Civil Engineering Reference
In-Depth Information
Fig. 10.20
Core melt penetrating into the subsoil below the foundation of the reactor building
[
87
]
Slowly, the groundwater could dissolve fission products out of this originally
molten and subsequently solidified mass. In a study [
88
] leaching rates roughly a
factor of 100 higher than those applied for vitrified HLW in a deep geological
repository waste were assumed. The leaching rate from the porous mass of the melt
is determined by processes such as molecular diffusion, adsorption, desorption, ion
exchange and colloid buildup. Further transport of the key radionuclides, Sr-90,
Tc-99, and Cs-137, requires consideration of the hydrodynamic transport equations
for advection and dispersion in the groundwater [
87
,
88
]. The radionuclides could
be carried through the groundwater to a well or into a river and then would move
downriver.
Radiation exposure of the public mainly from Sr-90 and Cs-137 would then be
possible through the intake of drinking water from the groundwater in the environ-
ment and downriver of the location of the core melt. Moreover, flooding by the river
could cause the flooded regions to be contaminated as a consequence of sedimen-
tation of radionuclides and drying up of the flooded regions.
10.3.6.3 Possible Countermeasures Against Core Melt into Subsoil
Countermeasures against the spreading of radionuclides would be possible [
87
]by
- installing sealing walls extending deep down to the contaminated groundwater,
- sinking wells to pump off radioactively contaminated groundwater.
If no such countermeasures would be taken, the groundwater of a relatively large
area, and over long periods of time, would not be fit for use as drinking water or for
irrigation of agricultural areas.
