In a nuclear facility, when a difference between the physical inventory listing and accountancy records is discovered, the French law (Article 11 of the "Décret 81-512") requires a declaration to the High Civil Servant for Defence of the Ministry in charge of Industry. Moreover, according to that same article, in case of a suspicion of loss, theft or diversion of nuclear material, the licensee has to declare this event to the police. In the meantime, an investigation is carried out in the facility, and in cooperation with other facilities if necessary. These measures are aimed at :
- Finding the lost nuclear material (if any),
- Understand the causes of the problem,
- Solve the differences by acting on the PIL or/and accountancy records,
- Act to prevent any other occurrence of this kind of event.
These actions can take place in the general field of a police investigation. After all these facts and information have been gathered, the licensee writes down a complete file which is transferred to the High Civil Servant for Defence of the Ministry in charge of Industry, in order to be analysed by his technical support body (IRSN). Thus, the IRSN is able to give it's conclusion to the authority about this event, especially regarding :
- The causes of the event,
- Relevance and completeness of investigations,
-Pertinence of the corrections,
- Relevance of corrective actions,
- Probability of another occurrence.
This system is useful to ensure a complete follow-up of the events occurring in the various nuclear facilities in France, to have an extensive overview of the problems on a national scale. If an item is found in a facility A, numerous questions must be answered :
- Where does it come from ?
- Since when is it in facility A ?
- How did it happened that this item has been transferred from facility B to facility A without the transfer of information ?
We will consider these issues through examples. This kind of event can be potentially very rich in terms of information feedback, analysis of possible weaknesses of systems of accountability of nuclear material in facilities, and improvement of these systems. Moreover, any loss or discovery of nuclear material in a facility can lead to an inventory of nuclear material in case of emergency.