Research of maximum accident of light-water power generating reactors

In reactors of the WWER-440 and WWER-1000 type the maximum credible accident is the rupture of the biggest piping of the biggest diameter in the primary circuit, i.e., pipes having a diameter of 500 mm in the former type and 850 mm in the latter type. The reactor protection system which includes reserve high- and low-pressure pumps and large-volume water tanks is therefore dimensioned in such a manner as to prevent radioactivity leak even in such a case. For such an event transients caused by coolant loss were computed and the theoretical aspects of the problem processed. Also described and schematically represented is the entire equipment of the WWER-440 designed for the elimination of such an accident. (O.K.)