There's alot of bad information floating around here. Fermi 2 is a BWR; it doesn't have steam generators. But that's irrelevant in this case. Read the following - basically an auxillary system sprang a leak (sort of like the air conditioning system for the reactor building)
Best source of info is the NRC reading room (http://www.nrc.gov/reading-rm/doc-collections/event-status/event/en.html). Here are the events that were reported to the NRC in chronological order (RCS=Reactor Coolant System):
UNUSUAL EVENT DUE TO UNIDENTIFIED LEAKAGE GREATER THAN 10 GPM
The licensee reported that it had indications of unidentified reactor coolant leakage greater than 10 gpm which placed the licensee into an unusual event emergency action level (EAL). Indication of drywell sump level increase and pump out rate gave an approximate leak rate of 30 gpm. The licensee also indicated that drywell pressure was above the normal range. The unusual event declaration was made at 1610 EST.
At 1619 EST, the licensee manually scrammed the reactor. The scram was uncomplicated with all rods fully inserting and all systems functioning as required. Decay heat is being rejected to the main condenser. There has been no ECCS injection actuation and reactor water level is being maintained by feed pumps. The licensee has no significant safety related equipment out of service.
The licensee stated that there is no indication of further degradation of the leak rate and the source of the leak is still under investigation
The licensee has notified the NRC Resident Inspector along with State, Local, and other government agencies.
* * * UPDATE FROM LICENSEE (SKORBEK) TO NRC (HUFFMAN) AT 1640 EST ON 1/24/05 * * *
At 1640 EST, the licensee upgraded to an ALERT following additional leak rate calculations that indicated the leak rate was approximately 75 - 80 gpm based on drywell sump pump out rate. The licensee's EAL for an alert is RCS leakage greater than 50 gpm. The NRC entered the monitoring mode at 1653 EST. The licensee stated that there has been no increase in drywell radiation levels and that sump water chemistry analysis is in progress.
In addition to the normal government agencies notified, the NRC also notified the Canadian Nuclear Safety Commission Duty Officer (R. Chamberlaine).
* * * UPDATE FROM LICENSEE (VIA MANAGEMENT BRIEFING) AT 1930 EST ON 1/24/05 * * *
The licensee has indications that the leakage may not be reactor coolant leakage. Chemistry results show that the sump water radiation levels are at a level less than would be expected for RCS leakage. In addition, a secondary cooling system was found in a lineup configuration that could have masked leakage from the system. The licensee is waiting to get additional chemistry results on the presence of corrosion inhibitors in the sump water to provide additional confirmation that the leakage is not from the RCS.
* * * UPDATE FROM LICENSEE (VIA MANAGEMENT BRIEFING) AT 2200 EST ON 1/24/05 * * *
The licensee confirmed the presence of corrosion inhibitors in the drywell sump. In addition, based on manipulations of the Reactor Building Closed Cooling Water system and the Emergency Equipment Cooling Water system the licensee believes that the leakage is from the Reactor Building Closed Cooling Water system and not RCS leakage. The plant is stable and the licensee is continuing to cool down with pressure now at 180 psi and decreasing.
* * * UPDATE FROM THE LICENSEE (STROBEL) TO NRC (VIA R3 IRC BRIEFING) AT 22:30 EST ON 1/24/05 * * *
The licensee terminated its Alert and Unusual Event at 22:28 EST based on sump water chemistry, activity, and Reactor Building Closed Cooling Water System manipulations that indicate the leakage is secondary cooling water and not from the RCS. The NRC secured from the monitoring mode at 22:36 EST.
How long did they say before they can go critical again?
FAS
My first thought was a recirc pump seal or maybe a letdown line break. Those would have been more problematic. But with a 30,000 gpm ECCS injection I doubt if 75 gpm would have led to any fuel damage.