Nuclear war aftermath...

Factual Questions
1

Say a nuclear war happened…with all major cities being nuked.

Many years, maybe generations later, people live off the carcass of the old civilization and are starting to rebuild. Think Fallout the game or something (actually, I am thinking of the old RPG game ‘Gamma World’)

Say a young man wishes to explore an old city.

What would radiation be like around this city? Would there be radiation pretty much everywhere that would get stronger the closer you get or would the radiation not be overly harmful but could spike rapidly high in certain areas?

2

It would be very hard to predict the extent of radioactive contamination of an area without more details. Was this an all-out nuclear war, with every weapon used against every possible target? Then you can assume nearly the entire Northern hemisphere is contaminated to one extent or another. Was it a limited counterforce strike? Then it would mainly spare major cities (with certain notable exceptions) but create large fallout plumes that would contaminate large areas. It’s hard to say for sure.

3

I’m sure someone with a better knowledge of decay rates will come along and be more specific, but in general.

  1. A lot of the most radioactive material would have decayed, less radioactive material would still remain (the more active an isotope is, the faster it decays). Less active material can still be dangerous through inhalation or ingestion.

  2. Wide open areas would be pretty safe, enclosed areas are more likely to still contain residue. Anything that stirs up large amounts of dust and dirt would be risky. You could expect the water to still be contaminated, but if you absolutely had to drink it, you’d want to very careful about sediment.

  3. Radiation distribution would be very variable due to complicated and none obvious factors (wind flow, contamination of indoor areas by people during the original event, movement of animals, rain etc). A geiger counter would be very handy.

4

How much radiation can be washed away due to years worth of rain?

Down storm sewers, to drainage ditches and rivers, out to sea?

5

Hiroshima and Nagasaki are vibrant cities today.

6

Yet Chernobyl will take about 500 years to be habitable again? Why so much difference different between Chernobyl and Hiroshima?

7

The bombs detonated at Hiroshima and Nagasaki, and the vast majority of the warheads detonated in a hypothetical all out nuclear war, were detonated above the cities (1,900 feet at Hiroshima, 1,500 at Nagasaki). I don’t know enough to give much detail, but essentially an air burst does more immediate damage over a wider area, while at the same time minimizing long term fallout.

8

Chernobyl had a lot more radioactive material than the bombs used again Japan. In addition, the 500-yr number only relates to part of the area; some of the contaminated areas seem to be recovering faster than expected, though some are recovering more slowly.

To go back to the OP’s question more directly: the radiation (long-term) is entirely due to radio-isotopes produced in the blast, which means everything started life as gas that condensed out and mostly became dust that you’d expect to mix with non-radioactive dust, ash, etc. To a large extent, you can follow it just by following wind and water.

Hot spots are definitely the biggest concern. A low point in storm drains would probably have a layer of runoff that is much higher in radioactivity than the streets or surface dirt. In fact, if this radioactive layer is covered up by later layers of mud from runoff, the dirt itself might protect a traveler from radiation as long as he doesn’t start digging around. Of course, post-apocalypse, digging around in cities might have its appeals.

The same issue might come up for enclosed spaces - perhaps a building’s basement gets a full dose of radioactive dust before the building collapses on top. Now the dust has nowhere to go until some luckless explorer opens it up and starts stirring dust around.

Just being exposed to the dust is bad, but you really want to avoid getting the dust inside of you by inhalation. If you’re wearing a breathing mask and carefully wash yourself off after exposure, the radiation you pick up might be fairly limited - just a few hours of time. If radioactive dust lodges in your lungs, it now has the rest of your life to irradiate you. Furthermore, some types of radiation are better than others at penetrating your skin; something lodged in your lung denies even that little bit of protection.

Either way, I think games like Fallout and Gamma World oversell the risk of sudden onset radiation poisoning and understate the long-term effects. It’s likely that exploring an irradiated city would have no effects until you develop cancer 5, 10 or 20 years later.

In terms of acute, sudden symptoms, I think the biggest risk would be from two sources. First, civilian radioactive waste. It might be easy to avoid nuclear power plants and uranium mining and enrichment sites, but hospitals use a lot of radioactive materials. Second would be unexploded munitions - a whole chunk of uranium or plutonium could kill you very quickly. If 20-40,000 warheads are used in an all-out exchange, I think it’s safe to expect a few hundred will fail to detonate and that their bomb casings will be damaged to some extent.

9

I think, though, that most of the isotopes used by hospitals have extremely short half-lives, about a year at most. So if you’re doing your exploring a decade or so after the war, that won’t be much of an issue.

10

I am pretty sure you can hold a chunk of plutonium with no ill effects. What radiation it emits is stopped by your skin.

Ingesting/inhaling plutonium would be very bad however.

11

If a salted bomb was detonated in this hypothetical war, then your amount of fallout would be much higher and possibly result in longer uninhabitable period.

12

Interesting stuff. Related question: if I wanted to build a rough geiger counter to stay clear of hot spots, could I do that using simple recent-post-apocalyptic technology? I’m assuming at least availability of basic electricity (generators/batteries) and scrap metals.

13

I’m not a science guy at all, so I doubt this is exactly what you’d be looking for, but here are directions for a Radon detector:

14

pure plutonium gets very hot from decay. I remember seeing a picture of a sphere of plutonium the size of a large marble glowing red.

Besides the heat though, plutonium is primarily an alpha emitter. Not particularly dangerous to touch if I remember my health physics lectures correctly.

As for radiation from a war, the immediate danger is over in a couple of weeks. After a couple of years, you have to worry about developing cancers from exposure, not getting directly sick from the radiation.

15

I think people have misconceptions about Chernobyl. It is not a healthy place to live nowadays, but then nowadays there are plenty of better places to live. So why live there. If a lot of the country’s area were similarly contaminated, people would have lived there and suffered higher rates of cancer. Maybe with life expectancy of 50 instead of 70. Maybe with higher child mortality. You can probably find an industrial location in China right now that is polluted enough to be comparably unhealthy to its inhabitants - but hey, a job is a job and a place to live is a place to live.

Civilians have gone to Chernobyl on trips to take photos e.g. see here www.kiddofspeed.com (there is an argument online whether the lady really went on motorcycle or by car). Such trips are all the more safe if you don’t drink the water or eat stuff that has grown from the local water. So, for the post-war young man, consider having him drive with a stockpile of water as well, if the area is particularly polluted. Or, at least, have him carry a meter to test the water before he drinks it.

16

Heck, you can build a cloud chamber using bronze age technology if you like.

17

That depends on the isotope. Plutonium 238 will heat itself to red-hot, but the other isotopes are more stable.

18

Best real world example would be the Nevada Test Site. According to Wikipedia the area still has 300 million curies of radiation since testing ended in 1992. The area will be dangerously radioactive for tens of thousands of years. Then again, the area was bombed 928 official times, so that’s way more than what would be expected in nuclear blasted cities.

19

Some of us grew up in a time of fear of the Bomb so its almost odd that modern youth barely recognise it as a threat. Its been supplanted by environmental worries.

In no sense do I want to minimise the destruction and death a nuclear weapon can inflict. However there is a lot of misinformation amongst the community so I am heartened by the rational posts here.

Against all conventional wisdom, plants and insects have reappeared at nuclear sites much earlier than predicted. Even Chernobyl power station isn’t particularly dangerous except at the core of the accident.

Nuclear particle radiation is potentially harmful but its also used daily in controlled circumstances to treat cancer and create electricity. It isn’t an all-seeing all-conquering immortal risk. If you survived the detonation (and most humans would even in an all-out war) then your chances of survival are high. Food and water would actually be bigger problems.

20

Yes, as I understand it recent research shows that long term exposure to low level radiation is much less of an issue than was previously thought, which didn’t really come as a huge surprise given the widely variable radiation levels within the natural environment.

That said though, a large scale nuclear attack on a city would involve multiple warheads that are individually much larger than the Hiroshima and Nagasaki bombs, so they aren’t great models to use either. There would also be more widespread radiation in the surrounding environment which would reduce the rate at which the radiation can be distributed to safe levels in the surrounding area (In other words, the wind might be blowing material away, but it would at least partially replace it with more).

You also need to be careful at pointing to the rapid recovery of insect and plant populations, these organisms are physiologically much more resistant to radiation, have a much shorter generation time for faster adaptation, and no-one really cares about all the bugs that die horribly of cancer in the mean time.

Depending on what you mean by “generations” I’d go with “mostly safe, but with dangerous hotspots” which probably works narratively well anyway. Water would probably be the biggest issue, but living organisms would probably concentrate radiation as well if you were eating them. You could probably find or construct safe water sources (like I said, sediment would be the big problem, as would paying attention to the original source and route of any water course). Radiation accumulating in meat might well differ substantially depending on specific animal, and especially between herbivore and carnivore.

Another factor to consider is that plutonium and other radioactive heavy metals are extremely toxic even aside from the radiation issue. I don’t know enough about the type of material released by bombs to judge whether this would be an issue.

Over this type of time frame I don’t think you’d see much positive adaptation of the human population to radiation, but you’d probably see a reduction in the number of people with a genetic predisposition to cancer and radiation induced cell damage. This wouldn’t be obvious to anyone who didn’t still have the capacity to screen for P53 gene mutations though :smiley: