An International Atomic Energy Agency (IAEA) mission has concluded that the operator, vendor and regulator shared responsibility for the 10 April fuel cleaning incident at Paks 2 (see NEI May 2003, p2 and June 2003, p14). The mission was requested by the Hungarian government to provide an independent assessment of the causes and actions taken by the plant and Hungarian authorities.
The IAEA team said that, though the Hungarian Atomic Energy Authority (HAEA) and Paks are committed to improving the safety of the plant, they did not use conservative decision-making in safety assessments for the "unproven fuel cleaning system" designed by Framatome ANP.
The team determined there was over-reliance on Framatome ANP. Time pressure on a fuel outage schedule, combined with confidence generated by previous successful fuel cleaning operations, contributed to a weak assessment of a new design and operation.
On regulatory oversight, the IAEA team said the HAEA underestimated the safety significance of the proposed designs for the fuel cleaning system, which resulted in a less than rigorous assessment than was necessary.
It also resulted in the issuance of a 'licence in principle', which lacked the requirement for an expanded review and assessment.
On the fuel cleaning operation in the course of the incident, the team found that the contractor worked without proper supervision of Paks personnel, who did not receive adequate safety training for this operation.
The team found that Paks undertook appropriate monitoring and assessments of the radiation exposure to staff. The team also agreed with Paks' and HAEA's assessment that the annual dose limits for the general public resulting from the release did not exceed IAEA limits.
The final report is due to be submitted to the Hungarian government this month.