What is a fast spectrum reactor?

What is a fast spectrum reactor?

A fast-neutron reactor (FNR) or fast-spectrum reactor or simply a fast reactor is a category of nuclear reactor in which the fission chain reaction is sustained by fast neutrons (carrying energies above 1 MeV or greater, on average), as opposed to slow thermal neutrons used in thermal-neutron reactors.

What is the fast neutron spectrum?

The fast neutron spectrum allows fast reactors to largely increase the energy yield from natural uranium as compared to thermal reactors. This high utilization of fuel can extend nuclear power programmes for thousands of years and provide significant improvements in nuclear waste management.

Why are fast breeder reactors not used?

Breeder reactors are costly to build and operate. Although it could be expected that once in production this cost ratio would decline, today few, if any, experts argue that breeder reactor capital costs could be less than 25 percent higher than that of similarly sized water cooled reactors.

Are fast reactors breeder reactors?

The conventional fast reactors built so far are generally fast breeder reactors (FBRs) implying a net increase in Pu-239 from breeding, due to a conversion ratio above 1.0. These have a ‘fertile blanket’ of depleted uranium (U-238) around the core, and this is where much of the Pu-239 is produced.

How does a fast reactor work?

Fast reactors are a versatile and flexible technology that promises to create or “breed” more fuel by converting nuclear “waste” into “fissile” material. “Fissile” material is nuclear fuel, usually uranium or plutonium that can sustain a fission chain.

What is the difference between a thermal and a fast reactor?

Fast reactors utilize liquid metal (liquid sodium or liquid lead) as coolant. Thermal reactors require low enriched fuel. Typically light water based reactors and gas cooled reactors require 3 – 5% enrichment, while heavy water based reactors require no enrichment (i.e. natural uranium can be used as fuel).

What are fast neutrons used for?

The use of fast neutrons in so-called ‘fast reactors’ allows for the production of more fissile nuclei than are destroyed, as the absorption of at least one neutron per fission by an uranium 238 nucleus transforms this uranium 238 into a fissile plutonium 239 nucleus.

Why are fast reactors important?

Fast reactors can thus be used to breed more fissile material than they consume or to burn nuclear waste or for a combination of these two tasks. In short, they offer significant benefits in making nuclear energy production more sustainable.

Are fast reactors safe?

But as the battle over a major fast-breeder reactor in the UK intensifies, skeptics warn that fast-breeders are neither safe nor cost-effective. Plutonium is the nuclear nightmare. A by-product of conventional power-station reactors, it is the key ingredient in nuclear weapons.

Why dont fast reactors need a moderator?

Currently, almost all operating reactors are thermal and thus require a moderator to slow down fast neutrons to the thermal level so that nuclear fission can continue. However, in fast reactors a moderator is not needed, and the neutrons within it move much more quickly.