As reported in NEI’s November issue (page 6), some test data for the neutron shielding material used in Japanese spent fuel transport casks, had been altered. The incident has been investigated by a panel set up by the Science and Technology Agency. The company responsible was Genden Koji (Genden Engineering and Construction Company) which is a wholly owned subsidiary of the Japan Atomic Power Company (which is abbreviated to Genden in Japanese).
On 3 December the two companies announced that Genden Koji will be closed down to take responsibility for the incident. Genden Koji will give up its shielding materials business immediately and cease all operations by the middle of next year.
A number of executives involved will receive salary cuts. Tokyo Electric Company and three other utilities will also punish some executives for failing to supervise their subcontractors adequately. The punishments include a 30% salary cut for 2 months.
Technically, the problem is probably not a serious one. The shielding material concerned is a two-part resin containing boron which is filled into cavities in the steel casks. The boron and hydrogen densities in the resin are checked after mixing and should meet specified values. In several batches, the specifications were not met, although the deviation was quite small, and the test data was altered to conceal the fact. Tokyo Electric has recalculated the shielding performance using the actual analysis data and taking into consideration design margins and allowances for analytical errors and has concluded that the overall shielding requirements are still satisfied. This is consistent with radiation measurements taken at site during handling of spent fuel which have always been less than the limit.
However, the incident has been a great embarrassment to the Japanese nuclear industry which has been trying to project an image of complete honesty and openness.