This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use wc, uld not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not ntx_essarilystate or reflect those of the United States Government or any agency thereof. The submitted manuscript has been authored by a contractor of the U. S, Government under contract No. W-31-109-ENG-38. Accordingly, the U. S. Government retains a nonaxclu$ive, royalty-free license to publish or reproduce the published form of thin contribution, or allow others to do 0o, for U. S. Government purpoms. August 1992 l_l_b']i_'i.i _,_,_ [J_ I_ Nr.JV I 19". 2 Presented at the Sixteenth International Symposium on Effects of Radiation on Materials. June 21-25, 1992. Denver. Colorado.