Kärnenergiteknik

This document specifies the suitable procedures and methods for the decommissioning of cyclotrons used by physics experiments and radioisotope production. For this purpose, computer simulation and real measurement of activated materials method can be employed.

ISO 7097-1:2004 describes an analytical method for the determination of uranium in pure product material samples such as U metal, UO2, UO3, uranyl nitrate hexahydrate, uranium hexafluoride and U3O8 from the nuclear fuel cycle. This procedure is sufficiently accurate and precise to be used for nuclear materials accountability. This method can be used directly for the analysis of most uranium and uranium oxide nuclear reactor fuels, either irradiated or unirradiated, and of uranium nitrate product solutions. Fission products equivalent to up to 10 % burn-up of heavy atoms do not interfere, and other elements which could cause interference are not normally present in sufficient quantity to affect the result significantly. The method recommends that an aliquot of sample is weighed and that a mass titration is used, in order to obtain improved precision and accuracy. This does not preclude the use of any alternative technique which could give equivalent performance. As the performance of some steps of the method is critical, the use of some automatic device has some advantages, mainly in the case of routine analysis.

The objective of this document is to characterize the gaseous effluents tritium and carbon-14 generated by nuclear facilities during operation and decommissioning and occurring in the same chemical species as hydrogen and carbon, e. g. as water vapour (HTO), hydrogen gas (HT, TT), carbon dioxide (14CO2), carbon monoxide (14CO), methane (CH3T, 14CH4). It concerns measurements on samples that are representative of a certain volume stream or volume of discharge during a given period of time and of the corresponding volume discharged. The result is therefore expressed in becquerels. This document applies to samples that were obtained by sampling methods according to ISO 20041-1 and describes — analysis methods for the determination of tritium and carbon-14 activities by liquid scintillation counting and — calculation methods to determine the tritium activities discharged as tritiated water vapour (HTO) and tritium in other chemical compounds (non-HTO) as well as carbon-14 activities discharged as carbon dioxide (14CO2) and carbon-14 in other chemical compounds (non-14CO2). This document does not apply to tritium and carbon-14 activity concentrations in the environmental air, e. g. in the vicinity of nuclear installations. The accountability rules of the activities discharged necessary for the establishment of regulatory reports do not fall within the scope of this document and are the responsibility of the regulatory bodies.