Prim M Flashcards
(50 cards)
State the functions of the Primary Loops
The functions of the primary loop is to remove heat from the core and transfer it to the SGs for steam production as well as:
To remove decay heat from the reactor while shut down.
To provide a barrier to reduce fission product release into the RC
State and define in details containment states 1, 1R & 2
CS1- Normal state, maintained at all times when possible, primary is intact, with boundary Vvs available, secondary available in 10 mins
CS1R- Interlocks on one set of doors defeated for machinery movement
CS2- Part of primary structure can be removed for maintenance, with a 3 bar DP Blank fitted immediately. subject to PAG, RSC door can remain open but must be capable of shutting within 10M without resource to emergency action
State and define in details containment states 3 & 4
CS3- Normal Sea going state, at CO discretion, RSC door interlock may be defeated and the outer door of each airlock may remain open to ease passage. inner door should remain shut
CS4- Complete relaxation of containment states. Breaches of permanent containment must be plugged unless necessary to permit repairs, Requires CPCA approval.
State and define in detail, plant states A & H
PSA- Normal operating state, reactor may or may not be critical. PSA is when any of these are true.
>1 CRDM Energised, Coolant is >168 degrees or coolant is > 35 bar
PSH -Permits most maintenance without lowering to PSB. all the following conditions to be met
Reactor shutdown, <1 CRDM energised, coolant is < 168 degrees, coolant < 35 bar
State and define in detail, plant state B & C
PSB - Normal shut down state, minimising the energy release from an accident. all the following conditions to be met:
Reactor shutdown, <1 CRDM energised, Coolant < 93 degrees, Coolant <35bar
PSC- Similar to B but with increased restriction due to being associated with CS4, All the following conditions to be met
Reactor shutdown, all CRDM Defused, Coolant <93 degrees, Coolant < 35 bar, Decay heat less than removal capacity, no steam bubble
State the function of the pressurising system
The function is to:
Maintain circuit pressure above saturation pressure
To accommodate volumetric surges during temperature changes
To provide the facility for removing dissolved gasses from the primary coolant
Allow for warming up the coolant and a route for emergency make-up from VOGS during loss of electrics
Describe the function of SLIV
The SLIV provides a means of isolating the pressuriser from the primary circuit in the even of primary circuit leak. The SLIV is water operated gate Vv to allow water from from the pressuriser to the RPV when shut .
Describe what type of Vv is the SLIV
The SLIV is water operated gate Vv, Which has a non-return feature that allows flow from pressuriser to the primary circuit when the Vv is shut
State how the Primary and Secondary methods of pressure control are achieved.
The Primary methods of pressure control is done by changing the heater load, while the secondary methods is done via spraying down Vvs
Why is the Primary method the method of choice
The primary is the normal choice to reduce thermal shock from operation of the spray down Vv and spray head.
To what positions do P502 & P505 fail n loss of 24V
P502 &P505 globe Vvs fail-shut on loss of 24V DC
State the function of the Non-return Vv P503
P503 is a non-return Vv used to prevent the flow of steam/water from the pressuriser into the primary circuit
State the functions of the relief system
In conjunction with the HP Scram trip, the relief system protects the primary circuit and pressuriser from over- pressurisation due to accidental or abnormal conditions
When will a RVIV shut automatically & what parameters control this?
The RVIV will shut automatically in the event of leaking/ failing reseat Vv being detected by flow and relevant RPV/Pressuriser instrumentation
If 0.115kg/sec flow is exceeded through a valve
State all event that could lead to a Primary relief valve lifting
- Failure of pressuriser control
- Continuous rod withdrawal accident
- Cold water addition accident
- Accidental closure of the surge line isolating valve (SLIV)
- Accidental running of the coolant make-up system make-up Pps
- Partial or complete loss of heat sink
- Accident shutting of the MIVs
State the restriction on the plant operation with isolated relief Vvs
If anyone Vv has been isolated, reactor plant can continue without restriction. if more than one is isolated the reactor must shut down.
Start up is not permitted with any relief Vvs are isolated
State the function of the coolant treatment system
The coolant treatment system is used to remove soluble and suspended radioactive corrosion and fission products from the primary coolant during operation, as well as maintaining PH
State the limitations imposed on Coolant treatment temp and flow and why
The main limitations are:
Coolant treatment flow must be kept below 0.63kg/s
Ion Exchange inlet temp must remain <58 degrees
State all condition under which W501 would be shut
W501 is used to isolate the system if any of the following occur
Primary coolant leakage from CTS
Primary coolant leakage from Coolant Sampling Systems
Coolant sampling station high activity
High coolant temp at ion exchange inlet
State what indication is used to confirm that W501 is open and why
Positive Vv position is unavailable for W501, monitoring its position is done using CT flow to indicate Open or SHUT
State the precautions imposed on the coolant treatment system and why
Major precautions listed below
CT flow must be kept below 0.63kg/s
Ion exchange inlet temp must remain <58 degrees
Port and Stbd loops must not be connected at the same time
W501 will not open if DP of 8.6 bar is exceeded in the normal direction of flow
State all the reason for sampling Primary coolant on a regular basis
To protect materials from general corrosion and long term stress cracking, to measure fission product activities for fuel cladding integrity.
To minimise build up of activity in the plant walls by controlling PH, to measure activity in the primary coolant,
To measure nuclides levels in the coolant to comply with discharge level to assess effectiveness of the CTS
To check for neutron source defects
State all regular test carried out on the primary coolant
Frequent tests performed are:
15m degassed activity & alpha activity
daily gross io1dine and iodine 131 activity
daily chloride
Occasional external PH & conductivity
Weekly decontamination factor
daily gaseous activity
Dissolve total gas & H2 concentration
Sate the function of the coolant discharge system
The function of the coolant discharge system is to allow for controlled discharge of primary coolant gas, steam and water from primary and secondary systems during warm-up and normal-ops of the plant
