Experimental Breeder Reactor II

The original emphasis in the design and operation of EBR-II was to demonstrate a complete breeder-reactor power plant with on-site reprocessing of solid metallic fuel.

The tubes were unsealed and reprocessed to remove neutron poisons, mixed with fresh U-235 to increase enrichment, and placed back in the reactor.

In this role, the high-energy neutron environment of the EBR-II core was used for testing fuels and materials for future, larger, liquid metal reactors.

As part of these experiments, in 1986 EBR-II underwent an experimental shutdown simulating complete cooling pump failure.

It demonstrated its ability to self-cool its fuel through natural convection of the sodium coolant during the decay heat period following the shutdown.

Each fuel element is placed inside a thin-walled stainless steel tube along with a small amount of sodium metal.

Clusters of the pins inside hexagonal stainless steel jackets 234 cm (92 in) long are assembled honeycomb-like; each unit has about 4.5 kg (9.9 lb) of uranium.

In April 1986, two special tests were performed on the EBR-II, in which the main primary cooling pumps were shut off with the reactor at full power (62.5 megawatts, thermal).

This test showed that it will shut down using inherent features such as thermal expansion, even if the ability to remove heat from the primary cooling system is lost.

The third and final phase of the decommissioning activity was "the placement of the reactor and non-reactor systems in a radiological and industrially safe condition".

[3] The objective of the EBR-II was to demonstrate the operation of a sodium-cooled fast reactor power plant with on-site reprocessing of metallic fuel.