Low energy neutrons from a 239PuBe isotopic neutron source inserted in moderating media
Several neutron applications share a common problem: the neutron source design. In this work MCNP computer code has been used to design a moderated 239PuBe neutron source to produce low energy neutrons. The design involves the source located at the center of a spherical moderator. Moderator media studied were light water, heavy water and a heterogeneous combination of light water and heavy water. Similar moderating features were found between the 24.5 cm-radius container filled with heavy water (23.0-cm-thick) and that made with light water (3.5-cm-thick) plus heavy water (19.5-cm-thick). A 239PuBe neutron source inserted in this moderator produces, at 27 cm, a neutron fluence of 1.8 x 10-4 n-cm-2 per source neutron, with an average neutron energy of 0.34 MeV, where 47.8 % have an energy ≤ 0.4 eV. A further study of this moderator was carried out using a reflector medium made of graphite. Thus, 15-cm-thickness reflector improves the neutron field producing a neutron fluence of 1.1 x 10-3 n-cm-2 per source neutron, whose average neutron energy is 0.098 MeV, where 75.8 % have an energy ≤ 0.4 eV.
| Main Authors: | , |
|---|---|
| Format: | Digital revista |
| Language: | English |
| Published: |
Sociedad Mexicana de Física
2002
|
| Online Access: | http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S0035-001X2002000500003 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|