Research Reactors

Fuels and Spent Fuel Management

Research reactors operate with a small quantity of enriched or highly-enriched uranium fuel.

RESEARCH REACTOR FUELS

Only a few kilograms of uranium are needed to fuel a research reactor, albeit more highly enriched (compared with perhaps a hundred tonnes in a power reactor). Highly-enriched uranium (HEU, i.e. more than 20% U-235) allowed more compact cores, with high neutron fluxes and also longer times between refuelling. Therefore many reactors up to the 1970s used HEU.

But security concerns grew, and a UN-sponsored "International Nuclear Fuel Cycle Evaluation" in 1980 concluded that to guard against weapons proliferation, HEU fuels used in research reactors should be reduced to no more than 20% U-235. This followed a similar initiative by the USA in 1978 when its program for Reduced Enrichment for Research and Test Reactors (RERTR) was launched.

The RERTR program concentrates on reactors over 1 MW, which have significant fuel requirements. About 40 research reactors in USA and abroad either have been or are being converted to low-enriched fuel. The Soviet Union made similar efforts from 1978, and produced fuel with enrichment reduced from 90 to 36%. It largely stopped exports of 90% enriched fuel in the 1980s.

NON-PROLIFERATION

Several international undertakings, supported by the IAEA, focus on conversion of research reactors from HEU fuel to LEU fuel, and repatriation of fresh and spent fuel to the country of origin to eliminate the inventories that represent a proliferation risk.

	Spent Fuel Cycle
SPENT FUEL MANAGEMENT The proper management of spent research reactor fuel requires adequate storage capacity; availability of high-density reprocessable fuel; and national self-sufficiency to deal with the domestic fuel. But managing spent fuel is not simply a technical issue. It also includes key concerns relating to nuclear non-proliferation, physical security and environmental protection.
For many countries, the option of reprocessing the fuel abroad is unlikely to be affordable. Moreover, if the fuel is shipped abroad for reprocessing, the problem of the final disposal of any returned high level waste will have to be addressed anyway. Sooner or later, every country with at least one research reactor, which continues to operate beyond the termination of acceptance programmes of the countries of origin, will need a final solution for spent fuel and/or high level waste. Clearly, access to a multinational long-term interim storage facility and eventually a multinational repository is the optimal solution.