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Fukushima Nuclear Worker Accidentally Toggles Off Cooling Pumps
An anonymous reader writes "A Tepco employee carelessly pressed a button shutting off cooling pumps that serve the spent fuel pool in reactor #4 — thankfully a backup kicked in before any critical consequences resulted. The question remains just how vulnerable to simple mistakes (such as a single button push) are these spent fuel pools, filled nearly to capacity as they are with over 12,000 spent fuel rods? From the article: 'The latest incident is another reminder of the precarious state of the Fukushima plant, which has suffered a series of mishaps and accidents this year. Earlier this year, Tepco lost power to cool spent uranium fuel rods at the Fukushima Daiichi plant after a rat tripped an electrical wire.'"
And the "rat" that tripped the braker in the previous incident is a 6 ft tall, glowing green rat with three eyes and a forked tail...
[3-eyed fish knowingly blinks its eyes (sequentially)]
the U.S. Navy is one of the largest and one of the oldest operators of nuclear power plants (by hours critical) and has a spotless safety record
If you don't count there loss of the nuclear submarines USS Thresher and the USS Scorpion, the radioactive contamination of the USS Guardfish, or both the USS Puffer and the USS Proteus discharging radioactive water into the oceans.
Not to mention I am sure there are a number of other incidents that haven't been declassified yet.
I don't know how well the US Navy ranks amongst other operators of nuclear power plants, but "spotless" is not an accurate description. They may do very well comparatively and the overall harm may be minimal, but they have made their share of mistakes.
In training we covered the incidents of the Thresher and the Scorpion, and neither will discharge anything of genuine concern around them. Even immediately following the shutdown of the reactors and assuming reactor coolant pumps and natural circulation failures, the decay heat would easily be absorbed by the sea water that would have filled the reactor compartment, thus it can safely be assumed that the core remained intact. The other areas that contain high amounts of contamination are the primary shield water tank, the ion exchanger, and the charcoal filters. These systems are closed systems designed to operate at incredibly high pressures and are made of very corrosion resistant materials. Although eventually leaks will form from corrosion, but the leakage would be very slow as there is not significant difference in densities, temperatures, pressures, etc, to cause rapid loss, and the leaks themselves would be quite small.
The other 'incidents' are more public embarrassment than actual environmental concerns. The 'radioactive' water that is discharged comes from the water that circulates through the reactor. Technically, there are radioactive contaminants that emit a small amount of gamma radiation. These contaminants are actually particles that will typically settle in the seabed, IIRC, and are typically borderline measurable in most plants as the water is continually circulated through an ion exchanger (resin bed) and an activated charcoal filter. However, the Navy is so anal it treats anything remotely contaminated as radioactive material. The 'father of Nuclear Power', Admiral Hyman Rickover, famously drank a glass of this water at a Congressional hearing to demonstrate how benign the water really is. I think it is also important to note that the Proteus is not a nuclear powered ship, but a sub tender.
Prior to some year, I forget which (1970, maybe?), the Navy would discharge all kinds of crap at sea, which is actually quite typical of many industries and nations even today. However, the Navy stopped discharge of highly radioactive materials, such as ion exchanger resin, and has set a fleet-wide goal to only discharge so much total annually, I think it's something like 50 Ci, and while I was in would regularly come in under that number.
'Radiation' can come from many other sources than nuclear power plants. I don't know if the limits have changed, but it used to be that coal plants would discharge far more radioactive materials than nuclear power plants, but this would never get mentioned anywhere except nuclear power propaganda. When we were going through our radiological controls training, we learned that porcelain dentures are among the highest sources that people are exposed to. One of the Navy's training facilities has a containment vessel built completely around a nuclear power plant, which is unusual, as containment usually only goes around the reactor compartment. This vessel was made of a material that contained a high amount of alpha radiation, and the subsequent painting with lead-based paint made the vessel itself a far higher in-practice contamination risk than the nuclear plant it contained! Keep in mind this is a product of the private contractor that build the vessel, not the Navy, and the vessel was quite old and built in a time when most people and organizations had less concern for such things.
[Useful comment needed]
This isn't wikipedia, where people can trot out two simple words and feel justifiably smug, you know.