Reactor Coolant System Flashcards
Natural circulation indications
-RCS subcooling- acceptable
-SG Pressure- Stable or Decreasing
-RCS hot leg temps- stable or Decreasing
-RCS cold leg temps- At saturation temperature for intact SG pressures
-Average 10 Highest TCs-Stable or decreasing
Minimum RCS temperature(not for criticality)
70F Assures that vessel flange minimum of 60F when vessel head is tensioned
BGP 100-1 (Heatup procedure) oxygen limitation
The RCS Oxygen concentration shall be less than 0.1 ppm with RCS
temperature > 250F. See TRM 3.4.b for transient limitations.
BGP 100-6 (Refueling) temperature/RCP condition limitation
RCS Temperature shall not be raised above 160F until at least one RCP
is running for solid water, low pressure operation. (CM-1)
CV charging taps-which cold legs?
A and B. Use of the normal and alternate charging shall be alternated over plant life, such that neither should be used for more than 60% of design transients. The transfer should be done in cold shutdown to avoid transients, starting with CV8147 A loop in cycle 1.
Core bypass flow
5.8%
Head bypass 2.3
flow through Crs and instr thimbles 2
Inlet to outlet nozzle bypass 1
Former and baffle 0.5
Penetrations that extend into the RCS piping
- PZR spray lines
- NR Thot RTD thermowell
- WR RTD thermowell
- Chemistry sampling line
One reason for RCS subcooling:
(Delta T)
ensure delta-T is accurate indication of reactor power
NR RTD description
Fast response RTDs located directly in the RCS loops. Three for each hot leg and only one for each cold leg. Each hot leg RTDs are averaged to compensate for streaming.
RTD open circuit/short circuit indications
Open-High resistance, high temperature
Short- Low resistance, low temperature
Stop valve internal relief mechanism
Vents excess water to Reactor during isolated loop warmup
Vents excess water between disks
DNBR requirements from TRM
including when pressure limit doesn’t apply.
Flow 386000 gpm
PZR pressure >=2209 psig
Tave <=593.1F
PZR pressure limit doesn’t apply during thermal power ramp>5%/min or Thermal power step of >10%RTP
BGP-6 refuel precaution max boron concentration
2450ppm to prevent unnecessary reduction in the NI response
Purpose of the reactor vessel
The reactor vessel is the pressure boundary which contains the nuclear fuel. The reactor vessel internals align and support the fuel, direct support equipment and instrumentation into the vessel, and direct the flow of coolant through the core.
Reactor vessel head purpose
- Supports CRDMs, restrains upper internals, and forms upper pressure boundary.
- Head bolted and sealed to reactor vessel.
- Two O rings between head and vessel, leakage sensed if O rings leak.
upper support plate and columns
Support plate- supports upper core plate
support columns- support upper plate and transmit load to lower core plate
RCCA guide tubes
Guide and support the control rods into and out of the fuel assemblies
Upper core plate
Transmits upward forces of fuel assemblies to upper support plate.
Core barrel
Transmits core/fuel weight to vessel flange.
Neutron pads
Attenuate fast neutrons, minimize embrittlement of the vessel wall.
Lower core plate
Aligns and supports fuel assemblies and distributes coolant flow to fuel assemblies.
Lower support columns
Transmits weight of lower core plate and the core to the core support.