Background: Nuclear materials accountancy must be developed for nuclear facilities

which is required by regulatory in China. Currently

there are some unresolved problems for nuclear materials accountancy of bulk nuclear facilities. Purpose: The retention values and measurement errors are analyzed in nuclear materials accountancy of Power Water Reactor(PWR) fuel plant to meet the regulatory requirements. Methods: On the basis of nuclear material accounting and evaluation data of PWR fuel plant

a deep analysis research including ratio among random error variance

long-term systematic error variance

short-term systematic error variance and total error involving Material Unaccounted For(MUF) evaluation is developed by the retention value measure in equipment and pipeline. Results: In the equipment pipeline

the holdup estimation error and its total proportion are not more than 5%and 1.5%

respectively. And the holdup estimation can be reagarded as a constant in the PWR nuclear material accountancy. Random error variance

long-term systematic error variance

short-term systematic error variance of overall measurement

and analytical and sampling methods are also obtained. A valuable reference is provided for nuclear material accountancy. Conclusion: In nuclear material accountancy

the retention value can be considered as a constant. The long-term systematic error is a main factor in all errors

especially in overall measurement error and sampling error. The long-term systematic errors of overall measurement and sampling are considered important in the PWR nuclear material accountancy. The proposals and measures are applied to the nuclear materials accountancy of PWR fuel plant

and the capacity of nuclear materials accountancy is improved.