ACKNOWLEDGMENTS The author wishes to acknowledge Mr. W. H. Zimmer (now of ORTEC, Oak Ridge), Dr. N. D. Wogman, and Dr. R. L. Brodzinski (of Battelle North- west Laboratory) for their assistance in technical advisement; to Dr. R. D. Fox (of Rockwell-Hanford Operations) for his assistance on editing and Ms. Trudy Jones (of Rockwell-Hanford Operations) the original paper. 704 for typing