The small number of available complete modern pump characteristics makes the safety analysis of nuclear and conventional power plants based on the characteristics made over half a century ago of specific speeds n _q=24.6, 147.1 and 261.4. The aim of the paper is to check sensitivity of the power plant system response for different complete pump characteristics - modern and available from older tests for n _q=24.6, 147.1 and 261.4. It has been shown that Suter's characteristics for modern pumps give a different response to the pumping system of a power plant in breakdown than those used so far.