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20 Cards in this Set
- Front
- Back
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State the purpose of the Automatic Depressurization System.
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A. Serves as backup to HPCI System
B. If HPCI does not provide sufficient makeup to maintain water level during a small break LOCA 1. ADS acts to depressurize the reactor vessel 2. Allows low-pressure injection systems to provide adequate core cooling |
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State the function of the following ADS components:
a. ADS Accumulator |
Utilized on SRVs served by ADS
Consist of 10 gallon accumulator (Sized for two valve operations at 38.5 psig drywell pressure) and Necessary check valves and piping. Purpose is to Store a volume of gas for ADS operation should instrument gas be lost (Long-term Nitrogen supply bottles associated with Instrument Gas for backup to compressors) Good for 2 cycles at 38# drywell pressure. - Utilized on SRVs served by ADS (SHMEK and CAN) - Consist of 10 gallon accumulator and necessary check valves and piping (Sized for two valve operations at 38.5 psig drywell pressure) - Store a volume of gas for ADS operation should instrument gas be lost |
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State the function of the following ADS components:
b. SRV Vacuum Breakers |
Two per SRV discharge line located upstream of suppression pool inlet in the drywell
Prevent drawing water into SRV discharge piping by opening when Drywell pressure exceeds SRV discharge pressure by 0.5 lbs - Two per SRV discharge line; Located upstream of suppression pool inlet in the drywell - Prevent drawing water into SRV discharge piping - Open when Drywell pressure exceeds SRV discharge pressure by 0.5 psi |
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State the function of the following ADS components:
c. Acoustic Monitors |
Two monitors for each valve (one is passive)
Monitor flow noise at SRV discharge Actuates one of three lights Located adjacent to valve switch on *0C626 Green - Valve closed Red - Valve open (Flow noise detected) Amber - Valve has lifted (locks in until manually reset) (Cannot reset any Amber light until its relief valve is shut Reset pushbutton on lower portion of *0C626) |
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State the function of the following ADS components:
d. SRV Solenoids |
- Once both Division 1 channels "A" and "E" initiation relays are energized, the "A" solenoid for each ADS valve is energized
- Once both Division 3 channels "C" and "G" initiation relays are energized, the "B" solenoid for each ADS valve is energized. - In addition to either of the above mentioned divisional logic systems, each individual ADS valve may be opened by placing either of its associated control switches in the "OPEN" position as follows: (1) For Division 1, the "AUTO-OPEN" control switch for each ADS valve, located on H12-P626, energizes the "A" solenoid (2) For Division 3, the keylock "AUTO-OPEN" control switch for each ADS valve, located on panel H12-P631 in auxiliary equipment room energizes the "B" solenoid |
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Summarize how each of the following support the operation of the ADS:
a. Vessel Instrumentation System |
- Reactor level instrumentation feeds into the auto-initiation logic for ADS
- Low reactor water level (-129") and - Confirmatory low reactor water level (+12.5") |
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Summarize how each of the following support the operation of the ADS:
b. RHR System |
- RHR pump running (125 psig discharge pressure) provides input into the auto-initiation logic for ADS
- "A" or "C" RHR pump feeds into Div 1 logic ("A" and "E" channels) - "B" or "D" RHR pump feeds into Div 3 logic ("C" and "G" channels) |
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Summarize how each of the following support the operation of the ADS:
c. Core Spray System |
- Core Spray pump running (145 psig discharge pressure) provides input into the auto-initiation logic for ADS
- "A" Core Spray pump feeds into Div 1 logic ("A" channel) - "C" Core Spray pump feeds into Div 1 logic ("E" channel) - "B" Core Spray pump feeds into Div 3 logic ("C" channel) - "D" Core Spray pump feeds into Div 3 logic ("G" channel) |
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Summarize how each of the following support the operation of the ADS:
d. Primary Containment Instrument Gas |
- SRV's are operated by nitrogen supplied from Instrument Gas via two redundant solenoid valves
- Loss of PCIG pneumatic supply affects ability of SRV for Solenoid Actuation, however ADS valves SHMEK have accumulators and RSP valves CAN have accumulators. |
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Summarize how each of the following support the operation of the ADS:
e. Suppression Pool |
- ADS utilizes five of the SRV's to relieve high pressure steam to the suppression pool.
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Summarize how each of the following support the operation of the ADS:
f. DC Distribution System |
- Power supply for solenoid "A" is from Div 1 DC
- Power supply for solenoid "B" is from Div 3 DC |
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List the three modes of ADS valve operation and the conditions/steps necessary for each, including setpoints where applicable.
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- ADS will automatically initiate upon receiving an initiation signal from either Div 1 or Div 3 logic system
- Div 1 and Div 3 logic systems are divided into logic channels. "A" and "E" for Div 1, and "C" and "G" for Div 3 - Channel "A", Division 1, inputs for automatic initiation: - High drywell pressure (1.68 psig) or 420 second high drywell pressure bypass timer timed out, AND - Low reactor water level (-129"), AND - Low confirmatory water level (+12.5"), AND - Time delay of 105 seconds, AND - RHR Pump "A" or "C" running (125 psig discharge pressure), OR Core Spray Pump "A" running (145 psig discharge pressure) - Channel "E", Division 1, inputs for automatic initiation: - High drywell pressure (1.68 psig) or 420 second high drywell pressure bypass timer timed out, AND - Low reactor water level (-129"), AND - RHR Pump "A" or "C" running (125 psig discharge pressure) OR Core Spray Pump "C" running (145 psig discharge pressure) - Once both Division 1 channels "A" and "E" initiation relays are energized, the "A" solenoid for each ADS valve is energized - Channels "C" and "G" of division 3 are similar to Channels "A" and "E" of division 1, with the following exceptions: - Channel "C" pump running inputs are from RHR pump "B" or "D" or Core Spray Pump "B" - Channel "G" pump running inputs are from RHR pump "B" or "D" or Core Spray pump "D" - Once both Division 3 channels "C" and "G" initiation relays are energized, the "B" solenoid for each ADS valve is energized. - Upon energizing either the "A" or the "B" solenoid, the following events occur: - Gas pressure, via a pneumatic operator, opens the SRV - Motive Gas is normally supplied by PCIG (N2) from Compressor operation and Receiver Tank - Loss of PCIG pneumatic supply affects ability of SRV for Solenoid Actuation, however ADS valves SHMEK have accumulators and RSP valves CAN have accumulators. |
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Summarize how each of the following support the operation of the ADS: - Manual Inhibit Switches
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- When both ADS "NORM - INHIBIT" switches (S15A and S15C), are rotated to the "INHIBIT" position, the "AUTO" logic is interrupted, preventing automatic ADS actuation
- Manual operation, via individual control switches or via the armed and depressed pushbuttons, is not inhibited - Manual inhibit switches do not terminate ADS operation once initiated |
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Summarize how each of the following support the operation of the ADS: - ADS Timer (Logic) Reset Pushbuttons
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- When both of the ADS "Drywell Pressure High/Reactor Level Low" reset pushbuttons (S3A and S3C) are depressed, the "AUTO" and manual (via manual initiate pushbuttons) logic is interrupted, preventing ADS actuation
- After depressing, and once the pushbuttons are released, the 105 second timer will restart - Once timer (logic) reset pushbuttons are depressed, the ADS valves will close (due to the removal of the open signal) if the valves were automatically opened OR if opened via the armed and depressed manual initiate pushbuttons. (ADS valves will not close if manually opened via individual control switches) - Once timer (logic) reset pushbuttons are released, armed and depressed manual initiate pushbuttons may be used to reinitiate ADS - Manual operation via control switches is not interrupted - At the end of the 105 second time delay, if all automatic initiating signals remain, ADS will re-initiate - Low Pressure ECCS Pumps Not Available - In the event the minimum required operating ECCS pumps are not available, ADS actuation will not occur via "AUTO" logic or via the armed and depressed manual initiate pushbuttons. - When the ADS logic is made up for Timer initiation and subsequent ECCS Pump Starts, the ADS Function will occur. |
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Summarize the effect that the following conditions have on ADS.a. RHR discharge pressure low
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- In the event the minimum required operating ECCS pumps are not available, ADS actuation will not occur via "AUTO" logic or via the armed and depressed manual initiate pushbuttons.
- When the ADS logic is made up for Timer initiation and subsequent ECCS Pump Starts, the ADS Function will occur. |
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Summarize the effect that the following conditions have on ADS.b. Core Spray discharge pressure low
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- In the event the minimum required operating ECCS pumps are not available, ADS actuation will not occur via "AUTO" logic or via the armed and depressed manual initiate pushbuttons.
- When the ADS logic is made up for Timer initiation and subsequent ECCS Pump Starts, the ADS Function will occur. |
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Summarize the effect that the following conditions have on ADS.
c. Reactor level instrument failure |
- If the wide range level instruments were to fail downscale, that channel(s) would be made up as if an actual low level is present. If they failed high, that channel would be prevented from automatically energizing, but can still be manually initiated.
- Narrow range level response for the ‘A’ and ‘C’ Channels would be the same as a. above. |
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Summarize the effect that the following conditions have on ADS.d. Loss of air (PCIG Pneumatics)
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- Loss of PCIG pneumatic supply affects ability of SRV for Solenoid Actuation, however ADS valves SHMEK have accumulators and RSP valves CAN have accumulators.
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Summarize the effect that the following conditions have on ADS.e. Loss of 125V DC Bus A or C
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- In the event of a loss of 125 VDC Bus A, the following Division 1 (logic channels A and E) components are affected:
- Power supply for solenoid "A" of each ADS valve is lost - Initiation logic, via Division 1 auto circuit and manual initiate pushbuttons, is lost - "AUTO-OPEN" control switches on H12-P626 will not function to open the ADS valves - Receive "Div-1 Logic Power Failure" alarm light in conjunction with "DIV 1 ADS OUT OF SERVICE" annunciator - In the event of a loss of 125 VDC Bus C, the following Division 3 (logic channels C and G) components are affected: - Power supply for solenoid "B" of each ADS valve is lost - Initiation logic, via Division 3 auto circuit and manual initiate pushbuttons, is lost - Keylock "AUTO-OPEN" control switches on H12-P631 in auxiliary equipment room will not function to open the ADS valves - Receive "Div 3 Logic Power Failure" alarm light in conjunction with "DIV 3 ADS OUT OF SERVICE" annunciator |
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Summarize the effect that the following conditions have on ADS.f. Drywell pressure instrument malfunction
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- If the Drywell Pressure instruments were to fail upscale, that channel(s) would be made up as if an actual high drywell Pressure is present. If they failed low, that channel would be prevented from automatically energizing, but can still be manually initiated.
- If the Drywell is depressurized with the primary containment breached, auto initiation could still occur but requires timeout of the Hi Drywell Pressure Bypass. |
