Special nuclear devices designed and used to sustain nuclear reactions, which may be subject to frequent core and lattice configuration change and which frequently may be used as mockups of reactor configurations
Department of Energy AREA SDMP, DOE Handbook, Glossary of Environment Safety and Health Terms, DOE-HDBK-1188-2006, D.C. 20585, USA 2006. http://www.hse.niordc.ir/uploads/86_24_dictionary_ 2006.pdf, (Envir Hlth and Sfty - Amer) {44}