Abstract: An analytical procedure for the separation and determination by zirconyl phosphate and chloroplatinate-precipitation for cesium is developed with an accuracy δb±0.5%. Decontamination factors for other nuclides are: 141Ce5.0×105,140La 1.2×105,140Ba≥1.7× 104, 103Ru. 5.4×104, 95Zr 7.0×104,95Nb 5.4×104,239Pu>3.5×103 and U>1.1×103. The calculated values of burnup with 137Cs and 144Ce as monitors are compared and differ by 1.6%, and the dependence of 134Cs/137Cs ratio on the burnup is determined.