Transport experience of uranium solution after JCO criticality accident

The criticality accident occurred on September 30, 1999 at JCO’s (formerly Japan Nuclear Fuel Conversion Co., Ltd.) uranium processing plant in Tokai-mura of Japan. The accident occurred in the operation which produce uranium nitrate solution as a product after the purification of uranium powder of less than 18.8% of U-235 enrichment. The detailed report on this incident was made available to the public by the Nuclear Safety Commission of Japan. [1] This paper details the steps taken by Japan Nuclear Cycle Development Institute (JNC) to transport the uranium nitrate solution including the fission products after the criticality accident (JCO’s Uranium Solution) from the JCO’s plant to the Tokai reprocessing plant of JNC. This report includes an explanation of the preparation of the packaging that would enclose the JCO’s Uranium Solution and its conformity to safety regulations, the transportation of the Uranium Solution, and disclosure of transport information In the preparation of the packaging, JNC would normally rely on packaging which could enclose the normal nitrate solution, but in this instance, JCO’s Uranium Solution needed a higher level of shielding than the normal nitrate uranium solution without fission products. Given this situation, and the challenges of handling the material at the facility, JNC decided to modify the existing packaging to increase its shielding properties. The design of the modification, and quality assurance plan for the fabrication of additional shielding was approved by the competent authority. Security concerns dictate that information concerning transportation of nuclear materials must be kept confidential. However, the weight of nuclear materials per transportation at once time was less than weight specified which would warrant additional protection measures. This weight-based assessment is the basis of national regulations for physical protection of nuclear materials. With these circumstances in mind, JNC decided on a limited disclosure of information on transport except for physical protection after consulting with concerned organizations. Also, JNC explained the safety of the transportation in the public hearing held by SAT and local governments.