NANTeL - National Academy for Nuclear Training e-Learning Nuclear Plant Systems Overview Questions and Answers 1

Question 1

In a Pressurized Water Reactor (PWR), what is the primary function of the steam generator?

Accepted Answer

To transfer heat from the primary coolant loop to the secondary loop, creating steam.

Answer

The steam generator is a heat exchanger that transfers thermal energy from the hot, pressurized water in the primary (reactor coolant) system to the water in the secondary system. This causes the water in the secondary system to boil and produce steam, which then drives the turbine-generator.

Question 2

A control room operator observes a gradual, unintended decrease in reactor power in a Boiling Water Reactor (BWR). Which of the following system changes could be a direct cause?

Accepted Answer

A decrease in recirculation flow, causing more steam voids in the core.

Answer

In a BWR, the water acts as both a coolant and a neutron moderator. Increasing the recirculation flow forces more liquid water through the core, reducing the number of steam voids. Fewer voids lead to better neutron moderation and an increase in reactor power. Conversely, a decrease in recirculation flow leads to more steam voids, which are less effective at moderating neutrons, thus causing reactor power to decrease.

Question 3

Which of the following best describes the primary role of the Emergency Core Cooling System (ECCS)?

Accepted Answer

To provide cooling to the reactor core to prevent fuel damage during a loss-of-coolant accident (LOCA).

Answer

The fundamental purpose of the ECCS is to provide emergency cooling to the reactor core in the event of a pipe break or other accident that results in a loss of normal coolant. This is crucial for removing decay heat and preventing the fuel from overheating and melting.

Question 4

What is the principal function of the containment building in a nuclear power plant?

Accepted Answer

To serve as the final barrier to prevent the release of radioactive materials into the environment during an accident.

Answer

The containment building is a massive, robust structure of steel and reinforced concrete designed to contain the energy and radioactive materials that could be released during a severe accident. It is the fourth and final barrier in a nuclear plant's defense-in-depth safety philosophy.

Question 5

In the context of a nuclear power plant's secondary system, what is the direct function of the main turbine?

Accepted Answer

To convert the thermal energy of steam into mechanical rotational energy.

Answer

High-pressure steam produced in the steam generators (in a PWR) or the reactor vessel (in a BWR) is directed to the main turbine. The steam expands and pushes against the turbine blades, causing them to rotate at high speed. This rotation is the mechanical energy used to turn the electrical generator.

(NANTeL) National Academy for Nuclear Training e-Learning Practice Test

(NANTeL) National Academy for Nuclear Training e-Learning Practice Test

NANTeL - National Academy for Nuclear Training e-Learning Nuclear Plant Systems Overview Questions and Answers 1