Applications of curium measurements for safeguarding at large-scale reprocessing plants
Safeguarding the plutonium passing through a large-scale reprocessing plant (such as one with 800 t of uranium per year) involves nondestructive assay measurements for plutonium at key points. The gamma-ray and neutron signals from the plutonium are generally hidden by the much larger backgrounds from fission products and actinides, so indirect measurements are routinely used. The intense neutron emission rate from spent fuel is from curium. In a spent fuel assembly at the head-end of a plant, the curium neutrons are used to deduce the amount of plutonium present. Coincidence and multiplicity counting are alternative ways to measure neutrons from spent fuel; they have advantages over total neutron counting in certain conditions and offer new opportunities for examining assemblies. New uses for measurements of curium`s neutrons are proposed to safeguard waste streams. From a year`s work at a large-scale plant, 4 to 7 kg of plutonium can remain in leached hulls and 4 to 22 kg of plutonium can remain in the vitrified high-level liquid waste. While the plutonium in these wastes has the safeguards advantage of being dilute, it is important to verify (a) that the many kilograms involved are in fact present and (b) that the declared masses are not higher than the actual amounts so that more concentrated plutonium cannot pass through the plant by masquerading as waste. Curium measurements on spent fuel assemblies, the accountability tank, and leached hulls would form a safeguards system around all the inputs and outputs of a plant`s head-end where the plutonium is always intimately mixed with the curium. A neutron measurement of the vitrified waste would help identify the presence of a diversion path upstream because essentially all of the curium measured in the spent fuel assemblies should also be found in the vitrified waste (on a batch basis). 7 refs., 4 figs.
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 513514
- Report Number(s):
- LA-UR-97-1449; CONF-970545-4; ON: DE97007178; TRN: 97:014574
- Resource Relation:
- Conference: 17. international conference on distributed computing systems, Baltimore, MD (United States), 27-30 May 1997; Other Information: PBD: 1997
- Country of Publication:
- United States
- Language:
- English
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