mit-crpg/openmc — pull request #300 by walshjon (2014-07-29 05:43:26+00:00)
Title: account for differences in band probabilities at different energies

In general, the cumulative probabilities corresponding to probability table cross section bands in the URR are not constant at different energies. That is, the ith band at the jth energy will not have exactly the same probability as the ith band at the (j+1)th energy. Cross section bands should be sampled using the distinct cumulative probabilities at each of the two bounding energies using the same random number. This will change the numerical results of integral tests that utilize probability tables. Anecdotally, the band probabilities at neighboring energies are often close, so the new results should most often be within the statistical uncertainties of the previous results.