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Title: Redesign of the Target-Moderator-Reflector-Shield Assembly for Optimization of the Neutron Flux in the 0.001 – 1 MeV at LANSCE

Abstract

These are the slides for a presentation at the 2016 Postdoc Summer Seminar Series at Los Alamos National Laboratory. The conclusions of the research presented are the following: we can provide a significant gain in intensity in the upper tier; lower and upper tier are coupled: translating the target in the FOV of the upper tier decreases the intensity in the lower tier; it is possible to balance the production between the upper and lower tier if we keep some of the material between the tiers.

Authors:
 [1];  [1];  [1];  [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA), Office of Defense Programs (DP) (NA-10)
OSTI Identifier:
1304749
Report Number(s):
LA-UR-16-26219
TRN: US1601792
DOE Contract Number:
AC52-06NA25396
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; KEV RANGE; NEUTRON FLUX; LAMPF LINAC; TARGETS; MODERATORS; OPTIMIZATION; SHIELDS; NEUTRON REFLECTORS; DESIGN; Accelerator Design, Technology, and Operations; Atomic and Nuclear Physics

Citation Formats

Nowicki, Suzanne Florence, Mocko, Michal, Wender, Stephen Arthur, and Ferres, Laurent. Redesign of the Target-Moderator-Reflector-Shield Assembly for Optimization of the Neutron Flux in the 0.001 – 1 MeV at LANSCE. United States: N. p., 2016. Web. doi:10.2172/1304749.
Nowicki, Suzanne Florence, Mocko, Michal, Wender, Stephen Arthur, & Ferres, Laurent. Redesign of the Target-Moderator-Reflector-Shield Assembly for Optimization of the Neutron Flux in the 0.001 – 1 MeV at LANSCE. United States. doi:10.2172/1304749.
Nowicki, Suzanne Florence, Mocko, Michal, Wender, Stephen Arthur, and Ferres, Laurent. 2016. "Redesign of the Target-Moderator-Reflector-Shield Assembly for Optimization of the Neutron Flux in the 0.001 – 1 MeV at LANSCE". United States. doi:10.2172/1304749. https://www.osti.gov/servlets/purl/1304749.
@article{osti_1304749,
title = {Redesign of the Target-Moderator-Reflector-Shield Assembly for Optimization of the Neutron Flux in the 0.001 – 1 MeV at LANSCE},
author = {Nowicki, Suzanne Florence and Mocko, Michal and Wender, Stephen Arthur and Ferres, Laurent},
abstractNote = {These are the slides for a presentation at the 2016 Postdoc Summer Seminar Series at Los Alamos National Laboratory. The conclusions of the research presented are the following: we can provide a significant gain in intensity in the upper tier; lower and upper tier are coupled: translating the target in the FOV of the upper tier decreases the intensity in the lower tier; it is possible to balance the production between the upper and lower tier if we keep some of the material between the tiers.},
doi = {10.2172/1304749},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2016,
month = 8
}

Technical Report:

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  • The facilities at the Los Alamos Neutron Science Center are described first. The target is being redesigned so that the Flight Paths (FP) in the upper tier provide a higher intensity in the epithermal and medium energy range. It is found that a 3-piece design looks promising: intensity in epithermal and medium energy range in upper tier is an order of magnitude higher than current Mark III, and intensity in the thermal energy range is higher in the lower tier than current Mark III. Time emission spectra show a bump due to the scattering of fast neutrons. Other investigations suchmore » as the addition of wings around the upper target will be conducted.« less
  • Los Alamos National Laboratory (LANL) supports scientific research in many diverse fields such as biology, chemistry, and nuclear science. The Laboratory was established in 1943 during the Second World War to develop nuclear weapons. Today, LANL is one of the largest laboratories dedicated to nuclear defense and operates an 800 MeV proton linear accelerator for basic and applied research including: production of high- and low-energy neutrons beams, isotope production for medical applications and proton radiography. This accelerator is located at the Los Alamos Neutron Science Center (LANSCE). The work performed involved the redesign of the target for the low-energy neutronmore » source at the Lujan Neutron Scattering Center, which is one of the facilities built around the accelerator. The redesign of the target involves modeling various arrangements of the moderator-reflector-shield for the next generation neutron production target. This is done using Monte Carlo N-Particle eXtended (MCNPX), and ROOT analysis framework, a C++ based-software, to analyze the results.« less
  • Calculations are carried out for a flux flattening experiment in the Organic Moderated Reactor critical assembly. It is proposed that the flux be flattened by varying the numbers of fuel plates per element to achieve variable fuel-tomoderator ratio. It is concluded that a reduction of the peak-to-average ratio from 1.69 to 1.17 can be achieved by this method; and that the power distribution is made more uneven by this method, so that variable fuel-to- moderator ratio is probably not desirable for full-scale power reactors. (auth)
  • Calculations were performed using the PUFF-TFT code to determine the thermo-mechanical response arising from incident mono-energetic X-rays on a beryllium substrate with a thin (300/angstrom/) impurity layer. The impurities were introduced into the material during typical fabrication processes. Responses were calculated for 5 nanosecond square wave pulses of monoenergetic X-rays (1 and 2 keV) with fluence levels corresponding to surface loadings of 1 and 5 cal/cm/sup 2/. The presence of these surface impurities was found to significantly alter the thermal response of the medium. As the concentration of surface impurities increased, the energy deposition increased, and the temperature gradient increased.more » In some cases, additional impurities resulted in a phase change in the medium. For the most part, the mechanical response was unaffected by the surface impurity concentration. 6 refs., 48 figs., 1 tab.« less