Measured Delayed Neutron Spectra from the Fission of U-235 and Np-237
Texas A&M University, in collaboration with Oak Ridge National Laboratory / the Japan Atomic Energy Research Institute, have been actively studying the delayed neutron emission characteristics of the higher actinide isotopes for several years. 1-3 Recently, a proton recoil detector system was designed, built, and characterized for use in measuring delayed neutron energy spectra following neutron induced fission. The system has been used to measure aggregate delayed neutron energy spectra from neutron induced fission of U-235 and Np-237. These spectra have also been compared to that calculated using individual precursor P, values, yields, and spectra from the ENDF/B-VI file. A proton recoil detector array consisting of three LND Model 28305 high- -pressure proton recoil detectors has been constructed at the Texas A&M University Nuclear Science Center. The array was characterized using several neutron and gamma- ray sources to check for efficiency, gamma-ray response, and reliability of the unfolding techniques. Resultant measured proton recoil distributions were unfolded using a modified version of the spectrum unfolding code PSNS (the new code was renamed SAC). SAC used response functions calculated using MCNP 4A. This feature allowed the inclusion of several inches of lead between the detector and the source to decrease the detector's sensitivity to gamma-rays, while appropriately accounting for the effect on the transmitted neutron spectrum. Following proper calibration of the array, highly-purified sources of U-235 were irradiated in the Nuclear Science Center Reactor (NSCR) at a power of 1 MW for 200
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Oak Ridge, TN
- Sponsoring Organization:
- USDOE Office of Nuclear Energy, Science and Technology (NE)
- DOE Contract Number:
- AC05-96OR22464
- OSTI ID:
- 1756
- Report Number(s):
- ORNL/CP-100048; 16 B3 61 80 2; ON: DE00001756
- Resource Relation:
- Conference: American Nuclear Society Winter Meeting, Washington, DC, November 15-19, 1998
- Country of Publication:
- United States
- Language:
- English
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