We present experimental and MCNP modeled results of neutron flux monitoring in an irradiator, which consists of a252Cf sealed source housed in the center of a cubic block of high-density polyethylene. This work is contributing to our... more
We present experimental and MCNP modeled results of neutron flux monitoring in an irradiator, which consists of a252Cf sealed source housed in the center of a cubic block of high-density polyethylene. This work is contributing to our development in the delayed gamma-ray spectroscopy non-destructive assay technique for nuclear safeguards and security applications. We evaluated the thermal and resonance flux values using the Westcott foil activation method for two measurement position count rates of 197Au and 115In. Comparisons between the calculated thermal fluxes from measurements and those from MCNP models show deviations of ~20%. However, both the measured and modeled thermal fluxes are two orders of magnitude higher than the fluxes at the resonance peak energies at both measurement positions, demonstrating that the irradiator is sufficient. Furthermore, this work showed that with a252Cf sealed source of a strength of 4.4 × 106 n.s-1, a thermal flux in the range 2-5 × 104 n.s-1.cm-2 is achievable in our compact irradiator making it suitable for active analysis techniques such as DGS.
Safeguards verification of uranium and plutonium in high-radioactivity nuclear material is currently performed using destructive analysis techniques. However, the preparation method is a burden on both the safeguards inspectors and... more
Safeguards verification of uranium and plutonium in high-radioactivity nuclear material is currently performed using destructive analysis techniques. However, the preparation method is a burden on both the safeguards inspectors and facility operators. While nondestructive assay (NDA) techniques would improve the efficiency and time, there are no passive NDA techniques available to directly verify the U and Pu content. As an alternative, the JAEA and JRC are collaboratively developing the Delayed Gamma-ray Spectroscopy (DGS) active-interrogation NDA technique to evaluate the fissile composition from the unique fission product yield distributions. To analyze the data we are developing an Inverse Monte Carlo (IMC) method that simulates the interrogation and evaluates the individual contributions from the mixed nuclear material to the composite spectrum. While the current nuclear data affects the ability to evaluate the composition, the IMC analysis method can be used to determine the s...
Abstract The Japan Atomic Energy Agency (JAEA) is collaborating with the European Commission Joint Research Centre (EC/JRC) to develop delayed gamma-ray spectroscopy (DGS). Toward this, the JAEA Integrated Support Center for Nuclear... more
Abstract The Japan Atomic Energy Agency (JAEA) is collaborating with the European Commission Joint Research Centre (EC/JRC) to develop delayed gamma-ray spectroscopy (DGS). Toward this, the JAEA Integrated Support Center for Nuclear Nonproliferation and Nuclear Security (ISCN) designed the Delayed Gamma-ray Test Spectrometer (DGTS) that uses a 252 Cf source (DGTS-C). This instrument is used to refine the design for a compact, induced-fission safeguards technique to supplement current nuclear material accountancy in reprocessing facilities. Experiments were performed at PERLA laboratory of the EC/JRC Ispra, Italy site to evaluate the neutron-irradiation and associated instrumentation capabilities to obtain delayed gamma-ray spectral signatures of assayed nuclear material. Neutron count-rate measurements were performed using a 3 He detector and confirmed with MCNP6 models that showed a fluence of ∼87.1×10 − 4 n cm−2 n s r c − 1 . Short time-pattern interrogations of various 235U and 239Pu samples resulted in quantifiable delayed gamma-ray peaks from fission products. The peak intensities and spectral signatures resulted in fissile nuclide distinction and linear mass-correlation results. Consequently, we confirm the practicality of this JAEA/ISCN instrument design for DGS interrogation safeguards capabilities.
