Accidental release of tritiated water – toward a better radiological assessment

Abstract

Abstract. The need of less conservative but reliable risk assessment for accidental tritium release was recognized in the frame of present debate on nuclear energy future. While the fusion reactor is only in research phase and risk assessment are not extremely stringent, Romania faces a debate on near future of nuclear energy with heavy water reactors, known to have a large load and release of tritium. Both tritium and 14 C are key radionuclide for CANDU and are also directly involved in the life cycle of plants and animals. An interdisciplinary approach is proposed in order to better handle the environmental transfer of tritium under accidental conditions and preparatory steps are presented.

Advanced nuclear reactors and tritium impacts. Modeling the aquatic pathway

“…The Specific Activity Ratio (SAR) is defined as the ratio between SA of OBT in the animal and SA of HTO in water. Previous work defined values of SAR and other transfer factors for different aquatic organisms from European rivers (Galeriu et al, 2009;Gontier and Siclet, 2011;Galeriu and Melintescu, 2010;Fontugneet al, 2005;Franco et al, 2006;Gleizon et al, 2009;Heling and Bezhenar, 2009;Howard et al, 2012;IAEA, 2008;Melintescu and Galeriu, 2011;Miyamoto et al, 2002). These values should not be used to tropical organisms without significant increasing in the uncertainty of model results.…”

“…This parameter allows evaluating the transfer coefficients used to assess OBT dynamics, so the uncertainty is propagated into the model. Other critical parameter is the OBT biological loss rate (K 0.5 ) that is the half-live of tritium on OBT form in the organism, so it is crucial to determine the dynamic of OBT concentration in different aquatic organisms (Galeriu et al, 2009;Melintescu and Galeriu, 2011). Laboratory experiments to Fig.…”

“…They are essential tools for using in the regulatory control of routine discharges (Boyer and Beaugelin-Seiller, 2002;Ciffroy et al, 2005Ciffroy et al, , 2006Goutalet al, 2008;Maranget al, 2011) to the environment and also in planning measures to be taken in the event of accidental releases. Also, environmental assessment models are used for predicting the impact of releases which may occur far into the future (Anderssonet al, 2008;Ehrhardtet al, 1997;Galeriu et al, 2009;Patryl, 2005, 2008;Lepicard et al, 2004;Raskob, 2007;Raskob et al, 2004;Singh et al, 2012;Slavnicu et al, 2009;Vamanu et al, 2010). It is important to evaluate, to the extent possible, the reliability of the predictions of such models, by comparing with measured values in the environment or by comparing with the predictions of other models (Huhet al, 2004).…”

“…Actually, terrestrial, and aquatic pathways have to be studied for a better knowledge of tritium environmental behavior and its impact for all weather conditions. The main differences between tritium routine and accidental releases are generally the largest orders of magnitude for the potential accidental releases, although their kinetics is also much shorter than the annual routine releases (Galeriu et al, 2009). The kinetic effects for tritium environmental behavior are a topic to be studied further.…”