ABC is determined to prove first-run scripted shows can work in the summer, dammit. The network announced it is ordering a second season of Rookie Blue, the Thursday-night cop drama some wags have dubbed “Grey’s Academy” because of its young cast. While Rookie has lost a bit of steam since it bowed to an audience of just over 7 million viewers three weeks ago, the show is doing dramatically better — up 125 among folks under 50 — than the repeats ABC aired Thursdays at 9 last summer. Oh, and Rookie also costs the network (relatively) next to nothing: Produced by Canadian network Canwest, ABC pays about $350,000 per episode for the right to air the show in the States, a person familiar with the financials said. That’s less than most network reality shows, and in line with what it might cost to air a repeat of an existing drama. ABC says it plans to air season two of Rookie next summer.