Reduced air injection time during containment testing due to the use of an ejector

Abstract

When testing the tightness of the containment and elements of the accident localization system at the Ukrainian NPP, the "absolute pressure" method is used. Using this method, as a result of measuring air pressure, temperature, and humidity, the Mendeleev-Clapeyron equation determines the mass of air present in the containment. That is, the turn is determined indirectly by determining the change in the mass of air in the containment over time. The tests consist of five stages: vacuuming; air injection, to achieve the required pressure value; parameter stabilization; measurement; pressure relief, and last more than 25 hours. During the tests, no work is carried out in the containment. A necessary condition for testing is to ensure overpressure in the containment. This is done by the operation of the compressor. Given the large volume of containment, this requires a relatively long time, which affects the economic performance of nuclear power plants. In this paper, it is proposed to use an ejector to reduce the time of air injection, the working environment for which is the air after the compressor. The environment for injection is taken from the environment (from the "pure" volume). The article calculates the time of air injection by the compressor to the containment under today’s conditions and when using an ejector. The pressure in the containment changes from 0 to 0.0686 MPa during injection. The ejector outlet pressure is optimized for designing relative to the minimum discharge time. The optimal pressure at the ejector outlet during design is 0.45 bar. It is shown that due to the use of an ejector, the injection time can be reduced by about 30 %.