Prim L Flashcards
(42 cards)
Define requirements of Integrity and responsibility, applied to the reactor
Integrity - Must scram when valid demand exists
Responsibility - Must NOT SCRAM unless valid demand existst
List methods of automatic SCRAM Protection
Automatic protection can be set to either FULL SCRAM
PARTIAL SCRAM (rod group 3 only)
List manual inputs into the reactor Protection System
Scram Mode selector
Manual SCRAM Switch
Battleshort Switch
Which SCRAM parameters have overrides associated with them
Low PWR and Start-Up Rate (LP&SUR)
Low Primary Loop Pressure
Low Reactor Inlet Temp (TC)
State parameters monitored by the SCRAM guardlines and whether they are full or partial SCRAM
Partial SCRAM
Low Power & SUR
High Reactor Outlet Temp (TH)
Power Flow & Power Range EHT
High Loop Pressure
Low Loop Pressure
Full SCRAM
Low Reactor Inlet Temp (TC)
HPDHR Vv Movement
Loss of Primary Loop Flow
Explain how the TC channel protects the Reactor
These channels protect the reactor from a uncontrolled restart following a Partial SCRAM by initiating a FULL SCRAM if Tc drops below a set value .
Additionally when the plant is SD the TC channel are used to give indications of the Temp of the core
Explain how TH channels protect the reactor
These channels protect the core against over temp while critical by initating a scram if the TH exceeds a set value.
This will prevent SG Reliefs
2 Channels per loop
AB-Port
CD - Stbd
Which Loop pressure channels are associated with which Loop and where are they indicated
Channel A/B port loop, displayed RP PORT
Channel C/D STBD loop, displayed STBD RP
State pressure at which the RPV outputs a trip signal
LPS guardlines
Relief flow alarms
LoTOP alarm
LPS-
Trips when pressure < 102.4 bar
Relief Flow Alarm-
Channel 1 at 132 bar
Channel 3 at 140.5 bar
Low Temp Operating Pressure (LoTOP)
Channels 2&4 trip signals at 35 bar, overridden when Temp is >130
What do the MUD pressure channels protect against, how and what pressure it works at
They protect against the release of fission products by initiating CAIS if pressure approaches MUD Relief would lift
The meter indicated 0-30 bar at the RWP. The alarm is set at 16.5 bar
What Function do the CWAP interlocks perform, which channels do they derive their inputs from
When the reactor is critical, these channels protect against a Cold Water Accident (CWA)
which would occur if a Loops flow had stopped. as the coolant in that loop would cool down
Interlocks - Prevents MCPs starting or MIVs opening in the stalled loop. CWAPs is initiated if flow falls below 0.03 bar
Channels- six identical narrow SG DP
Explain the arrangement of VPDs associated with each MIV, and why the SHUT input interface with the LPS
Each MIV has 2 VPDs, one at the top and bottom of the Vv to indicate OPEN and SHUT respectively. Each VPDs consists of 4 Reed switches (only 2 are used on shut indication)
SHUT VPD also feeds into Leak Protection System, this is because they are required on initiation of FLP. MIVs are shut automatically, indications is required as feedback to isolate the VOGS form the gas supply and vent off the VOW valve (preventing continued operation of the MIVs)
Describe MCPM and how it protects the reactor
4 channels in the RIA monitor both sets of MCPs. these monitor Voltage & HZ of the supplying busbar. A&B are Port Loop, C&D are Stbd loops.
When critical, FULL SCRAM will be initiated if all Pps are detected as OFF or their Supplies are outside Limits.
At all times. POWER must be less then FLOW, if power equals or exceeds flow, the reactor must be Scrammed
What indications are available of changed pump states
Flow signal can be used by the S/D Supervisor when Pps switching as a indication. additional indications of changed Pp flow rates are
Change is SG DP, change if flow through coolant treatment, altered Spray Rate if spraying down. and IPB indication at RP ( indicating a breaker state change)
list 6 functions performed by the pressuriser pressure channels
Signals to Control Heaters and Spray Vvs,
High pressure trip to LPS heater cut-out (144bar)
Automatic cut-out of start up heaters at NOP
Pressuriser pressure indication at RPAP and Discharge panel
Low pressure trip to LPS SLIV and IMIC on RWP at 79BAR ( can be overridden at RWP)
Low pressure alarm on Reactor System Alarm (127bar)
Steam relief line flow alarm override (122bar)
Steam Relief line isolation Vv trip override (124bar)
State the alarm outputs of the pressuriser level narrow channels including when they alarm.
(Plant state A) low level
will alarm when levels fall below 3.15M
high level alarm at 5.4M
State the outputs of the pressuriser level wide channels
Plant State B Low Level Alarm - 1.64m
Pressuriser Empty Alarm 0.56m
Heater cut-out - if the level in the pressuriser falls to 1.64m on both channels
Describe how the MASTER PHC is selected and how this PHC controls the Slave PHC
Two position switch on RPAP that selects which PHC is master or slave
The master PHC compares the pressure signal for its associated pressuriser pressure channel and compares it with a pre set point. to derive an error signal which is sent to the other 3PHCs so that all 4 PHCs process the same error signal
What is the function of the PO/PS switch on the PHC
?
The PO/PS switch is used to change between pressure levels to control PHCs depending on plant state due to the different operating pressures.
These options are Pressure Operating for PSA and Pressure Shutdown for PSH and PSB (29bar)
At what RPV pressure will all the pressuriser heater trip off? When can this be overridden and how do you clear the trips
When the RPV pressure reaches 102.4 bar on 3 of 4 pressure channels all heaters will cut out.
This can be overridden when the pressuriser is <129bar.
This trip can be reset by operating the LPS Logic Reset button on the RWP
What pressuriser level will all the pressuriser heaters cut out.
When pressuriser levels falls to 1.64M as sensed by the selected pressuriser level channels (wide) channel all the heaters will cut-out
List the methods of opening and shutting the SLIV
The SLIV can be operated by IPBs at the RP.
And manually from the RSC. The SLIV is automatically tripped shut by LPS if the pressuriser falls to 79bar ( unless overridden)
State parameters measured by the SGWLC system
Feed Flow
Steam Flow
SG Level
SG Pressure
Program Level
State how Steam Flow and Feed Flow indication is derived
Steam Flow:
Steam Flow is measured using DP cells across a venturi in the Main Steam pipework in the MMS. this is fed to the auto feed water control system.
It is also combined with SG pressure to give steam mass flow
Feed Flow:
Feed flow is measured using DP cell across a venturi in the DG room, This is also compensated for by temperature. The output from this is fed to the auto feed water control system.
