Uncertainty propagation and sensitivity analysis in the aleph monte carlo burnup code: Applications to fission pulse decay heat calculations

Uncertainty propagation and sensitivity analysis for burnup codes are key topics in the nuclear field because of their huge involvement in safety-related problems. Consequently, a correct evaluation of a given response variation after propagating the system parameter uncertainties is a primary feature for any burnup code. In this paper we described the options of linear sensitivity analysis, either forward or adjoint, recently implemented in the ALEPH Monte Carlo burnup code. The testing phase was carried out against the fission pulse decay heat problem for 239Pu thermal fission and compared to total Monte Carlo results, also produced by the code through its dedicated routines. The different techniques give comparable results thus supporting the consistency of the methods. To conclude, we also calculated and listed the parameters that contribute the most to decay heat perturbations.