EPRI FINAL EXAM 2026 QUESTIONS AND ANSWERS
GRADED A+
✔✔Automatic Trips/Relief - ✔✔If safety significant parameters deviate too far from
normal, the equipment can take two actions to protect itself. In the case of over
temperature, voltage, pressure, etc. the equipment can automatically trip to stop the
addition of more energy. In the case of pressure, the equipment can additionally relieve
the energy through the use of relief valves. It is possible for the equipment to be
designed to either relieve or trip first. Then if the condition doesn't improve, it could
perform the other.If safety significant parameters deviate too far from normal, the
equipment can take two actions to protect itself. In the case of over temperature,
voltage, pressure, etc. the equipment can automatically trip to stop the addition of more
energy. In the case of pressure, the equipment can additionally relieve the energy
through the use of relief valves. It is possible for the equipment to be designed to either
relieve or trip first. Then if the condition doesn't improve, it could perform the other.
✔✔(Emergency Operating Procedures/Operator Action)- - ✔✔The operators are
scanning the safety significant parameters to make sure they are not moving too far out
of the setpoints without action being taken. If the parameter passes the point where an
automatic trip or relief should have taken place, operating procedures will have the
operators take action.
✔✔Technical Specification Limit- - ✔✔All alarms or actions taken before this point
should prevent the equipment from reaching the tech spec limit. The plant is analyzed to
survive a design basis accident with the parameter less than that value. This is the
plant's licensing basis
✔✔Design/Test Limit - ✔✔This is the highest value for a specified parameter that a
piece of equipment is designed to survive and remain operational. In some cases, this is
a value where the equipment was tested.
✔✔Break Point - ✔✔The point where the equipment actually fails is somewhere above
the design limit. There is no way to know this value without an actual failure.
✔✔Describe core cooling during operation (PWR) - ✔✔1.1.1. - the heat energy
produced by the fission process is transferred to the highly pressurized, subcooled
water circulated through the steam generators. The water transfers its heat via
conduction across the steam generator heat exchanger tubes and turns the fluid on the
secondary side into steam. The steam drives the turbine which turns the generator. This
transfer of heat is continuous; the coolant removes heat from the fuel and transfers it to
the secondary side via the steam generators, producing the steam that turns the turbine
generator. This process removes the heat produced in the nuclear fuel and prevents it
from exceeding its design temperature limits.
, ✔✔Describe core cooling during power operation (BWR) - ✔✔1.1.1. the heat energy,
produced by the fission process, is transferred out of the fuel pin and into the reactor
coolant via convective heat transfer, which increases the water's temperature. The
reactor recirculation pumps force water from the reactor vessel's downcomer region
through the reactor core, where it is changed to a steam/water mixture. Steam quality is
then improved to 90% in the steam separators and then to 99% in the steam dryers,
after which it is sent out to the turbine generator to produce electricity. The main
condenser condenses the steam and returns it to the reactor vessel downcomer region
by the condensate and feedwater system. The water removed from the steam is
directed to the reactor vessel's downcomer region and preheats the feedwater before it
is forced into the reactor core.
✔✔Describe core cooling mechanisms while shutdown (IMMEDIATELY-PWR) -
✔✔1.1.1. PWR-
(Immediately)
Normally, after a reactor shutdown or reactor trip, the reactor coolant system (RCS)
continues to operate to remove the decay heat from the nuclear core. The reactor
coolant pumps circulate water through the RCS, transfering the decay heat from the fuel
to the secondary fluid in the steam generators. While the reactor is shut down, the heat
sink for this steam is typically either the condenser or atmosphere. This process is
similar to power operation except that steam is not sent to the turbine to generate
electricity.
✔✔Describe core cooling mechanisms while shutdown (long term-pwr) - ✔✔When
reactor coolant temperatures are too low to support adequate steam formation in the
steam generators, the residual heat removal (RHR) system* is used to remove most of
the remaining decay heat. This system moves reactor coolant from the RCS and passes
it through a heat exchanger, transferring the heat to a separate cooling water system.
The RHR system removes heat from the RCS to cool the plant to an ambient
temperature for maintenance or refueling operations and maintain the RCS temperature
below saturation conditions
*The RHR is known as the decay heat removal (DHR) system in Babcock and Wilcox
(B&W) plants or the shutdown cooling system in Combustion Engineering (CE) plants
✔✔Describe core cooling mechanisms while shutdown (BWR) - ✔✔Recirculation
Pumps continue to operate (remove heat) and steam is sent to the condenser instead of
the Turbine.
Once temps are low enough that you can not produce steam, you switch to RHR.
In shutdown mode, if you
✔✔emergency core cooling mechanisms (accident) (pwr) (5) - ✔✔safety injection
water sources
high head SI pumps
GRADED A+
✔✔Automatic Trips/Relief - ✔✔If safety significant parameters deviate too far from
normal, the equipment can take two actions to protect itself. In the case of over
temperature, voltage, pressure, etc. the equipment can automatically trip to stop the
addition of more energy. In the case of pressure, the equipment can additionally relieve
the energy through the use of relief valves. It is possible for the equipment to be
designed to either relieve or trip first. Then if the condition doesn't improve, it could
perform the other.If safety significant parameters deviate too far from normal, the
equipment can take two actions to protect itself. In the case of over temperature,
voltage, pressure, etc. the equipment can automatically trip to stop the addition of more
energy. In the case of pressure, the equipment can additionally relieve the energy
through the use of relief valves. It is possible for the equipment to be designed to either
relieve or trip first. Then if the condition doesn't improve, it could perform the other.
✔✔(Emergency Operating Procedures/Operator Action)- - ✔✔The operators are
scanning the safety significant parameters to make sure they are not moving too far out
of the setpoints without action being taken. If the parameter passes the point where an
automatic trip or relief should have taken place, operating procedures will have the
operators take action.
✔✔Technical Specification Limit- - ✔✔All alarms or actions taken before this point
should prevent the equipment from reaching the tech spec limit. The plant is analyzed to
survive a design basis accident with the parameter less than that value. This is the
plant's licensing basis
✔✔Design/Test Limit - ✔✔This is the highest value for a specified parameter that a
piece of equipment is designed to survive and remain operational. In some cases, this is
a value where the equipment was tested.
✔✔Break Point - ✔✔The point where the equipment actually fails is somewhere above
the design limit. There is no way to know this value without an actual failure.
✔✔Describe core cooling during operation (PWR) - ✔✔1.1.1. - the heat energy
produced by the fission process is transferred to the highly pressurized, subcooled
water circulated through the steam generators. The water transfers its heat via
conduction across the steam generator heat exchanger tubes and turns the fluid on the
secondary side into steam. The steam drives the turbine which turns the generator. This
transfer of heat is continuous; the coolant removes heat from the fuel and transfers it to
the secondary side via the steam generators, producing the steam that turns the turbine
generator. This process removes the heat produced in the nuclear fuel and prevents it
from exceeding its design temperature limits.
, ✔✔Describe core cooling during power operation (BWR) - ✔✔1.1.1. the heat energy,
produced by the fission process, is transferred out of the fuel pin and into the reactor
coolant via convective heat transfer, which increases the water's temperature. The
reactor recirculation pumps force water from the reactor vessel's downcomer region
through the reactor core, where it is changed to a steam/water mixture. Steam quality is
then improved to 90% in the steam separators and then to 99% in the steam dryers,
after which it is sent out to the turbine generator to produce electricity. The main
condenser condenses the steam and returns it to the reactor vessel downcomer region
by the condensate and feedwater system. The water removed from the steam is
directed to the reactor vessel's downcomer region and preheats the feedwater before it
is forced into the reactor core.
✔✔Describe core cooling mechanisms while shutdown (IMMEDIATELY-PWR) -
✔✔1.1.1. PWR-
(Immediately)
Normally, after a reactor shutdown or reactor trip, the reactor coolant system (RCS)
continues to operate to remove the decay heat from the nuclear core. The reactor
coolant pumps circulate water through the RCS, transfering the decay heat from the fuel
to the secondary fluid in the steam generators. While the reactor is shut down, the heat
sink for this steam is typically either the condenser or atmosphere. This process is
similar to power operation except that steam is not sent to the turbine to generate
electricity.
✔✔Describe core cooling mechanisms while shutdown (long term-pwr) - ✔✔When
reactor coolant temperatures are too low to support adequate steam formation in the
steam generators, the residual heat removal (RHR) system* is used to remove most of
the remaining decay heat. This system moves reactor coolant from the RCS and passes
it through a heat exchanger, transferring the heat to a separate cooling water system.
The RHR system removes heat from the RCS to cool the plant to an ambient
temperature for maintenance or refueling operations and maintain the RCS temperature
below saturation conditions
*The RHR is known as the decay heat removal (DHR) system in Babcock and Wilcox
(B&W) plants or the shutdown cooling system in Combustion Engineering (CE) plants
✔✔Describe core cooling mechanisms while shutdown (BWR) - ✔✔Recirculation
Pumps continue to operate (remove heat) and steam is sent to the condenser instead of
the Turbine.
Once temps are low enough that you can not produce steam, you switch to RHR.
In shutdown mode, if you
✔✔emergency core cooling mechanisms (accident) (pwr) (5) - ✔✔safety injection
water sources
high head SI pumps
