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Table 2

Description of environmental source terms for Slovakian NPP's (VVER-440/213 unit).

Source term name STC6-8d STC10-8d STC30-8d
Reactor type VVER VVER VVER
Initiating event STATION BLACKOUT– total loss of Alternate Current (AC) power Break on main circulation line (28 cm2) Break on the SG primary collector head (14 cm2)
Description of scenario Primary circuit depressurization– SAM;
Core damaged;
Corium in-vessel retention by application of SAM;
CONT damaged;
Core damaged;
RPV failure (SAM– reactor cavity flooding not successful)
CONT early damaged;
Primary circuit depressurization– SAM;
Core damaged;
Corium in-vessel retention by application of SAM;
CONT late damaged;
Begin of release (after end of chain reaction) 11 h (after 56 h through CONT break; height: 25 m) 4 h (after 18 h through CONT break; height: 25 m) 14 h (after 92 h through CONT break; height: 25 m)
Duration of release 181 h (136 h through damaged CONT) 188 h (174 h through damaged CONT) 178 h (100 h through damaged CONT)
Total release
   131I 67 PBq 105 PBq 3.7 PBq
   137Cs 12 PBq 18 PBq 0.7 PBq
   133Xe 930 PBq 2 000 PBq 6 400 PBq
Radiological equivalent of 131I activitya 630 PBq 920 PBq 38 PBq
INES category 7 7 6
a

Radiological equivalent of the 131I has been calculated according to INES (2009) methodology.