Simulation of 36S stable isotope enrichment by square single withdrawal cascade

Among the four stable isotopes of sulfur, the heaviest isotope, 36S, has found many applications in radioisotope production and neutron activation. In the present work, due to the very low natural abundance of 36S, the single withdrawal cascades are used to separate this isotope. The concentration distribution equations in the transient state are separated using the Laasonen method and linearized by the q iteration method to simulate the cascade. The code is validated using existing experimental results. To separate the 36S isotope to a high concentration of 90% by a fixed number of centrifuge machines, different arrangements of the square single withdrawal cascades, the feed stage location, and the feed flow rate were investigated. In the arrangement with 15 stages and eight centrifuge machines at each stage, the concentration of 36S in the reservoir reaches 95% after 1460 hours. The results showed that reducing the feed flow of the cascade and increasing the distance of the feed stage from the reservoir leads to an increment in the concentration of 36S in the reservoir.