Breeder reactor

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Sasahara

LMFBR schematics2

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MSRE Core

Breeder reactor is a type of nuclear reactor that generates more fissile material than it consumes. These reactors are significant in the context of nuclear power generation because they can extend the fuel supply for nuclear energy production by generating more fuel than they use up. This is achieved through a process called breeding, in which fertile materials, such as Uranium-238 (U-238) or Thorium-232 (Th-232), are converted into fissile materials, such as Plutonium-239 (Pu-239) or Uranium-233 (U-233), respectively.

Overview

Breeder reactors are designed to address the issue of finite uranium resources by efficiently utilizing the abundant, but non-fissile, U-238 available in natural uranium. Through neutron absorption and subsequent nuclear reactions, these reactors convert U-238 into Pu-239, a fissile material that can sustain a nuclear chain reaction. Similarly, when thorium is used as fuel, Th-232 is converted into U-233, another fissile material.

Types of Breeder Reactors

There are two main types of breeder reactors, based on the type of neutron used in the breeding process: Fast Breeder Reactors (FBRs) and Thermal Breeder Reactors.

Fast Breeder Reactors

FBRs use fast neutrons to convert fertile material into fissile material. They do not require a neutron moderator, as the fast neutrons are more efficient at breeding fissile material from fertile material. The most common coolant used in FBRs is liquid sodium, which has excellent thermal properties and does not moderate neutrons.

Thermal Breeder Reactors

In contrast, thermal breeder reactors use thermal (slow) neutrons and require a moderator to slow down the neutrons produced by fission. An example of a thermal breeder reactor is the Molten Salt Reactor (MSR), which uses a mixture of molten salts as both fuel and coolant, and can operate with thorium as fuel.

Advantages and Disadvantages

Breeder reactors offer several advantages, including better utilization of natural uranium resources, the ability to generate their own fuel, and the potential to reduce nuclear waste by burning long-lived actinides. However, they also face challenges such as higher costs, technical complexity, and concerns related to nuclear proliferation due to the production of plutonium.

Current Status and Future

As of now, several countries have pursued breeder reactor programs, with varying degrees of success. Russia has been operating a fast breeder reactor, the BN-600, for several decades, and has developed a newer model, the BN-800. Other countries, including India and China, are also developing breeder reactor technology.

The future of breeder reactors depends on advancements in technology, economic factors, and societal acceptance of nuclear power. Research continues into making breeder reactors more economically viable and addressing proliferation concerns.