Looking at (non-weapon) nuclear reactions: Bright enough light to blind?

Question about nuclear reactions (such as those inside a nuclear reactor, or the kind when a plutonium core is accidentally allowed to go critical, as happened in some 1950s fatal accidents): Is there a lot of light emitted, and is it bright enough to blind someone? (I read that in one of those accidents there was a bright blue light but can’t remember if it was written as being a split-second pulse only.)

If you stuck your head into the reaction chamber of a civilian nuclear reactor to see the reaction, would it just be bright light? (Ignoring, for now, the other harmful effects that sticking your head into it would do)

I don’t think you’d see any light at all in a civilian reactor, but I’m not sure. There may be a steady glow of Cerenkov radiation, depending on what was around the radioactivity. There is in pools of water where they store weak, spent cores.

I read something like you did, about a practice they called something like “tickling the tail of the dragon”, which sounded like it was brilliantly bright and perhaps enough to blind. I think this was a light that grew exponentially brighter over a second or two, and then decayed exponentially as soon as the unfortunate scientist got the subcritical masses apart again. This was in the book “Brighter than 1000 Suns”.

From Louis Slotin - Wikipedia
“On 21 May 1946, with seven colleagues watching, Slotin performed an experiment that involved the creation of one of the first steps of a fission reaction by placing two half-spheres of beryllium (a neutron reflector) around a 3.5-inch-diameter (89 mm) plutonium core. The experiment used the same 6.2-kilogram (13.7 lb) plutonium core that had irradiated Harry Daghlian, later called the “demon core” for its role in the two accidents. Slotin grasped the upper 228.6 mm (9-inch) beryllium hemisphere with his left hand through a thumb hole at the top while he maintained the separation of the half-spheres using the blade of a screwdriver with his right hand, having removed the shims normally used. Using a screwdriver was not a normal part of the experimental protocol.
At 3:20 p.m., the screwdriver slipped and the upper beryllium hemisphere fell, causing a “prompt critical” reaction and a burst of hard radiation. At the time, the scientists in the room observed the blue glow of air ionization and felt a heat wave. Slotin experienced a sour taste in his mouth and an intense burning sensation in his left hand. He jerked his left hand upward, lifting the upper beryllium hemisphere and dropping it to the floor, ending the reaction. However, he had already been exposed to a lethal dose of neutron radiation.”

It’s not quite as I remembered – there was a glow but they don’t say it was very bright, let alone blinding.

In fiction, “Noisy” Rhysling went blind from looking at a core, in Heinlein’s The Green Hills of Earth.

I have never read about a bright light from a criticality event. Hopefully someone like Stranger in a Strange Land will comment.

There is certainly a burst of radiation, but not peaking in the visible. Such was described in the Slotin accident. And of course Pu will get red hot in large enough amounts.

But a super bright light? I don’t think that happens.

I think you mean Stranger on a Train

Pretty much all the reports mention a flash of light and instantaneous blast of heat. Then there is a burning sensation, because ionizing radiation acts as a nonspecific irritant. Then a slow, messy death.

Ref.: Museum of Radiation and Radioactivity

Since the result of a criticality event is lots of neutrons and X-rays, there isn’t going to be much visible light. The reason that a nuclear explosion is so bright is that the x-rays are absorbed by the atmosphere, and re-radiated as visible light as the energy is dissipated. A “criticality excursion” isn’t going to generate enough energy to heat the atmosphere to luminescence.

It is possible to see a blue flash due to eg Cherenkov radiation (fast charged particles) and not be instantly struck blind- as noted above it’s not a fireball. You’ll just die of acute radiation poisoning within a few days.

Interesting. I always thought nuclear reactions were like mini-Suns, very bright.

Note that, even if you survive a criticality accident, cataracts and eventual blindness are a definite possibility. It’s not like in the comics where you develop awesome superpowers.

Here’s a photo of a working reactor core.

Here’s a picture without the Alamy watermarks:

It’s a public domain picture, so not sure why Alamy is trying to sell it. Anything to make a buck, I guess.

Anyway, the blue glow is actually coming from the water around the reactor, not from the reaction itself. It’s called Cherenkov radiation. It’s basically due to charged particles coming out of the reactor at speeds greater than the speed of light through that water (about 75 percent the speed of light in a vacuum).

More info:

In a criticality accident (or just having your head inside the reactor) I wonder how much of the light seen would be due to processes in the eye or other meat of the head, including the brain? Astronauts report cosmic ray visual phenomena, which seem to at least partially be due to direct nerve stimulation by high-energy particles, not photons.

Well, this guy took a 70 GeV proton beam to the head, which produced a “flash brighter than a thousand suns”, so the phosphene/nerve stimulation phenomenon exists.

Particles from a nuclear reactor may have more modest energies than cosmic rays, but could still result in Cherenkov radiation in the eyeball.

My HS physics class visited the research reactor at Reed College, which was at the bottom of 25’ of water, with an air tube that they would use to expose stuff to neutrons. They drew the control rods, then turned off the room lights so we could see the Cherenkov radiation. Even in regular room light, it is not bright enough to see, at least for a TRIGA-class reactor.

Holy crap, he took an accelerator beam to the head and didn’t develop any superpowers? I’m really starting to doubt the accuracy of some of those books I picked up in the drugstore when I was a kid.

Oops. I did.
I refer to him as Stranger so much I forgot his full title!
Hopefully he isn’t planning on being a stranger to the dope. I haven’t run across any of his posts for a while. :frowning:

That’s just a ‘comic book’ meme now, but before those comics (and 1950’s movie dramas) were written, it was a scientific theory.

Naive Darwinism was never compatible with the known age of the Earth. Up until the 70’s, there were various theories advanced, with more or less success, to account for the difference. One of the theories that failed was the idea that radiation could lead to enhanced variance and constructive mutation. That theory made it into popular culture before being rejected.

At the Tokai-mura criticality incident (JCO rinkai accident) in 1999, those present reported a blue flash.