Abstract
Limited literature (Pomaro et al., 2011; Mirhosseini et al., 2014; Salomoni
et al., 2014; Andreev and Kapliy, 2014) is available on the structural analysis
of irradiated concrete biological shield (CBS), although extended operations
of nuclear powers plants may lead to critical neutron exposure above
10+19 n/cm2. To the notable exception of Andreev and Kapliy, available
structural models do not account for radiation-induced volumetric expansion,
although it was found to develop important linear dimensional change of the
order of 1%, and, can lead to significant concrete damage (Le Pape et al.,
2015). A 1D-cylindrical model of an unreinforced CBS accounting for temperature
and irradiation effects is developed. Irradiated concrete properties
are characterized probabilistically using the updated database collected by
Oak Ridge National Laboratory (Field et al., 2015). The overstressed concrete
ratio (OCR) of the CBS, i.e., the proportion of the wall thickness being
subject to stresses beyond the resistance of concrete, is derived by deterministic
and probabilistic analysis assuming that irradiated concrete behaves as
an elastic materials. In the bi-axial compressive zone near the reactor cavity, the OCR is limited to 5.7%, i.e., 8.6 cm (3 1/2 in.), whereas, in the tension
zone, the OCR extends to 72%, i.e., 1.08 m (4 1/2 in.). These results, valid
for a maximum neutron fluence on the concrete surface of 3.1E+19 n/cm2
(E > 0.1 MeV) and, obtained after 80 years of operation, give an indication
of the potential detrimental effects of prolonged irradiation of concrete in
nuclear power plants.
