The group has had a long-term program for the measurement of one of the most important of these cross sections-the neutron-induced fission cross section of /sup 235/U. The primary mission of the Neutron Interactions and Dosimetry Group at the National Bureau of Standards (NBS) is the measurement of the standard neutron cross sections. A computed value of 1245 mb is obtained using an evaluated /sup 252/Cf fission neutron spectrum and ENDF/B-IV for the /sup 235/U(n,f) cross section. The observed /sup 235/U fission cross section is 1204 +- 29 mb.
Five scattering corrections were applied to the data source capsule (0.6 +- 0.8) percent, fission chamber (1.1 +- 0.4) percent, support structure (0.6 +- 0.5) percent, platinum deposit backing (1.3 +- 0.8) percent and total room return (0.5 +- 0.2) percent. Uncertainty in the Manganous Bath comparison of NBS-I and the Cf source was +-0.4 percent the /sup 235/U fissionable deposit masses have been ascertained to +-1.3 percent. The /sup 252/Cf neutron source strength was determined with a Manganous Sulfate Bath relative to the internationally compared Ra-Be photoneutron standard neutron source, NBS-I, presently more » known to +-1.1 percent. In this geometry the effect of source position errors is small. The fission chambers are mounted 10 cm apart on opposite sides of a small volume, single encapsulated /sup 252/Cf source (4 x 10/sup 9/ n/sec, 0.34 cm/sup 3/ capsule vol approximately 2 g steel and aluminum). (United States) Additional Journal Information: Journal Volume: 81:2 Country of Publication: United States Language: English Subject: 73 NUCLEAR PHYSICS AND RADIATION PHYSICS NEUTRON REACTIONS FAST FISSION URANIUM 235 TARGET BERYLLIUM 7 CROSS SECTIONS DATA COVARIANCES EXPERIMENTAL DATA FISSION CHAMBERS FISSION NEUTRONS FISSION SPECTRA FISSIONABLE MATERIALS KEV RANGE 100-1000 LABORATORIES LITHIUM 7 MEASURING METHODS MEV RANGE 01-10 NEUTRON FLUX NEUTRON SOURCES PLASTIC SCINTILLATORS PULSE TECHNIQUES STANDARDS TIME-OF-FLIGHT METHOD US NBS ALKALI METAL ISOTOPES ALKALINE EARTH ISOTOPES BARYON REACTIONS BARYONS BERYLLIUM ISOTOPES BETA DECAY RADIOISOTOPES DATA DAYS LIVING RADIOISOTOPES ELECTRON CAPTURE RADIOISOTOPES ELEMENTARY PARTICLES ENERGY RANGE EVEN-ODD NUCLEI FERMIONS FISSION HADRON REACTIONS HADRONS INFORMATION IONIZATION CHAMBERS ISOTOPES KEV RANGE LIGHT NUCLEI LITHIUM ISOTOPES MATERIALS MEASURING INSTRUMENTS MEV RANGE NATIONAL ORGANIZATIONS NEUTRON DETECTORS NEUTRONS NUCLEAR REACTIONS NUCLEI NUCLEON REACTIONS NUCLEONS NUMERICAL DATA ODD-EVEN NUCLEI PARTICLE SOURCES PHOSPHORS RADIATION DETECTORS RADIATION FLUX RADIATION SOURCES RADIOISOTOPES SPECTRA STABLE ISOTOPES TARGETS US DOC US ORGANIZATIONS 652026* - Nuclear Properties & Reactions, A=220 & above, Experimental- Spontaneous & Induced Fission- =, number = ,Ī measurement of the absolute /sup 235/U fission cross section for /sup 252/Cf spontaneous fission neutrons has been performed with two double fission chambers in compensated beam geometry.
Developing technology to harness nuclear fusion as a source of energy for heat and electricity generation is the subject of ongoing research, but whether or not it will be a commercially viable technology is not yet clear because of the difficulty in controlling a fusion reaction.Authors: Wasson, O A Duvall, K C Meier, M M Publication Date: Tue Jun 01 00:00: Research Org.: National Bureau of Standards, Washington, DC 20234 OSTI Identifier: 6936961 Resource Type: Journal Article Journal Name: Nucl. Fusion is the source of energy in the sun and stars. Nuclear energy can also be released in nuclear fusion, where atoms are combined or fused together to form a larger atom. This reaction is controlled in nuclear power plant reactors to produce a desired amount of heat. This process is called a nuclear chain reaction. These neutrons continue to collide with other uranium atoms, and the process repeats itself over and over again. More neutrons are also released when a uranium atom splits. During nuclear fission, a neutron collides with a uranium atom and splits it, releasing a large amount of energy in the form of heat and radiation. All nuclear power plants use nuclear fission, and most nuclear power plants use uranium atoms. In nuclear fission, atoms are split apart, which releases energy.