individual cell voltage is within acceptable limits during the service test?
Response: Yes.
- d. At least every 60 months, is the capacity of each battery verified by performance of a discharge test?
Response: Yes.
- 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?
Response: No, this testing is performed every 18 months, rather than annually, to better fit our refueling cycle. This prevents battery removal from service (and EDG unavailability) for this testing during unit power operation. Although our frequency for this testing is longer, the parameters checked for the weekly and quarterly PTs would serve as an indicator of battery capability.
Question 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?
Response: Yes.
- b. Reactor coolant system integrity and isolation capability are maintained?
Response: Yes.
Attachment E Page 5 of 6
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- c. Operating procedures, instrumentation (including indicators and annunciators), and control functions are adequate to indicate systems as required to maintain adequate core cooling?
Response: Yes.
Question 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.
Response
Justifications for the negative response to question 7.e is provided above.
Attachment E Page 6 of 6 J