PCT Controller described a loss of separation event during visual approach procedures to the Runway 01 complex; noting the failure of a proper relief briefing and data block observance as causal factors.

Narrative

I was working all three finals at Dulles combined; having just relieved another Controller. During the briefing the Controller advised me that a SF34; approaching the airport from the west; had been 'cleared for the visual'. I incorrectly assumed he meant cleared for the visual to 01C; when in fact he had been cleared for the visual to 01R. Had I checked the scratch pad I would've realized this; or had I picked up on something he added at the end of the briefing; that 01C was now open but had been closed and so I could expect several aircraft to be tagged for 01R no matter where they were approaching from. Unfortunately; I didn't realize the problem and turned the SF34 in for 01R; believing the A330 was heading to 01C. After I had cleared the SF34 for the visual reference the airport I realized the issue and called traffic to the SF34 in an attempt to gain visual separation. He eventually sighted the A330; but at this point separation had diminished to below 2.5 miles lateral; I'm not sure what the vertical separation was. Additionally; the SF34 was significantly faster than the A330 and advised that he was slowing to his approach speed. I acknowledge his transmission and switched him to the Tower; but lateral separation continued to diminish; eventually forcing a go-around. This error was the result of inattention to briefing items on my part and an incomplete briefing from the Relieved Controller. However; the responsibility must lie with me to verify the landing runway assignment of all aircraft when assuming control of the position. Relieved Controllers should advise specifically of any unusual situations; such as an aircraft cleared for; an other than; expected runway. Relieving Controllers must verify all scratch pad data and ask for any clarification if there is doubt about a particular aircraft's plan.