Abstract: DISSOLUTION OF UNIRRADIATED LMFBR（U，PU）O_2FUELZHANG SHAOQI；WEI XIUFANG；HOU XIAOLIN（China Institute of Atomic Energy，P.O. Box 275，Beijing，102413）WANG SHOUXIN；GAO YAOBIN；CHENG QINCHENG（Lan Zhou Nuclear Fuel Complex,P.O.Box 508,732850）ABSTRACT Dissolution behaviour of unirradiated LMFBR（U，Pu）O_2 fuel in HNO_3 is studied.Theeffects of HNO_3 concentration，dissolution temperature（U，Pu）O_2 pellet fabrication method（mechanical blending and AUPUC coprecipitating）and PuO_2 content on dissolution rate aredescribed in detail． The content of undissolved residues and the percentage of Pu（Ⅵ）in dis-solution solution are determined. Key words Fuel dissolution UO_2（U，Pu）O_2