Answer the following for an Ideal Cascade Gaseous Diffusion

Answer the following for an Ideal Cascade Gaseous Diffusion Enrichment Plant the following conditions:

Tails Assay=0.3 w/o

What are the number of enricher, stripper and total stages required?

Data 1000 MWe PWR require 2 MTU of 5.0 w/o per year Data: 1000 MWe PWR require 2MTU of 5.0 w/o per year. Heads Separation Factor: =1.003 Enrichment Plant Energy Consumption = 1.8 MWHr/(Kg)SWU Feed Material = 0.71 w/o You can ignore U losses during various process steps. Costs: Ore : $15/#U308 3 8 Conversion : -$5/#U Produced as UF 6 Enrichment 0/SWU

Solution

Uranium found in nature consists largely of two isotopes, U-235 and U-238. The production of energy in nuclear reactors is from the \'fission\' or splitting of the U-235 atoms, a process which releases energy in the form of heat. U-235 is the main fissile isotope of uranium.

Natural uranium contains 0.7% of the U-235 isotope. The remaining 99.3% is mostly the U-238 isotope which does not contribute directly to the fission process (though it does so indirectly by the formation of fissile isotopes of plutonium). Isotope separation is a physical process to concentrate (‘enrich’) one isotope relative to others. Most reactors are light water reactors (of two types – PWR and BWR) and require uranium to be enriched from 0.7% to 3-5% U-235 in their fuel. There is some interest in taking enrichment levels to about 7%, and even close to 20% for certain special power reactor fuels.

Uranium-235 and U-238 are chemically identical, but differ in their physical properties, notably their mass. The nucleus of the U-235 atom contains 92 protons and 143 neutrons, giving an atomic mass of 235 units. The U-238 nucleus also has 92 protons but has 146 neutrons – three more than U-235 – and therefore has a mass of 238 units.

The difference in mass between U-235 and U-238 allows the isotopes to be separated and makes it possible to increase or \"enrich\" the percentage of U-235. All present and historic enrichment processes, directly or indirectly, make use of this small mass difference.

Some reactors, for example the Canadian-designed Candu and the British Magnox reactors, use natural uranium as their fuel. (For comparison, uranium used for nuclear weapons would have to be enriched in plants specially designed to produce at least 90% U-235.)