The 2H(d,n)-and 2H(d,p)-reactions are studied for deuteron energies below 200 keV. It is shown that the R-matrix approach of Konopinski and Teller, which is very sensitive to the channel radius used, can be approximated in a way that the dependence on the channel radius does not appear explicitly. This approach appears to be formally equivalent to a kind of "direct approach" of Boersma. This equivalence answers the question why a direct approach to these reactions works at all at low energies. Each reaction is described by three parameters which are determined in a fit to the up to now available data.