Seals broken on monitoring equipment cabinet of IAEA and Euratom at Posiva’s encapsulation plant
The facility for the final disposal of spent nuclear fuel is during the Trial Run of Final Disposal already preparing for operation as a nuclear facility. The spent fuel, which is the nuclear material used in the nuclear facility, as well as the handling of the fuel are monitored by international atomic energy organisations, among others. In August 2024, the seals on the monitoring equipment cabinet at the encapsulation plant were found to be broken.
The International Atomic Energy Agency, IAEA, which operates under the United Nations, as well as the European Atomic Energy Community, Euratom, detected in connection with the inspection of their monitoring equipment in Olkiluoto that the seals on the server cabinet of the monitoring equipment at Posiva’s encapsulation plant were broken. The situation had not been reported internally according to Posiva’s expectations. An investigation that has been carried out showed that the seals had been broken as a result of a human error. Deficient understanding and experience as concerns the monitoring equipment of IAEA and Euratom are evaluated to be contributing factors.
The server installed in the cabinet transmits monitoring data related to the handling of spent nuclear fuel to the monitoring network of IAEA and Euratom. The monitoring implemented remotely by IAEA and Euratom is designed to verify that nuclear material is only used for peaceful purposes in accordance with the Treaty on the Non-Proliferation of Nuclear Weapons. For the final disposal operation, this means that all of the spent fuel transported to the encapsulation plant is packed in cannisters and the cannisters are deposited in the final disposal holes demonstrably following the plans announced by Posiva.
The breaking of the seals is a severe event and a special report as referred to in Nuclear Safety Guide has been drawn up about the event. The report was submitted to the Radiation and Nuclear Safety Authority of Finland and to Euratom at beginning of September 2024. Posiva has implemented corrective actions to prevent the recurrence of a similar event. All equipment installed at Posiva’s facilities have now been provided with better designations. The room in which the monitoring equipment is located is from now on to be kept locked at all times and access rights to the room are restricted. In addition, the integrity of the monitoring equipment is brought up in training.
At the time of the event, the encapsulation plant was being prepared for the Trial Run of Final Disposal with a large number of employees working at the plant, and access rights had not yet been restricted to the extent they will be during production operation.
Spent nuclear fuel is not yet handled in Posiva’s facilities. The various stages of encapsulation and final disposal are tested using empty test assemblies and cannisters. The Trial Run of Final Disposal will also provide useful experience in the implementation of national and international monitoring, complete with notification and reporting procedures as well testing of remote monitoring. The event was not of any significance to nuclear or radiation safety. The safety significance of the event is associated with compliance with agreed practices and procedures as well as deficient reporting of a nonconformance.
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