
Most NJOY processing sequences start with RECONR. It fills two
roles. First, it goes through all the reactions included on the
ENDF tape and chooses a union grid that allows all cross sections
to be represented using linear interpolation to a specified
accuracy. This step removes any nonlinear interpolation ranges
(e.g., loglog, linearlog). It also makes it possible
for all summation reactions to be reconstructed as the sum of
their parts (e.g., total, total inelastic, total fission).
Second, for resonance materials, it reconstructs the resonance
cross sections (elastic, fission, capture) on a union grid that
allows them all to be represented within certain accuracy
criteria, and then combines the resonance data with the other
linearized and unionized cross sections. The results are
written in PENDF format.
RECONR is fairly easy to use. Issues that deserve more
discussion include:
 Linearizarization and Unionization  how are the energy
grids chosen?
 Resonance Reconstruction  what options are available?
 Integral Thinning  practical libraries vs full
accuracy.
 Numerical Precision  how many significant figures
are used to represent energies and cross sections?
 Unresolved Treatment  how does RECONR interact with
UNRESR and PURR?
They will be discussed on the pages to follow.
