United States and Russian Federation have been in process of reducing their nuclear arsenals since 1993, when both sides signed agreement, which started the Megatons to Megawatts Program. The program was designed to convert weapon-grade uranium into commercial-grade uranium suitable for making fuel for nuclear reactors. It took seven more years, before the USA and Russia were able to reach another agreement concerning disposal of weapon-grade plutonium, even more dangerous than the uranium component of nuclear arms. The Plutonium Management and Disposition Agreement was signed in September 2000. Let’s take a closer look at why it took so long. In order to answer this question it is necessary to compare disposal process for uranium and plutonium.
Natural uranium ore consists of less than 1% of uranium-235 (U-235). Nuclear fuel for power plant reactors requires concentration of U -235 from 3 to 5% .This is called low-enriched uranium or LEU. After that uranium could be enriched even more to create weapon-grade uranium, also called high-enriched uranium or HEU. The Megatons to Megawatts Program eliminates HEU from nuclear warheads by using a relatively simple process of downblending uranium from its high-grade enriched form to low-enriched form.
Plutonium-239, used in nuclear warheads, cannot be found in natural form. It is produced in nuclear reactors from uranium-235. This process is irreversible, which means weapon-grade plutonium cannot be simply downblended as uranium can. The Department of Energy had explored about forty possible options for plutonium disposal from storage and immobilization to irradiation. The final decision was made in favor of irradiating plutonium in commercial reactors. In order to do that, weapon-grade plutonium must be fabricated into mixed oxide uranium-plutonium (MOX) fuel.
According to the Plutonium Management and Disposition Agreement, each country will dispose 34 metric tons of weapon-grade plutonium (combined it equals to 17,000 nuclear warheads), but in order to achieve that, new facilities must be built. The Department of Energy has been constructing three facilities at its Savannah River Site in South Carolina, which planned to start operations in 2016. Russia has already fabricated limited amount of MOX fuel, but it needs to modify existing facilities in order to meet the agreed-upon disposition rate. The full-scale disposal of weapon-grade plutonium is expected to start in 2018.
1. .National Nuclear Security Administration. Plutonium Disposition.
2. National Nuclear Security Administration. Reducing the Nuclear weapons Stockpile.
3. USEC Inc. Megatons to Megawatts.
4. 2000 Plutonium management and Disposition Agreement. April 13, 2010.
5. NRC: Fact Sheet on Uranium Enrichment.