Core modifications of the Texas A and M Nuclear Science Center reactor for improved commercial utilization

As a result of increasing demand for reactor services by industrial organizations as well as university experimenters, the Texas A and M Nuclear Science Center recently modified its core design with the objective of providing more irradiation positions with a higher neutron flux. This was accomplished by loading a core comprised of 87 FLIP fuel elements with peripheral bundle locations left vacant on three of the four core faces. Minor problems were encountered in predicting and achieving sufficient core excess reactivity as well as in maintaining adequate linearity of monitoring instruments positioned near the notches. The final core design was successful in providing three core slots with effective neutron fluxes of approximately 2.5 x 10{sup 13}, an increase by a factor of 3-4 over previously available irradiation positions on the core face. Other reflector and face irradiation facilities showed slight increases as well. Appropriate sample holders have been designed for the new positions and initial customer reaction has been positive. Higher sample specific activities result in lower cost per curie of activity for commercial users, and the increased capability allows academic researchers to pursue projects previously impractical due to insufficient flux. (author)