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2024 ANS Annual Conference
June 16–19, 2024
Las Vegas, NV|Mandalay Bay Resort and Casino
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Commercial nuclear innovation "new space" age
In early 2006, a start-up company launched a small rocket from a tiny island in the Pacific. It exploded, showering the island with debris. A year later, a second launch attempt sent a rocket to space but failed to make orbit, burning up in the atmosphere. Another year brought a third attempt—and a third failure. The following month, in September 2008, the company used the last of its funds to launch a fourth rocket. It reached orbit, making history as the first privately funded liquid-fueled rocket to do so.
Tomohiko Iwasaki, Toshimitu Horiuchi, Daisuke Fujiwara, Hironobu Unesaki, Seiji Shiroya, Masatoshi Hayashi, Hiroshi Nakamura, Takanori Kitada, Nobuo Shinohara
Nuclear Science and Engineering | Volume 136 | Number 3 | November 2000 | Pages 321-339
Technical Paper | doi.org/10.13182/NSE00-A2162
Articles are hosted by Taylor and Francis Online.
Capture reaction rate ratios of 237Np relative to 197Au were measured in 11 thermal neutron fields provided by the Kyoto University Critical Assembly and the Kyoto University Reactor Heavy Water Neutron Irradiation Facility. In the measurement, both samples of 237Np and 197Au were irradiated at the same time, and their gamma activities were measured. The typical experimental error was 3.5%. The analysis was performed by three steps: full-core calculation, self-shielding correction of the sample, and perturbation correction of the sample. Three full-core calculations by a continuous-energy Monte Carlo code (MVP), a transport code (TWOTRAN), and a diffusion code (CITATION) were made with the JENDL-3.2 library. The self-shielding factors were derived by an analytical formula, and the perturbation factors were calculated by another MVP calculation. The reaction rates were derived by multiplying the neutron spectrum, the two correction factors, and the capture cross sections of 237Np and 197Au.As a result, the three full-core calculations provided almost the same neutron spectra at the sample position and gave almost the same calculated-to-experimental values (C/Es) for the capture reaction rate ratios of 237Np relative to 197Au. Based on the capture cross section of 237Np taken from the JENDL-3.2 library, the C/Es were between 0.97 and 1.04, and the average C/E among the 11 cores was 1.01. On the other hand, the C/Es using the ENDF/B-VI and the JEF-2.2 were 1.02 to 1.06 for harder spectrum cores, whereas the C/Es for the softer spectrum cores were 1.08 to 1.16. It is concluded that the JENDL-3.2 library has good accuracy for the capture cross section of 237Np but the ENDF/B-VI and the JEF-2.2 libraries overestimate that of 237Np >10% in the thermal neutron energy region.