HIBALL A Conceptual Heavy Ion Beam D r i v e n F u s i o n Reactor Study A p r e l i m i n a r y concept f o r a heavy-ion beam d r i v e n i n e r t i a l c o n f i nement f u s i o n power p l a n t Is pre s e n t e d . The h i g h r e p e t i t i o n r a t e of the RF a c c e l e r a t o r d r i v e r i s u t i l i z e d to serve f o u r r e a c t o r chambers a l t e r n a t l n g l y . In the chambers a no v e l f i r s t w a l l p r o t e c t i o n scheme i s used. At a t a r g e t g a i n of 83 the t o t a l net e l e c t r i c a l output i s 3 . 8 GW. The r e c i r c u l a t i n g power f r a c t i o n i s below 1 5 * . The main g o a l of the comprehensive HIBALL study (which i s c o n t i n u ing) i s to demonstrate the c o m p a t i b i l i t y of the design of the d r i v e r , the t a r g e t and the r e a c t o r chambers. Though p r e l i m i n a r y , the present d e s i g n i s e s s e n t i a l l y s e l f c o n s i s t e n t . T e n t a t i v e c ost e s t i m a t e s are g i v e n . The cost s compare w e l l w i t h those found i n s i m i l a r s t u d i e s on oth e r types of f u s i o n r e a c t o r s .