1. Institute for Reactor Materials, Nuclear Research Centre (KFA) Jülich, Federal Republic of Germany
2. Fuel Chemistry Division, Bhabha Atomic Research Centre, Bombay 400085, India
3. Technical University of Wrocław, Wybrzeże S. Wyspiańskiego 27, 50-370 Wrocław, Poland
4. Institute for Solid State Physics, Nuclear Research Centre (KFA) Jülich