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.
Nuclear waste transmutation performance assessment of an accelerator driven subcritical reactor for waste transmutation (ADS-NWT)
Abstract As a concept of lead–bismuth cooled accelerator driven sub-critical reactor, ADS-NWT was proposed for nuclear waste transmutation by FDS Team. In this paper, preliminary transmutation performance assessment on ADS-NWT was performed by using metallic dispersion fuel and metal alloy fuel. The studies were committed to improving the Discharge Transmutation Support Ratio (DTSR) under three key design constraints. Subject to the design constraints on the effective multiplication factor, the peak linear power and the peak fast neutron fluence, the design studies had been performed for ADS-NWT blanket. From these studies, the results showed that the maximum DTSR was primarily related to the MA/Pu ratio, the peak fast neutron fluence and fuel design under imposed design constraints. The maximum DTSR could be ∼47 in one refueling cycle time when the thermal power was fixed to 1000 MW and the effective multiplication factor was 0.98 based on the specific design.
Experimental energy barriers to anions transporting through nanofiltration membranes.
Environmentally relevant contaminants fluoride, chloride, nitrate, and nitrite face Arrhenius energy barriers during transport through nanofiltration (NF) membranes. The energy barriers were quantified using crossflow filtration experiments and were in the range of 7-17 kcal·mol(-1), according to ion type and membrane type (Filmtec NF90 and NF270). Fluoride faced a comparatively high energy barrier for both membranes. This can be explained by the strong hydration energy of fluoride rather than other ion properties such as bare ion radius, fully hydrated radius, Stokes radius, diffusion coefficient, or ion charge. The energy barrier for fluoride decreased with pressure, indicating an impact of directional force on energy barriers. The influence of temperature-induced pore radius variability and viscosity on energy barriers was considered. The novel link between energy barriers and ion properties emphasizes the importance of ion hydration and/or partial dehydration mechanisms in determining transport in NF.