Estimation of systematic uncertainty in calculated results by PHITS with nuclear data

Hashimoto, Shintaro  ; Iwamoto, Osamu  ; Sato, Tatsuhiko   ; Niita, Koji*

PHITS has been used for many purposes such as radiation shielding in accelerator facilities. The PHITS result involves not only statistical error related to the number of trials in the Monte Carlo method but also systematic error attributed to uncertainty of nuclear data and nuclear reaction model. We developed a method to estimate the influence of covariance of JENDL on the PHITS result. In this method, we change the cross section within the covariance, and execute PHITS using each cross section. The result depends on the cross section. We regard its variance as the systematic error. PHITS can give both the statistical and systematic errors. We can discuss the reliability of the result of the radiation shielding. This method is applied to estimate the systematic error of neutron flux in neutron shielding calculations. The systematic error of the calculated flux depends on the depth in shielding material due to the number of scattering.