Heavy water reactor

Definition

A heavy water reactor is a type of nuclear reactor that uses heavy water (D2O) as both a neutron moderator and coolant. This type of reactor allows for the use of natural uranium as fuel, making it distinct from light water reactors that require enriched uranium. Heavy water reactors have unique operational features that influence their efficiency and the type of isotopes produced.

5 Must Know Facts For Your Next Test

1. Heavy water reactors can operate with natural uranium, making them more accessible for countries without enrichment facilities.
2. These reactors are capable of producing plutonium, which can be used in nuclear weapons, leading to concerns about proliferation.
3. Heavy water has a higher density than regular water, which helps improve the moderation of neutrons and enhances reactor efficiency.
4. Examples of heavy water reactors include the CANDU (Canada Deuterium Uranium) design, which is widely used in Canada and other countries.
5. The use of heavy water allows for a different neutron economy compared to light water reactors, affecting their design and operation.

Review Questions

• What advantages do heavy water reactors have over light water reactors regarding fuel use?
  • Heavy water reactors can utilize natural uranium as fuel without the need for enrichment, which makes them more accessible for nations that lack advanced nuclear technology. This ability to use unprocessed uranium can reduce the overall cost of nuclear fuel and provides a pathway for countries to develop nuclear energy programs without investing in enrichment facilities. Additionally, the use of heavy water improves neutron moderation, leading to greater reactor efficiency.
• How does the choice of heavy water as a moderator impact the safety and efficiency of nuclear reactors?
  • Using heavy water as a moderator enhances neutron slowing compared to light water, improving the probability of sustaining fission reactions. This leads to greater reactor efficiency and allows for lower enrichment levels in fuel. However, the unique properties of heavy water also necessitate careful design considerations for safety systems and containment measures. The increased efficiency can lead to more energy output per unit of fuel consumed, but also raises concerns regarding potential proliferation risks due to the production of plutonium.
• Evaluate the implications of heavy water reactors on global nuclear proliferation concerns and international policy.
  • The ability of heavy water reactors to produce plutonium from natural uranium has significant implications for global nuclear proliferation. Countries using this reactor type could potentially develop weapons-grade material more easily than those relying on light water reactors that require enriched uranium. This has led to international policy discussions focused on regulating access to heavy water technology and ensuring that it is not used for military purposes. Balancing the benefits of civilian nuclear energy development while preventing nuclear proliferation remains a complex challenge for policymakers worldwide.

Related terms

Deuterium: An isotope of hydrogen with one proton and one neutron in its nucleus, used in heavy water reactors as it replaces the usual hydrogen in water.

Natural Uranium: Uranium found in nature, primarily consisting of the isotope U-238, which can be used as fuel in heavy water reactors without enrichment.

Neutron Moderator: A material used in nuclear reactors to slow down fast neutrons, increasing the likelihood of fission when they collide with fissile material.