Unless otherwise directed by an order of the senior circuit judge, not more than two (2) grand juries shall be drawn or impaneled during a calendar year at or for a term or terms of the circuit court in any county or judicial district of a county; provided, however, upon impanelment, a grand jury may be convened and reconvened in termtime and in vacation. It shall continue to serve from term to term until the next grand jury is impaneled, and it may return indictments to any term of court, notwithstanding that a term of court at which criminal business may be conducted shall intervene between the time the grand jury is impaneled and the time an indictment is returned.