Pd is a concern, because like Ni, it attacks SiC, which has been proposed for some advanced nuclear fuel concepts. Having a symmetric fission, e.g., product of two palladium (Pd) atoms is possible, but has lower probability than two nuclei of different species, although the probability of a symmetric fission increases with energy of the neutrons. In fission, after a neutron (or incident particle) is absorbed, the excited nucleus splits (fissions) into two nuclei of similar size. Usually, in a spallation reaction, one or more of the products is similar in size to the incident (projectile) particle that hits a nucleus, e.g., (n,p), (p,n), (n,d), (n,α), or even (p, #n), where the # depends in the energy of the incident p and the target. Spallation reactions do release some energy, but it's more the case they transform energy.
I don't believe that losing energy (or endothermic reaction) is a qualifier for a reaction being classified as 'spallation', but perhaps it could be. Mass difference in U-235 + n - (Pa-234 + d) = -0.004265397 u (-3.973191522 MeV) indicating an endothermic reaction, or threshold of ~ 4 MeV.Īre classified as "spallation" not "fission" because they lose rather than release energy. Masses of U and Pa isotopes, respectively Fertile (or fissionable) atoms like U-238 or Pu-240, require fast neutrons to induce fission, otherwise, they tend to emit gamma radiation instead of fissioning. The nuclei of fission products are more tightly bound than the original U-235 (or Pu-239,-241). Where the masses of the products of a reaction are less than the reactants, the difference in mass is manifest in the kinetic energy of the products, and is exothermic, i.e., produces excess energy. The absolute fission yields of 46 fission products in 1 remains constant throughout due to the strong preference for the formation of the deformed 88n shell, which is also favorable from the N/Z point of view.May I ask you to try to explain the reason behind the drop in the total mass, please? Receipt Date: 31-DEC-70 Country of Publication: United States Language: English Subject: N36550* -Physics (Nuclear)-Nuclear Properties & Reactions, A >= 90-Nuclear Reactions & Scattering AMERICIUM 241- AMERICIUM 242- CURIUM 243- CURIUM 245- FISSION- NEUTRON BEAMS- PLUTONIUM 238- PLUTONIUM 241- THERMAL NEUTRONS- URANIUM 232 FISSION YIELD PROMPT NEUTRONS CURIUM 244- SPONTANEOUS FISSION PLUTONIUM ISOTOPES Pu-241/neutron fission of, prompt neutron yield from thermal, (E) URANIUM ISOTOPES U-232/neutron fission of, prompt neutron yield from thermal, (E) PLUTONIUM ISOTOPES Pu-238/neutron fission of, prompt neutron yield from thermal, (E) CURIUM ISOTOPES Cm-244/fission of, prompt neutron yield from spontaneous, (E) CURIUM ISOTOPES Cm-245/neutron fission of, prompt neutron yield from thermal, (E) AMERICIUM ISOTOPES Am-242/ neutron fission of isomeric, prompt neutron yield from thermal, (E) NEUTRONS, THERMAL/reactions (n,f) with A = 232 to 245 nuclei, prompt neutron yield from, (E) AMERICIUM ISOTOPES Am-241/neutron fission of, prompt neutron yield from thermal, (E) CURIUM ISOTOPES Cm-243/neutron fission of, prompt neutron yield from thermal, (E) Sponsoring Org.: USDOE OSTI Identifier: 4116213 Report Number(s): ANL-7625 NSA Number: NSA-24-040600 DOE Contract Number: W-31-109-ENG-38 Resource Type: Technical Report Resource Relation: Other Information: UNCL. Authors: Jaffey, A H Lerner, J L Publication Date: Wed Jan 01 00:00: Research Org.: Argonne National Lab., Ill.