Accession Number : AD0711839

Title :   TIME-DEPENDENT FAST NEUTRON AND SECONDARY GAMMA RAY SPECTRUM MEASUREMENTS IN CONCRETE. VOLUME I.

Descriptive Note : Final rept. 1 Mar 68-15 Nov 69,

Corporate Author : GULF GENERAL ATOMIC INC SAN DIEGO CALIF

Personal Author(s) : Harris,L. , Jr. ; Kendrick,H. ; Naliboff,Y. D. ; Sperling,S. M.

Report Date : 17 NOV 1969

Pagination or Media Count : 253

Abstract : An experimental method was developed for studying simultaneously fast-neutron transport and secondary gamma-ray production and transport in shields. An electron linear accelerator (Linac) was used to produce intense 50-nsec pulses of photoneutrons. These neutrons streamed down an evacuated 52-meter long drift tube to strike concrete slabs up to 40 in. thick. A 5 in. by 5 in. cylindrical NE-213 scintillator was positioned behind the concrete slabs to detect both fast-neutrons and secondary gamma rays produced in the concrete by (n, x gamma) and (n, gamma) reactions. Three parameters: time, pulse-height, and neutron/gamma-ray identification were recorded for each detection event. Fast-neutrons and gamma rays produced by (n, x gamma) reactions were recorded for times 0.87 to 2.84 microsec (corresponding to incident neutron energies 1.8 to 20 MeV). Capture gamma rays were detected for times up to 1500 microsec after the Linac pulse. Pulse-height spectra were binned according to time for neutrons and gamma rays. Then, for each time interval, these pulse-height spectra were unfolded to produce time-dependent fast-neutron (2.0 < E < 20 MeV) and gamma-ray (0.8 < E < 9.0 MeV) energy spectra. Thirty-group P3S16 (Lobatto) 1DF neutron transport calculations were performed, and results were compared with measured leakage neutron energy spectra.

Descriptors :   (*SHIELDING, CONCRETE), (*CONCRETE, DAMAGE), (*NUCLEAR RADIATION SPECTROSCOPY, CONCRETE), NEUTRON TRANSPORT THEORY, GAMMA RAY SPECTROSCOPY, FAST NEUTRONS, GAMMA NEUTRON REACTIONS, FLOW CHARTING, (U)FLOW CHARTING

Subject Categories : Nuclear Radiation Shield, Protection & Safety

Distribution Statement : APPROVED FOR PUBLIC RELEASE