U-238 fission and Pu-239 production in subcritical assembly

EPJ Web of Conferences, 2017

Two Np-237 samples and one Pu-239 were irradiated in spallation neutrons produced in ADS setup QUINTA. The accelerated beam consisted of protons of energy 660 MeV. The method was based on gamma-ray spectrometry measurement. During analysis of the spectra several fission products and one actinide were identified. Fission product activities gave the number of fissions. The actinide (Np-238), a result of neutron capture by Np-237 gave the number of captures. In a similar manner the number of fissions in Pu-239 was determined. The Pu-240, a product of neutron capture by Pu-239, activity was impossible to measure.

Physical Review C, 2015

Using dual-fission chambers each loaded with a thick (200-400-mg/cm 2) actinide target of 235,238 U or 239 Pu and two thin (∼10-100-µg/cm 2) reference foils of the same actinide, the cumulative yields of fission products ranging from 92 Sr to 147 Nd have been measured at E n = 8.9 MeV. The 2 H(d,n) 3 He reaction provided the quasimonoenergetic neutron beam. The experimental setup and methods used to determine the fission product yield (FPY) are described, and results for typically eight high-yield fission products are presented. Our FPYs for 235 U(n,f), 238 U(n,f), and 239 Pu(n,f) at 8.9 MeV are compared with the existing data below 8 MeV from Glendenin et al.

Physical Review C

The fission fragment yield distribution has been measured in the 239 Pu(n th ,f) reaction in the mass region of A = 126 to 150 using the Lohengrin recoil-mass spectrometer. Three independent experimental campaigns were performed, allowing a significant reduction of the uncertainties compared to evaluated nuclear data libraries. The long-standing discrepancy of around 10% for the relative yield of A = 134 reported in JEF-2.2 and JEFF-3.1.1 data libraries is finally solved. Moreover, the measured mass distribution in thermal neutron-induced fission does not show any significant dip around the shell closure (A = 136) as seen in heavy-ion fission data of 208 Pb(18 O, f) and 238 U(18 O, f) reactions. Lastly, comparisons between our experimental data and the predictions from Monte Carlo codes (GEF and FIFRELIN) are presented and discussed.

ND2007, 2007

Relativistic protons or deuterons hit the thick, lead target. Emitted neutrons were multiplied by fission inside the uranium blanket. The high energy neutron field produced in the setup was measured by the means of threshold reactions in activation foils. The comparison with MCNPX 2.6.C simulations was done.

Inpc 2013 - International Nuclear Physics Conference, Vol. 1, 2014

The radiative capture cross section of 238 U is very important for the developing of new reactor technologies and the safety of existing ones. Here the preliminary results of the 238 U(n,γ) cross section measurement performed at n_TOF with C 6 D 6 scintillation detectors are presented, paying particular attention to data reduction and background subtraction.

2007

Transmutation at the Nuclotron 2.52 GeV Deuteron Beam in Neutron Field Generated in U/Pb-Assembly ®Energy Plus TransmutationP reliminary results of theˇrst experiment with deuteron beam with energy 2.52 GeV at the electronuclear setup which consists of Pb-target (diameter 8.4 cm, length 45.6 cm) and nat Ublanket (206.4 kg), transmutation samples of 129 I, 237 Np, 238 Pu and 239 Pu (radioecological aspect) are described. Hermetically sealed samples in notable amounts are gathered in atomic reactors and setups of industries which use nuclear materials and nuclear technologies were irradiated in theˇeld of neutrons produced in the Pb-target and propagated in the nat U-blanket. Estimates of transmutations were obtained as result of measurements of gamma activities of the samples. The information about the space and energy distribution of neutrons in the volume of the lead target and the uranium blanket was obtained with help of sets of activation threshold detectors (Al, Co, Y, I, Au, Bi and others), solid-state nuclear track detectors, 3 He neutron detectors and nuclear emulsion. Comparison of the experimental data with the results of simulation with the MCNPX program was performed. The investigation has been performed at the Veksler and Baldin Laboratory of High Energies and at the Dzhelepov Laboratory of Nuclear Problems, JINR.

Cnr '09: Second International Workshop on Compound Nuclear Reactions and Related Topics, 2010

The production cross sections of neutron-rich fission residues produced in reactions induced by a 238 U beam impinging onto Pb and Be targets were investigated at the Fragment Separator (FRS) at GSI using the inverse kinematic technique. These data allowed us to discuss the optimum energies in fission for producing the most neutron-rich residues.

Agenzia nazionale per le nuove tecnologie, l'energia e lo sviluppo economico sostenibile (ENEA),

Bulletin of the American Physical Society, 2020

Precise integral measurement of fast neutron-induced fission product yields for various actinides is of high interest for applied nuclear science. The goal of this effort is to improve uncertainties in fission product yield values of 239 Pu. Fission was induced in a pure 239 Pu (> 99%) target using the Godiva-IV critical assembly in burst mode. The irradiated sample was transferred to a high-resolution γ-ray detector within 45 minutes. γ-ray list mode data was collected from 45 minutes to 1 week after the irradiation. γ-ray spectroscopy was performed to analyze the time dependent γ-ray yields using an automated peak search algorithm to identify isotopes by their decay γ-ray energy and half-life. The initial activity for each isotope identified was used to calculate their fission product yield.

Nuclear Physics A, 2011

The yields of various fission products in the 10 MeV bremsstrahlung-induced fission of 232Th, 238U and 240Pu were determined using a recoil catcher and off-line γ-ray spectrometric techniques. From the yield data, mass yield distributions were obtained using charge distribution corrections. The higher yields of fission products around mass numbers 133–135, 138–140, 143–145 and their complementary products in the neutron and bremsstrahlung-induced fission of 232Th, 238U and 240Pu were interpreted based on nuclear structure effects. From the mass yield distribution, the peak-to-valley (P/VP/V) ratio was also obtained for the above fissioning systems. The present data, along with data from the literature on different bremsstrahlung- and mono-energetic neutron-induced fissions of 232Th and 238U are interpreted to examine the influence of excitation energy on the peak to valley ratio. For the same compound nucleus 240Pu⁎, the data in the 10–30 MeV bremsstrahlung-induced fission of 240Pu were compared with similar data of thermal to 14 MeV neutron-induced fission of 239Pu and the spontaneous fission of 240Pu to examine the role of excitation energy due to bremsstrahlung radiation and mono-energetic neutrons.