Fugen Nuclear Power Plant, Advanced Thermal Reactor, was permanently shut down in March 2003 and it is at the decommissioning stage. Decommissioning Engineering Support System, DEXUS, has been developed to help planning of the optimal dismantling process and for carrying out the dismantling work safely and effi ciently. Worksite Visualization System (WVS), as part of Dismantling Work Support System of DEXUS, has been developed to support the fi eld workers to deal with the information on the dismantling facilities comprehensibly and intuitively. In this chapter, outline of the dismantling process of Fugen is fi rst introduced, then a feasibility study on WVS is described.