Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Why is my dryer radioactive?

physics.stackexchange.com

Post reply on HN
Print view View original

121–130 of 170 posts

Re: Why is my dryer radioactive?

#121

Post by jojobas »

antognini wrote: post #66
BetterGeiger wrote: post #33

I think the core of the explanation given is correct but some of the adjacent details need adjustment. The important part is: "Clothes dryers are very effective at making statically charged surfaces. (Dryer sheets help.) So when radon and its temporary decay products are blown through the dryer, electrically-polarized molecules tend to be attracted to the charged surfaces" What that commenter misses is that nearly al…

> hobbyist grade detectors (Geiger tubes) are not sensitive to alpha but they are highly sensitive to beta and a little sensitivity to gamma. This was part of the reason why it took so long to discover the cause of Alexander Litvinenko's death by Polonium-210 poisoning. Doctors (and later detectives) had suspected some form of radiation poisoning, but the early tests used Geiger counters and came back negative. But P…

Polonium-210 is a very rare example of near pure alpha-decay chain, radon decay products are short-lived and emit both beta and gamma particles.

Re: Why is my dryer radioactive?

#122

Post by pfdietz »

schiffern wrote: post #113
pfdietz wrote: post #95

Earlier quoted context omitted.

The alternative to LNT is to conservatively assume radiation has the maximum effect not ruled out by evidence (after all, radiation is not a criminal defendant that's innocent until proven guilty). This would make low level radiation more dangerous than predicted by LNT, not less.

>The alternative to LNT is to conservatively assume radiation has the maximum effect not ruled out by evidence No, the alternative is to use real data, rather than fabricate fraudulent data to fit the LNT model. Namely, you need to look at the actual shape of the dose-response curve in the real world, instead of externally imposing a certain predetermined shape by fiat and fudging data to fit. Here's one of the relev…

The LNT is consistent with the real world data, cherrypicked bullshit from pseudoscientists notwithstanding.

This is why the NRC recently rejected a call to stop using LNT in setting regulations. Their responses to the details of the petitions are pretty damning.

https://www.regulations.gov/document/NRC-2015-0057-0671

Now, at the very low doses typical of large scale exposure from nuclear accidents, it's true that the evidence does not directly require LNT. That's because the effect predicted by LNT is so small at those doses that it's swamped by noise and unmodelled biases. No practically obtainable data could do the trick.

But note what this means: the data at those low doses is so poor that it's consistent with an effect greater than from LNT. It cannot rule this out.

I'll add that a favorite pseudoscientific claim from the radiation apologists, radiation hormesis, would imply a larger effect from radiation at low doses than predicted by LNT. That's because hormesis putatively acts by inducing repair mechanisms above some dose, bending the curve downward. Below that putative threshold, the curve has a high slope (and thus more damage per increment of dose) than the linear curve of the LNT.

Re: Why is my dryer radioactive?

#123

Post by BetterGeiger »

xenadu02 wrote: post #35
r3trohack3r wrote: post #2

We had this issue in the Midwest (central Illinois). Can’t remember exactly why, but radon would accumulate in the basements. Had to have sensors and ventilation for it.

Because the rock formations in some areas are more prone to production of Radon gas which slowly diffuses through the soil. Basements in those areas tend to have Radon infiltration. It is obviously very slow but the basement is a low point and often not well ventilated which can allow the Radon to accumulate. Poured slabs are less permeable, not a low point, and tend to have better ventilation either intentionally or…

It is a myth that radon collects in "low points", concentrations are low and it diffuses as the molecules bounce around. However, as you said radon is entering into those areas primarily, which means it will naturally be higher in those areas. Secondly basements often have poor ventilation, which is not to say that the radon cannot otherwise escape, but ventilation can disperse it much more rapidly than diffusion.

Re: Why is my dryer radioactive?

#124

Post by nocoiner »

BetterGeiger wrote: post #33

I think the core of the explanation given is correct but some of the adjacent details need adjustment. The important part is: "Clothes dryers are very effective at making statically charged surfaces. (Dryer sheets help.) So when radon and its temporary decay products are blown through the dryer, electrically-polarized molecules tend to be attracted to the charged surfaces" What that commenter misses is that nearly al…

Man, so glad I decided to finally click on the comments after seeing the article at the top of hn most the day - we don’t have radon where I live (I don’t think?) so I figured the dryer thing wasn’t applicable to me.

But for the vast majority of my life, I’ve always wanted a Geiger counter, and once they were cheap and readily available on Amazon, I was just about to pull the trigger. And then Fukushima happened a week later and sent prices into the stratosphere.

A few times recently I idly looked at the ones on Amazon but never got around to it because I couldn’t tell which were junky crap and which were somewhat more expensive junky crap.

But very cool to see a knowledgeable manufacturer explaining his product in a highly relevant comment thread. Finally, the radiation detector for me!

There’s a former 12 year old kid out there who still remembers the Geiger counter exhibit from taking a pre-9/11 NPP tour who’s going to be very excited for something coming in the mail in the next week or two.

Re: Why is my dryer radioactive?

#125

Post by BetterGeiger »

sbierwagen wrote: post #54
dotBen wrote: post #4

Related: HNer recommendations for home geiger counters? (serious request - for general fun/experimentation/curiosity satiation)

GQ makes several dosimeters, I own the dual-tube GMC-500+. The cheaper single tube dosimeters will max out and saturate at radiation levels far below those that are immediately harmful to human health. (This was the source of the famous "3.6 roentgen per hour, not great, not terrible" meme-- he was looking at a meter that was reading off-scale high at 0.001 R/s) If you're buying a dosimeter with the threat in nuclear…

You are right max range is important for some applications, and most cheap Geiger counters saturate very easily (that two tube device you mentioned being a notable exception). Even still it is not great to refer to them as dosimeters because measuring dose with a low cost Geiger counter is risky at best. That's because they are calibrated to Cs-137. Some so-called energy-compensated Geiger tubes exist and give more accurate dose information, but they are not used in consumer-grade devices (or at least none that I've seen, and I own a ton and constantly study the market). Also Geiger tubes can pick up a lot of beta, and in that case it will dramatically overestimate dose because beta should be blocked in order to get an accurate dose reading, and none of the usual suspects do that. Even if beta is blocked, dose is often strongly overestimated due to the lack of energy-compensation I mentioned. That's one of the reasons I developed the Better Geiger S-1, to have an accurate and fool-proof high range dosimeter at a consumer-friendly price point ($149).

Re: Why is my dryer radioactive?

#126

Post by schiffern »

pfdietz wrote: post #122
schiffern wrote: post #113

Earlier quoted context omitted.

>The alternative to LNT is to conservatively assume radiation has the maximum effect not ruled out by evidence No, the alternative is to use real data, rather than fabricate fraudulent data to fit the LNT model. Namely, you need to look at the actual shape of the dose-response curve in the real world, instead of externally imposing a certain predetermined shape by fiat and fudging data to fit. Here's one of the relev…

The LNT is consistent with the real world data, cherrypicked bullshit from pseudoscientists notwithstanding. This is why the NRC recently rejected a call to stop using LNT in setting regulations. Their responses to the details of the petitions are pretty damning. https://www.regulations.gov/document/NRC-2015-0057-0671 Now, at the very low doses typical of large scale exposure from nuclear accidents, it's true that th…

>The NRC, however, does not use the LNT model to assess the actual risk of low dose radiation. Instead, the NRC uses the LNT model as the basis for a regulatory framework that meets the “adequate protection” standard of the Atomic Energy Act of 1954, as amended (AEA). Furthermore, the LNT model is applied so that the framework can be effectively implemented by an agency that regulates diverse categories of licensees

This matches exactly what the presenter says: LNT makes great policy. It's just bad science, which the NRC demonstrates here by immediately throwing the LNT under the bus when questioned.

The NRC is literally calling LNT an "assumption" here. How much more of a hint do you need?

>The 1991 final rule explained that the NRC based its radiation protection regulations upon three assumptions. The first assumption concerned the use of the LNT model, which was described as follows:

>The first assumption, the linear nonthreshold dose-effect relationship, implies that the potential health risk is proportional to the dose received and that there is an incremental health risk associated with even very small doses

Re: Why is my dryer radioactive?

#127

Post by BetterGeiger »

nocoiner wrote: post #124
BetterGeiger wrote: post #33

I think the core of the explanation given is correct but some of the adjacent details need adjustment. The important part is: "Clothes dryers are very effective at making statically charged surfaces. (Dryer sheets help.) So when radon and its temporary decay products are blown through the dryer, electrically-polarized molecules tend to be attracted to the charged surfaces" What that commenter misses is that nearly al…

Man, so glad I decided to finally click on the comments after seeing the article at the top of hn most the day - we don’t have radon where I live (I don’t think?) so I figured the dryer thing wasn’t applicable to me. But for the vast majority of my life, I’ve always wanted a Geiger counter, and once they were cheap and readily available on Amazon, I was just about to pull the trigger. And then Fukushima happened a we…

Fantastic! Let me know if you have any questions... and be sure to find a current 12 year old kid to plant the seed of interest in radiation. :)

Re: Why is my dryer radioactive?

#128

Post by pfdietz »

schiffern wrote: post #126
pfdietz wrote: post #122

Earlier quoted context omitted.

The LNT is consistent with the real world data, cherrypicked bullshit from pseudoscientists notwithstanding. This is why the NRC recently rejected a call to stop using LNT in setting regulations. Their responses to the details of the petitions are pretty damning. https://www.regulations.gov/document/NRC-2015-0057-0671 Now, at the very low doses typical of large scale exposure from nuclear accidents, it's true that th…

>The NRC, however, does not use the LNT model to assess the actual risk of low dose radiation. Instead, the NRC uses the LNT model as the basis for a regulatory framework that meets the “adequate protection” standard of the Atomic Energy Act of 1954, as amended (AEA). Furthermore, the LNT model is applied so that the framework can be effectively implemented by an agency that regulates diverse categories of licensees…

Go back and read about the malfeasance of the petitioners there. They do things like cite a study, neglecting later data from the same study where the effect they want no longer shows up in the better data.

Policy has to go beyond what is rigorously demonstrated. It's not like criminal law. Technologies are not innocent until proven guilty. Just because LNT cannot be demonstrated at the doses relevant to nuclear accidents doesn't mean regulators should assume no effect.

Re: Why is my dryer radioactive?

#129

Post by schiffern »

pfdietz wrote: post #128
schiffern wrote: post #126

Earlier quoted context omitted.

>The NRC, however, does not use the LNT model to assess the actual risk of low dose radiation. Instead, the NRC uses the LNT model as the basis for a regulatory framework that meets the “adequate protection” standard of the Atomic Energy Act of 1954, as amended (AEA). Furthermore, the LNT model is applied so that the framework can be effectively implemented by an agency that regulates diverse categories of licensees…

Go back and read about the malfeasance of the petitioners there. They do things like cite a study, neglecting later data from the same study where the effect they want no longer shows up in the better data. Policy has to go beyond what is rigorously demonstrated. It's not like criminal law. Technologies are not innocent until proven guilty. Just because LNT cannot be demonstrated at the doses relevant to nuclear acci…

Claims of malfeasance go in both directions.

>Policy has to go beyond what is rigorously demonstrated.

Thanks. I can see we're done here.

Re: Why is my dryer radioactive?

#130

Post by antognini »

jxf wrote: post #105
antognini wrote: post #66

Earlier quoted context omitted.

> hobbyist grade detectors (Geiger tubes) are not sensitive to alpha but they are highly sensitive to beta and a little sensitivity to gamma. This was part of the reason why it took so long to discover the cause of Alexander Litvinenko's death by Polonium-210 poisoning. Doctors (and later detectives) had suspected some form of radiation poisoning, but the early tests used Geiger counters and came back negative. But P…

How did it get detected?

His symptoms were consistent with radiation poisoning and because he was a high profile dissident his case attracted enough attention that the Atomic Weapons Establishment tested his blood and urine.

They performed gamma ray spectroscopy but did not discover any strong signals, except for a very small spike at 803 keV. Some of the scientists were talking about the case and they were overheard by an older scientist who had worked on the UK's atomic weapons program back in the 50s. The early bombs relied on Po-210 and he recognized that 803 keV line as being characteristic of Po-210. Although the decay is almost exclusively via alpha particles, a very small fraction of decays happen via emission of a gamma ray at 803 keV.

Once they had the connection to Po-210 it was straightforward to test for its presence in his body.

Post reply on HN