mass number

atomic number

chemical properties

position in periodic table

U233andPu239

U23iandPu233

U235andPu235

U238andPu239

it is generating power to rated capacity

it is capable of generating much more than rated capacity

there is danger of nuclear spread

chain reaction that causes automatic splitting of the fuel nuclei has been established

reduce temperature

extract heat from nuclear reaction

control the reaction

cause collision with the fast moving neutrons to reduce their speed

heavy water

concrete and bricks

graphite and concrete

graphite.