Exponential Vasicek model

Dothan model, Black-Karasinski model, and the Exponential Vasicek model given below imply that r is log-normally distributed. While this finding may seem reasonable it is the cause for the explosion of the bank account, that is from a single unit of money one may be able to make, in an infinitesimal interval of time, and infinite amount of money. Sandmann and Sondermann model overcomes this problem by modelling the short rates as above. 

The Extended Exponential Vasicek model (Brigo and Mercurio) is... 

Vasicek, O., Fong, H.G., 1982. Term structure modelling using exponential splines. J. Financ. 

Vasicek, O., and H. G. Fong. 1982. Term Structure Modeling Using Exponential S pXmcs. Journal of Finance 2), May, 339-348. 

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