Enhancement of CsI Aerosol Size in Superheated Steam in Reactor Piping under Severe Accidents
It is recognized in the source term evaluation of light water reactors that large uncertainties still remain in the fission products aerosol behavior in reactor coolant system during severe accidents<SUP>(1)</SUP>. Especially the aerosol size distribution has a great impact on the deposition behavior onto the inner surface of pipe wall through several mechanisms such as gravitational sedimentation and impaction. The present analytical models<SUP>(2)(3)</SUP> used in source term evaluation consider the growth of aerosol size due to steam condensation onto aerosol particles. However the effect of condensation is neglected in superheated steam. In an early stage of severe accident sequence the generated FP aerosol will be transported to primary circuit by superheated steam. Therefore it is essential to evaluate the aerosol size distribution under superheated steam. In the present experiments, the CsI gas and aerosol behaviors at a PWR hot leg inlet was simulated and the effect of difference in carrier gas, nitrogen and steam, on the CsI behavior in pipe was investigated.
- Journal of nuclear science and technology
Journal of nuclear science and technology 33(10), p.804-806, 1996-10-25
Atomic Energy Society of Japan