The present research intends to investigate some chemical aspects of Molten-Salt Reactors (MSR) specifically in TRU burning application taking a particular interest in the facts under which being misled carelessly by immaturity of the MSR technology as exclusively established for thorium utilization. Topics include density assumption of fuel salt with high actinide concentration; chemical effect of PuF3 fission comparing with that of UF4; suspected validity of the fuel slat as a solution of FLiNaK and an alternative fuel salt constitution procedure. Chemical processes applicable to on-line, front-end and back-end of the Fast Molten Salt Reactor with U-Pu fuel cycle (FMSR-U/Pu) are discussed in encouraging and stimulating its development.