In book R. Göbel, P. Hill, Wolfgang "Abelian Group Theory and Related Topics", I found next Beaumont -Pierce Principal theorem: Any torsion-free ring $R$ of finite rank is quasi-equal to $S\oplus N$, where $N$ is nilradical, and $S$ is subring of $R$.
My question is: is $R$ need to be commutative in this theorem. If "No", what nilradical mean for noncimmutative rings?