blinding energy

Q: nuclear fission 同nuclear fussion 用blinding energy 去拆開佢
A: Nuclear fission and fusion involve the release of binding energy, which comes from the mass defect of nuclides before and after the reaction.
[be aware that it is "binding" energy, not "blinding" energy].

Q: 咁假如mass defect係吾係一定係用reaction前 去減reaction後既 mass 先搵到正數?
A: If the total mass of nuclides after the reaction is larger than that before the reaction, such reaction could only take place with the input of energy. As said in the answer to the last question, fission and fusion reactions involve energy output, hence the total mass after the reaction is smaller than that before the reaction.

Q: 又說nuclear fission會組合成一個個重D既necleus,,,咁到底出黎個products個overall 個mass係吾係都係吾機會重過之前既nelcus?
A: Nuclear fission is the splitting of a heavy nucleus into light ones, whereas nuclear fusion is the combination of light nuclei into a heavy one (it seems that you have made it wrongly in your question).

In the fusion process, a heavy nucleus means that it has a higher (atomic) mass number than those possessed by individual nuclei before the reaction. It doesn't mean that the total mass of nuclei after the reaction is larger than that before the reaction. There is still a loss of mass during a fusion process.