There is a need to improve the availability of data and the method for dealing with the effects of nitrogen originating in gas pressurizers, on heat transfer in emergency conditions.

5.1.1. Severe accident in an integral reactor

There is a significant increase in safety of the integral reactor in comparison with the loop type reactor, due to a reduction in accident initiators and the use of passive safety features and inherent characteristics.

Integral reactor accident sequences have not been fully analyzed. It would be expedient to carry out such analyses since the results could influence reactor design. It is also necessary to carry out probabilistic safety analysis.

The reliability of available codes (RELAP/SCDAP/MELCOR) should be evaluated for severe accident analysis in integral reactors and the need for modification and validation determined. International cooperation could play a key role in code validation for integral reactors.