Neutronic studies for an integrated beam line shield package at the Lujan Center Page: 2 of 8
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Neutronic Studies for An Integrated Beam Line Shield Package at the Lujan Center
G. Muhrer, G. J. Russell and E. J. Pitcher
Manuel Lujan Jr. Neutron Scattering Center
LANSCE-12, MS H805
Los Alamos National Laboratory
Los Alamos, New Mexico 87545
(505) 665-8806ABSTRACT
We have designed an integrated beam-line shielding
package in the Experimental Area 1 (ER-1) for two new
scientific instruments (NPT-Gamma and IN500) being
constructed at the Manual Lujan Jr. Neutron Scattering
Center (Lujan Center). In this work we investigated the
neutronics of a guillotine shutter, looked at possible
neutron streaming paths, and designed an integrated beam
line shield package.
I. INTRODUCTION
During the upgrade of the Luajn Center Target-
Moderator-Reflector-System (TMRS), two new back-
scattering moderators were installed upstream of the
spallation target. One of them is a partially coupled water
moderator. The other one is a partially coupled liquid
hydrogen moderator. Each of these moderators is capable
of delivering neutrons to two neutron flight paths. In the
case of the liquid hydrogen moderator, the two new
scientific instruments being built are NPT-Gamma (flight
path 12) and IN500 (flight path 13). Because of the small
angle between the two flight paths (a=10.5 ), there is
limited space between the two flight paths in ER-1. It was
decided that these beam lines should be shielded by an
integrated shielding package and not individually
shielded. To accomplish this, we investigated possible
streaming paths, the neutronic performance of a guillotine
shutter just outside the bulk shield, a beam line shield
surrounding the shutter, and a "horse collar"-shield
downstream of the shutter.
II. SOURCE
The first thing one who has experience with these kind of
Monte Carlo problems realizes is that it is very time
consuming to perform these types of calculation within
one run. Therefore, we decided to break up the problem
into two runs.--.Location of the Source
r' 'r
Fig. la: Neutron Source-Term geometry for flight path 12.
1.0E+14 -V!
r 1
E
1
01
0
01
0
-1
za--
ppp3~
-0E+13
.0E+12
.0E+11
.0E+10
.0E+09
.0E+080.01 0.1
10
1
Theta,Fig. lb: Neutron Source-Term for flight path 12.
100
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Muhrer, Guenter; Russell, Gary J. & Pitcher, Eric J. Neutronic studies for an integrated beam line shield package at the Lujan Center, article, January 1, 2001; United States. (https://digital.library.unt.edu/ark:/67531/metadc928013/m1/2/: accessed March 28, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.