Printer-friendly versionPrinter-friendly version Share this


Update 6:45 p.m. --  San Onofre has cancelled the alert issued earlier and now reports that its onsite emergency response team has contained the release and cleaned up hazardous material at the unit following an ammonia leak. The leak had no impact on radioactive material or cooling units.  



Plumbing union expert involved with installation of piping and ammonia monitoring system at plant speaks with ECM

By Miriam Raftery


 November 1, 2011 (San Diego) – Staff at a unit at the San Onofre Nuclear Generation Station have been evacuated, ECM has learned. 

 “The San Onofre Nuclear Generating Station (SONGS) notified the County of San Diego that the alert at the plant is due to an ammonia leak at one of its units,” the San Diego County Operational Area Emergency Operations Center (EOC) stated in a media release issued at 4:40 p.m.

The EOC confirmed that “there is no radioactive material involved in the leak and no protective action is recommended for the public...We will continue to monitor the situation very closely and advise the public of any changes,” the EOC alert states. “All resources and support personnel have been identified and are on standby, ready to be mobilized if needed.”

A Level Two emergency has been declared after detection of a leak at 3 p.m. in the No. 3 water treatment system at a non-nuclear section of the plant, according to the Los Angeles Times. Under federal regulations, there are four emergency levels, depending on the severity of the situation. Level Two involves any "potential substandard degradation in the level of safety of the plant."Other sections of the plant continue to operate normally, the Times reports.

Dexter Levy was head of the plumbers and pipefitters union when its members installed all of the piping used to handle the ammonia as well as instrumentation for detecting it. He told ECM that ammonia is a cooling agent and in the nuclear industry, a byproduct of refrigeration.

“Normally it is controlled, but ammonia is a very dangerous product,” he said in a phone interview today. “It finds holes where there aren’t holes. It is a very touchy product and it’s very corrosive...The biggest thing is that it is absolutely deadly. When you have a large amount of ammonia, there is no oxygen so you’d suffocate, and it burns.”

There are two ways to get rid of the ammonia, Levy explained. One is to use water to dilute it and get it into a state where it can be handled. “There are sprayers, all kinds of ways,” he noted, “or they can use a very slow venting. There are a whole bunch of scenarios.”

Despite potential risk that an ammonia leak can pose to workers at any facility using the material, Levy sees little chance of a threat to the nuclear reactors or to people outside the plant.

“Not unless there’s a big release,” he concluded, adding that plant monitoring would provide adequate notice of any major release to shut down roadways nearby and do a broader evacuation in time, in the unlikely event of such an occurrence. “But I think it’s only a matter of time before it dissipates," he assured.

According to NBC TV, officials at the plant said 25 gallons of ammonia leaked. Emergency sirens sounded and San Onofre officials indicated people close by were called within 15 minutes in accordance with plans.

For additional information regarding this alert, the EOC asks that calls be placed to the Public Information Hotline at 2-11. Do not call 9-1-1 unless there is a life-threatening emergency.

Sign up to receive free Viejas Wildfire & Emergency Alerts via e-mail at the top right side of our page and also receive a free weekly newsletter from East County Magazine with top news and events from our region.  You can also follow Viejas Alerts at Twitter for brief text alerts.

We recommend ALL of the above through your work and home contacts since you can't be sure what communications will be working in a major regional emergency.

Error message

Support community news in the public interest! As nonprofit news, we rely on donations from the public to fund our reporting -- not special interests. Please donate to sustain East County Magazine's local reporting and/or wildfire alerts at to help us keep people safe and informed across our region.


Agrees with Everyguy

I can't agree with the other person who posted more. I work specifically in this field. Specifically, I'm a consultant for ammonia refrigeration safety. Ms Raftery would have done her credibility a little justice had she consulted another person in addition to the welder. While his comments are 'true', there are things that I would like to point out. When he talks about it being "absolutely deadly", I have to ask any reader of this article a question - Do you own a chainsaw? Well, those too are absolutely deadly and exceptionally dangerous. You can also say that they cause a significant and extensive amount of injuries to persons every year and they are the leading cause of injury in home tree removal. All true statements, but denying the fact that, if you are trained to use it, you respect it, and you maintain it, all of these factors are virtually eliminated. How about ownership of a car next? By the time you finished reading this blog post, there will likely have been more deaths by vehicle in that time period as there have been in the ammonia refrigeration community in the past year or potentially the last SEVERAL years.

"Where there you have large amounts, you suffocate? Sure. Where there is a large amount of CO2, you suffocate. It burns? It sure does, but the average Joe will NEVER be in a situation where they are near the concentration levels necessary to burn and trained persons are going to be prepared with personal protective equipment.

By the way, Ms Raftery, maybe you should have interviewed someone who would remind everyone that every time you sweat and pee, you are putting off ammonia. Oh no! Stop peeing! You're a danger to us all. Sorry for being too cheeky folks.

A 25 gallon leak is a pretty serious thing and needed to be properly be dealt with as noted, but can be dealt with properly and easily with trained persons and proper procedures.

By the way, virtually everything you eat or drink has been cooled or frozen at some point in time by an ammonia refrigeration system. Ammonia refrigeration is THE refrigerant of choice for the industrial refrigeration world.

Ammonia leaks

Ammonia is used for cooling in a lot of different industrial situations, and although it's pretty nasty stuff, I don't think it's as dangerous as Mr. Levy has made it out to be.

I worked as a refrigeration mechanic in a fish processing plant in Alaska that used ammonia to cool its blast freezers and storage freezers and often performed maintenance on ammonia refrigeration systems. It was an old plant, and now and then we'd have a leak to deal with.

Although ammonia is toxic it has a couple of points that tend to mitigate the hazard. First of all, it smells so bad that no one is going to stay around it long enough to get a dangerous dose unless they are trapped and cannot leave. The smell threshold is around 5 parts per million, while the 15-minute safe exposure limit set by OSHA is 7 times that. Outside of enclosed areas, it dissipates quickly into the atmosphere because it is lighter than air. Also, ammonia naturally occurs in the bodies of mammals, including humans, and they have a biological mechanism to eliminate excess amounts, so short-term exposure that does not cause immediate injury will also not cause long-term effects.

I saw this in action myself. Whenever there was an ammonia leak in our plant, no one had to call for an evacuation. The workers left of their own accord immediately because they couldn't stand the smell, and the plant was shut down until the leak was fixed (which I did while wearing a gas mask). I imagine that that is probably what happened at San Onofre.