RPS Flashcards
(45 cards)
What is the purpose of the RPS System?
Initiates a scram to preserve the integrity of the fuel cladding and primary system and to minimize the energy, which must be absorbed to prevent criticality following a LOCA
How many RPS trip systems exist and channels per trip system?
2 trip systems - A & B - 2 automatic and 1 (A3/B3) manual) channels per trip system
What are the design functions of RPS?
Prevent release of radioactive materials
Prevent fuel damage following single element malfunction
Function independently of other plant instrumentation
Function safely following any single component failure
How quickly can a half scram signal be reset? How quickly can a full scram signal be reset?
half-scram - immediately
Fully Scram has a 10 second time delay for reset
What is the condition of RPS relays on a scram?
Relays de-energize
What is the logic scheme for all RPS Trips other than NI?
One out of two twice
What is the RPC logic scheme for NI Trips?
IRM’s one out of 4; APRMs - one out of 3
What normally pressurizes the scram air header?
What happens on a loss of pressure?
Intrument Air; loss of pressure the Scram inlet and outlet valves go open - dicharge volume vents and drains go closed
Which Scram Solenoid pilot valves are associated with which RPS channel?
117 - A Channel
118 - B channel
How many CRs are associated with each RPS Channel “Group”
Approximately 25%
What is the purpose of the Scram Dump Valves?
Reposition to port air off the scram discharge volume vent and drain valves - thus closing them
What powers the scram dump valves - 20A/B valves?
Powered by RPS A/B
What powers the SSPVs?
117 powered by RPS BUS A
118 powered by RPS BUS B
What is the purpose of the Back-up scram valves? Power source?
Ensure control rod insertion by de-pressurizing the scram air header when both RPS channels trip simultaneously. - backup to 117 and 118 valves incase they don’t reposition
Powered by 2A-1 (19A) and 2B-1 (19B)
Where does the 19A/B Backup scram relays fall in the relay scheme?
THey are in parallel to the 10 second reset time delay - Both relays energized on full scram
What is the normal condition o fthe SDV Vent/drain valves?
Scram dump valves?
Backup Scram Balves
SSPVs?
SDV - Normally - De-energized - Instrument Bus
Backup Scram - Normally Den-energized - 2A-1/2B-1
Scram Dump Valves - Normally Energized - RPS A; RPS B
SSPVs - Normally Energizzed - RPS A; RPS B
How are teh RPS Subchannels Tested?
4 keylock test switches - one for each channel - located on the 902-15/17 panels - will introduce half-scram by de-energizing 108 relays
What are the SCRAM Signals for RPS?
Turbine Stop Valves Not Full Open (<90%) Turbine Generator Load Reject - 40% load mismatch as measured at Tb 1st stage pressure - FASTC <590# SDV Hi-Hi MSIV Not Full Open Low Condenser Vacuum DW Pressure Hi RX Pressure Hi RX Level Lo (+8")
What is the RPS Turbine Stop Valve Closure Scram designed to prevent?
How many valves need to close to cause half-scram? full scram?
Designed to prevent fuel damage resulting from a pressure increase due to a rapid closure of the turbine stop valves:
1 SV not full open results in no action:
Specific combinations of 2 may cause half scram - if add to 5 will not - another other WILL be half scram
ANY COMBINATION OF 3 OR 4 will be FULL SCRAM
What is the Bypass for Turbine Stop Valve Closure and Tb Generator Load Reject Scrams?
Automatically bypassed when Tb Power is <38.5% for 10 seconds
- 4 pressure switches sense FASTC oil pressure at supply of control valves and de-energize the same relay as the generator reject scram - set point at 590# PSIG
When Rx power <38.5% pressure/power transient from turbine trip not enough to violate MCPR
What conditon does the Turbine Stop Valve Closure Bypass alarm identify? What is still possible?
Alarm comes in at <38.%% when only ONE pressure switch is activated. A full scram is still possible
What is the Generator Load Reject Scram? Can it be bypassed?
Loss of generator load could cause a turbine overspeed, therefore the control valves will react by closing causing a reactor pressure increase if power is greater than the bypass valve capacity. The anticipatory scram prevents fuel damage and lifting of safety valves.
Scram signal comes from pressure sensing switch sensing EHC (FASTC) fluid pressure between CV fast acting solenoid and disk dump valve
Bypassed when reactor power <38.5% at 1st stage for 10 sec
How many valves must close for Gen. Load Reject Scram?
Single valve gives half scram - Full Scram from 1 or 2 and 3 or 4.
What turbine first stage pressur indicates RX power of ~38.5%?
210psig
