Supplementary Diorit decommissioning project at PSI meets protection objectives

In January 2024, the Paul Scherrer Institute (PSI) submitted a supplementary decommissioning project for the Diorit nuclear installation. The Swiss Federal Nuclear Safety Inspectorate (ENSI) has examined the documents and drawn up an expert report.

In preparing the expert report, ENSI ensured that PSI took into account the relevant provisions of the Nuclear Energy Act, the Nuclear Energy Ordinance, the Radiological Protection Act and the Radiological Protection Ordinance as well as other relevant regulations and the relevant ENSI guidelines. Moreover, ENSI also checked whether the supplementary decommissioning project complies with the requirements of the International Atomic Energy Agency (IAEA) and takes into account the latest state of the art.

• Requirements for a decommissioning order met

  In its expert report, ENSI has come to the conclusion that, given due consideration of 14 stipulations, the conditions for the issue of the supplementary decommissioning order have been complied with.

  The conditions relate to various aspects of the decommissioning project. Among other things, they govern the subdivision into three decommissioning phases as well as the release requirements for individual decommissioning steps of the individual dismantling phases.

  In its decommissioning project, PSI was able to demonstrate comprehensibly that during the decommissioning work:

  • the basic protection objectives of nuclear safety can be adhered to;
  • the requirements of nuclear security can be met;
  • the dismantling work can be carried out safely;
  • personnel, population and the environment can be protected against ionising radiation;
  • sufficient personnel with suitable qualifications and an appropriate organisation can be made available;
  • all radioactive waste can be delivered to a final disposal facility in a suitable condition.

PSI decided on decommissioning in 1977

In 1977, the Diorit research reactor, operated at the time by the Swiss Federal Institute for Reactor Research (EIR), underwent final shutdown with the remaining nuclear fuel subsequently being removed from the plant. On the basis of a decommissioning project, a decommissioning order was issued on 26 September 1994. Today, the remains of the largely dismantled Diorit research reactor remain in the building of the Diorit nuclear installation.

Based on new findings, PSI has now decided to completely dismantle the nuclear installation in line with the 1994 decommissioning order so that nuclear energy legislation will no longer apply to the site. Due to the interruption, a procedure pursuant to Art. 62 of the NEA in conjunction with Art. 49 et seq. of the NEA is to be carried out to obtain a supplementary decommissioning order.

The compiled expert report serves as the basis for this supplementary decommissioning order, which is issued by the procedural authority, the Swiss Federal Office of Energy SFOE, on behalf of the Department of the Environment, Transport, Energy and Communications (DETEC).

Further information

• Expert Report on the Supplementary Diorit Decommissioning Project of the Paul Scherrer Institute