Page:4SIGHT manual- a computer program for modelling degradation of underground low level waste concrete vaults (IA 4sightmanualcomp5612snyd).pdf/61



The calculations of are based upon a set of assumptions. For completeness, these are assumptions are"are assumptions" or "assumptions are" [sic] enumerated here:
 * 1) The vault system is, and remains, water saturated. This should be valid for all but the most arid locations.
 * 2) Darcy flow is valid, even at the bottom of the slab which might not be in direct contact with liquid.
 * 3) There is sufficient oxygen present for corrosion. This aThis is a [sic] conservative approach to corrosion.
 * 4) The concrete vault begins service approximately 100 days after casting. Therefore, the transport properties have reached about 90% of their assymptoticasymptotic [sic] values.
 * 5) The external ion concentration and hydraulic head are constant over the life of the vault.
 * 6) As the sulfate front advances, the concrete in its wake can be treated like soil and the external conditions can be advanced to this point.

The authors wish to acknowledge the financial support of the U.S. Nuclear Regulatory Commission (NRC). Mr. Jacob Philip was the NRC Program Manager and his advice was greatly appreciated. The authors would also like to express their thanks to Dr. James Pommersheim of Bucknell University and Mr. Dale Bentz of NIST for their discussion and comments.