The Swiss Federal Nuclear Safety Inspectorate (ENSI) has said it is satisfied with the plans set out by the Paul Scherrer Institute (PSI) for decommissioning the Proteus research reactor. The reactor was mostly used for neutron physics experiments with different nuclear fuels. PSI submitted an application in April 2013 to the Federal Office of Energy (FOE) for permission to decommission the reactor, which was closed in 2011. ENSI was mandated to examine the decommissioning project and to submit an opinion to the FOE.

ENSI said PSI "has taken into account all the relevant provisions of the Nuclear Energy Act, the Nuclear Energy Ordinance, the Radiation Protection Act and the Radiation Protection Ordinance and the guidelines of ENSI and other relevant regulations". In addition, ENSI said it has ensured the decommissioning project complies with international requirements, including those of the International Atomic Energy Agency, the Western European Nuclear Regulators Association and the OECD Nuclear Energy Agency. The project also takes into account the current state of science and technology.

PSI had comprehensively explained in the application documents for decommissioning Proteus that "the protection of human health and environment against radiation can be ensured during the dismantling of the plant, that a feasible concept for dismantling exists and that it has been proven for the disposal of waste generated". ENSI said the conditions for issuing a decommissioning licence for the Proteus reactor have been met, but identified 11 conditions that must be met.

These include removing the fuel from the reactor before the start of demolition work. Another conditions calls for PSI to request permission from ENSI to proceed through each of the various phases of decommissioning. Based on ENSI’s opinion, the Department of the Environment, Transport, Energy and Communication will decide on whether or not to issue a licence to PSI. A decision is expected by the end of this year.

Proteus is a "zero-power" nuclear research reactor that began operating in 1968. The thermal power of the reactor was limited in operation to a maximum of 1kW. As the reactor was operated at such a low power, a cooling medium was not required. In April 2011, PSI decided to permanently shut the reactor, which had hardly been used in the previous two years. PSI expects Proteus to be dismantled by a small demolition team within two years.