#285346 - 08/09/17 07:17 PM
Radiation Detectors
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Veteran
Registered: 02/20/09
Posts: 1372
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Does anyone here have any practical experience with radiation detectors? I am talking about devices that can give accurate measurements of background radiation levels in the environment.
I realize that when the "radon levels in houses" issue received a lot of hype. there were people touting "inexpensive home test units". I am highly skeptical of this low-dollar technology. Is there a device that is truly reliable, for a price that is not astronomical?
BTW, just to clarify. I am talking about handheld survey meters. Some models measure only beta and gamma radiation. But some can measure alpha/beta/gamma, and perhaps neutron radiation as well. That's what I am looking for.
Thanks, Pete
Edited by Pete (08/09/17 08:06 PM)
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#285347 - 08/09/17 08:34 PM
Re: Radiation Detectors
[Re: Pete]
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Geezer in Chief
Geezer
Registered: 08/26/06
Posts: 7705
Loc: southern Cal
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Are you wishing to measure radon within your dwelling? Why the skepticism about "inexpensive home test units"? I am curious, because i used a fairly reasonable test technique some years ago for my dwelling and got good results. That was then, and this is now, of course.
_________________________
Geezer in Chief
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#285350 - 08/10/17 12:48 AM
Re: Radiation Detectors
[Re: Pete]
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Geezer
Registered: 06/02/06
Posts: 5357
Loc: SOCAL
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We picked up a radiation detector similar to the Radiation Alert Ranger / Radiation Survey Meter - a ß y x. I like this one better -- USB output and it runs on AA rather a 9V; I may upgrade. Then again, it's been 6 years since the Fukashima meltdown panic and no real need. The radiation panic following meltdown in Japan didn't really happen here, although I'm still not sure some of the oceanic die offs I read about aren't related. Whatever, mine is only similar looking but not the same model. The specs below are quoted from the link and may be of interest. ... Detector Internal Halogen-quenched, uncompensated GM tube with thin mica window, 1.4-2.0 mg/cm2 areal density. Effective diameter of window is 45 mm (1.77 in.).
Operating Range mR/hr - .001 (1µR) to 100 CPM - 0 to 350,000 µSv/hr - .01 to 1000 CPS - 0 to 5000 Total Counts- 1 to 9,999,000 counts Accuracy (Referenced to Cs137) Typically ±15% from factory, ±10% with NIST Source Calibration
Energy Sensitivity Detects Alpha down to 2 MeV. Detects Beta down to .16 MeV; typical detection efficiency at 1 MeV is approx. 25%. Detects Gamma down to 10 KeV through the detector window. 3340 CPM/mR/hr (137Cs). Smallest detectable level for 125I is .02 µCi at contact. ... Get a known radiation source you can use for testing.
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#285355 - 08/10/17 04:07 AM
Re: Radiation Detectors
[Re: Pete]
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Veteran
Registered: 02/20/09
Posts: 1372
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Russ ... thanks. I will check it out. I was also wondering about calibration ... known radiation souces. Need to investigate this too.
I am not worried about Fukushima. I am very unhappy that they are dumping enormous quantities of tritium into the ocean. and i am not convinced that it's "harmless". But i am not worrying about it.
I live on the West Coast of the USA. We are watching the situation in N. Korea with a good deal of concern. Perhaps the two sides will negotiate a settlement. But right now the direction of events is moving towards a "use of force". If one or more nuclear explosions take place on the Korean peninsula, i would like to be able to monitor radiation levels independently.
I do not fear a grave threat. but the biggest thing i learned from the whole Fukushima incident ... when it comes to radiation leaks, no government ever reveals the truth. I think the public is better served if there are independemt sources of data. This also stops people from exploiting bad news and creating "false crises", if a real concern does not exist.
cheers, Pete
Edited by Pete (08/10/17 02:19 PM)
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#285358 - 08/10/17 02:38 PM
Re: Radiation Detectors
[Re: Pete]
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Addict
Registered: 05/23/08
Posts: 483
Loc: Somerset UK
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I keep a couple of Geiger counters to hand and have others in long term storage. The basic model uses a color coded bar graph display. For those whose interest in radiation is surviving it, rather than academic study, the coarse resolution of a 7 stage display is fine. GREEN=NORMAL YELLOW=PREPARE TO PANIC RED=PANIC geiger counter The instrument fits in a shirt pocket and is very easy to use, I understand that the emergency services use this model. It uses standard 9 volt batteries. I also have a couple of more sophisticated Geiger counters, but no point in recommending them as they are no longer made.
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#285359 - 08/10/17 03:08 PM
Re: Radiation Detectors
[Re: adam2]
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Veteran
Registered: 02/20/09
Posts: 1372
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Adam ... you might want to give some thought ... exactly what level of radiation causes your instrument to jump to a YELLOW condition. When workers at nuclear labs wear a protective device, they are working in a specific location. if something goes wrong, they can.always get tested and go home. The problem for you ... if your monitor goes YELLOW ... should you keep living at your house (with the windows closed), or go to a different location?
Pete
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#285363 - 08/10/17 03:59 PM
Re: Radiation Detectors
[Re: Pete]
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Addict
Registered: 05/23/08
Posts: 483
Loc: Somerset UK
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Adam ... you might want to give some thought ... exactly what level of radiation causes your instrument to jump to a YELLOW condition. When workers at nuclear labs wear a protective device, they are working in a specific location. if something goes wrong, they can.always get tested and go home. The problem for you ... if your monitor goes YELLOW ... should you keep living at your house (with the windows closed), or go to a different location?
Pete
The first yellow light comes at 0.5 micro Sieverts per hour, brief and occasional lighting of the first yellow warning lamp is to be expected at normal background radiation levels. Prolonged lighting of this first warning would cause for mild concern. If this level was reached outdoors, then I would stay indoors. If such a level was regularly reached indoors then depending on world news I might either shelter in place or seek better shelter. As a very rough guide, a ordinary house will reduce the radiation dose to about one tenth of that received out in the open. A deep concrete basement but without any specific radiation protective measures will reduce the dose to about one hundredth of that received outdoors. A crude but purpose built shelter will reduce the dose to about a thousandth of that received out in the open. Following the news is as important as monitoring the radiation level. How many bombs have been used, and where ? Is the prevailing wind likely to take the fallout towards, me, or away from me ? Are further attacks likely ? Is the wind direction forecast to change ?
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#285383 - 08/10/17 10:53 PM
Re: Radiation Detectors
[Re: Pete]
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Veteran
Registered: 02/20/09
Posts: 1372
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I think one of the real values of these discussions ... it encourages everyone yo educate themselves more. That includes me. I need to sit down and re-educate myself about 'safe' radiation levels. And after that, i need to ask myself all the same questions that I asked you. What level of radiation would cause me to go indoors, and seal off the windows and air leaks in my house? And what level of radiation would cause me to abandon the house comoletely and go elsewhere? I haven't got specific answers, but i need them. Now is the time for research.
Your questions are also excellent. How many bombs, or radiation hazards, hit the USA? what level of radiation at ground zero? and what are the prevailing winds?? These are exactly the answers that we need from our news sources. And I have to say that I have 0% confidence that "the system" will give them to us - in a timely manner for evacuation.
Pete
Edited by Pete (08/10/17 10:57 PM)
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#285384 - 08/10/17 11:54 PM
Re: Radiation Detectors
[Re: Pete]
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Addict
Registered: 05/23/08
Posts: 483
Loc: Somerset UK
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There is no simple answer to the question as to how much radiation is safe or how much is dangerous.
Low levels carry some risk, and high levels can be quickly fatal, but there is no clear dividing line.
As a CRUDE guide a dose of one Sievert is likely to be fatal, and one tenth of that dose carries significant risk.
One Sievert=one thousand milli Sieverts, or one million micro Sieverts.
Consider a dose rate of ten micro Sieverts per hour, that is many times normal background levels, but is of little short term danger. 10 micro Sieverts an hour if continued for 10,000 hours is a total of 100,000 micro Sieverts. That is one tenth of a Sievert, a significant risk. 10,000 hours is just over a year.
The same dose rate for 1,000 hours would carry some risk, a small risk by wartime or emergency conditions, but still far, far in excess of the dose and consequent risks allowed in peacetime for workers in a nuclear power plant, or nuclear weapons facility.
A lot depends on the general health of the victim, and on what medical care is available.
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