Shielding concerns at a spallation source
Neutrons produced by 800-MeV proton reactions at the Los Alamos Neutron Scattering Center spallation neutron source cause a variety of challenging shielding problems. We identify several characteristics distinctly different from reactor shielding and compute the dose attenuation through an infinite slab/shield composed of iron (100 cm) and borated polyethylene (15 cm). Our calculations show that (for an incident spallation spectrum characteristic of neutrons leaking from a tungsten target at 90/degree/) the dose through the shield is a complex mixture of neutrons and gamma rays. High-energy (> 20 MeV) neutron production from the target is approx. =5% of the total, yet causes approx. =68% of the dose at the shield surface. Primary low-energy (< 20 MeV) neutrons from the target contribute negligibly (approx. =0.5%) to the dose at the shield surface yet cause gamma rays, which contribute approx. =31% to the total dose at the shield surface. Low-energy neutrons from spallation reactions behave similarly to neutrons with a fission spectrum distribution. 6 refs., 8 figs., 1 tab.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 6311646
- Report Number(s):
- LA-UR-89-765; CONF-8810182-23; ON: DE89009406
- Resource Relation:
- Conference: International collaboration on advanced neutron sources (ICANS), Los Alamos, NM, USA, 3 Oct 1988; Other Information: Portions of this document are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
NEUTRON SOURCES
SHIELDING
DOSE RATES
GAMMA RADIATION
NEUTRON SPECTRA
STAINLESS STEELS
ALLOYS
ELECTROMAGNETIC RADIATION
HIGH ALLOY STEELS
IONIZING RADIATIONS
IRON ALLOYS
IRON BASE ALLOYS
PARTICLE SOURCES
RADIATION SOURCES
RADIATIONS
SPECTRA
STEELS
654003* - Radiation & Shielding Physics- Neutron Interactions with Matter