Conventional Cold Fusion reactor has serious disadvantage that reaction rate is so low due to the lower concentration of D around the reaction site. Thus, I would like to propose the conceptualized Cold Fusion Reactor with D confined in the grain boundary of poly crystalline metal grain boundary, because D can stay in the grain boundary due to the smaller size of D+ . In order to increase the reaction site the reactor has the multilayer metal film stacks. This reactor can transmute element with larger current of femto H2. Thus, I also would like to propose the conceptualized transmutation reactor with H2 gas to prove the mechanism of Cold fusion because with H2 femto H2 can have two protons it will show the femto D2 hypo of Cold Fusion mechanism is correct. The transmutation reactor needs to have target metal on the downside for femto H2 to fall on it, and target metal need to be heated to increase the reaction rate of transmutation

Keywords : Cold Fusion Femto D2, Femto H2, Transmutation Nucleus Model Neutron