Neutronic design study of accelerator driven system (ADS) for Jordan subcritical reactor as a neutron source for nuclear research.
In this paper, a preliminary neutronic design study of an accelerator driven subcritical system for Jordan Subcritical Assembly (JSA) is presented. The conceptual design of coupling the JSA core with proton accelerator and spallation target is investigated, and its feasibility as a neutron source for nuclear research, and possibly for target irradiation and isotope production evaluated. 3D MCNPX model of the JSA reactor, the accelerator beam, and the Pb target was developed, based on actual reactor parameters. MCNPX calculations were carried out to estimate the absolute radial and axial neutron flux in the reactor, and to calculate the multiplication factor Keff and heat generated in the reactor. Numerical results showed an enormous increase in the neutron flux, by seven orders of magnitude, compared to the current JSA core design using Pu-Be source. In this research the results obtained are discussed and compared with those of the JSA, and do confirm the feasibility of utilizing the JSA as a viable nuclear research facility with adequate neutron flux.
Neutronics Analysis and Optimization for Fusion Driven Subcritical Spent Fuel Burning System
Neutronics analysis and optimization including general performances, burnup calculation analysis, materials activation characteristic and irradiation damage analysis of blanket for fusion driven subcritical spent fuel burner (FDS-SFB) were performed. The results showed the fission blanket could reach high performance in a long burn up when the mass percent of transuranic nuclides reach to 15 %, depleted uranium added to the blanket could improve the ability of nuclear waste incineration and fuel breeding and FDS-SFB is able to achieve efficient utilization of nuclear waste to produce energy without additional new nuclear waste production.
Determination of neutron multiplication of subcritical HEU systems using delayed neutrons
Abstract This report presents a new method for the nondestructive analysis of highly enriched uranium (HEU). The method uses a source of 14-MeV neutrons to induce fission in the HEU sample. The 14-MeV neutron source is pulsed at a rate of 50 Hz. Between pulses, neutrons are detected with a medium-efficiency 3 He-based neutron detector. These neutrons are delayed neutrons from fission products that result from HEU fission events induced during the pulse and from fission events induced by the delayed neutrons from the fission products. The time history of neutron detection is recorded and subsequently analyzed according to the Feynman reduced variance method to yield rates of detection of one ( N 1/s), two ( N 2/s), and three ( N 3/s) neutrons from fission events. Ratios of ( N 2/s)/( N 1/s) and ( N 3/s)/( N 1/s) are compared with model calculations to extract the neutron multiplication. The rate N 1/s is used to deduce the HEU system mass. Measurements were performed on a set of spherical HEU samples enriched to 93% metal. The samples were assembled from a set of nesting hollow hemispheres. The mass of the HEU samples ranged from 592 to 13722 g. Experimentally determined total neutron multiplications for the HEU samples were compared with calculations performed with the ONEDANT code. Overall agreement was better than 5%. Experimentally determined mass values agreed with the stated mass values to better than 5%.