In PWR, fast neutron produced from fission in fuel has been moderated into thermal neutron by the a series of collisiion with coolant,i.e. H2O. So the multi-group neutron flux in coolant and fuel pin has much diffenrce, e.g. the relative higher fast neutron in fuel pin and relative higher thermal neutron in coolant as to the uniform. Are there specific data about comparision of multi-group neutron flux in coolant and fuel pin in PWR, if it don't need to use MCNP to simulate it ? Thank you very much.