Sunday, December 22, 2013
An Urban Legend
In 1955 I moved from New York with my wife and child to Los
Angeles. On November 15 of that year I
started working at a division of one of the aircraft companies, North American
Aviation, called Atomics International, often abbreviated as AI. The purpose of this new division was to
establish a foothold for the parent company in the new field of nuclear reactor
power. Nuclear power was touted at the
time as being “clean” power. Nuclear
power stations did not emit black soot, oxides of carbon and sulfur, and
radioactive material that occurs naturally in coal.
The company secured a number of contracts for developing
types of power reactor. Many of these
contracts dealt with portable power units for military use. These contracts developed information that
was classified. Another government
contract was for a prototype reactor in which the coolant was sodium rather
than water. Coolant is the fluid that
extracts heat from the fissioning fuel elements and delivers it to a rather
conventional power unit through a heat exchanger. The advantages of sodium rather than water
were based on the fact that sodium remains a liquid from its melting point at
97o C to above 1,000o C.
Since it could operate at such a high temperature, the power plant would
have a higher Carnot efficiency than one in which water was used to transfer
the heat. In addition to improved thermodynamic
efficiency, a sodium cooled reactor had no need for pressure containment. All parts of the reactor operated at
atmospheric pressure. Only the steam
produced in the final heat exchanger operated at high pressure.
The disadvantages of using sodium relate to the chemical and
physical properties of the element. It’s
chemically very reactive. Air, and
especially oxygen and water vapor, must be kept away from the liquid
sodium. In addition it has a negative
reactivity coefficient with respect to the generation of neutrons. It absorbs them and the reaction produces radioactive NA24 which decays to magnesium. Because it absorbs neutrons, any gap or
bubble in the sodium in close contact with the uranium fuel produces a slight
increase in the efficiency of producing neutrons. If a sodium cooled reactor suddenly lost all
its coolant, the reactor would start a power excursion as well as experiencing
an immediate rise in temperature of the fuel.
A different effect occurs with a water-cooled reactor. Water absorbs few neutrons and also is a good
moderator. Loss of water causes a power
reduction in such a reactor. Of course,
the fuel elements get very hot, just as in the case of a sodium reactor with
loss of coolant.
Atomics International built the Sodium Reactor Experiment
(SRE) at the Rocketdyne-AI Field Test Station in the Simi Hills between Los
Angeles and Simi Valley. The reactor
began operation to demonstrate its ability to support a power plant in about
1957. In 1959 the reactor had an
accident that resulted in damage to 13 of the 42 fuel elements. There are numerous reports written at the
time about various aspects of the accident.
These reports state:
- · Some of the fuel elements broke open and released radioactive fission products.
- · These fission products were contained within the sodium coolant. The sodium was so radioactive that it couldn’t be disposed of. It was used in the subsequent re-start of the reactor next year, in 1960.
- · There is a free surface to the sodium in the reactor core. The space above the sodium is normally filled with helium. The helium is periodically vented to storage tanks and later vented. Fresh helium is introduced. After the accident the cover gas consisted of helium and also two inert gases: xenon and krypton. These were transferred along with the helium to the storage tanks and later vented. These are radioactive gases. Being gases without chemical activity, they rapidly dispersed and did not contribute to any appreciable radioactive contamination of the site.
- · Measurements were made and reported regarding the amount and kinds of radioactive fission products that were retained in the sodium. The report I read was written by Bob Hart, whom I knew when I worked at AI.
- · In July 1959 the reactor experienced a power excursion. The operators shut the reactor down. The coolant was drained. Equipment was used to open various plugs in the top of the reactor vessel to enable a camera to take pictures of the fuel elements. The fuel elements were then removed. There was no damage observed to coolant tubes, the moderator logs, moderator cans, or other fixed parts of the reactor vessel. Frank Fillmore, whom I knew, wrote a report about the power excursion. He concluded that the excursion was the result of bubbles in the sodium coolant that would produce the positive reactivity coefficient mentioned above.
- · Since there was no damage to the reactor vessel, including all the tubes, it was decided to load the reactor with new fuel and start it again. It resumed operation in 1960 and operated without any problems for another four years.
- · The cause of the accident was found to be a leak of an organic fluid used to cool the motors of the sodium pumps through a rotating seal into the sodium. The fluid formed carbonaceous clumps, similar to the clumps formed in a frying pan when food is badly scorched. The clumps partly plugged some of the coolant tubes and allowed the fuel elements in those tubes to overheat and be damaged.
In spite of what I’ve just written, there is a persistent
belief among some people that there was a melt-down, a large release of
radioactive material, and consequent increase in people living within a few
miles of the site experiencing cancers.
Since the presumed melt-own is not reported in any official or responsible
document, this belief is supported by a presumption that the government and the
contractors involved (AI, Department of Energy, Defense Department) are “covering
up” the truth.
I have a problem. How
do I go about convincing any of these melt-down believers that there was no
melt-down and no cover-up?
Comments:
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Hello there!
I've been researching this very incident lately to see if I can get a book out of it. I write novels for middle-school age kids, and have been looking for more math and science-oriented subjects to write about. In this case, I've been wondering whether a kid living in 1959 Simi Valley, perhaps who enjoys exploring up in the canyons, might have been able to stumble upon regarding the SSFL and the SRE. The idea hasn't fully taken shape yet because it's been hard for me to get an idea of what's realistic. So far, what I've been able to find has either been official reports that treat the incident as not a very big deal or exaggerated claims from hysterical anti-nuclear groups. There's been very little in between.
I think the reason so many people have accused the government of covering something up is because of when the media first paid any attention to the accident - 1979, right after Three Mile Island and The China Syndrome and twenty years after the accident took place. The idea that people involved with the accident at the time simply didn't think it was worth bothering the public about doesn't sound as believable.
But then, I think a lot of people are much too paranoid about nuclear power anyway. When the meltdowns happened at Fukushima, I was making jokes about Californians rushing out to buy iodine tablets and thinking nothing of driving down the freeway at 80mph while talking on their cell phones when they did it.
I've been researching this very incident lately to see if I can get a book out of it. I write novels for middle-school age kids, and have been looking for more math and science-oriented subjects to write about. In this case, I've been wondering whether a kid living in 1959 Simi Valley, perhaps who enjoys exploring up in the canyons, might have been able to stumble upon regarding the SSFL and the SRE. The idea hasn't fully taken shape yet because it's been hard for me to get an idea of what's realistic. So far, what I've been able to find has either been official reports that treat the incident as not a very big deal or exaggerated claims from hysterical anti-nuclear groups. There's been very little in between.
I think the reason so many people have accused the government of covering something up is because of when the media first paid any attention to the accident - 1979, right after Three Mile Island and The China Syndrome and twenty years after the accident took place. The idea that people involved with the accident at the time simply didn't think it was worth bothering the public about doesn't sound as believable.
But then, I think a lot of people are much too paranoid about nuclear power anyway. When the meltdowns happened at Fukushima, I was making jokes about Californians rushing out to buy iodine tablets and thinking nothing of driving down the freeway at 80mph while talking on their cell phones when they did it.
To Mr. Black,
There were two articles published on what happened at the Sodium Reactor Experiment (SRE) within a few months of the event in July 1959. I interviewed the Senior Engineer who was in charge of the SRE at the time of the incident. I met him through Al Saur. What he told me is that they really could not tell the media what happened right away because a reactor is not like other energy sources - you can't just shut them down and study them immediately. He called it a "post mortem" - after the reactor had cooled for a few weeks - certain gases such as iodine would have decayed away safely, only then could you go in with your equipment and begin to look into the core to see what had occurred. This link will provide you with the initial story given to the press, and to which newspapers it was sent to:http://www.etec.energy.gov/Library/Main/Doc._No._38_SRE_Press_Release_August_25_1959.pdf.
There were 700 copies of the "SRE Fuel Element Damage" report. There was no cover up - the issues of what happened at this reactor are covered in the literature where scientists and engineers published and learned from this experimental reactor.
Thank you to Al for your post. I will comment on it after I see if this post works.
There were two articles published on what happened at the Sodium Reactor Experiment (SRE) within a few months of the event in July 1959. I interviewed the Senior Engineer who was in charge of the SRE at the time of the incident. I met him through Al Saur. What he told me is that they really could not tell the media what happened right away because a reactor is not like other energy sources - you can't just shut them down and study them immediately. He called it a "post mortem" - after the reactor had cooled for a few weeks - certain gases such as iodine would have decayed away safely, only then could you go in with your equipment and begin to look into the core to see what had occurred. This link will provide you with the initial story given to the press, and to which newspapers it was sent to:http://www.etec.energy.gov/Library/Main/Doc._No._38_SRE_Press_Release_August_25_1959.pdf.
There were 700 copies of the "SRE Fuel Element Damage" report. There was no cover up - the issues of what happened at this reactor are covered in the literature where scientists and engineers published and learned from this experimental reactor.
Thank you to Al for your post. I will comment on it after I see if this post works.
# posted by 
: 12:35 AM
: 12:35 AM
Mr. Rowe,
Wow, thank you! That's terrific. It's always great to have original source material.
I knew the claims that the SRE was a "secret project" were inaccurate, because Edward R. Murrow did an episode of See It Now on it in 1957, when they lit up the town of Moorpark (where I live now, by the way). These days, people are much too willing to cry "cover up" whenever the facts aren't what they want.
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Wow, thank you! That's terrific. It's always great to have original source material.
I knew the claims that the SRE was a "secret project" were inaccurate, because Edward R. Murrow did an episode of See It Now on it in 1957, when they lit up the town of Moorpark (where I live now, by the way). These days, people are much too willing to cry "cover up" whenever the facts aren't what they want.
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