f. ezazi

In the first year of fuel loading of nuclear power reactors, uranium enriched at different levels is used (in the type of VVER-1000 reactor, the levels of enrichment are 4.0, 3.6, 3.3, 0.3, 2.4, 2.2, and 1.3%). In this work, for the production of enriched uranium in the first cycle, two parallel methods have been used, one using square cascades and the other using symmetrical tapered cascades. Computational codes have been developed for the design and optimization of the cascades. The meta-heuristic PSO method has been used for optimization. The results show that: 1. if square cascades are used, it is possible to directly produce all uranium enriched with different levels; 2. if tapered cascades are used, it is possible to produce all uranium indirectly, and uranium enrichment at different levels is only possible with a mixing unit in the enrichment facility; 3. The total number of centrifuges or cascades used to produce enriched uranium shows a reduction of about 22–39% compared to the square cascades. 4. If gas centrifuges with high separation capacities are used in square and tapered cascades, the total number of gas centrifuges required for the production of enriched uranium will be close.

In the present work, the performance of a square cascade in the separation phase of tellurium stable isotopes is studied. In this cascade, the selection of an appropriate feed stage, the first stage cut, and the cut of the cascade are the effective parameters. The results showed that in the various separation factors, selection of the middle feed stage leads to appropriate results. Also, if the cut of the first stage is selected in such a way that the cuts of stripping section are obtained the same, it is one of the cut-offs for which the two grouping parameters of components will have the highest possible value. Based on the selection of this cut, one of the possible strategies available through using the code-named SQCASSIM for the separation of tellurium stable isotopes to the enrichment of more than 90% is presented.