Event Number: 49618
Notification Date: 12/09/2013
Notification Time: 09:20 [ET]
Event Date: 12/09/2013
Event Time: 08:00 [CST]
"At approximately 0748 [CST] on 12/9/2013, an electrical fault occurred resulting in a fire and explosion on the ANO [Arkansas Nuclear One] Unit 2 Unit Auxiliary Transformer. This caused a unit trip and a loss of power to Startup 3 Transformer, which is one of the two offsite power feeds to ANO Unit 2. ANO Unit 2 is currently in a stable shutdown condition. With Startup 3 and Unit Aux Transformer unavailable, power was lost to the Reactor Coolant Pumps and Circulating Water Pumps. RCS [Reactor Coolant System] natural circulation is in progress removing core decay heat. Emergency Feedwater actuated due to low steam generator levels and is supplying both steam generators. The unit is steaming to the atmosphere. 2A-1 and 2A-3 are powered from SU [Startup] 2 Transformer. 2A-4 is powered from 2K-4B Emergency Diesel Generator.
"ANO Unit 1 is currently operating at 98% power. The auto transformer tripped off line with the fault in ANO Unit 2 Unit Auxiliary Transformer. This has caused Startup Transformer 1 to be inoperable. This places ANO Unit 1 in a 72 hour Technical Specification action statement (T.S 3.6.1 for Loss of the SU-1 Transformer).
"No significant injuries were reported as a result of this condition and offsite agencies have been notified."
The Arkansas Democrat-Gazette had some details...
Arkansas Department of Emergency Management spokesman Tommy Jackson said that the fire had not extinguished within the 15 minutes of detection.Later in the day, the The River Valley Leader mentioned that "The interruption of electrical power to Unit 2 caused protective systems to shut down the reactor." Meaning, it scrammed, and is now (according to NRC) steaming to atmosphere outside containment with residual heat removal powered with EDGs [Emergency Diesel Generators] and one source of grid power.
"The auxiliary transformer exploded in Unit Two, and there was fire within the protected area," he said.
Gov. Mike Beebe said after a speech Monday at the Arkansas Electric Cooperatives Directors' Winter Conference in Little Rock that he had been briefed on the fire and that there was "no damage to the actual nuclear reactor."
But the interesting part is that it took more than an hour to extinguish the blaze, because the Entergy decision-makers on-site decided to let the "oil fire" burn itself out. From UA/LR Public Radio -
"The issue was that the transformer itself contains oil. The fire was contained very rapidly. However, because the fire involved oil, after it was contained the responders made the decision to let the oil fire burn off," says Bowling.Now, this is an interesting tidbit. Transformer explosion and fire, involving electrical equipment at a nuclear power plant, that was allowed to "burn itself out" because it was just an "oil fire." Deal is, such fires are a significant health hazard all by themselves...
Fire-related incidents are defined as incidents involving electrical equipment containing PCB's in which sufficient heat from any source causes the release of PCB's from the equipment casing. In soot-producing incidents an actual fire occurs in or near the PCB-containing electrical equipment eventually resulting in exposure of the PCB's to extremely high temperatures and in the formation and distribution of a black, carbonaceous material. PCB's have been identified in soot following numerous electrical equipment fires.11-17 Polychlorinated dibenzofurans (PCDF's)11-15,17-20 and polychlorinated dibenzo-p-dioxins (PCDD's)12-15,17-20 have also been identified following this type of fire-related incident. Laboratory studies have confirmed that PCDF's and PCDD's are formed from the pyrolysis of PCB's21-24 or chlorobenzenes25 at temperatures ranging from 500° to 700°C (932° to 1292°F).The photo above from the River Valley Leader shows a considerable amount of soot from the fire. Because the location was a closed area they were able to isolate (fire walls between chambers), it was determined to let it burn on out rather than go in there with human firefighters to try and put it out. The unit will remain shut down until the incident has been fully investigated and all necessary clean-up and repair/replacement work done. As it should be.
In addition to PCDD's and PCDF's, other polychlorinated hydrocarbons have been identified in soot from electrical equipment fires. Polychlorinated biphenylenes,13,26 polychlorinated pyrenes,26 and polychlorinated diphenyl ethers18 have been detected in soot samples collected following capacitor or transformer fires.
The regulations on fires at nuclear plants are pretty strong, in that any fire in any system that lasts more than 15 minutes must be immediately reported as a serious incident for response. Yet this fire was allowed to "burn itself out" over more than an hour and a half, and it took another hour to notify the NRC. Even though there's an NRC 'resident inspector' on site. This is something that isn't SOP for nukes, or at least, it shouldn't be.
Relatively speaking, it is perhaps better to let it burn and the volatile hazardous substances to escape into the atmosphere for dispersion than to send a bunch of humans in there to put it out, as there would be considerable harmful exposure even if they're wearing protective masks with supplied air. Spreading out the 'harm' to a much wider area and larger population will lessen the dangers to each individual, as well as make it harder to later prove damages in court. Liability, you know. A bunch of sick and/or dead firefighters versus rural residents or townsfolk who maybe develop vague symptoms sometime down the line. If you're a corporation, what are you gonna decide to do or not do?
Or, more importantly, what is the NRC's practice on enforcement on its fire rules at nuclear power plants, that Entergy could decide for itself on the spot to let this "burn itself out" and still not even bother to tell the NRC for another hour afterwards? Well, ProPublica had an article on March 11, 2011 - the day Fukushima's disaster began - about this very issue.
The Nuclear Regulatory Commission is routinely waiving fire rule violations at nearly half the nation's 104 commercial reactors, even though fire presents one of the chief hazards at nuclear plants.Huh. Doesn't look like things have improved much in the years since, does it?
The policy, the result of a series of little-noticed decisions in recent years, is meant to encourage nuclear companies to remedy longstanding fire safety problems. But critics say it is leaving decades-old fire hazards in place as the NRC fails to enforce its own rules.
Fires are common at U.S. plants. In all, there have been at least 153 since 1995 [this was 2011, remember], or an average of about 10 a year, according to NRC records. Small fires, brief fires and fires in areas that were not considered critical to reactor safety have damaged essential equipment and forced emergency shutdowns, reports reviewed by ProPublica show.So. We might ask ourselves why the NRC would want to ignore its own regulations of the industry it's supposed to be regulating, when we know that there are some serious issues with antiquated transformers, electrical switching and such at these huge 35-40 year old Big-Megawatt plants...
"The agency takes full credit for the grace of God," said George Mulley, who wrote several scathing reports about lax fire enforcement while chief investigator at the NRC's Office of Inspector General.There you have it. The more things change, the more they remain the same. They don't even have to bother to ring up the NRC these days when shit happens. Just let 'em know at some point when it's all over.
The five-member commission has procrastinated on the issue for a simple reason, he said: "They don't want to cost the industry money."