ADVANCEMENT OF LEAKAGES TESTING TECHNOLOGY FOR TESTING REACTOR CONTAINMENTS OF NEW ATOMIC VESSELS
For safe operation of atomic icebreakers, one of the most important attributes is radiation and nuclear safety. In case of maximum design accident, radioactive emission in environment shall be limited to requirements, set in vessel design. Leakage degree of reactor containments of Russian and foreign atomic objects is specified by parameter called Permissible relative leak rate of test medium (air) at peak pressure of emergency medium. The achieved relative rate of leakage of protective shells of reactor compartments of icebreakers is 50 times worse than Russian nuclear power plants, and 100 times worse than the best foreign nuclear facilities. For the first time in the history of Russian shipbuilding reactor containments of new atomic icebreakers shall be tested with excessive pressure, that exceeds existing values (0.4 MPa instead of 0.1 MPa) in 4 times, and permissible relative leak rate shall be reduced in 25 times (in accordance with requirements of Russian Maritime Register of Shipping). Due to the above, increase of air relative leak rate detection threshold (i.e. increasing sensitivity of leakage monitoring) and automation of trials of reactor containments of new atomic icebreakers and other floating structures are now becoming an actual task. This article describes ways of increasing sensitivity of leakage monitoring of reactor containments of atomic vessels: application of monitoring procedures involving tared leakages and calibrated holes, analysis of mathematical models of traditional monitoring procedures, use of automated leakage monitoring system.