Yesterday Progress Energy's Brunswick Nuclear Power Plant on the Cape Fear River in southeastern North Carolina reported an "Unusual Event" when the reactor vessel sprung a leak during startup. The plant, Brunswick Unit-2 [a GE BWR that came on-line in 1975], had been shut down for maintenance requiring reactor disassembly, and was at about 7% power when the leak occurred.
News reports yesterday said operators noticed an increase in drywell drain level of more than 10 gallons per minute during start-up, so they manually brought the reactor back down. Which "diminished the leak."
Today it was reported that the NRC will be sending a special inspection team in on Monday. The purpose is apparently to try and figure out why when they were putting the reactor back together they 'forgot' to tighten the bolts on the head. Or determine some other reason for the situation.
Yes, that's what now is being blamed for the incident. Before I found that report I was trying to figure out where a 10+ gmp LOCA "at the top of the reactor" [i.e., above the fuel] would be coming from that would release to the small containment structure of these Fukushima-style BWR plants. Pipes and connections and fittings do sometimes fail, this is another of those notorious antiques nobody builds anymore. But coming out the head? Whoa.
A LOCA [Loss Of Coolant Accident] of 10+ gpm is 'small' enough not to present much of a problem keeping the core covered, depending on location and whether the reactor is brought down quickly. Is overall less immediately severe in a BWR than in a PWR, as in the pressurized water system a break is also a pressure leak and the core runs much hotter. Without pressure the water temperature rises very quickly and can develop 'voids' that effect heat removal (for the worse). But no matter what kind of reactor you're running, a LOCA isn't supposed to happen.
So the NRC isn't concerned about possible danger to workers and the public to send in this special inspection team. The containment sumps can pump the leaked water, likely a few hundred gallons - to tanks, they can decontaminate the drywell. The water is probably not extremely radioactive, can be processed and returned to the closed primary loop. The leak wasn't a burst pipe or fitting between the reactor out-flow and the containment wall. Good news for Progress' pocketbook. Unless they now end up with a hefty fine or two or three from NRC for this kind of 'operator error'. If indeed the bolts weren't duly tensioned by the expensive portable hydraulic tensioning systems sold to nuclear plants for this very purpose after the head was refitted onto the reactor vessel.
You don't just 'forget' to tighten the bolts, honestly. It's quite a process and involves more than a few people. A size-Big work order that MUST be part of the maintenance scheduling and checklist. 'Overlooking' such a thing is a serious failure. Not of the machinery, but of the humans in charge of running the machinery. Brunswick, like all other facilities, has at least one full-time NRC functionary assigned to oversee general operations and maintenance. He should have initialed the checklist (which would by then have 'made the rounds' of management and duly initialed) before startup approval was given. Paperwork, paperwork. Are we to believe they ALL missed the fact that the job didn't get done at all? That's kind of like believing live nuclear weapons could be "accidentally" loaded onto a bomber in North Dakota and flown all the way to Louisiana without anybody noticing.
Highly unlikely, IMO. The alternative scenario isn't any better given previous NRC attention to the issue of bolt cracking/failure. They are to be inspected every time they go in or come out, replaced as necessary. So the 'official' word yesterday was that . I wonder if we'll ever find out how this happened, as the public is reassured it's no big deal. Radiologically that's true. But it had damned sure better be a big deal for the licensee and the regulators.
Once again I will say this technology is far too dangerous to entrust to for-profit corporations who can't be bothered to install proper seismic monitors in an earthquake zone, or remember to tighten the bolts on the reactor lid before starting the damned thing up. We must insist as loudly as we can, as often as we can, that it be stopped. Then all we'll have to worry about is what to do with the deadly waste for the next 10,000 years…