[en] The results of a 3-1/2 year program to evaluate the state of knowledge of short-term shutdown heating in LWR's is presented. The work has consisted of three main types of effort. First, the sources of uncertainty inherent in summation calculations, and their propagation through these calculations to produce uncertainties in the derived decay power were examined. Second, the various incremental effects on decay power which might be expected to affect the predicted values of an idealized case as applied to real operation of a light water reactor were examined. Finally, the various experiments on decay power, particularly the recent ones of high precision, both to validate the summation method and to aid in the formulation of new standards were studied