抄録
A cold moderator using liquid hydrogen is one of the key components in a MW-scale spallation target system. which directly affects the neutronic performance both in intensity and resolution. Flow visualization experiments were carried out in order to clarified a flow field in a cold moderator vessel, so that jet induced flows such as recirculation flows and stagnant regions were obserbed. As for a cylindrical moderator vessel, analytical results of velocity distributions obtained with a standard k-ε turbulent model agreed well with experimental results obtained with a PIV system. However, analytical heat transfer coefficients of a bottom of the vessel could not predict experimental values well.
