The importance of the nuclear and neutronic properties of candidate space reactor materials to the design process has been acknowledged as has been the use of benchmark reactor physics experiments to verify and qualify analytical tools used in design, safety, and performance evaluation. Since June 1966, the Cross Section Evaluation Working Group (CSEWG) has acted as an interagency forum for the assessment and evaluation of nuclear reaction data used in the nuclear design process. CSEWG data testing has involved the specification and calculation of benchmark experiments which are used widely for commercial reactor design and safety analysis. These benchmark experiments preceded the issuance oflthe industry standards for acceptance, but the benchmarks exceed the minimum acceptance criteria for such data. Thus, a starting place has been provided in assuring the accuracy and uncertainty of nuclear data important to space reactor applications. (FI).

This paper is dedicated to the memory of R.D. McKnight, which gave a seminal contribution in establishing methodology and rigorous approach in the evaluation of the covariance of reactor physics integral experiments. His original assessment of the ZPPR experiment uncertainties and correlations has made nuclear data adjustments, based on these experiments, much more robust and reliable. In the present paper it has been shown with some numerical examples the actual impact on an adjustment of accounting for or neglecting such correlations.

This workshop was designed to meet the needs of those currently involved in or are planning a nuclear programme involving research and/or power fission reactors. The workshop had a broad scope including not only fission reactor core calculations, but also safety, fuel management, waste disposal reactor licensing. The lectures and computer exercises covered almost all aspects of the operation of fission reactors.This workshop introduced participants to the methods currently used in fission reactor calculations and to some computer codes in which these methods are used.