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10-14 February 2020
Europe/Vienna timezone

Certification bodies play an increasingly important role in the NMAC of bulk nuclear facilities in China

Not scheduled
Paper PP: Nuclear material accounting and control


Mr duohong li


In recent years, the threat of international nuclear terrorism is becoming increasingly serious, and the risk of the proliferation and loss of nuclear materials is increasing. In order to ensure the safety of human beings and the international community and prevent nuclear materials being stolen and illegally transferred, effective technology is needed to account and control nuclear materials. The accuracy of nuclear material measurement needs to be evaluated by uncertainty. IAEA has issued 6 international target values for the protection and calculation of nuclear materials so far, namely, 1983, 1987, 1988, 1993, 2000 and 2010. Both the facilities and the inspection agencies need the reference value of the measurement method performance index, which is used to determine the volume, quality or isotopic composition of the measured object. The target value can be used as a reference standard to judge the validity of the measurement.
In production practice, all kinds of errors are superimposed and transmitted each other. In the bulk nuclear facilities, the total error variance is influenced by random error, long term system error and short term system error. In order to make MUF closer to the real value, in accounting, we need to seize the key main error factors, improve the measurement system and the measurement accuracy. The target value includes the random error and the system error. It is necessary to carry out the experiment and data comparison for each material and each method of analysis and measurement to get the effective uncertainty target value. Uranium forms are mainly uranium hexafluoride (depleted, natural, low concentration), natural uranium, low enriched uranium, uranium oxide, uranium metal. Taking the measurement of 235U enrichment as an example, it can be divided into DA and NDA methods. Comparison activities involve many factors such as sample preparation, distribution, transportation of radioactive materials, activity organization and other factors. It will be faced with many challenges in the future.
Especially, there is no very effective scientific method for estimating the holdup in equipment and pipeline of bulk plant. Domestic laws and regulations require that all the accounting data in the balance period should be the actual measurement value, while the holdup in equipment and pipeline can not be measured and can not meet the requirements of accounting evaluation. At present, the operator of nuclear facilities mainly adopt the empirical estimation method to estimate the holdup amount in process equipment and pipelines, with a large uncertainty. In the measurement of holdup, the international target value can not be achieved.
The target value realization relies on a variety of factors, combining with the actual situation in China, the topics of discussion are: the sub item uncertainty, holdup measurement, need of standard references, Carry out comparison activities , the establishment of certification bodies, including development of measurement software and so on. Careful planning and organization through certification bodies, enhancing the exchange of experience among various nuclear facilities will be a challenge in the future.

Gender Male
State China

Primary author

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