The mini-series, “Joan of Arc,” isn’t a lot more interesting than its sweeps competition, which on NBC consists of Atomic Train (Sunday and Monday, May 16 and 17; 9 to 11 p.m.), with Rob Lowe managing to save only his extended family from the nuking of Denver by a leftover Soviet missile; and on ABC consists of Double Platinum (Sunday, May 16; 9 to 11 p.m.), with Diana Ross and Brandy, both of whom would’ve been much more fun in concert than they are as the singer mother and the singer daughter who haven’t seen each other for eighteen years and have miles to go and issues to resolve before a furious Brian Stokes Mitchell will sit still for their duet. Atomic Train wastes Edward Herrmann, and Double Platinum wastes Harvey Fierstein.