1. Nuclear Research Centre (KFA), Jülich, Institute for Reactor Materials P.O. Box 1913, D-5170 Jülich, Federal Republic of Germany
2. Japan Atomic Energy Research Institute, Tokai Research Establishment Tokai-mura, Naka-gun, Ibaraki-ken, Japan
3. Oak Ridge National Laboratory, P.O. Box X, Oak Ridge, Tennessee 37831