Steve Jackson Games - Site Navigation
Home General Info Follow Us Search Illuminator Store Forums What's New Other Games Ogre GURPS Munchkin Our Games: Home

Go Back   Steve Jackson Games Forums > Roleplaying > GURPS

Reply
 
Thread Tools Display Modes
Old 10-13-2021, 04:27 PM   #1
Michael Thayne
 
Michael Thayne's Avatar
 
Join Date: May 2010
Default GURPS effects of exposure to a nuclear fuel source

GURPS Disasters: Meltdown and Fallout goes into some detail about dramatic ways nuclear technology can do bad stuff to you. But what if there's no meltdown, no fallout, and instead you're just directly exposed to a nuclear fuel source—say because some idiot decided to dissect a nuclear bomb or radioisotope thermoelectric generator? I've tried to research this and it turns out to be a somewhat confusing subject, because AFAICT the main types of nuclear fuel are all alpha emitters. Since alpha particles don't penetrate skin very well, alpha emitters are only dangerous if ingested or inhaled. Except alpha emitters often have much more dangerous isotopes in their decay chains. So how do you figure out the rads accumulated for, say, handling a fuel rod / pellet / etc. with no better protection than a pair of iron tongs?
Michael Thayne is online now   Reply With Quote
Old 10-13-2021, 04:42 PM   #2
Anthony
 
Join Date: Feb 2005
Location: Berkeley, CA
Default Re: GURPS effects of exposure to a nuclear fuel source

An unused nuclear fuel pellet really isn't a short term radiation hazard at all (long term cancer risk, but not radiation sickness), unless you manage to turn bomb parts supercritical. A fuel pellet that's actually been used inside of a reactor can be extremely hot because of fission byproducts but that effect will be extremely variable with time.
__________________
My GURPS site and Blog.
Anthony is offline   Reply With Quote
Old 10-13-2021, 06:05 PM   #3
thrash
 
thrash's Avatar
 
Join Date: Aug 2004
Location: traveller
Default Re: GURPS effects of exposure to a nuclear fuel source

Have you looked at OSHA's Radiation Emergency Preparedness and Response page? There's a lot about the more dramatic stuff, but they also cover (e.g.) "Lost, found, or orphan (i.e., no longer under proper control, abandoned) radioactive material sources." This includes links and cross-references (as in the quote).
thrash is online now   Reply With Quote
Old 10-13-2021, 06:46 PM   #4
Anthony
 
Join Date: Feb 2005
Location: Berkeley, CA
Default Re: GURPS effects of exposure to a nuclear fuel source

For those who are curious: if you have purified U-235, something like 92% of total decay energy will be alpha decay from U-235 to Th-231, another 8% will be Th-231 to Pa-231, and unless you leave it for thousands of years, everything else is negligible (Th-231 has a half-life of 25.5 hours so it reaches equilibrium quickly, but Pa-231 has a half-life of 32,000 years). Decay rate is 4.5e-16/sec with a decay energy of 2e+9J/g for an energy output of 9e-7W/g. 1J/kg is 100 rads, so for a 70 kg person that works out to 1.3e-6 rad/sec (about 1 rad per 9 days) if you absorb it all, which pretty much means swallowing powdered uranium.

Now, for nuclear fuel that has been used in a reactor, radiation output starts at around 6.5% of the total thermal power output of the reactor (so probably more like 20% of electrical power output), which will kill people impressively fast.
__________________
My GURPS site and Blog.
Anthony is offline   Reply With Quote
Old 10-13-2021, 08:09 PM   #5
Michael Thayne
 
Michael Thayne's Avatar
 
Join Date: May 2010
Default Re: GURPS effects of exposure to a nuclear fuel source

Quote:
Originally Posted by Anthony View Post
For those who are curious: if you have purified U-235, something like 92% of total decay energy will be alpha decay from U-235 to Th-231, another 8% will be Th-231 to Pa-231, and unless you leave it for thousands of years, everything else is negligible (Th-231 has a half-life of 25.5 hours so it reaches equilibrium quickly, but Pa-231 has a half-life of 32,000 years). Decay rate is 4.5e-16/sec with a decay energy of 2e+9J/g for an energy output of 9e-7W/g. 1J/kg is 100 rads, so for a 70 kg person that works out to 1.3e-6 rad/sec (about 1 rad per 9 days) if you absorb it all, which pretty much means swallowing powdered uranium.

Now, for nuclear fuel that has been used in a reactor, radiation output starts at around 6.5% of the total thermal power output of the reactor (so probably more like 20% of electrical power output), which will kill people impressively fast.
This is really helpful. What's the equivalent math look like for the plutonium-238 in an RTG?
Michael Thayne is online now   Reply With Quote
Old 10-13-2021, 08:35 PM   #6
Anthony
 
Join Date: Feb 2005
Location: Berkeley, CA
Default Re: GURPS effects of exposure to a nuclear fuel source

Quote:
Originally Posted by Michael Thayne View Post
This is really helpful. What's the equivalent math look like for the plutonium-238 in an RTG?
The main decay path there is Pu-238 -> U-234, which is an alpha reaction, so also mostly an internal risk, though the total amount of radioactivity is much larger.
__________________
My GURPS site and Blog.
Anthony is offline   Reply With Quote
Old 10-14-2021, 05:09 PM   #7
johndallman
 
Join Date: Oct 2010
Location: Cambridge, UK
Default Re: GURPS effects of exposure to a nuclear fuel source

I think what you want is someone being careless with food irradiation equipment. Gear that will sterilise bulk meat will do nasty things to living humans. The source it's easiest to be careless with is Cobalt-60, which produces lots of 1.17 and 1.48 MeV gamma rays, which have plenty of penetrating power.
johndallman is online now   Reply With Quote
Old 10-14-2021, 05:24 PM   #8
Michael Thayne
 
Michael Thayne's Avatar
 
Join Date: May 2010
Default Re: GURPS effects of exposure to a nuclear fuel source

Quote:
Originally Posted by Celjabba View Post
Civilian radiation sources can and have killed by unshielded contact or proximity.
Such as the one used in medical devices, food chain irradiation or RTG.
Fuel rods, probably not, unless exposed to fluor based acids, and someone breath the fumes ? I think there was such a case at one time.

Some real life deadly accidents :

https://en.wikipedia.org/wiki/List_o...tion_accidents

Some of those match your descriptions, such as the ones on September 13, 1987, or December 2, 2001 (RTG)

Not to mention https://en.wikipedia.org/wiki/Demon_core
(weapon core that went supercritical by mishandling)

However, I am not sure how to calculate the Accumulated Dose for Gurps consequences.
I am on my phone, but I think there was information in either space or THS, I will check later.
If I understand the relevant science correctly, the Demon Core could in some ways have become more dangerous after the two incidents it was involved in, since briefly going critical would have produced some relatively long-lasting gamma-ray sources, possibly including cesium-137 (I say "possibly" because I'm not sure if plutonium fission does that, or just uranium). Also not sure how hot the thing would have gotten just sitting around.

Quote:
Originally Posted by johndallman View Post
I think what you want is someone being careless with food irradiation equipment. Gear that will sterilise bulk meat will do nasty things to living humans. The source it's easiest to be careless with is Cobalt-60, which produces lots of 1.17 and 1.48 MeV gamma rays, which have plenty of penetrating power.
Yeah—cobalt-60 is also used in medical equipment, and has been a source of nasty mishaps in the real world. Though it has a shorter half-life than many fairly dangerous isotopes—how long would it take for a hunk of cobalt-60 to become less dangerous than an equivalent mass of nuclear waste?

(Edit: I mean nuclear waste from a reactor—old cobalt-60 is of course another variety of nuclear waste.)

Last edited by Michael Thayne; 10-14-2021 at 05:30 PM.
Michael Thayne is online now   Reply With Quote
Old 10-18-2021, 04:03 PM   #9
Pursuivant
 
Join Date: Apr 2005
Default Re: GURPS effects of exposure to a nuclear fuel source

Quote:
Originally Posted by Michael Thayne View Post
GURPS Disasters: Meltdown and Fallout goes into some detail about dramatic ways nuclear technology can do bad stuff to you. But what if there's no meltdown, no fallout, and instead you're just directly exposed to a nuclear fuel source—say because some idiot decided to dissect a nuclear bomb or radioisotope thermoelectric generator?
In such cases, the main risk to everyone involved is irradiated particulate matter, especially if it is an aerosol or finely ground dust which is easily suspended in air or water so it gets ingested or inhaled. While safety equipment is specifically designed to protect against such threats, there's always the risk of equipment failure or some other source of unprotected exposure.

If someone does inhale/ingest alpha or beta particles, or get them on their body or clothing, the race is on to get them decontaminated and on chelating drugs or otherwise remove as much radioactive material from their body as fast as possible. Hunting down potential victims in time treatment to do any good might be an adventure in itself.

Another possible avenue for exposure is objects or materials which have spent so much time in such close proximity to strong radiation emitters that they have become radioactive themselves. While they're unlikely to be so strongly radioactive that they cause burns or radiation illnesses, they have a strong potential to be long term cancer risks. The list of radiation accidents referenced above gives a good selection of such incidents.

A final risk from low level radiation is that it could be weaponized and scattered across a wide area. While the actual radiation risks are very low and likely to dissipate quickly, just the knowledge that the area is irradiated will get most normal people in a panic.

Quote:
Originally Posted by Michael Thayne View Post
Except alpha emitters often have much more dangerous isotopes in their decay chains. So how do you figure out the rads accumulated for, say, handling a fuel rod / pellet / etc. with no better protection than a pair of iron tongs?
I'd assess radiation exposure in terms of effective Rads per day or week. These might be relatively high for completely unprotected exposure where you might accidentally ingest alpha or beta particles to almost nil if you take suitable safety precautions.

Effects of long term low-level radiation exposure can take the form of penalties to Aging rolls, Susceptibility to certain cancers, the Sterility feature, and possibly the equivalent of 1-2 levels of Short Lifespan.

OSHA, CDC, DOE, etc. web sites have all sorts of info on these sorts of hazards.
Pursuivant is offline   Reply With Quote
Reply

Tags
meltdown and fallout, radiation

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Fnords are Off
[IMG] code is Off
HTML code is Off

Forum Jump


All times are GMT -6. The time now is 07:32 PM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2022, vBulletin Solutions, Inc.