201.20 SSPS Flashcards
- 201.20 SSPS*
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Functions of SSPS
Monitors parameters and initiates protective function to ensure w/in Tech Spec limits
Maintains fuel clad integrity via Rx Trip for Condition I and II events
Actuates ESF Systems to mitigate Condition III and IV events to ensure offsite dose w/in 10CRF50.67 limit
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ANS Classification of Accidents
Condition I - normal ops and operational transients
no clad damage
Condition II - faults of moderate frequency
no clad failure or fuel melting, rad release < 10CFR20, at worst trip with return to power
Condition III - infrequent faults
small amount of fuel damage, rad release small fraction of 10CFR50.67, considerable outage time
Condition IV - limiting faults
rad release < 10CFR50.67
- 201.20 SSPS*
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Acutation Train Urgent Alarm
Causes
Loss of power (Slave Relay Cabinet or Test Cabinet)
Actuation train in test
Test Cabinet in test
- 201.20 SSPS*
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Logic Cabinet Urgent Alarm
Causes
Loose or removed circuit card
“Respective” Actuation Train Urgent
Associated Rx Trip Bypass Breaker racked in and closed
Test Switches:
Input Error in INHIBIT
Logic Test Switch A in other than OFF
Permissive Test Switch in other than OFF
Memory Test Switch in other than OFF
- 201.20 SSPS*
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SSPS Trouble Alarm Train R and S
Causes
Loss of any 15 VDC or 48 VDC
Any Actuation Train in test
Any Actuation Train loss of power
MRDS Switch in other than NORMAL
Multiplexer Test Switch in INHIBIT
- 201.20 SSPS*
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Reactor Protection Channel Bypassed Alarm
Causes
Any protection channel bypassed in the 7300 process cabinets.
Specific channel determined by bistable indications.
- 201.20 SSPS*
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3 “systems” that should NOT be tested concurrently
- Reactor Trip System (RTBs)
- Reactor Protection System (Instruments, 7300 and Rx Trip part of Logic Cabinets)
- Solid State Protection System (Rest of the Logic and Actuation Cabinets)
Work on any 1 is fine
Work on 2 parts or 2 channels / trains needs thought:
Will this cause a trip or actuation?
Will this place the plant in an unanalyzed condition? (LCO 3.0.3)
- 201.20 SSPS*
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First Out Annunciator Panels
Indicate cause of Rx Trip, SI, or Turbine Trip on CP-005, CP-006
Basic Operation:
Initially all trip signals currently in will flash rapidly
Main Panel reset causes all but initiating signal to go solid
Depressing first out reset clears all windows
Manual trip signal may be delayed and look like a Turbine Trip.
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Generic SSPS Tech Spec Information
If OOS may be left as is or bypassed for 72 hours
If OOS for 72 hours must be placed in tripped condition
Permissives verified in proper state within 1 hour (if less than minimum channels operable)
Containment Spray receives special treatment – placed in BYPASS because it is energize to trip
P-4
Rx Trip Breakers are Open
Setpoint - both Rx Trip and Bypass bkrs open for that train 2/2
What it does:
Turbine Trip
Allows FWI on Low Tavg (574°F)
Allows manual block and reset of SI
Closes SB isolations if SR Flux Trip blocked
Why - Reactor Protection
P-6
Setpoint
What it does
Why
Source Range Trip Block Permissive
Setpoint - 10-10 amps IR power (1/2)
What - Block of SR High Flux Trip, removes power from SR detectors
Why - Ensures IR overlap prior to power ascension
Protects SR detectors from excessive flux while energized
P-7
Setpoint
What does it allow?
Why?
At-Power Permissive
Setpoint - P-10 OR P-13
What - At power Rx Trips:
PZR low press / high level
RCS low flow (2/4 loops)
RCP UV / UF
Why - Allow normal plant shutdown / cooldown without tripping shutdown banks
P-8
Single Loop Loss of Flow Permissive
Setpoint - 40% on PR NIs (2/4)
What - Rx Trip on low flow in one loop
(if not true, requires 2 loops low flow to trip)
Why - prevents DNB conditions
P-9
Turbine Trip / Reactor Trip Permissive
Setpoint - 50% on PR NIs (2/4)
What - C-8 to cause Rx Trip
Why - Rods can reduce power 10% step load change; Steam dumps can handle a 40% load rejection.
P-10
Power Range low FLux Trip Block Permissive
Setpoint - 10% on PR NIs (2/4)
What -
Allows block of IR flux trip and rod stops (C-1)
Allows block of PR high flux (low) trip
Backup, automatic input to SR NI blocks
Ensures SR NIs do not energize at power and trip the Rx if IR NIs fail
P-7
P-11
Low Pressure SI/SLI Block Permissive
Setpoint- Pressurizer Pressure < 1985 psig (2/3)
What- Block of Low PZR Pressure SI AND Low Steamline Pressure SI/SLI
(When blocked, SLI protection is provided by the high negative rate signal)
Closure of SI Accumulator outlet valves
Why- Prevent SI actuation on normal plant cooldown
P-12
Low Tave Steam Dump Permissive
Setpoint - Tave < 563 F (2/4)
What - Vents air from steam dump operators
(bypass allows 3 valves to remain open)
Why - Prevent overcooling
P-13
Turbine At-Power Trips Permissive
Setpoint - 10% impulse pressure (1/2)
What - P-7
Why - At-power Trips apply with either nuclear or turbine power at 10%
P-14
S/G Hi-Hi level Trip
Setpoint - 87.5% 2/4 in any 1 S/G
What - Trips Main Turbine, SGFPs, and SUFP
FWI
Why - prevent overcooling and protect turbines from carryover
P-16
Rx Trip to Trip Turbine
Setpoint - P-4 OR SSPS Logic Train requests Rx Trip
What - Trips Main Turbine
Why - Prevent overcooling
Help mitigate ATWS with loss of feedwater
C-1
IR High Flux Rod Stop
Setpoint - IR NI current equal to 20% Rx power (1/2)
What - Stops ALL rod out motion
Why - Limits power excusion from events beginning in IR
C-2
C-3
OTΔT Rod Stop
Setpoint - PR NIs w/in 1.5% of current OTΔT setpoint (1/4)
What - stops ALL rod out motion
Why - DNB protection
C-4
C-5
Low Turbine Impulse Pressure Rod Stop
Setpoint - PT 505 pressure equivalent to 15% Turbine power
What does it do?
ONLY stops AUTO rod out motion
Why?
Below 15%, impulse pressure is not an accurate input Tref
C-7
Steam Dump Load Rejection
Setpoint - >10% step load loss (PT-0506)
rate of load loss faster than 5%/min (PT-0506)
What - Arms the steam dumps in load reject mode
Why - Load is dropping faster than rod control can handle alone steam dumps will be needed to prevent overheating the RCS
C-8
Turbine Trip
Setpoint - EH pressure <1245.8 psig (2/3) OR TVs closed (2/4)
What - Reactor Trip (if P-9 is true)
Main Generator Trip
Arms the steam dumps in Trip Mode
Blocks the load reject controller
Why - Prevent overheating the RCS
Prevent reverse power of Main Generator
Turbine tripped ⇉ PT-0506 is no longer a valid input.
C-9
Condenser Available for Steam Dumps
Setpoint - Any CW pump breaker closed AND Condenser Vacuum > 22”Hg (2/3)
What - Vents air from the steam dump operators
Why - Prevent dumping steam to a condenser that cannot support it.
C-11
Rods at Top Rod Stop
Setpoint - Bank D at 248 steps
What - Stops AUTO rod out motion ONLY
Why - I’m givin’ her all she’s got, cap’n!
C-17
Stop Turbine Loading
Setpoint - Tavg – Tref too negative (auctioneered low)
Tavg < 563 °F (auctioneered low)
What - Prevents raising turbine load
Why - prevent overcooling
C-20
AMSAC Armed
Setpoint - BOTH (505 and 506) turbine impulse pressure > 30% of full load pressure
What - Arms AMSAC (ATWS Mitigation System Actuation Circuitry)
Why - AMSAC is a backup to SSPS for certain trips, but is not needed < 30% power
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Describe controls available to operate Rx Trip Breakers
UV trip removes 48 VDC from UV coils on trip breakers
Shunt trip applies 125 VDC to shunt coil, which activates plunger to trip breaker
- Auto - same train (R,S) trip bkr and opposite train bypass UV coils*
- same train trip bkr and bypass shunt*
- Manual Switches - Trip and SI control all 4 UV coils*
- Trip controls all 4 shunt coils*
