Hi. I have a problem with some calculations. I have to find atom or weight fraction in MOX fuel. MOX fuel is a mixture of UO2 and PuO2. It can be mixed with a various enrichment of PuO2. The fraction of isotopes of uranium and plutonium are as here: U234 234,041 0,00002 U235 235,044 0,002 U236 236,046 0,00001 U238 238,051 0,99797 Pu239 239,052 0,936 Pu 240 240,054 0,059 Pu 241 241,057 0,004 Pu 242 242,059 0,001 Do you have any ideas how to count this? It have to depend on a enrichment of PuO2. I have a problem with finding atom/weight fraction of oxygen in fuel. Thank you in advance !