Nuclear Data Needs Supporting Gen-IV Applications - INL Perspective and Initiatives

Studies conducted in connection with the Department of Energy (DOE) Generation IV (Gen-IV) and Advanced Fuel Cycle (AFC) programs show that the transuranic nuclides can strongly influence the neutronic behavior of some advanced nuclear energy systems of interest. Essentially all integral nuclear parameters computed using modern reactor physics codes and data libraries are affected by propagation of uncertainty in the underlying nuclear data used in the computational models. These parameters include: Criticality (multiplication factor) Reactivity feedback coefficients (e.g., Doppler, Coolant Void) Kinetics parameters (e.g., Effective Delayed Neutron Fraction) Reactivity loss during irradiation (Burnup Swing) Peak power value Conversion ratio of sustainable cores Transmutation potential of burner cores Max dpa, maximum helium- and hydrogen-production, etc. Decay heat, radiotoxicity, and neutron and gamma radiation levels However, the necessary cross section information may be unavailable with the required accuracy from the current nuclear databases for some key nuclides of interest. As a specific example, recent sensitivity analyses for the Very High Temperature Gen-IV reactor concept (Taiwo et al, 2005a, Salvatores et al., 2005, Taiwo et al, 2005b), which features a somewhat harder thermal neutron spectrum and a significantly higher fuel burnup target than is the case for standard light-water reactors, show a potential need for improved cross sections for some isotopes, including 238U, 239Pu, 240Pu, 41Pu, and 243Am, primarily in the resonance energy range, in order to satisfy the defined accuracy requirements on key computed integral parameters. Other transuranic nuclides may be of similar importance for some of the other Gen-IV concepts, although the primary needs appear to be currently focused around a few plutonium and americium isotopes. The target accuracies identified in these studies are very stringent and will be a challenge to achieve in many cases. In this article we briefly review the conclusions and recommendations of recent international workshops on nuclear data needs for Gen-IV. Following this is a discussion of two specific activities undertaken by the Idaho National Laboratory (INL) to participate in the international effort to address these needs.