No abstract

This report describes calculations that examine the sensitivity of actinide isotopes to various reactor parameters. The impact of actinide isotope build-dp, depletion, and decay on the neutron source rate in a spent-fuel assembly is determined, and correlations between neutron source rates and spent-fuel characteristics such as exposure, fissile content, and plutonium content are established. The application of calculations for evaluating experimental results is discussed. I.

Nondestructive measurement of the passive neutron sig¬ natures of irradiated light-water reactor fuel assemblies is a rapid and simple technique for verifying operatordeclared exposure values. Fuel assemblies from four differ¬ ent reactor facilities have been measured to establish the functional relationship between the operator-declared ex¬ posure values and the experimentally measured neutron emis¬ sion rates. Experimentally measured neutron emission rates of small fuel rod sections have been shown to agree with the predicted results from our calculational model. Destructive results for the actinide isotopes also agreed very well with our prediction. Neutron emission rates varied by 30 to 40% between opposite corners of the source fuel assembly. Sym¬ metrical neutron detector systems that measure all sides simultaneously were evaluated. whereas the Cm chain goes 241 Pu 242 Pu 243 Am-• 243 Pb ojp 244 *Both Am and Am have metastable states.

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This interim report reviews the potential role of nondestructive measure¬ ments on irradiated light-water reactor (LWR) fuels. The study is being per¬ formed for the Savannah River Interim Spent-Fuel Storage Project Office, with technical review by Savannah River Laboratory. Until recently, the scope of this study watt to develop the conceptual design of a spent-fuel nondestructive verification and assay system (VAS) for future away-from-reactor (AFR) spentfuel storage facilities and to fabricate, test, and demonstrate a prototype VAS syitem. The design of a prototype VAS is "'•80% complete, and some of the hardware already has been procured* Recent cha;-.-jas in Government policy regarding the acquisition and storage of excess spent fuel in federally operated AFR storage facilities may terminate the present study* At the same time, the Department of Energy (DOE) is pursuing a new policy for implementing new technologies to enable the domestic nuclear power industry to store its own spent fuel at reactor sites as much as possible, pending the startup of spent-fuel reprocessing plants* In the meantime, the nuclear power industry, under the joint sponsorship of DOE and the Electric Power Research Institute (EPRI), is investigating new fuel management and stor¬ age techniques aimed at using high-burnup fuels* Techniques in an advanced stage of development include high-density fuel storage, fuel-bundle disassembly with repackaging of new assemblies, and compaction and storage of high-burnup rods* Nuclear materials accounting and control for safeguards and nonproliferation and for new spent-fuel management technologies require nondestructive measurements that span a wide range of fuel characteristics and fuel types (Table S-I). In addition to satisfying safeguards requirements, these measure¬ ments can satisfy facility requirements, such as in-plant materials management, process control, and criticality control* Several nondestructive techniques are already well advanced, primarily because of this project and the US program of technical assistance to the International Atomic Energy Agency (IAEA)* The applicability of these nondestructive techniques is not limited to LWR spentfuel assemblies* The basic technology can be applied to any spent-fuel material (material test reactor and liquid-metal fast breeder reactor fuel materials). This new spent-fuel nondestructive measurement technology should be transferred to the nuclear industry* Specific recommendations of this interim study include • The Cerenkov viewing device and the neutron ring detector, both already developed for the IAEA/ should be transferred to the domestic nuclear industry* These devices are portable, relatively easy to use, and provide confirmation of the integrity and the burnup of spent-fuel assemblies. • The spent-fuel nondestructive VAS should be completed, and a program of field testing and demonstration should be carried out. This system would be the prototype for future in-plant, nondestructive measurement systems at spent-fuel storage and reproc...