What dosimeter to buy?

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Given the recent posts on KI tablets, possible problems with Russian and Ukrainian nukes running on 286/386 knock-offs and Clinton's order to destroy old CivDef geiger counters, does anyone have links for Direct Reading Dosimeters (apart from TACDA)? I e-mailed one company RE a ~$200 dosimeter and its performance during Chernobyl, but no response.

-- Nelson Isada (isada@alaska.net), August 03, 1999


Let me hitch on to this thread with a similar question.

How do I calibrate my old civil defence rediation detector (gieger counter)? There used to be a radioactive element that was used. I of course, don't have one. Where can one be had? Or what can I susbstitute?

watch six and keep your...

-- eyes_open (best@wishes.net), August 03, 1999.


I would not recomend that you invest in a dosimeter, rather a good Geiger Counter purchased from Edmond Scientific or I typed in Geiger Counter to Yahoo and got:


this unit for rock hounds. The 10mR scale for this is a bit on the low side, but you can get one with a meter that goes to 200R (you do not want to be in a 200R field for very long. Get some dose tables and thin foils to help you determine alpha, beta, gamma fractions.

This will give you a much better idea of what your envirnment is, and if you need to shelter. The dosimeters are electro static, have a way of getting Dropped and giving FALSE readings. You do not want to get false readings, I know I have scared myself a couple of times, it is not fun thinking there is a problem when it is just a bad dosimeter.

The Geiger is a good tool for the type of questions you are asking.

-- helium (heliumavid@yahoo.com), August 03, 1999.


Thanks for the link and background info. I just attended a local Gem and Mineral society meeting (very popular hobby, given gold, jade, Kennecott copper, etc here in Alaska; I'll see if anyone even _has_ a geiger counter.

What type of radiation is released in a melt-down? I saw the article in 1993 in the Am Journal of Medicine (being a doc) on the effectiveness of KI after Chernobyl, and wondered, who'd really need this info?

-- Nelson Isada (isada@alaska.net), August 03, 1999.


The simple answer to your question of "What type of radiation is released in a meltdown' is all of the basic types. Note that the problem to watch for at a Nuc plant is how much of their Radioactive "Inventory" was released. In a major breach, radioactive material is released. This radioactive materal (radioiosopes) all emit different types of radiation.

Your first worry is Prompt Radaiation, or the Radiation Field. This can be measured with the Geiger counter. You would not want to stay in an area where the meter is registering over 100mr/hr for extended periods. You can go into fields of several Rads per hour for short periods, but this should be left to trained individuals if at all possible. Remember you Geiger counter is in Rads not REM which is what really counts and the REM is a function of the type of radiation (alpha, beta, gamma, or neutron) which is producing the field. The general rule of thumb is that a whole body dose of 500R is the LD 50/50 or the dose at which 50% live and 50% of those exposed will die within the near term after the exposure. (not cancer, that takes a long time)

The second big worry is radioisotopes that are absorbed into the body. This is what the iodine is all about. The use of iodine supplements is to keep your thyroid from absorbing the radioactive isotopes that are likely to be in the lost "inventory" in a plant "meltdown". It is really more of a long term insurance rather than protection from prompt death.

If you are on your own and you find that you are in an EVENT You can use your geiger counter to monitor your cloths or skin for "fallout" that has contaminated you. If you point the active widow of the counter at your skin or clothing and you find that the reading increases you need to "decontaminate" yourself. This can be as simple as rinsing off with soap and water (if you are lucky), then get remove the fluid with the contamination away from your local shelter.

I could go on for a long time, but I hope this answers some of your questions.

-- helium (heliumavid@yahoo.com), August 03, 1999.


There are many services that can calibrate your detector.

I use:

Radiation Detection Company

162 Wolfe Road

Sunnyvale, CA 94088-3414


408/735-0126 (fax)


However the following web site has other services:


It is not cheap to calibrate these things as they are regulated by the state in which the company operates and they have to buy all sorts of standards and the like. I paid about $100 last year to calibrate. Costs and Mileage may differ in your location.

-- helium (heliumavid@yahoo.com), August 03, 1999.

I vaguely recall seeing an article in an electronics magazine several years ago, Radio Electronics I believe, that had directions for making your own small basic Geiger counter. It used a 555 timer chip, audio transformer, and Cockroft-Walton (voltage doubler) bridge to create the +400VDC the little tube ran on. Accuracy is dubious at best but if the thing were to go mad detecting whatever I'd be inclined to be elsewhere a.s.a.p.

Geiger counters are uually only reliable enough to tell you that you need be elsewhere NOW.

If anyone finds info on building a Geiger counter, please post it. I'll check my sources as well and will post what I find.

The electronics madman on the loose, known only as...

-- OddOne (mocklamer_1999@yahoo.com), August 04, 1999.

Thanks for the information.

Interesting that this appeared in yesterday's Drudge Report:



North Korea's official news agency on Tuesday warned that there is "no guarantee for the safety of the U.S. mainland when the U.S. ignites a war against the north in the Korean peninsula."

The threat came on the same day North Korea acknowledged for the first time that it is preparing to test a missile. U.S. military officials now believe that North Korea could, within the next few weeks, test a Taepodong 2 missile -- a powerful new rocket with a range of 3,800 to 6,000 miles that would put Alaska or Hawaii within its reach.

"Whether we test-fire a satellite or a missile is a legitimate, independent right to be exercised by a sovereign state," the Korean Central News Agency stated.

-- Nelson Isada (isada@alaska.net), August 04, 1999.

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