After the initial blowdown phase of a design basis LOCA what are the next two phases to occur?
refill, reflood
The blowdown phase of a design basis LOCA is considered terminated when which of the following occurs?
the RCS pressure approaches the valve of containment pressure
In a large break LOCA, the safety injection accumulators function to:
provide an immediate refill of the reactor vessel lower plenum up to the bottom of the fuel assemblies
Select the statement which best describes the purpose of the safety injection pumps:
inject borated water during a small to medium break LOCA
Select the function of the safety injection pump cold leg injection path during a design basis LOCA:
initial injection of the RWST into the RCS once RCS pressure is less than pump shutoff head
What is the “power lockout” feature found on some of the ECCS valves designed to prevent?
inadvertent operation which could result in degraded ECCS performance
During a plant heat up, the SI accumulator discharge isolations remain isolated until RCS pressure is between 700 and 1000 psia.
Why does the crew wait until RCS reaches this pressure band prior to unisolating the accumulators?
to prevent the accumulators from injecting into the RCS
A plant cooldown is in progress. Why are all SI pumps procedurally rendered incapable of injecting into the RCS before RCS cold leg temperatures go less than 226F?
to prevent cold over pressurization of the reactor coolant system due to excessive mass addition
The design of the emergency core cooling system includes the capability for the injection of borated water from the RWST to:
the RCS cold legs via the SI pumps following a large LOCA
Safety injection was manually actuated and all ECCS equipment operated as designed.
Which of the following statements describe the response of the following CVCS components?
RCP seal return isolation valves CLOSED on CIA. Charging flow control isolation valves CLOSED on SI
The RWST is at low level alarm set point when a large LOCA occurs. Approximately how long will it take to reach the RWST low low level alarm?
30-35 mins
The power lockout switch for 3SIH*MV8835, “SI COLD LEG INJ” is turned ON. Which of the following is true?
the valve can be operated from the control switch on the main control boards
Why are the “A” and “B” recirc spray pumps preferred over the “C” and “D” recirc spray pumps when aligning for cold leg recirculation?
the “A” and “B” RSS pumps have recirculation valves which protect the pumps on medium break LOCAs
Which of the following is not a function of the SI pumps?
inject borated water during a loss of normal charging
What is the purpose of the ECCS?
remove stored heat and fission product decay heat from the RCS, and provide reactor shutdown capability for various accidents by means of boron injection
