1. Institute of Thermomechanics; Academy of Sciences of the Czech Republic; Dolejškova 5 182 00 Prague Czech Republic
2. Reactor Mechanical Engineering Division; 999-111 Daedeok-Daero Daejeon 305-353 Yuseong-gu Korea
3. Department of Aerospace Engineering Sciences; University of Colorado Boulder; Boulder 80309-429 CO USA