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Breaking ground on a new approach to construction
The drive to Kairos Power’s reactor demonstration site in Oak Ridge, Tenn., is not only scenic—it’s historic. Nearly 85 years ago, roughly 30,000 construction workers transformed orchards and farmland into a key Manhattan Project site. Depending on your route, you may pass by one of the three gatehouses that were once military checkpoints controlling access to Atomic Energy Commission production facilities.
C. Budtz-Jørgensen, H.-H. Knitter
Nuclear Science and Engineering | Volume 79 | Number 4 | December 1981 | Pages 380-392
Technical Paper | doi.org/10.13182/NSE81-A21389
Articles are hosted by Taylor and Francis Online.
The neutron-induced fission cross section of 240Pu was measured in the neutron energy range from 10 keV to 10 MeV using the 7-MV Van de Graaff and the electron linear accelerator of the Central Bureau for Nuclear Measurements as pulsed neutron sources, which delivered monoenergetic and continuous neutron spectra, respectively. The neutron-induced fission events were detected with a parallel plate ionization chamber that provided a fast and narrow output signal allowing nanosecond timing, but where the time integral of the pulse contained, at the same time, the energy information of the ionizing particle. This detector permitted a high discrimination between alpha particles and fission fragments at an alpha emission rate of some 107 s−1. The fission cross-section data below 400 keV are especially remarkable since they were taken with an energy resolution almost one order of magnitude better than any other published data set. In this region, large structures in the fission cross section due to Class II states in the second well of the double-humped fission barrier were found. The spontaneous fission half-life of 240Pu was measured to be (1.15 ± 0.03)·1011 yr.