Temperature Dependence of the Primary Species Yields of Liquid Water Radiolysis by 0.8-MeV Fast Neutrons

The yields of species such as e-aq, H•, •OH, H2 and H2O2, formed from the radiolysis of neutral liquid water by the incidence of 0.8-MeV neutrons at temperatures between 25 and 350°C, were calculated by using Monte Carlo simulations. The slowing down of these neutrons through elastic scattering produced recoil protons elastically of ~0.5057, 0.186, and 0.0684 MeV which had linear energy transfers (LETs) of ~40, 67 and 76 keV/µm, respectively, at 25°C. The effects of neutron radiation can be predicted based on the contribution of those first three recoil protons by neglecting the radiation effects due to oxygen ion recoils. Then, the fast neutron yields could be estimated by summing the yields of contributing protons after corresponding weightings were used according to their energy. In this work, yields were calculated at 10-7 and 10-6 s after incidence of neutron radiation in water at the aforementioned temperature range. Overall, there is a reasonably good agreement between our calculated and existing experimental G-values for the entire temperature range. However, we proposed an hypothesis that the not very significant difference between experimental data and our calculated data is due to the different measuring time used in obtaining the experimental data as compared to the ones used in our calculation. Our computed yields for 0.8-MeV fast neutron radiation show an essentially similar temperature dependences over the range of temperature studied with 2-MeV fast neutron and low-LET radiation, but with lower values for yields of free radicals and higher values for molecular yields.Received: 04 October 2014; Revised: 23 March 2016; Accepted: 23 March 201

LOW-LINEAR ENERGY TRANSFER RADIOLYSIS OF SUPERCRITICAL WATER AT 400 °C: DENSITY DEPENDENCE OF THE G(•OH)

Monte Carlo simulations were used to predict the yield of primary specie •OH denoted as g(•OH) that is formed from the radiolysis of pure, deaerat- ed supercritical water (SCW) (H2O) at 400 °C in the range of water density between ~0.15 and 0.6 g/ cm3. It is known that •OH, is one of the oxidizing species that significantly can increase the possibil- ity of various corrosion and material degradation as well. The thorough radiolysis processes in SCW- cooled reactor is not established currently, and it is believed to be a challenge in developing chemis- try control strategies for future Supercritical Water Reactor (SCWR). Since SCWR technology is now still under the conceptual design, hence there is only limited information published on the yields of radiolysis under these conditions. In this work, g(•OH) was calculated at spur lifetime (τs/ minimum time needed before the species within spur distributed homogeneously into the bulk solu- tion), 10-7 and 10-6 sec after the ionization event at all densities. From this work, it is shown that the data measured by other researcher at lower density (0.35 g/cm3) is taken about near the spur lifetime. Finally, more experimental data are highly required in order to examine more thoroughly modeling calculation.

Temperature Dependence of the Primary Species Yields of Liquid Water Radiolysis by 0.8-MeV Fast Neutrons

The yields of species such as e-aq, H•, •OH, H2 and H2O2, formed from the radiolysis of neutral liquid water by the incidence of 0.8-MeV neutrons at temperatures between 25 and 350°C, were calculated by using Monte Carlo simulations. The slowing down of these neutrons through elastic scattering produced recoil protons elastically of ~0.5057, 0.186, and 0.0684 MeV which had linear energy transfers (LETs) of ~40, 67 and 76 keV/µm, respectively, at 25°C. The effects of neutron radiation can be predicted based on the contribution of those first three recoil protons by neglecting the radiation effects due to oxygen ion recoils. Then, the fast neutron yields could be estimated by summing the yields of contributing protons after corresponding weightings were used according to their energy. In this work, yields were calculated at 10-7 and 10-6 s after incidence of neutron radiation in water at the aforementioned temperature range. Overall, there is a reasonably good agreement between our calculated and existing experimental G-values for the entire temperature range. However, we proposed an hypothesis that the not very significant difference between experimental data and our calculated data is due to the different measuring time used in obtaining the experimental data as compared to the ones used in our calculation. Our computed yields for 0.8-MeV fast neutron radiation show an essentially similar temperature dependences over the range of temperature studied with 2-MeV fast neutron and low-LET radiation, but with lower values for yields of free radicals and higher values for molecular yields

Cooling of a Fermi quantum plasma

We propose an adiabatic magnetization process for cooling a Fermi electron gas to ultra-low temperatures as an alternative to the known adiabatic demagnetization mechanism. We show via a new adiabatic equation that at the constant density the increase of the magnetic field leads to the temperature decrease as T ~ 1/H2. This process is identified in our numerical calculations, in which we also recover the adiabatic demagnetization mechanism for certain range