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Title: IMPLEMENTATION OF A BE REFLECTOR-FILTER IN THE DESIGN OF THE MANUEL LUJAN JR. CENTER TARGET MODERATOR REFLECTOR SYSTEM

Authors:
 [1];  [1]
  1. Los Alamos National Laboratory
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1321613
Report Number(s):
LA-UR-07-2475
DOE Contract Number:
AC52-06NA25396
Resource Type:
Conference
Resource Relation:
Conference: 18TH INTERNATIONAL COLLABORATION ON ADVANCED NEUTRON SOURCES ; 200704 ; DONGGUAN CITY
Country of Publication:
United States
Language:
English

Citation Formats

MOCKO, MICHAL, and MUHRER, GUENTER. IMPLEMENTATION OF A BE REFLECTOR-FILTER IN THE DESIGN OF THE MANUEL LUJAN JR. CENTER TARGET MODERATOR REFLECTOR SYSTEM. United States: N. p., 2007. Web.
MOCKO, MICHAL, & MUHRER, GUENTER. IMPLEMENTATION OF A BE REFLECTOR-FILTER IN THE DESIGN OF THE MANUEL LUJAN JR. CENTER TARGET MODERATOR REFLECTOR SYSTEM. United States.
MOCKO, MICHAL, and MUHRER, GUENTER. Fri . "IMPLEMENTATION OF A BE REFLECTOR-FILTER IN THE DESIGN OF THE MANUEL LUJAN JR. CENTER TARGET MODERATOR REFLECTOR SYSTEM". United States. doi:. https://www.osti.gov/servlets/purl/1321613.
@article{osti_1321613,
title = {IMPLEMENTATION OF A BE REFLECTOR-FILTER IN THE DESIGN OF THE MANUEL LUJAN JR. CENTER TARGET MODERATOR REFLECTOR SYSTEM},
author = {MOCKO, MICHAL and MUHRER, GUENTER},
abstractNote = {},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Apr 13 00:00:00 EDT 2007},
month = {Fri Apr 13 00:00:00 EDT 2007}
}

Conference:
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  • We measured neutron beam fluxes at LANSCE using gold foil activation techniques. We did an extensive computer simulation of the as-built LANSCE Target/Moderator/Reflector/Shield geometry. We used this mockup in a Monte Carlo calculation to predict LANSCE neutronic performance for comparison with measured results. For neutron beam fluxes at 1 eV, the ratio of measured data to calculated varies from /approx/0.6-0.9. The computed 1 eV neutron leakage at the moderator surface is 3.9 /times/ 10/sup 10/ n/eV-sr-s-/mu/A for LANSCE high-intensity water moderators. The corresponding values for the LANSCE high-resolution water moderator and the liquid hydrogen moderator are 3.3 and 2.9 /times/more » 10/sup 10/, respectively. LANSCE predicted moderator intensities (per proton) for a tungsten target are essentially the same as ISIS predicted moderator intensities for a depleted uranium target. The calculated LANSCE steady state unperturbed thermal (E < 0.625 eV) neutron flux (at 100 /mu/A of 800 MeV-protons) is 2 /times/ 10/sup 13/ n/cm/sup 2/-s. The unique LANSCE split-target/flux-trap-moderator system is performing exceedingly well. The system has operated without a target or moderator change for over three years at nominal proton currents of /approx/25 /mu/A of 800-MeV protons. 17 refs., 8 figs., 3 tabs.« less
  • During the design of the Manuel Lujan, Jr., Neutron Scattering Center target, a simplified Monte Carlo model was used to estimate target system performance and to aid engineers as decisions were made regarding the construction of the target system. Although the simplified model ideally would perfectly reflect the as-built system performance, assumptions were made in the model during the design process that may result in deviations between the model predictions and the as-built system performance. Now that the Lujan Center target system has been completed, a more detailed, as-built, model of the target system has been completed. The purpose ofmore » this work is to investigate differences between the predicted target system performance of the simplified model and the as-built model from the standpoint of time-averaged moderator brightness. Calculated discrepancies between the two models have been isolated to a few key issues. Figure 1 shows MCNP geometric plots of the simplified and as-built models. Major differences between these two models include details in the moderator designs (plena) and piping, full versus partial moderator canisters (only in the direction of the extracted neutron beam for the simplified model), and reflector details including cooling pipes and engineering tolerance gaps. In addition, Fig. 1 demonstrates that the detailed model includes shielding and additional material beyond that which was modeled by the original simplified model.« less
  • High in the northcentral mountains of Los Alamos, New Mexico, is the Manuel Lujan Jr. Neutron Scattering Center (LANSCE), a pulsed-spallation neutron source located at Los Alamos National Laboratory. At LANSCE, neutrons are produced by spallation when a pulsed 800-MeV proton beam impinges on a tungsten target. The proton pulses are provided by a linear accelerator and an associated Proton Storage Ring (PSR), which alters the intensity, time structure, and repetition rate of the pulses. In October 1986, LANSCE was designated a national user facility, with a formal user program initiated in 1988. In July 1989, the LANSCE facility wasmore » dedicated as the Manuel Lujan Jr. Neutron Scattering Center in honor of the long-term Congressman from New Mexico. At present, the PSR operates with a proton pulse width of 0.27 [mu]s at 20 Hz and 80 [mu]A, attaining the highest peak neutron flux in the world and close to its goal of 100 [mu]A, which would yield a peak thermal neutron flux of 10[sup 16] n/cm[sup [minus]2]s[sup [minus]1]. This paper discusses the target/moderator/reflector shield system, the LANSCE instruments, the facility improvement projects, and user programs.« less
  • We have measured the neutron beam characteristics of neutron moderators at the Manuel Lujan Jr. Neutron Scattering Center at LANSCE. The absolute thermal neutron flux, energy spectra and time emission spectra were measured for the high resolution and high intensity decoupled water, partially coupled liquid hydrogen and partially coupled water moderators. The results of our experimental study will provide an insight into aging of different target-moderator-reflector-shield components as well as new experimental data for benchmarking of neutron transport codes.