IMPROVEMENT OF PRECOAT TYPE CONDENSATE FILTER PERFORMANCE

The precoat type condensate filter system. equipping most BWR plants i n Japan, is sought to be improved in terms of filtering performance-i. e. to lower the concentration of crud in filtered condensate water and to extend the filter run length. Laboratory experiments were performe d on various measures for improving the filter performance, among whic h those found to be promising were: (a) Use of more suitable precoat m aterial (cation resin of suitably low cross-linkage and mixture with f ibrous cation exchange resin), (b) Adoption of improved precoating pro cedure (body feed coating-i.e. feeding precoat material continuously d uring filter operation), (c) Improvement of flow pattern through filte ring vessel (insertion of draft tube), and (d) Modification of filter system operating mode (swelling operation-i.e. interruptions in indivi dual filter use in-between backwash operations). Trial application on actual plants of some of the above measures has demonstrated that the envisaged improvement of filter system performance can duly be expecte d to be realized.