# How 'bright' would a lethal dose of radiation be?

I watched the Chernobyl TV series with my family and my mom and brother seemed to have a hard time understanding how radiation works, and thought the show was overstating its effects.

It can be hard to understand something we can't see, so I thought what if I could demonstrate different levels of radioactivity by bringing those radioactive particles into the visible spectrum.

The Question I asked myself is "If you were standing in a room with a 100W light bulb and the photons were replaced with radioactive decay particles, how much radiation would you be exposed to"

You could also compare it by equivalent energy because the energy of the particles is much higher than visible light. So you could either go for the same number of photons, or the same amount of energy.

I would vote for total power though. A 100W incandescent bulb is only ~5% efficient, so that would be 5 Joules per second.

In Chernobyl, a firefighter picked up a chunk of graphite that was the equivalent of 4 million chest x-rays, which by the shows math (3.6 Roentgen = 400 xrays) would be 36000 Roentgen. Wikipedia says one roentgen deposits 0.0096 Gy (0.96 rad) in soft tissue. A Grey (Gy) is defined as 1 joule of radiation absorbed per Kg, so the graphite chunk in the firefighters hand would be emitting 345.6 Joules of absorbable radiation. So compared to a 5% efficient incandescent bulb, that would be a 7000W bulb. But thats just the amount of radiation absorbed, i'm sure it is emitting much more that is not absorbed.

Anyway, thats as far as i've gotten. I would like to make a YouTube video on this and i want to get it right. Im sure there are some inaccuracies, but is this an accurate representation? I also want to compare different radioactive materials. like showing how it would only take a very tiny amount of Plutonium-241 to equal the decay rate of U-235.

Thanks, Kevin

• You seem to be mixing up joules (energy) and watts (power). A Grey is an amount of energy. A radioactive source like your lump of graphite releases energy over time. The half life of radioactive carbon is about 6,000 years, so your half of your 345.6 Joules of radiation would be emitted in 6,000 years, which is an average power of about 2 nanowatts (and hence the fire fighter was not in much danger of dropping dead while making the program). – alephzero Jun 23 at 21:07
• You might consider that a typical radiotherapy dose to destroy a tumour is about 60 to 80 Greys, and that is typically delivered over a 30 day period - so the average "radioactive power" is 2 greys per day, or 2 joules of energy per day for a (large) 1kg tumor. The actual treatment time is typically 5 minutes per day to deliver each dose of 2 greys. Compare that with your 100W light bulb which consumes 2 joules of energy in 1/50 of a second. Note, I have no idea what the bottom line of this comparison is supposed to be - you are creating your video, not me! – alephzero Jun 23 at 21:11
• At work we had a 20,000 Currie source, which emitted 300W of power. Full exposure to humans was a lethal dose in seconds, space craft components faired much better. – JEB Jun 23 at 21:16
• The lethal dose depends on whether you mean enough to kill within hours,within weeks or within years. Litvinyenko was poisoned by a drop of highly radioactive Po 210 put into his tea. Po 210 is an alpha emitter,so only ingested amount6s would do serious damage. It took over three weeks to kill Litvinyenko. A much smaller exposure to radioactive materials might take decades to kill,as it did with Marie Curie and one of her daughters. I have been exposed to C14,a beta emitter,for many years,but it seems to have done me no harm. – Michael Walsby Jun 24 at 12:36
• Alephzero, I see what you are saying, but in the TV show the firefighters hand was badly burned almost instantly. no way thats nanowatts! youtube.com/watch?v=qqZpjRxUZwA As i read more about it, im understanding the radiation meters are giving units in Roentgen per hour. so through the dodgy math i did before 36000 Roentgen would be an average of 0.096 watts absorbed by the body per second.. I was also reading 1 gram of plutonium-238 has a power density of .54 watts per gram, and polonium-210 (because of its high decay rate) emits 140 watts per gram. – Kevin Jun 24 at 22:22