AN ALTERNATIVE PERSPECTIVE ON THE WEIGHTED POINT MODEL FOR PASSIVE NEUTRON MULTIPLICITY COUNTING

The failure of the point model for highly multiplying Pu metal items is largely a result of the fact that at larger masses the leakage multiplication is not constant throughout the item. This represents a violation of the underlying assumptions of the point model. One way to tackle this dilemma is to introduce finite extent parameters into the model by integrating the multiplication terms present in the basic point model equations over the spatial dimension(s). Here we consider simple cases of weapons grade Pu spheres and squat cylinders in both a non-reflective geometry and surrounded by a basic packing material reflector. The reduced spatial moments, gn = /n, as a function of Pu mass are evaluated and the prospect of using these functions as weighting factors for terms in the point model is considered.