Ever heard of SL-1?

According to a report by the Los Alamos National Laboratory, there were 60^† criticality accidents between 1945 and 1999. All told, these incidents claimed a total of 21 lives. Seven of these fatalities took place in the United States, and three of them occurred almost simultaneously on the night of January 3, 1961, at the site of SL-1.

† Sixty criticality accidents!

Unbelievable!

A criticality accident is one where the atomic materials begin to detonate. If the reaction is not stopped, an atom bomb explosion
is the result.

Sixty! Sixty!

Stationary Low-Power Reactor Number One—“SL-1” for short—was a small experimental nuclear reactor built by the US Army. It was located at the National Reactor Testing Station (NRTS), a remote facility 40 miles west of the town of Idaho Falls, Idaho. The reactor was undergoing tests to see if it could provide suitable amounts of heat and electrical power to remote army bases north of the Arctic Circle and in the DEW^† Line.

† Distant Early Warning. Sites looking for ballistic missiles coming towards the US from over the poles.

On the night of January 3, three technicians were getting ready to fire up SL-1 after it had been shut down for the holidays. Army Specialist Richard Leroy McKinley (27), a trainee, was observing the routine maintenance procedure, standing off to the side; Army Specialist John A. Byrnes (22) was the one actually performing the operation (standing on top of the reactor); and Navy Seabee Construction Electrician First Class Richard C. Legg (26) was supervising, likewise standing atop the reactor.

Something, however, went wrong. Badly wrong.

At 9:01 PM, an alarm went off at the National Reactor Testing Station. A heat sensor in the reactor room had detected an unusual spike in temperature. Six firemen immediately suited up to respond, though they probably weren’t expecting much: two false alarms had occurred earlier that day. As they approached the reactor site, the firemen noticed that steam was rising from the Support Facilities Building (where the reactor was housed), but that wasn’t unusual for a cold January night in Idaho.

The firefighters attempted to hail the technicians known to be working inside the Support Facilities Building, but received no answer. A security guard opened the gate for them. The firemen donned their Scott Air-Paks and went inside to investigate.

Scott Air-Paks are designed to deal with smoke, NOT a highly radioactive environment. After entering a lethal radioactive environment wearing the wrong equipment, did the firemen all die too?

At first, nothing appeared out of the ordinary—except for the fact that McKinley, Byrnes, and Legg were nowhere to be found. Three still-warm mugs of coffee were sitting in the break room. Three winter coats still hung from their pegs. Puzzled, the firefighters moved on to the reactor control room.

That’s when they saw the radiation warning light glowing angrily on the control panel. That was the first sign of trouble.

As the firemen climbed the stairs towards SL-1’s reactor room, their handheld radiation detector suddenly roared to life. The indicator jumped beyond its maximum range—200 röntgens per hour (R/hr). Thinking (or perhaps hoping) that the device was malfunctioning, the firefighters returned downstairs and retrieved a second detector. The readings on this new machine also maxed out as they climbed the stairs. The firemen retreated once again.

At 9:17, a US Army health physicist arrived. He and the assistant chief firefighter, with oxygen tanks and masks, started for the stairs to the reactor room. Their radiation detectors jumped to 25 R/hr, and they briefly withdrew. Armed with a higher-range ion chamber detector, the two men attacked the staircase again. The detector registered 500 R/hr as they climbed.

When they reached the top of the staircase and peered into the reactor chamber, they couldn’t believe their eyes. The room was dim, and filled with steam. The floor was strewn with gravel, rocks, twisted metal, and other debris. There even appeared to be pieces of the reactor embedded in the ceiling. The two men saw nobody, either living or dead. Stunned, they went back downstairs to await the arrival of SL-1’s lead health physicist, Ed Vallario, and Operations Supervisor Paul Duckworth.

When Vallario and Duckworth arrived, they suited up, climbed the stairs to the reactor floor, and entered the reactor chamber proper. Poking through the wreckage, Vallario heard someone moaning in pain. He found McKinley, unconscious and in shock, his battered body all but buried under debris. Vallario and Duckworth located Byrnes soon thereafter, dead, his body likewise battered and bloody. Legg was nowhere to be found. Vallario and Duckworth decided to head back outside and get help for the wounded McKinley.

McKinley’s rescue took two hours, and several members of the rescue team were forced to strip off their masks and breathe contaminated air in order to save him. He was eventually retrieved from the reactor room and loaded into an ambulance, but before the vehicle could reach nearby Highway 20, McKinley breathed his last. He was pronounced dead at 11:14 PM.

As McKinley was borne away, four more men entered the reactor room to search for Legg, the third SL-1 technician. Eventually, they located him…above their heads. What rescuers had initially thought was debris embedded in the reactor chamber ceiling was actually the body of Legg, pinned to the ceiling. He had been impaled by one of the reactor’s shield plugs. He, like Byrnes, had been killed instantly.

It quickly became apparent that a horrific accident had killed McKinley, Byrnes, and Legg. SL-1, for reasons unknown, had apparently ruptured with enough force to spray radioactive steam and debris all over the reactor chamber and kill all three of its operators—pinning one of them to the ceiling like some sort of grotesque holiday decoration.

The investigation of the accident’s cause had to wait until the bodies of Byrnes and Legg could be retrieved. A team of men recovered Byrnes’s corpse, coated with blood and steel pellets, the following night. Legg’s body proved problematic, for obvious reasons. Not only was it difficult to reach, but it was by far the most contaminated by radioactivity. It took four days to plan the operation. First, a welder, working from a lead-shielded box attached to a crane, cut open the reactor chamber ceiling. On January 9, a ten-man team, working in relays of two (each relay only being allowed 65 seconds in the reactor room apiece), used long poles with sharp hooks at the ends to snag Legg’s mangled corpse, free it from the shield plug, and drop it onto an enormous stretcher suspended from a crane outside the building.

With the retrieval operation complete, investigators set themselves the task of determining what had caused the accident that had claimed the lives of three young men in such a gruesome fashion.

They initially doubted that this was a criticality accident. SL-1 and reactors like it were believed to be completely safe, and incapable of going critical in such a drastic fashion. But forensic evidence proved otherwise. Neutron-activated materials in the deceased men’s effects—copper-64 in McKinley’s cigarette lighter and the band of Byrnes’s wristwatch, and gold-198 in Legg’s wedding ring—conclusively proved that the reactor had gone prompt critical. This, in turn, indicated that the reactor had undergone a power excursion. Investigators were later able to determine that SL-1, designed to operate at three megawatts, (3,000,000) had jumped to a staggering 20 gigawatts (20,000,000,000) in the span of four thousandths of a second! 

This power excursion—6,000 times what the reactor was rated for—had caused the event which subsequently killed the reactor’s three operators.

But what had caused the excursion?

A vital clue lay in the procedure which Legg, Byrnes, and McKinley had been performing the night of January 3, and the design of SL-1. The reactor was designed to have a large central control rod which was capable of greatly accelerating the nuclear reaction in SL-1’s core if it was removed too far. Part of SL-1’s pre-startup checklist required the technicians to pull this rod up four inches in order to connect it to its drive mechanism. Post-accident analysis, including examination of scratches found on the rod, revealed that the rod, instead of being withdrawn four inches, had been withdrawn twenty inches.

The results were catastrophic. With the rod withdrawn so far, nothing could stop the nuclear fission reaction going on inside the reactor from racing out of control. A 20-gigawatt power excursion ensued, sealing the three technicians’ doom.

From Wikipedia

In four milliseconds, the heat generated by the resulting enormous power excursion caused fuel inside the core to melt and to explosively vaporize. The expanding fuel produced an extreme pressure wave that blasted water upward, striking the top of the reactor vessel with a peak pressure of 10,000 pounds per square inch. The slug of water was propelled at a speed of about 172,800 miles per hour with average pressure of around 500 pounds per square inch. 

This extreme form of water hammer propelled the entire reactor vessel upward at about 29,520 miles per hour while the shield plugs were ejected at about 172,800 miles per hour. From the six holes on the top of the reactor vessel, high pressure water and steam sprayed the entire room with radioactive debris from the damaged core. A later investigation concluded that the 26,000-pound (11 3/4 ton) vessel had jumped 9 feet 1 inch, parts of it striking the ceiling of the reactor building before settling back into its original location, and depositing insulation and gravel on the operating floor. If not for the vessel’s #5 seal housing hitting the overhead crane, the pressure vessel had enough upward momentum to rise about 10 feet, which would have put it through the roof. The excursion, steam explosion, and vessel movement took two to four seconds.

The spray of water and steam knocked two of the operators to the floor, killing one and severely injuring the other. The No. 7 shield plug from the top of the reactor vessel impaled the third man, up through his groin and out his shoulder, pinning him to the ceiling.

Byrnes had withdrawn the control rod too far and caused the disastrous power excursion that killed him and two other men. Investigators were left with only one question.

Why?

Why had Byrnes, a trained technician, made such an egregious breach of protocol and committed such a foolhardy and dangerous act?

Yes and why were ordinary technicians making adjustments to an atomic reactor without an expert in atomic power supervising them?

Theories ranged from the mundane to the outlandish: suicide, murder-suicide, an attempt to smooth the rod’s transition in and out of the reactor, or simple clumsiness. The best theory investigators were able to come up with (based on post-accident experimentation) was that the control rod had become stuck as Byrnes withdrew it, and in his attempts to jar it loose, Byrnes accidentally withdrew it too far, causing the power excursion and the resulting disaster.

But the truth is…we’ll never know.

There were only three witnesses to the event—Byrnes, McKinley, and Legg. Two were killed instantly and the third died shortly afterward, denying us their testimony. There were no closed circuit TV cameras to record the event. We’ll never know exactly why Control Rod No. 9 was withdrawn twenty inches instead of the regulation four. The mystery of the SL-1 incident will never be solved.

In my opinion, with atomic power, even a big wave can cause a horrible nuclear accident! One moment of human error can cause an atomic bomb to explode! At the end of a shift, the wrong switch is flipped, a gauge is mis-read, the wrong lever is pulled—the result? BOOM! Another location on planet Earth becomes unapproachable for 100,000 years.

Fission-powered, water-cooled nuclear reactors

ARE TOO DANGEROUS

SAFE THORIUM POWER SHOULD REPLACE
DANGEROUS FISSION POWER IMMEDIATELY!

The longer we wait to do this,
the closer we come to another huge nuclear tragedy like

• • the cave in Russia where 55 gallon drums of “spent” nuclear fuel leaked and started to go critical almost resulting in a china syndrome event! (human error)
• • Three Mile Island (a stuck open valve and human error)
• • Chernobyl (human error)
• • Fukushima (a tidal wave destroyed the only generators providing power to the water pumps—human error for not having any tsunami-proof back-up generators in a country that experiences tidal waves ALL THE TIME)
  
  
  

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