Fast multiplicity counter featuring stilbene detectors for special nuclear material assay
The Treaty on the Nonproliferation of Nuclear Weapons demands for new instruments to prevent diversion of fissile material and safeguard controls. We present a fast neutron multiplicity counting system based on organic scintillators, i.e. liquid EJ-309 and stilbene. The system is able to detect fission correlated counts and photon and neutron multiplets, needed to quantify fissile mass, without the need of complex electronic circuitry and unfolding procedures, required in moderated systems. Moderated system, typically based on helium-3 detectors, feature a gate time of hundreds of microseconds. Conversely, the use of organic scintillators allows an exceptionally short gate time of hundreds of nanoseconds. This results in a reduction of accidental neutron coincidence. In our system, the superior gamma-neutron discrimination capabilities of stilbene scintillators allow to measure high-order multiplicities (> 3) and the inspection of complex source terms. This counter is thus also suitable for the assay of newer fuels containing plutonium and other fissionable actinides. A prototypal version of the well-counter was assembled and tested at the University of Michigan, using a spontaneous fission and an (a,n) neutron source, i.e. 252Cf and PuBe respectively. Presented measured results show excellent agreement with simulations. The viability of the system to discriminate time-correlated fission neutrons from random, uncorrelated neutrons was proved. An experimental campaign will be carried out at Idaho National Laboratory in August 2015 to characterize weapon grade plutonium samples.
- Research Organization:
- Idaho National Lab. (INL), Idaho Falls, ID (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA)
- DOE Contract Number:
- DE-AC07-05ID14517
- OSTI ID:
- 1405303
- Report Number(s):
- INL/CON-15-35247
- Resource Relation:
- Conference: IEEE Nuclear Science Symposium, San Diego, CA, USA, October 31–November 7, 2015
- Country of Publication:
- United States
- Language:
- English
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