Solid formation in a simulated high level liquid waste (HLLW) was experimentally examined at 2M and 0.5M nitric acid concentrations. The precipitation studies were conducted by refluxing the simulated HLLW around 100°C. Zr, Mo, Te and Ru were major precipitation elements in both 2M and 0.5M HNO3 solutions. The amount of precipitate in 2M HNO3 solution decreased with decreasing Zr concentration and no precipitation was found in the solution without Zr. Only about 10% of Zr, Mo and Te were precipitated, if the Mo/Zr ratio in the 0.5M HNO3 solution was kept below 0.5. Complete removal of Zr and Mo was the most effective way to prevent solid formation in the solution with 2M and 0.5M HNO3 concentrations.
The acidity change and solid formation in a simulated high level liquid waste (HLLW) containing precipitate were experimentally examined, when the acidity was reduced from 2M to 0.5M by denitration or simple dilution. The acidity of the simulated HLLW containing precipitate could be adjusted from 2M to around 0.5M by means of denitration or dilution, as well as the case of simulated HLLW without precipitate. The precipitation fractions of Zr, Mo and Te during denitration decreased with increasing amount of the precipitate already contained in the simulated HLLW. The amount of solid formed in the dilute simulated HLLW also decreased with increasing amount of precipitate in the simulated HLLW. Two process flow sheets for preparing HLLW for transuranic elements extraction were developed. One was a denitration process and the other a dilution process.
Authors:T. Aze, M. Fujimura, H. Matsumura, K. Masumoto, N. Nakao, H. Matsuzaki, H. Nagai, and M. Kawai
In order to estimate the total radioactivity induced in a concrete shield by thermal neutron-capture reactions at high-energy
accelerator facilities, the observed activity of 36Cl in the concrete is expected to serve as an indicator of the thermal neutron fluence. Since 36Cl can also be produced from K and Ca by spallation reactions, we measured these production rates in order to clarify the
contribution of each reaction. The Cl, K, and Ca targets were irradiated with neutrons having a maximum energy of 500 MeV.
As a result, the production rates of 36Cl from Cl were only two orders higher than those from K and Ca. It was found that the 36Cl production ratios from Cl, K, and Ca were 6.7%, 6.8%, and 86.5%, respectively, and Ca was the main source of 36Cl production.
Authors:H. Haba, H. Matsumura, Y. Miyamoto, K. Sakamoto, Y. Oura, S. Shibata, M. Furukawa, and I. Fujiwara
The recoil properties of 26 radionuclides produced in the photonuclear reactions on Cu at bremsstrahlung end-point energies
(E0) of 250 to 1000 MeV have been investigated using the thick-target thick-catcher method. Kinematic properties of the product
nuclei were calculated by the two-step vector velocity model. The calculated mean kinetic energies,T, of product nuclei increase with increase of the mass difference between products and target, reflecting the resonance natures
and absorption mechanisms. TheT atE0≥600 MeV were well reproduced by a calculation performed by PICA code byGabriel andAlsmiller atE0=400 MeV, except for (γ,xn) products by giant-resonance.
Authors:K. Ninomiya, H. Sugiura, T. Nakatsuka, Y. Kasamatsu, H. Kikunaga, W. Sato, T. Yoshimura, H. Matsumura, K. Takamiya, M. Kubo, K. Sueki, A. Yokoyama, Y. Hamajima, T. Miura, K. Nishiyama, and A. Shinohara
The electronic X-ray energies of muonic atoms were precisely measured. The atomic number (Z) dependence of the energy difference between electronic X-rays of muonic atoms and Z-1 atoms (energy shift) was systematically investigated. The energy shifts in the low-Z region were compared with those of the high-Z region that had been obtained experimentally and theoretically in previous work. An obvious difference between these two
regions was found in the atomic-number dependence of the energy shift. We also compared the energy shifts of muonic atoms
with those of pionic atoms.