A FEASIBILITY STUDY AND APPLICATION OF VERIFICATION TECHNIQUE FOR DETERMINING THE NUMBER OF FUEL ASSEMBLIES IN A PILED UP SHIPPING CONTAINER

Year
1990
Author(s)
R. Abedin-Zadeh - International Atomic Energy Agency
Kazuo Nidaira - Nuclear Material Control Center Safeguards Analytical Laboratory
Y. Hirato - Safeguards Analytical Laboratory, Nuclear Material Control Center
P. Karasuddhi - International Atomic Energy Agency
H. Sano - Japan Nuclear Fuel Limited
R. Kurokawa - Safeguards Analytical Laboratory, Nuclear Material Control Center
T. Iwamoto - Science and Technology Agency, Prime Minister' s Office, Japan
N. Hirose - Science and Technology Agency, Prime Minister's Office, Japan
Abstract
The establishment of NDA verification technique for the determination of the number of LWR fuel assemblies in a shipping container without moving or opening it is a pressing need in the fuel fabrication plant, in which usually a large amount of these inventory items exists with 4 to 5 flights of containers piled-up in the storage area. In the measurement system developed, a detector with a specially designed cpllimator is set in the space between the shipping containers, and is moved transversely over the selected container (consequentially, above the fuel assemblies). The 186 keV gamma-ray peak pattern - the scanning profile of the gamma-ray intensity - is obtained by the moving collimated detector. The number of assemblies in the container can be easily determined from the obtained gamma-ray peak pattern. The measurement system is composed of a portable multichannel analyzer. a Nal (Tl) detector, a \"mole-like\" lead collimator with wheels, and a laptop computer. A feasibility study of this technique was carried out in the presence of IAEA inspectors for an acceptance test at the Japan Nuclear Fuel Co. . Ltd. (JNF, Kanagawa) plant. It was found. from the in-situ application at me plant, that this technique was\" satisfactory for the determination of the number of assemblies in the packed and stationary container for the detection of gross defect, and could be applied to other LWR fuel fabrication plants of this kind. This technique was actually used jointly with IAEA at the JNF plant as an authorized safeguards technique in :he Physical Inventory Verification (PIV).