The process, for production of isotopes including transuranic elements by reaction of neutrons, employs means for generating neutrons having a high average energy, slowing down and scattering the neutrons by projecting them through a medium of an element of a class including H, He, Be, C, Si, and Pb, and then passing the neutrons into a mass of material containing an element capable of forming a radioactive isotope by neutron capture, including radioactive isotopes capable of emitting beta rays.
US PATENT 2,524,379 (Neutron Velocity Selector), Enrico Fermi, Oct 3, 1950.
The present invention relates to neutron velocity selector apparatus and particularly to apparatus of this type which utilizes a rotating shutter.
US PATENT 2,708,656 (Neutronic Reactor), Enrico Fermi and Leo Szilard, May 17, 1955.
The present invention relates to the general subject of nuclear fission and particularly to the establishment of self-sustaining neutron chain fission reactions in systems embodying uranium having a natural isotopic content.
US PATENT 2,714,577 (Neutronic Reactor); E. Fermi, W.H. Zinn; August 2, 1955.
A heavy water moderated neutron reactor has been designed to employ as fuel uranium metal of natural isotopic composition. The composite fuel rods are suspended from the cover so as to extend well into the reactor tank. Each rod is composed of an aluminum portion extending vertically into the tank from the cover and a thermal neutron fissionable portion secured to the lower end of the aluminum portion. Heavy water fills the tank to a level above the juncture of the aluminum portion with the fissionable portion of each composite rod so as to cause the fissionable portion to be wholly immersed.
US PATENT 2,768,134 (Testing Material in a Neutronic Reactor); E. Fermi et al.; October 23, 1956.
A means of testing the nuclear properties of materials to be used in a nuclear reactor is given. This is accomplished by placing in an operating reactor the materials loaded on a transverse stringer or tray-type device of sufficient length that upon withdrawing the portion containing the materials tested a portion containing the customary reactor components is drawn into place, thereby completing the reactor core integrity. A cadmium control rod suitably indexed is used to maintain constant flux density in the reactor, thus, by comparing the two readings of the control rod positions, a relationship may be established between the nuclear properties of the tested material and the normal reactor components. Such information is an important aid in atomic research.
US PATENT 2,780,595 (Test Exponential Pile); E. Fermi; February 5, 1957.
A nuclear fission test pile is described which is designed to measure the fissioning chain reaction induced in a sub-critical mass of natural U by a neutron source. The pile comprises a number of cells containing natural U, disposed in a graphite moderator, and adjacent to an independent source of neutrons for the purpose of causing in the test pile a chain reaction that cannot be self-sustaining. Measurements are made of the radioactivity induced in strips of indium foil which are inserted in appropriate slots or channels in the core. This pile permits the taking of such measurements from a reactor requiring a reduced amount of valuable material, and eliminates the possibility of a dangerous buildup of reactivity.
US PATENT 2,798,847 (Method of Operating a Neutronic Reactor); E. Fermi et al.; July 9, 1957.
A method of operating a reactor and particularly the operation of the shim and control rods to maintain an operational reactivity factor of unity is described. The shim rods of a highly neutron absorbent material are gradually withdrawn to compensate for the build up of fission product poisons, which would otherwise decrease the innate reactivity factor, whereas the control rods compensate for the normal fluctuations of the power level and for the power demand of varying loads or start up procedure.
US PATENT 2,807,581 (Neutronic Reactor); E. Fermi, L. Szilard; September 24, 1957.
Reactors of the type employing plates of natural uranium in a moderator are discussed wherein the plates are uniformly disposed in parallel relationship to each other thereby separating the moderator material into distinct and individual layers. Each plate has an uninterrupted surface area substantially equal to the cross-sectional area of the active portion of the reactor, the particular size of the plates and the volume ratio of moderator to uranium required to sustain a chain reaction being determinable from the known purity of these materials and other characteristics such as the predictable neutron losses due to the formation of radioactive elements of extremely high neutron capture cross section.