Analysis of difficulties in accounting and evaluation of a nuclear fuel project

Through the statistical data of the nuclear material that it had been used in the project, the date of Material Unaccounted For (MUF) is calculated, then it is used to calculate the standard deviation (σ_MUF) and relative standard deviation (δ_MUF) by the method of MUF evaluation. The one of results showed that the date of MUF is less than the double σ_MUF, it accounts for that the confidence coefficient of MUF is more than 95%, it conforms with the standard of the national laws and regulations; but another showed the date of δ_MUF is more than 0.3%, it did not meet the requirements of evaluation standards. The possible reasons were discussed in this article, it is suggested to establish and improve the system retention measurement method, select appropriate measurement method, analysis method and sampling method to improve the nuclear material balance work. (authors)