EVALUATION BY PHYSICAL MEASUREMENTS OF SHIELDING ANALYSIS METHOD USED FOR TN-12/1

TN -12/ 1 package containing 12 spent fuel assemblies have been shipped from PWR power plants in Japan to overseas reprocessing facility in accordance with the regulations for safe transport of radioactive materials. The Kansai Electric Power Co. , Inc. has introduced a TN-12/ 1 packaging using a new basket that was designed by the Transnuc leaire S. A. in France. In this basket, the conventional sintered B.C/ Cu plates have been replaced by a boron/ aluminum alloy (P.Meyer et al., 1989), and stainless stee l shielding blocks have been used as some parts of the basket sector. This replacement was accompanied by a revision of the documents of safety analyses for TN- 12/ 1 package including shielding calculations. After introducing the new basket, the Comp any carried out the shipping of the first TN- 12/ 1 packages containing spent fuel assemblies. During the shipp ing process, the Company jointly with Transnuclear Ltd. measured the dose equivalent rates around the TN-12/ 1 packages. The measured values were compared with the values determined by the eval uation method for dose equivalent rate in the shielding analysis. This comparison demonstrated that the calculated values coincide with or slightly exceed the measured values. At the same time, the shielding performance of the new basket was also checked.