Nuclear Technology / Volume 168 / Number 3 / December 2009 / Pages 970-974
Miscellaneous / Special Issue on the 11th International Conference on Radiation Shielding and the 15th Topical Meeting of the Radiation Protection and Shielding Division (PART 3) / Radiation Measurements and Instrumentation
Upon reaching 180 kW, approximately one-eighth of its designed full power, the Spallation Neutron Source (SNS) became the brightest pulsed neutron source in the world in August 2007. This state-of-the-art neutron-scattering facility is expected to attract 1000 to 2000 scientists and engineers each year from universities, industries, and laboratories around the world. The activation level of users' samples must be estimated before the experiment for proper sample preparation, storage, and postexperiment treatment in compliance with the safety regulations at SNS. A program written in Perl, SAPEU (Sample Activation Program for Easy Use), was developed to serve such requests from the SNS user community. The CINDER'90 library was implemented within the program for tracking the transmutation products of the irradiated sample. The SAPEU program assumes that the incident neutron flux attenuates with the total absorption cross section and calculates the radionuclide inventory, radiotoxicity categories, radiation dose rate, and gamma spectrum during each irradiation period from a simple user input. The SAPEU program can estimate the sample activation due to a cold neutron spectrum, not limited by the 5-meV lowest energy boundary of the CINDER'90 cross-section library. For validation, the SAPEU program methodology was compared to a full analysis involving MCNPX for the flux calculation and CINDER'90 for the activation analysis for typical sample activation cases. The results were in good agreement. Although this program was developed for SNS, it may be useful as a general sample activation prediction tool at any neutron-scattering facility.