The systematic errors on the nuclear material accountancy

The measurement errors are an integral part of the judgment criteria of significance in the MUF and SRD evaluation on the material accountancy and the judgment criteria of the operator's declared values verification with inspector's DA/NDA. On the safeguards, these errors are classified into three kinds, namely, the random error, the short-term systematic error and the long-term systematic error. However it is said that as the short-term systematic error and the long-term systematic error are not familiarity in general, it is difficult to understand them. Accordingly to help understanding them, this paper describes the necessity of the classification between the short-term systematic error and the long-term systematic error on the evaluation of the material accountancy. And this also indicates that the short-term systematic error might have the effect as like either as the random error on some conditions of the application, or as the long-term systematic error on the other conditions. Therefore it is noted that the values of the random error, the short-term systematic error and the long-term systematic error should be estimated corresponding to purpose of the usage of them. (author)