In this work the TENDL 2015 nuclear data uncertainty of the JET structural materials has been propagated to uncertainties for neutron and photon flux around the JET KN2 irradiation ends and uncertainties for the reaction rate in KN2 for the two reactions 93Nb(n,2n)92mNb and 115In(n,n’)115mIn. The work has been performed for both DD and DT plasmas. For DD plasmas it is found that the uncertainty in the total neutron flux around KN2 is ~1 % and that the uncertainty in the 115In(n,n’)115mIn reaction rate is 1-2 %. For DT plasmas it is found that the uncertainty in the total neutron flux around KN2 is ~3 % and that the uncertainty in the 115In(n,n’)115mIn reaction rate is 3 - 4.5 % and for the 93Nb(n,2n)92mNb the uncertainty in the reaction rate is 1.1 – 2,6 %. The difference between average TENDL2015 values and FENDL2.1 is also investigated and the difference is found to be in the same range as the nuclear data uncertainty.
It is concluded that the uncertainty due to transport nuclear data needs to be included in the uncertainty analysis for neutron yield determinations using activation foils; in particular for DT plasmas. Activation reactions with high thresholds, such as the 93Nb(n,2n)92mNb reaction can significantly reduce the transport nuclear data uncertainty. This observation needs to be considered in the selection of materials for the KN2 activation system. Further work on the underlying nuclear data co-variance information is needed to have more inclusive and justified co-variance information.