NANTeL Plant Systems Overview 2 — Questions and Answers
Question 1: What is the primary function of the Emergency Core Cooling System (ECCS) in a nuclear power plant?
- To regulate steam pressure in the secondary loop
- To inject water into the reactor core during a loss-of-coolant accident (Correct answer)
- To cool the spent fuel pool during normal operations
- To control reactor power through neutron absorption
Correct answer: To inject water into the reactor core during a loss-of-coolant accident
The ECCS injects large volumes of water into the reactor core to prevent fuel damage during a loss-of-coolant accident (LOCA).
Question 2: In a pressurized water reactor (PWR), which component maintains the primary coolant at operating pressure?
- The steam generator
- The reactor coolant pump
- The pressurizer (Correct answer)
- The condenser
Correct answer: The pressurizer
The pressurizer uses heaters and spray nozzles to maintain primary system pressure, preventing coolant from boiling in the reactor.
Question 3: What is the role of the turbine bypass system in a nuclear power plant?
- To divert neutrons away from the reactor core
- To route steam directly to the condenser, bypassing the turbine during transients (Correct answer)
- To bypass the feedwater heaters for maintenance
- To redirect reactor coolant around the steam generators
Correct answer: To route steam directly to the condenser, bypassing the turbine during transients
The turbine bypass system diverts excess steam to the condenser during transients or load rejections, preventing overpressure in the secondary system.
Question 4: Which plant system is responsible for removing residual decay heat after reactor shutdown?
- The Chemical and Volume Control System (CVCS)
- The Residual Heat Removal (RHR) system (Correct answer)
- The Service Water System
- The Containment Spray System
Correct answer: The Residual Heat Removal (RHR) system
The RHR system circulates coolant through heat exchangers to remove decay heat from fission product decay after the reactor shuts down.
Question 5: In a boiling water reactor (BWR), where does steam generation occur?
- In a separate steam generator on the secondary side
- Directly in the reactor pressure vessel (Correct answer)
- In the pressurizer vessel
- In the condenser hotwell
Correct answer: Directly in the reactor pressure vessel
In a BWR, coolant water boils directly in the reactor pressure vessel, producing steam that drives the turbine without a secondary loop.
Question 6: What is the purpose of the containment isolation valves in a nuclear plant?
- To isolate individual reactor fuel assemblies
- To prevent release of radioactive material to the environment by closing penetrations in the containment boundary (Correct answer)
- To isolate the turbine from the steam generator
- To control flow between the primary and secondary loops
Correct answer: To prevent release of radioactive material to the environment by closing penetrations in the containment boundary
Containment isolation valves automatically close on isolation signals to maintain the containment pressure boundary and prevent fission product release.
Question 7: Which parameter does the reactor protection system (RPS) monitor to initiate an automatic reactor trip?
- Grid frequency and voltage only
- Turbine shaft vibration only
- Multiple process variables such as high neutron flux, low coolant pressure, and high coolant temperature (Correct answer)
- Generator output power and power factor
Correct answer: Multiple process variables such as high neutron flux, low coolant pressure, and high coolant temperature
The RPS monitors numerous process variables and automatically trips the reactor when any monitored parameter exceeds a safety setpoint.
NANTeL Plant Systems Overview 2
What is the primary function of the Emergency Core Cooling System (ECCS) in a nuclear power plant?