5/17/2013: * Updated the May
* As of 22:00 UT/GMT, NOAA forecasts a 75% chance of more M-class flares, and a 45% chance of X-class. The most recent was an M-3. The Earth might encounter a glancing CME impact at some point today.
5/14/2013: * Solar flare update. For anyone following this page, click on the above link to Space Weather. Asof 03:00 UT/GMT, NOAA is predicting a 50% chance of more X flares (we've had an X1.7, an X2.8, and an X3.2) plus an 80% chance of M class over the next 48 hours from large sunspot AR-1748, which is rolling around to face Earth.
5/12/2013: * Updated the May
* Ran tests with lead shields against background radiation, finding no sky to ground bias at my location (elevation: 90 feet).
* Ran more air draws (no residuals --that I could detect).
5/6/2013: * Another
air filter draw.
* More speculation about radon levels.
5/5/2013: * Updated the April
* Started May graph
* Did air filoter draws
* Speculations about what brings higher radon/daughter readings.
4/30/2013: * Updated April graph
4/25/2013: * Updated April graph.
4/21/2013: * Updated April graph.
4/16/2013: * Added Greg's Lab to the available radiation monitoring systems/networks.
4/14/2013: * Updated April graph.
* Updated Methods.
4/12/2013: * Updated Methods.
4/11/2013: * Updated April graph.
4/8/2013: * Updated my RadNet information.
4/7/2013: * Updated April graph.
4/4/2013: * Started April graph.
4/1/2013: * Completed the
* Edited down this long list of updates, leaving latest significant items.
3/28/2013: * Updated information about the NETC network.
3/17/2013: * Added a month averaged day graph.
3/16/2013: * Cleaned up earlier graphs.
* Revised my "About" and EPA-RadNet entries.
3/15/2013: * Updated my solar flare comments.
3/4/2013: * Solar/flares update
2/28/2013: * Updated my run-downs on available radiation monitoring systems/networks.
2/22/2013: * Added a note to my first graph, re: a possible extra galactic radiation source.
2/18/2013: * * Noted unexpected "radon inversion" air filter results.
2/13/2013: * Noted odd dip --lowest in at least 9 months.
2/07/2013: * Added a radon decay chain graphic plus comments.
1/31/2013: * Starting with February, graph entries/points will reflect midpoint times plus 10 minutes, instead of the approximate, 1/3rd day period times. Since I'll still be holding to 100 minute counts during the same (Night, AM, Afternoon) periods, there's hardly any break in continuity with past record keeping --just a bit more precision than before.
1/30/2013: * While there've been no days without sunspots in 2012 or 2013 (there were 260 spot-free days in 2009), there's currently no flaring and the Sun has been unusually quiet for quite a while now --thankfully.
1/27/2013: * Resumed reading filters from 5m3 air draws.
1/24/2013: *The issue of "Poisson distribution" keeps coming up (in our correspondence and chat), for which see *here*.
1/16/2013b: * Finished cleaning up the old graphs --removing air filter data. (No air filters to date had any detectable residual radiation.)
1/14/2013c: * Posted the first of my digital graphs --for December and January, to which will be added replacements for missing and incomplete graphs. These are thanks to Palam Software's freeware "ZGrapher" and will result in great savings of web space. (I've been up against the free web space limit here.) Along with their being cropped, many annotations on the old graphs have been stripped away, but hardly any of them were of lasting significance. Instead, I'll be posting notes about exceptional readings/circumstances --here and below the graphs.
11/4: * I learned that there is no provision for backup power to the spent fuel pools --!
10/25: * Revised summary to reflect my current monitoring methods.
* We've entered a long and scary period of solar activity --which will reach well into the year 2013. Good luck, everyone! At this writing, the wicked X-class flare emitting Sun spot number AR1598, which has been turning to face the Earth, just happened to decay when it had us in range. You can follow these events at: http://www.spaceweather.com/ . Our approaching election and the political process (Dr. Jill Stein's campaign excepted) seems oblivious to this deadly game of wholesale Russian Roulette that we're being made to play.
10/01: * On the 27th I noticed that one of my 100 minute averages nearly reached 39cpm (11.14 uR/hr, but I've seen as high as 12 uR/hr here), so I did an air filter draw (the usual 10 cubic meters in 2 hours). The initial reading was 506cpm above background (beating the August 22nd record), the decay rate was like radon/daughters, and in 2 days the gross (alpha, beta, gamma) reading was the same as background. The day had warmed up 21 degrees from a cold night, so maybe that drove radon out of our sandy soils, dunes, and beaches.
* Again: my many air filter runs have yet to produce any
residual radiation (indicating longer half-life "hot particles", from some
type of radiological fallout or aerosol pollution). At one point I placed
dozens of my old filters against high speed film for days-long exposures,
which was sensitive enough to detect slightly radioactive ink in a pen
from Japan. (I've been unable to repeat that with other pens of the same
type and brand). Arnie Gundersen's team reported negative results in looking
for "hot particles" since detecting them in March and
April of 2011 (at which time I was only doing background radiation monitoring here).
9/24: * We now have gamma spectrometry on several Oregon
beach sand, soil and dunal sand samples. Again: this is courtesy of "Anti-Proton"
--who is very generous with his precious free time and resources, and
who will be the first to point out that he's neither formally trained nor
otherwise accredited to do this work. You can find his accumulating test
http://naturaluranium.com/ --Please note that these analyses trust you to see and to understand all of the natural radiation which was detected and reported. These isotopes are found in sand and soils almost everywhere. Oregon's beaches and sand dunes (and I've been able to briefly scan about 100 samples with a Geiger counter) compare most favorably to beaches elsewhere --as to common, naturally radioactive components such as the Thorium-232 series (represented by Lead-212, Thallium-208, Bismuth-212, Actinium-228); and the Uranium series (represented in the dune sample by Lead-214, Bismuth-214, and Radium-228).
Here's some perspective: http://www.youtube.com/watch?feature=fvwp&NR=1&v=RvgAx1yIKjg
* The bad guy isotope Cesium-137 --barely detectable traces of which have turned up, has a "half-life" of 30 years --which means a strong dose of it might hang around for 150 years or more. It's most frequently a symptom of past accidents (Chernobyl) and atomic bomb testing. Neither Cesium-134 (2 years), nor Iodine-131 (only 8 days) has yet been detected.
* I've also been reading sand samples with a Geiger counter here, mostly to get a "base line", should any serious increases take place in the future. I can guess at what I'm reading, since it's pretty easy to ID some isotopes like radon daughters and potassium-40, but otherwise I can only say how many "counts per minute" I've measured, and under what circumstances.
* 17 month summary of readings (since April 17, 2011): ~ None of my 5 or 10 cubic meter air sample filters have resulted in sustained residual gamma, beta or alpha radiation --measurable above background levels with my equipment and methods. (9/25: It could be that my filtering has been as much about available micron and larger dust particles --as it's been about the fall-out of the (atomic and molecular sized?) isotopic emitters which cling to them. It might be that my efforts here have not been very meaningful. If so: my apologies.)
~ I did detect some slightly radioactive ink in a pen from Japan --which I'd used to mark identification on several of my air filters. (You could vaguely read my contact printed marks on the film I was using at the time.)
~ I've seen what looked like (then, and still today) significant increases in background radiation: often to 12 uR/hr (would have been 42cpm with an Inspector GC) in the April-May 2011 graph. More often than not, these increases have since correlated with periods of higher radon levels, but I wasn't doing good air filter tests at the time, so it could have been something else.
~ Poisson distribution - I've always done timed gamma count averages here. As I increased the time period, my counts settled ever closer to something like a 36.5cpm (10.43 uR/hr) norm.
~ It's difficult to choose a suitable counting period. Short periods can catch and alert us to transient events, but a 1 minute count^ with an "Inspector" or a Mazur PRM-9000 in a constant 36cpm field of radiation will be giving you readings which vary from 30cpm to 42cpm, and will quite likely give you readings between 18cpm and 54cpm in the course of an afternoon. (Google the Wiki for "Poisson distribution".) A 4 hour average should get you down to within +/-0.4cpm of true, but you (of course) have to double that error when subtracting the background from a 4 hour sample reading. I've finally settled on doing 100 minute counts.
^ Be mindful that what you read in the "CPM" mode of a Medcom or an SEI "Inspector" is based upon a very short counting period. At low count rates, an Inspector counts for 30 seconds, then doubles that count for the display. Consequently: expect meaningless jumps of up to (plus or minus) +/-8cpm in the "CPM" display, and a daily range of up to +/-24 --even when the background level is actually constant).
* At high count rates, the counting period can be as short as 3 seconds. That is, of course, no problem. Just stay in the timed count mode and choose a suitable period (from 1 minute to 24 hours), and restart it as needed.
* The reason for this is the range of probability with which gamma rays --passing by and passing through us, will just happen to connect with the little Geiger-Mueller tube in your counter. Only about 2% of them make it fire and count.
~ For a "pancake" G-M tube in an average (30cpm) environment, during any given second of time, the changes are 50-50 that a gamma ray will connect. Over a period of (say) 4 seconds, the chances are much better. You're likely to see a count of "2" --especially if you chart it out over a long period of time --broken into two second increments. The "standard error" or "deviation" is then assumed to be +/- the square root of the average count --equals the square root of 2 equals +/-1.414 --and you'd expect to frequently see counts reported in the range of zero to 4.
~ In fact, and over the course of (say) an hour, you shouldn't be surprised to see a range 3 times as large: 2cpm +/-4.24 or (many zero counts) to maybe 7cpm.
~ Similarly: A Medcom Inspector in a field of 30cpm will register (on average) 15 counts over its (low range) sampling period of 30 seconds. The square root of 15 is 3.87 --so let's call that "4". Since we double that 15 to get a display of "30cpm", we also have to double the expected error --for: 30cpm +/-8 --and don't be surprised to see 30cpm +/-24 (ie: a range of 6cpm to 54cpm) over the course of an afternoon (on top of what actual background variations you might be encountering). Again: use your Inspector GC in a timed mode --say: 10 minutes, which will reduce the period-to-period swings to the square root of 300 = 17.3 --divided by 10 = +/-1.7 (and let's call that +/-2cpm --or more like a range of +/-5cpm for a long run of counts) --which sure beats +/-24.
* Old versus new data at my monitoring station: For those of you archiving my graphs and data, here's the latest comparison between my Radex RD1503 Geiger counter (used for the earlier graphs) and my Medcom "Inspector". The "source" was average background gamma in my office. This was a two-part test with the detectors sitting in the same location, placed corner to corner. After the first 100 minutes, I switched their positions and ran them for another 100 minutes. Meanwhile I monitored the Medcom unit with the GeigerGraph program for any unusual events --with the following findings.
~ One position read higher than the other with both Geiger counters (8% and 1.6%), but the differences were less than the margins for statistical error.
~ The combined averages for both units were 10.48 uR/hr for the Radex and 10.55 uR/hr for the Medcom: basically the same.
~ Earlier runs, which were not nearly as controlled, usually indicated that the Radex read between 5% and 8% low (which is well within the acceptable cesium-137 calibration error (+/-15%) for a freshly factory calibrated Geiger counter), but that was usually with the Medcom GC in the (possibly) hotter position.
~ The very long term averages of my graphs suggests that these two GCs do read nearly the same --and that there has not been a detectable (with my equipment and methods) sustained rise in background gamma radiation --in this part of Oregon.
~ It might be that all of my Medcom
based readings are slightly higher (maybe 2% at 10.43 uR/hr = 36.5cpm,
but that would actually reflect a fixed, weak local source of about 0.2
uR/hr or 0.7cpm at the test bed position).
7/15a: The CME wave hit us (quite mildly) at 18:24:02 Universal Time on the 14th of July --per:
The last forecast was for impact at 09:17 UT/GMT, to which was appended "+/- 7 hours" when it didn't happen. When 7 hours had passed, there was no further comment to be seen at the Space Weather web site. Finally, at 9+ hours, their magnetometer spiked. Within 5 minutes Space Weather posted notice of impact "as expected". A while later the time was fudged to "approximately 18:00" hours, which was supported by a line drawn on a graph labeled as 18:09 GMT --the abscissa time being very obscure with mixed graduations. We chide our great-grandchildren when they attempt to trim the truth like that.
It of course comes as a relief that the impact was of no consequence, and NASA's pettiness would mainly be a disappointment, except that such deceptions can lead to disaster. Denial about our institutional inability to pin down a CME's arrival any closer than +/-9 hours could easily result in a failed attempt to cope with the arrival of a serious CME event.
To be very clear:
At this point, we'd need to shut down our power grids for most of a day and night in order to minimize serious damage from a major flare and CME. However: our culture would prefer to fool itself --perhaps into not interrupting the flow of electrical power at all, in the face of a serious flare and CME.
A case in point: The Obama administration has gone ahead with subsidizing new nuclear power plant starts, even after the events in Fukushima Daiichi have made it obvious that any type of nuclear energy on an industrial scale is likely to cripple civilization and the entire biosphere. (Perhaps it already has.) But that wasn't bad enough. In April of 2011, Hillary Clinton was dispatched to arrange for the importation of more Japanese seafood. (Damn!)
* I fear we're going to collectively fail the Darwin test.
6/23: * This web page is starting to turn up via Google searches, so people write and ask me if it's safe to go to the beach, to go clamming, to eat seafood and such. Gosh --dunno. My wife an I are still eating seafood (and worrying about it). Tuna, of course, is strictly off of our menu (our pet's menu as well), 15 out of 15 blue fin tuna having tested positive for cesium-137/134 --and that was last summer. No more tests are scheduled until mid-summer. The entire catch needs testing, but our FDA only tells us not to worry.
* We recently collected samples of sea water, sea weed, beach sand and dunal sand. I was unable to detect anything from water or weeds, but we learned that all beach and dunal sand are radioactive to some degree, which must be mild up and down our coast. Our samples measured about 50% above background when in contact with the Geiger counter (through a film of thin plastic). This appeared to be only beta radiation, which I'm tentatively taking to be potassium. The dune sand read slightly higher. Better methods should detect thorium (black sands), radium and uranium. Later, I'll be reading samples of black sand from our igneous beaches north of here. Last year, thanks to Steven Michael (aka: "the Sandman") who collected it over a period of years, I was able to briefly scan hundreds of (in their test tubes) samples from up and down the Oregon coast, finding nothing which stood out --judging from audible *clicks* --at least hard beta and gamma-wise.
* I also tested two shrimp, weighing about 8 grams each, and separately purchased from a local favorite restaurant. They read at background levels, thankfully. This is, of course, little assurance and no substitute for a competently run gamma spectrum analysis.
6/1: Radioactive tuna have turned up --as of last August, and we only learned of it a few days ago. No more tests are scheduled until mid-summer. The entire catch needs testing, but our FDA only tells us not to worry.
* I don't expect to have much more than a "yes"/"no" and maybe a "gee whiz" here as to the detection of lingering alpha radiation. I was recording some fast fading initial alpha (using the new Medcom GC) when I started reading my air filters --which I took to be a small build-up of 3.1 minute half-life polonium-218 (which follows the 3.8-day half-life radon-222 isotope in the uranium series). I decided to simply block that alpha response, since it clutters the familiar radon/daughter decay curve and doesn't seem (to me) to be useful information. Instead, I wait out 18+ hours for short-lived stuff to die down, then check my filters again for any long-lived emitters, including alpha.
4/18: I've posted a coherent report about what transpired at the Fukushima Daiichi power plant.
^ Radon is bad stuff and some days I see quite a lot of it here. It's also endemic, so the parent radon may or may not be blowing in from Japan or elsewhere upwind. I did a lot of testing and record keeping in an effort to figure out what is driving our local radon/daughter levels but with no conclusions. (My air sample intake point and filter are over 9 feet above ground and 2 feet above the rain gutter --to lessen the chance that I'm sniffing it up out of our own yard or foundation.) Since there's been no correlation between environmental factors and radon levels, I'm largely discontinuing the posting of weather information, but am continuing to record it (available upon request).
^ Early in January of this (2012) year, Dr. Busby/associates measured soil samples from Fukushima and found an amazing and completely unexpected level of the isotope lead-210, which was assumed to have come out of the reactors for reasons unknown. "Mr. Potr" (a fellow who posts anonymous YouTube presentations via "potrblog") concluded that that lead-210 is the near-end decay chain from vast volumes of radon --driven out of the ground by extremely hot melt-throughs (and melt-downs) of corium. If that was the case, I think we'd have been hearing a lot more about radon/daughters near ground zero. *I don't totally discount the theory, nor that the excessive levels of radon daughters being widely reported have some other chain of connection to the events in Fukushima, or perhaps to nuclear power plants in our own country. Another possibility is that immense amounts of radon are expelled with immense earthquake activity. (I Googled that:
http://www.nuclearfreeplanet.org/ (authoritative --Dr. Helen Caldicott's web site.
http://www.fairewinds.com/ (authoritative, updates at long intervals --the Gundersen's web site. videos + transcripts.)
http://rt.com/programs/big-picture/ (Thom Hartmann --videos)
May-June 2011 (Note: 10 uR/hr = 35cpm with the new Geiger counter)
August 2011 (Note: 10 uR/hr = 35cpm with the new Geiger counter)
October 2011 (Note: 10 uR/hr = 35cpm with the new Geiger counter)
December 2011 (Note: 10 uR/hr = 35cpm with the new Geiger counter)
February 2012 (Note: 10 uR/hr = 35cpm with the new Geiger counter)
April 2012 (10 uR/hr = 35cpm with the new Medcom Geiger counter)
The graphs beyond this point change scale and are primarily calibrated in (Medcom "Inspector") CPM,
sometimes with supplemental uR/hr equivalents on the right margin. (10 uR/hr = 35cpm with the new Medcom Geiger counter)
June 2012 (Note: 10 uR/hr = 35cpm with the new Geiger counter)
* That increase in variation after the 11th is due to reducing the averaging period from hours to 100 minutes. We expect +/-0.6cpm of jiggle at this level of detection and averaging of "Poisson distributed" radiation data.
23rd: Confirmed high BG with 2 extra mid-day 100min counts; 26th: +24.5/14.4cpm mid-day AFs. (Mid-day 10min BGs of 38 & 41.2cpm.)
Last year I tried to get a handle on whether or not I was experiencing an average daily variation in background levels. The
above graph is in uR/hr, and the 10.6 uR/hr average equals 37.1cpm (Medcom "Inspector") for the period studied. I
decided to pretty much avoid late afternoon and evening hours --for my 100 minute averages.
Here's the most recent search for a daily variation --now based on (Medcom "Inspector") CPMs and a 24 hour day which begins at
11pm (23:00 hours) and is broken into units of 1/100th day (plotted at .05day = 72 minute intervals). Post-midnight and
mid-afternoon appears to be the most stable in February --rather the opposite of my earlier graph, but there doesn't appear to be
enough variation to worry about during the winter months.
BG = special background note for an unusual, supplemental, short period averaged reading.
2/7/2013 update - Here's an illustration of the radon decay chain:
^I've switched from weather service estimates of area aerosols (which I understand to be the net-sum of airborne whatever) to simply logging what I actually see on my air filters, since I've definitely seen dirt on officially clear days. We have mining going on in an unstable nearby dune, plus there's that on-going issue of "chemtrails"/"geo engineering", which is often quite evident in our sky. Perhaps I'll see a relationship to evidence of actual local dust. (I can't reliably chart aerial spraying since it's often invisible within or well disguised as natural cloud cover.)
* I've let this section go to seed: more a jumble of equipment notes than a coherent presentation, so here's a brief summary of how I currently go about monitoring.
* In response to the events in Fukushima Japan, also in response to the non-feasance, confusion and extremely sparse monitoring of the EPA's "RadNet" system, I ordered a Geiger counter and set about the task of setting up a private radiation monitoring effort --here on the coast of Oregon. I found it hard to believe that my effort was initially the only effort along our entire coast, public or private --!
While I've attempted to monitor food, water, our beaches and the air itself (with my humble equipment --and my efforts to sample volumes of air continue), my first effort was the best: to simply post a public record background radiation here. It's been pretty much continuous since April 17, 2011.
* Here's how it works, and why I do it in such a fashion.
* Currently, my main Geiger counter ("GC") is a Medcom brand "Inspector" (sorry: they don't use model numbers) with a "pancake" Geiger-Mueller ("G-M") tube, which is about the most sensitive type used in a general purpose GC. Normally, such an instrument is only useful for such as screening casualties and locating emergency shelter during a local radiological emergency. With care and methodical practices, however, its reach can be extended to doing at least "first responder" level assessments of lesser contamination --perhaps that associated with heavy fall-out from a distant radioactive event.
* As part of a network, GCs might be very useful for early warnings of acute radiological incidents, as well as following the drift and accumulation of contamination across large areas --such as Radiation Network's coverage of the North American Continent.
* Geiger counters are very good for the early detection (if not accurate measurement) of radon encroachments --into ones neighborhood or into one's living spaces. I expect that as Radiation Network grows, we'll start noticing patterns, which might reveal significant sources and regional concentrations.
* The greatest on-going concern has been about radiation from nuclear power plant ("NPP") incidents, in the United States and abroad --perhaps soon to be joined by a nuclear war with North Korea. This radiation might reach us as "shine down" from passing clouds of radioactive gas, or as particulates which "fall out" or "rain/wash out" of passing air masses.
The "shine" and fall-out from a nearby (50 miles) event should be very apparent by means of a Geiger counter, but most authorities don't think that an ordinary GC --in the hands of an ordinary (even though diligent) radiation worker, is going to detect the sparse particles which reach us from an over-seas event. Consequently, we must guard against taking false assurance from negative readings, when using such humble instruments and walk-around style "survey" techniques. It was estimated by Fairewinds and associates that the average outdoors person in Seattle Washington inhaled 5 to 10 "hot particles" --radioactive isotopes, electrostatically bonded to dust motes (perhaps --my interpretation). There's an on-going concern that radioactivity could once again become dispersed in the spring, with the release of pollens to the air.
To stand a better chance of detecting such particles, short of them becoming a deluge, I've been attempting to capture and concentrate them by drawing large volumes of air through an "N95" filter --one small enough to be read in its entirety under the 1-3/4 inch (alpha, beta, gamma radiation sensitive) aperture of my Geiger counter. That type of capture, along with the disciplined use of long period counts (100 minutes, now-a-days), extends a GC's sensitivity to the point at which the natural radioactivity of some food stuffs (due to potassium-40, say) and building materials becomes an interfering problem.
* Short of building a thick lead isolation chamber, one must subtract the long period averaged local background ("BG") radiation from a long period averaged radiation count on a sample or air filter --always using the same setup geometry. One is consequently at the random mercy of hourly and daily BG variations --as a limiting and variable sensitivity factor. You'll find that issue explored on this page.
That all being said, the only residual radiation I've so far detected here (and that was photographically), was from the slightly radioactive ink in a pen which came from Japan --a few months after the events of 2011.
Check sources: To make rational use of a calibrated check
source, you need to do the geometry and the math to get it right, but that's
rather like counting the money in your pocket: it doesn't change the amount
--it is what it is. To see if you're at least in the ballpark for sensitivity,
check the faint gamma coming out the front of a typical smoke detector
with 1 uC or 0.9uC of Americium-241 (measure it above the chamber area).
You won't measure the copious alpha from the pellet inside (and don't inside
to get at that pellet --the thing will eventually get loose in the house
--a "loaded gun" for a kid or an unwary adult to find), but the incidental
(158 KeV and less) gamma plus some beta ("bremsstrahlung" secondaries?)
might add 30 uR (micro-REM) to your background reading. It added another
113cpm to the background reading of my Medcom Inspector GC (86cpm with
an aluminum plate blocking the beta component).
To keep these filters (cut from face masks) from humping up in the test well/chamber, I cut them down again after the air draw --to the exposed diameter.
(This doesn't work)
--my effort was doomed to fail: you simply can't filter out and measure radioactive particles. The stuff is molecularly dissolved --and/or becomes salts. The only way is to either do whole sample (water, milk, whatever) gamma spectrometry --or: to have so damned much cesium-134/137 (or gamma emitting whatever) in it that you can read the stuff with a Geiger counter.
Again (and see the next item): you're very unlikely to read beta or alpha coming out of a liquid --or out of food, unless you dehydrate it. You might get such readings from a dusting of fall-out that's been deposited on food. I've never measured anything above background from either liquids or filtrates. I have measured the normal beta emitting potassium-40 content of dried and thin slices of somewhat moist foods.
Contrary to some advice I've seen posted, it is difficult to measure even strong beta radiation in liquids (let alone alpha) by immersing a bagged Geiger counter. It seems that the particles upon which the nuclides ride have to be caught in a filter (or paper towel "wipe" patch), and then the water squeezed out (per those "Pissin' On The Roses" videos). Professionally, alpha and beta in liquids are read via a "scintillation cocktail", counting light bursts from outside of a glass vial.
* While potassium is 90% a beta source (as is iodine-131 and strontium-90), surely the gamma radiation of a liquid containing a significant amount of cesium-137 or cesium-134 (actually: it's the intermediate, high-state barium-137 daughter that we read) --would be detectable with a Geiger counter --you'd think.
* On 9/23/2011 I took test readings in 480 milli-liters of distilled water, comparing them to readings in the same water with 1 gram and then 10 grams of dissolved potassium chloride (KCL). This resulted in samples with 33 and 330 becquerells (BG) of radioactivity which was primarily (90%) beta (1.3 MEV) plus 10% gamma (1.5 MEV --maybe out of Geiger-Mueller tube range). That's similar in nature to but 1.5x to 2x stronger in energy than iodine-131 or strontium-90. My small gamma and beta sensitive Geiger counter was plastic bagged and immersed in these test samples. (Note that The EPA limits milk to 170 bq/Liter (or kilogram), and 0.11 bq/Liter in drinking water.)
* Despite easily measuring potassium chloride radioactivity as dry granules (it set off the 30 uR/hr alarm in my Geiger counter), I measured no averaged increase above my averaged ambient radiation levels.
* While first evaporating the water might work for nuclides with a half-life of many hours, boiling the water off seems a bad idea, especially if cesium-137 is present, since (as I've read) boiling is how Fukushima's cesium got airborne.
It's my guess that food contaminated with a gamma emitting nuclide (Cs-137) would test reasonably well (if not sufficiently to prevent the ingestion of just a few scattered particles), but per my experience with liquids (above), I expect that measuring beta emitting contamination requires either desiccating the food item, mixing reasonably transparent food with a scintillating substance in a blender, or doing something like spectrometry on the incidental gamma radiation involved (which takes honorable equipment).
My Medcom "Inspector" Geiger Counter
* I've used the GeigerGraph program to identify what, at least locally, appears to be the most stable times of day, radiationwise, and to see if I can detect any patterns of daily variation.
My (old) Russian Geiger Counter
Some while ago I was able to speak with Arnie Gundersen. It's his opinion that, at the levels his colleagues were detecting airborne "hot particles" in Washington and Oregon during April of 2011 (and he reports that there's been nothing detected since), it's unlikely that I'd measure a sufficiently increased level (over background) as to be reasonably sure of detection with a standard Geiger counter --even as concentrated in my air sampling filters.
* Should we start getting serious fall-out, I'm pretty sure I'd get more than radon daughter Geiger counter readings off of my air filters. If you read the procedure for effectively decontaminating a lab area by using a standard Geiger counter, it's hard to believe that a significant beta and/or gamma emitting hot particle (cesium-137, say) wouldn't be noticeable, tested as shown.
On 12/21/2011, my Congressman, the Honorable Peter DeFazio, got back to me with a strong position statement against going any further down the road with nuclear power. (Yay! and good on ya, Mr. DeFazio.)
Also: I see that the Green Party (USA) has been opposed to nuclear power plants for years --never having bought into the greenwashing of nuclear energy.
The Solar Flare Threat
If we do get a double peak, the second one might have us weathering a series of "X-Class" flares and coronal mass ejections ("CMEs"). Whether one of them smacks the Earth and shuts down some of our power grids is a game of roulette.
* Nuclear power plants, despite that they might end up literally bursting with thermal energy, are designed such that they're unable to power their own cooling pumps --in the event that there's a local failure of the power grid. On-site diesel-electric backup power then takes over to run the pumps, controls and instrumentation.
* I know that's hard to believe, so rather than simply discounting my concerns here, please confirm it for yourself. Google on "station blackout". Newer designs use steam power to run turbine driven water pumps, but they still require electricity to open valves and turn those pumps on.
* Because the spent fuel pools (SFPs) were only meant to hold 1/4th or 1/8th of what was eventually crammed into them, there was no provision to supply them with emergency backup power.
* To be very clear about this: there has been no provision to connect the diesel backup generators to the SFP's cooling pumps --!! The plan was to simply let the water in the pool coast up --to the boiling point, if needs be (which might take as little as 24 hours), and to then replace boiled off water by means of manually deployed fire hoses.
* The SFPs are crammed with old fuel rod assemblies because there's no place to store nuclear wastes, and because the operator/owners of nuclear power plants are too cheap to use "dry cask storage".
* There are several deadly important things to understand about "spent" fuel pools and rod assemblies:
~ Their radioactivity is far more deadly than fresh nuclear fuel rods.
~ There's serious question as to whether their 40 year-old liners can stand the strain of boiling water.
~ If the zirconium cladding on the fuel rods gets hotter than 1800 degrees Fahrenheit, it oxidizes with steam and water, releasing explosive hydrogen. Above 2000F, the oxidation process turns into a furiously burning fire which destroys the rod, releasing its radioactive contents.
* As to keeping a reactor's containment cool after a shut-down, months of mechanically forced water cooling are required --but the U.S. Nuclear Regulatory Commission has only required that nuclear power plants be independently capable of supplying diesel-electric backup power for 72 hours, plus 4 hours worth of battery backup power --to cover any delay in getting their diesel engines to turn over.
~ The Fukushima Daiichi power station reactors had 8 hours of battery backup power. They used every bit of it.
~ The NRC might have recently started upgrading that requirement t 8 hours of battery and more on-site diesel fuel. The recent near nuclear disaster at New Jersey's Salem nuclear power plant established that they had a store of 7 days worth of diesel fuel on hand.
~ While SFPs might require mechanical/forced cooling for a year, I don't know how long mechanical cooling is required to remove residual heat from a normally shut down, intact reactor in order to maintain "cold shutdown". The damaged reactors in Fukushima have required months of cooling.
~ Backup power will continue to be available at a nuclear power plant if more diesel fuel can be delivered to the power plant, if the diesel generators remain operable, and operator personnel can be persuaded to remain at their posts. (The regular Fukushima crew initially fled, but was successfully ordered to return. The head of TEPCo has stated that, in the event of a fuel fire, he'd have no way of ordering his crews to face certain death in order to mitigate the situation.)
* A report by the Oak Ridge National Laboratory stated that over the 40-year licensing term of a nuclear power plant, solar flare activity adds up to a 33 percent chance of it experiencing a long term power loss: a risk significantly greater than that of earthquakes and tsunamis --!
* Federal government studies have suggested that extreme solar flares could result in regional blackouts lasting months or even years, since critical power grid components like EHV (extremely high voltage) transformers are made in places like India and we have scant spares here in the United States. There are more than 300 aging, vulnerable EHV transformers in substations across this nation and the existing over-seas manufacturers of these transformers currently have a 3-year backlog of standing orders.
* A severe solar storm might destroy hundreds of transformers world-wide, leaving vast populations without water, sewers, hospitals, TV/radio broadcasts, fire and basic safety services. Military escorts would have to bring in fuel tankers through the ensuing chaos from our strategic reserves, since the pumps which normally transfer gasoline and diesel fuel wouldn't be operating, nor would refineries be making more.
* I understand that nothing material has been done to provide for the recovery of our power grid.
* As of 1/22/2012, the prediction was for a long, quiet series of solar cycles, following the 2013 maximum. Since our nation has already passed up years of opportunity to prepare for a solar flare disaster, and since it would take about 3 years to prepare if we started now, there are only two meaningful things to be done.
1) Shut down all nuclear power plants (before a solar flare strikes).
2) An executive order which would establish a national emergency force and plan to provide for a year's worth of backup power. Under National Guard protection and execution, helicopter deliveries of stockpiled fuel, replacement diesel generators, and replacement operating and management personnel would be made available to all of our nuclear power plants, once it becomes apparent that blackouts are imminent.
Realistically, this is unlikely to happen before the dangerous 2012-2013 period has passed --unless key government and military officials can be made to think about, and publicly discuss --how dangerous it is to continue operating our nuclear power plants. Let's hope and pray that our luck holds through 2013.
Sources: John Kappenman of Storm Analysis Consultants and Metatech Corporation, as commissioned under Executive Order #13407, NASA Planetary Sciences Director James L. Green (See the February issue of Sky & Telescope), National Research Council Chair Daniel N. Baker (Space Physicist),
* I started it by default of anyone else doing this work for my part of Oregon. It has links to other radiation monitoring networks and their maps (below), plus the record and humble methods of my own monitoring.
* I no longer make much of an effort to popularize my own monitoring
numbers --which (to date, and thankfully) have been pretty mild here
in Oregon. I worry about giving people false assurances. Should my numbers
go up, I'd worry about spreading false alarms. However, it would be wrong
to stop keeping and posting this record.
Available Radiation Monitoring Services
* State of Oregon Monitoring:
The State of Oregon announced "enhanced sampling", as of April, 2012
Oregon Health Authority monitoring (for iodine-131 and cesium-137): "Radiation Protective Services is collecting and analyzing ocean water, drinking water and beach sand from the same three locations as previously monitored."
(EEEUU^ --how embarrassing --and apologies to all! Our Oregon Health Authority persists in conflating inhaled and ingested radioactive particles with external Xray exposure.) (^Word learned from our great-granddaughter :-)
Rain, drinking and sea water:
This would be more convincing if they did have readings each month "from the same 3 locations" (as stated) and if their format wasn't posted for water analysis. I've been able to get some independent spectrometry, courtesy of "Anti-Proton" --who is very generous with his precious free time and resources, and who will be the first to point out that he's neither formally trained nor otherwise accredited to do this work. You can find his accumulating test results at:
http://naturaluranium.com/ --BUT: please note that these analyses trust you to see and to understand all of the natural radiation which was detected. These isotopes are found in sand and soils almost everywhere. Oregon's beaches and sand dunes (and I've been able to briefly scan about 100 samples with a Geiger counter) compare most favorably to beaches elsewhere --as to common, naturally radioactive components --such as the Thorium-232 series (represented in the most recent beach sample by Lead-212, Thallium-208, Bismuth-212, Actinium-228); and the Uranium series (represented in the one dune sample by Lead-214, Bismuth-214, and Radium-228).
Here's some perspective: http://www.youtube.com/watch?feature=fvwp&NR=1&v=RvgAx1yIKjg
* The bad guy isotope Cesium-137 --a barely detectable trace of which might have been present in the dune sample, has a half-life of 30 years (which means a strong dose of it might hang around for 300 years) and is most frequently a symptom of past accidents (Chernobyl) and atomic bomb testing. Neither Cesium-134 (2 years), nor Iodine-131 (only 8 days) has been detected, but we're going to 4 times as much sample sand (which is tested naturally damp) --to make sure.
* I'm also reading sand samples with a Geiger counter
here, mostly to get a "base line", should any serious increases take place
in the future. All of my tests are penciled in on my posted graphs now
(since June of 2012). The posted readings are "gross": alpha, beta, gamma
combined, under which I attempt to sort out the components. I can guess
at what I'm reading, since it's pretty easy to ID some isotopes like radon
daughters and potassium-40, but otherwise I can only say how many "counts
per minute" I've measured, and under what circumstances.
* Greg's Lab:
Greg's Lab is everything that the EPA and other private monitoring networks should be --but often aren't: map based "at a glance" clarity, the basis of the displayed radiation levels clearly explained, simple, concise, all aspects freely and publicly accessible.
* The EPA's RadNet:
As of 3/10/2013, this is the EPA's map-based link for accessing their station gamma graphs. Understand that you can't see a "national picture" at this web page (as we do at the German, European, or the private network pages). However, you can get at the most recent gamma energy channeled graphs for whatever station might be closest to your areas of interest. Unfortunately, that data is compressed such that a week's worth is only 3/8 of an inch long (as of 1/30/2013 on my monitor). Moreover, what might be really useful gamma spectrometry (to a professional or an advanced amateur particle physicist/radiologist) --is presented to us as just those 10 channels of information. I suppose that beats the single channel of our three amateur networks --except that few people have any basis to understand what the EPA's counts per minute amount to. (You can try this effort to explain it:
* After it's performance in the aftermath of 9/11/2001, I became downright dismissive of the EPA --and my prejudice became strongly reinforced after the events of 3/11/2011 (per: *link*and*link*).
* Previously, my link to the EPA's data was via Alexander
Higgin's web page at:
--but hurricane Sandy destroyed his home, servers --everything --per:
** However: we now have "Greg's Lab" for California and the "Nuclear Emergency Tracking Center", which has placed what appears to be RadNet's gross gamma and beta data onto an integrated national map. Each station is counted twice (I think), once for beta^ and again for gamma data (although how the NETC totals that isn't clear to me), plus these stations are keyed for their trends. You also get your choice of graphed time periods --except the NETC put that vital information behind their pay wall: about $20 per year to subscribe.
^ As of 4/8/2013, the EPA's station graphs no longer
include a line for "Gross Beta" which (no surprise) underwent a lot of
excursions (those ephemeral radon daughters, I presume). That scared people.Now
you're supposed to access that information via the EPA's "Query Tool" --per:
--and the usual RadNet obstacle course ľas commented
My impression is that our "the air is safe to breath" EPA's purpose is mainly to waffle-baffle us. When I followed it in the summer of 2011, the EPA's analysis was months late and I suspect we simply don't see worrisome results.
* I gather that this is how we're supposed to get at their
current analyses of milk, drinking water and such:
--and good luck with that.
* The lack of an adequate, trusted, and well funded program of up-to-date
national radiation monitoring with comprehensive and comprehendable interpretation
for anyone who's interested --is government negligence. Compare what we
have versus what Germany provides its citizens (and
* Radiation Network:
* At "Message", Mineralab/Radiation Network owner Tim investigates and posts what I consider to be honest and rational reports about unusual readings across his network. (Yes: he has identified what appear to be actual radiation alerts.)
* Radiation Network's stations report in "CPM".
* For presentation on their map, the determination of individual station trends and "Alert" status is being averaged over intervals longer than a minute.
* An iconic distinction is made between high and normal sensitivity Geiger counters.
* Radiation Network's current "Alert Level" of 100 CPM seems a good choice, but it will probably be individually adjusted later to accommodate the disparities among their monitoring stations.
* None of the stations are characterized as to what's
being counted or how and where those instruments are positioned --but (again),
high and low sensitivity stations are identified and their responses are
being equalized as to alert and trend status.
* Online Geiger Counter:
* Black Cat's equalized stations uniformly report in uR/hr.
* Above their map is the statement: "Share this page so [your friends] can see things are currently normal", which I once read while a station was reporting a very high reading.
* None of the stations are characterized as to what's
being counted, what instrument/s are doing the counting, or how and where
those instruments are positioned --but (again), they are equalized --presumably
to a standardized cesium-137 equivalent of their CPMs.
* Nuclear Emergency Tracking Center:
* This is an interesting web site which has networked a few stations of its own plus NETC has somehow rounded up beta and gamma CPMs from the EPA's RadNet system. (Radiation Network and Black Cat stations were once on the map, then off.) Presenting the EPA's RadNet data on a national map is one helluva valuable service --at least to the extent that the EPA's RadNet numbers are meaningful in the first place. The "beta" seems to be what RadNet terms "gross beta". Im not sure if NETC's RadNet gamma CPMs are based on the whole count, or some portion of RadNet's several energy level channels.
* NETC (just my guess) uses a formula to identify unreliable stations, which (when de-selected) dropped a number of RadNet appearances from their full service map. (This and the screen capture here is based on what I got to see, before they put it behind a pay wall.)
* All of this data is integrated onto the same national map and you can quickly bring up the NOAA national weather map (although I saw no wind directions on it). Each station is iconized for trends and are graphed (your choice of periods), but only for subscribers. As of 2/28/2013, it appeared that the public map included "Unreliable" monitoring stations --which could be turned off when you accessed their Member Map.
* It appears that the EPA's RadNet stations are counted twice: once as beta stations, and again as gamma reporting stations.
* The monitoring stations are assigned numbers. NETC's own stations use to have "#1" designations and are still listed first in the legend. As of 3/28/2013, the #2 legended stations are the EPA's beta reporting stations, while the EPA's gamma reportage is 3rd. Japan's stations are in 4th place as "Limited" and in 5th place as "Full".
* As of 3/9/2013, only the EPA's stations were characterized as to what's being counted. None were characterized as to what instrument/s are doing the counting, or how and where those instruments are locally positioned with respect to open air and the ground. However: automatic averaging and deviation calculations were being used to equalize relative gains and losses of CPM counts.
* As of 3/28/2013, check-a-box options for "Relative" and "Absolute" suggested that NETC equalization can be optionally turned off.
* The NETC is indicating 5 status levels per station:
"N.O.R.M" through "Radcon 5 Alarm".
* While it's original purpose might have been to pacify the public (since gamma levels change but little with significant particle fallout), compare Germany's monitoring service to what we have available in the United States:
* Click on any of those 1800(!) government funded/networked monitoring stations for a graph of its history. There are also plenty of helps explaining what the numbers mean. Much of Europe has a similar, if less extensive monitoring network. (The downside: it's gamma/(hard beta?) only. The upside: Germany is abandoning nuclear power.)
* The detectors (gamma and [presumably] hard beta counting Geiger
counters) are described as to photos, drawings, commentaries and specifications.
They're all the same, they're mounted the same, they're all 1 meter above
ground level, all isolated in a clearing and all protected.
(Your browser must allow "pop-ups" for this web sight)
* The only aspect of this system which worked for me was (what I take to be) total (gross?) gamma. The extent of monitoring stations is impressive, if not nearly as densely placed as Germany's
* Check out the options! It's at least contemplated that we'll eventually be able to run down and map out the distribution of any sort of radiation or isotope which commonly comes to mind. (All I got was a flashing "Refresh Map", however.)
* I haven't followed this system down to its specifications, but it's a safe guess the whole thing is uniformly instrumented.
* Unlike the German network, you can't click on a given station for a graph.
Fukushima: Probability theory is unsafe
By KENICHI OHMAE
Special to The Japan Times (posted at: http://www.japantimes.co.jp/text/eo20120418a4.html )
--and partly copied as text below, in case of Internet disruptions in Japan.
(C) All rights reserved - The Japan Times
A year has now passed since the complete core meltdowns of three boiling water reactors at Tokyo Electric Power Co.'s Fukushima No. 1 plant. Because of the limited and biased information issued by the Japanese government, the world does not know what really happened when the earthquake and the tsunami hit the six Fukushima nuclear reactors. There are many important lessons that must be learned to avoid a future disaster. These lessons can be applied to all the nuclear reactors globally. People around the world deserve the right to know what happened.
As a nuclear core designer and someone who earned a Ph.D. from the Massachusetts Institute of Technology in nuclear engineering, I volunteered to look into the situation at Fukushima No. 1 in June of 2011. Mr. Goushi Hosono, minister of nuclear power and environment, personally gave me access to the information and personnel who were directly involved in the containment operations of the post-disaster nuclear plants. After three months of investigation, I analyzed and wrote a long report detailing minute by minute how the nuclear reactors were actually disabled (pr.bbt757.com/eng/)
Here are the highlights of my findings:
1. Three of the six reactors of Fukushima No. 1 had a complete core meltdown a few days after the tsunami hit. The molten fuel penetrated not only through the bottom of the thick pressure vessel, but also poked holes at the bottom of the containment vessel, thus releasing fission materials into the environment. The meltdown itself started at 11p.m. on the day of the tsunami, March 11, 2011.
2. As expected, the meltdown caused the fuel cladding material, zircaloy (zirconium alloy), to react with vapor and to create large quantities of hydrogen and zirconium oxide, which caused the catastrophic hydrogen explosion that blew out three reactor buildings. The hydrogen explosion took place on March 12, 14 and 15. The Japanese Government did not admit to the meltdown until three months later, nor did they admit to the damage to the containment vessels until a half year later. Our government tried to hide this important information for some reason, though judging from the amount of fission material released and from the size of the hydrogen explosion, the meltdown of the entire core was undeniable for anyone who has studied reactor engineering.
3. The earthquake on March 11 damaged all of the five independent external power supply systems, and the 15-meter-high tsunami damaged all of the pumps and motors of the main and emergency cooling systems that were constructed along the shore line, thus disabling the cooling system that pumps in sea water.
4. The tsunami also sent massive amounts of water into the reactor buildings and the turbine housing, thus soaking the emergency diesel engines and batteries, which were stored in the basement of these buildings. This meant that all sources of emergency backup power stored in the basement of the reactors were totally destroyed.
5. There was an air-cooled diesel engine sitting atop a hill close to Reactor No. 6. Its air fins were too big to fit into the basement and was luckily placed outside, and as such, this engine started to generate electricity. With a pump brought in from outside, it started to cool not only Reactor No. 6, but had enough power to cool Reactor No. 5. Of the 13 emergency generators associated with the six plants, this was the only one of the three air-cooled backups, and hence not dependent on water as the heat sink. This air-cooled diesel engine was the only one not entirely submerged in water, but in fact at one point the water level did reach up to half its height. A few weeks later Reactors No. 5 and No. 6 were brought to a cold shutdown.
6. The buildings of reactors No. 1 and No. 3 were blown away by an explosion of hydrogen generated by the core meltdown. Reactor No. 4 eventually exploded, though its core had no fuel inside due to a periodic inspection that meant the fuel rods were stored elsewhere. It turned out that the Reactor No. 4's building filled with hydrogen that leaked from Reactor No. 3 through their common gas release ducts. Reactor No. 2 escaped from the massive explosion, although its core had completely melted. Its windows were blown away most likely by the explosions from neighboring reactors No. 1 and No. 3 and the hydrogen inside Reactor No. 2 escaped into the air.
These facts teach us one important lesson: The Fukushima accident could have been avoided if the plant had had the capacity for electricity generation of any form along with the appropriate heat sink.
Assumptions and probability are for the theoretical dreamers.
If you have a hot reactor, submerged in water and this reactor is without
the power to circulate the coolant that can shut it down, then you have
to find another way to cool it no matter what. If you have lost your last
resort of power and heat sink, you should not have taken on the responsibility
to operate a nuclear plant in the first place. That is the lesson of Fukushima.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~end of article quotes
There is much more to read at the link, and it's well worth the while.
(posted at: http://www.japantimes.co.jp/text/eo20120418a4.html )
The Fukushima experience doesn't seem to have persuaded Dr.Ohmae to abandon the quest for "safe" nuclear energy, but surely: implementing "fail safe" procedures would, alone, tip the competitive balance of power generation in favor of renewables --as would several other factors (not subsidizing NPP loans, insurance, disposal --and not subsidizing routine emissions with public health).
My Choice of Radiation Units
(revised: 5-27-2012; 7/18/2012)
* This page use to report Geiger counter ("GC") radiation measurements in terms of indicated "uR/hr" (microREMs per hour, which equals uSv/hr times 100). The use of GC "REM" units (Roentgen equivalent man") is usually invalid, since it's supposed to be about a hypothetical person's received bodily dose from a single, defined, external, isotopic source. My Geiger counters' REM calibrations were only roughly correct for a cesium-137 source, and for other types of radiation --like external alpha radiation, which doesn't even penetrate the skin, it becomes meaningless. In short: a Geiger counter counts alpha, beta, weak and strong gamma as equal *clicks*.
* The alternative of using "CPM" (counts/clicks per minute) is much more honest. Unfortunately, people are using many different GCs which report varying CPMs for the same kind and intensity of radiation. However: they've mostly been factory calibrated to yield similar uR/hr or uSv/hr values for cesium-137 --such that we can at least hope to be in the same ballpark with respect to "background" and other readings --which, like cesium-137 radiation, are largely gamma in nature.
* Now that I have a Medcom GC with alpha sensitivity, all of my future readings will originate as "counts", most of which will be averaged to CPM. Consequently, the main calibration of my graphs is now in (Medcon "Inspector") CPM --with supplementary uR/hr equivalents on the right margin.
* The average outside and inside office ambient (or "background") readings here usually vary from about 8 to 12 uR/hr with one excursion to 17 (see the graphs). Outside and inside readings have been nearly the same here (the few times they've been checked against each other). I can see more variation by moving my GC around inside the house. The best policy (for my purposes) is to keep a Geiger counter in one place --bringing samples to it for testing.
* The local background averages close to 10 uR/hr, at which level the Radex RD1503 GC clicks at a rate of 17.3 CPM. For the Medcom Inspector, it's 35 CPM. Consequently, a 10 minute total Medcom GC count is significantly more valid and consistent than the 13 minute averages I've been doing with the Radex GC. (The 1503's readings have been surprisingly consistent --by comparison.)
* 10 uR/hr equals 0.10 uSv/hr, which is a traditionally low, natural level for a monitoring station only 93 feet above mean sea level. Let's hope it stays that way!
Characterizing CPM Variations and Accuracy
Using the Inspector GC's counter and doing a lot of manual subtractions from the automatic GeigerGraph spreadsheet totals, I got the sums of 50 and 60 minute-long counts during each hour of three 24 hour periods --spanning May 21 to June 4.
* The grand totals were 44,371 counts for the first 24 hour period in May and 44,326 for the 2nd period. Dividing each by 1200 minutes gives 36.98cpm and 36.94cpm respectively.
* The traditional "standard error" estimate (for things like radiation, which conform to a "Poisson distribution" of results) --for those 24 hour periods, is simply the square root of 44,371 (ie: +/- 211) divided by the 1200 minutes = +/- 0.18cpm. The two 24 hour counts I checked sure got that beat --at +/- 0.02 --which is probably mostly due to chance.
* For a typical 50 minute long subtotal count of 1848, the standard error estimate is the square root (43) divided by 50 minutes, or =/- 0.86cpm --but let's round that to +/- 1cpm (about +/- 0.29 uR/hr for the Medcom GC).
* There is indeed some wander in the background/ambient radiation throughout the day and night. Unless something wicked is blowing over, that variation appears to be rather random --save, perhaps, for an evening slump and a late afternoon jump. Sunrise to 1pm seems to be best.
* To read during late morning/noon hours and use longish background counts as practical, but to otherwise not worry much about being fooled by variations in ambient radiation.
* For long half-life samples, clearly: a pair of 24 hour counts should be very accurate (just like the Medcom manual tells us).
I'll switch to an ugly mono-space font --for to keep my columns straight for the May numbers.
Periods CPMs Dev'n uR/hr CPMs uR/hr Dev'n Avg (algebraic)
00:00-01:00 39.6 +2.6 11.3 38.8 11.1 +1.9 +0.3
01:00-02:00 36.2 -0.8 10.3 35.8 10.2 -1.1 -1.0
02:00-03:00 37.6 +0.6 10.7 38.6 11.0 +1.7 +1.2
03:00-04:00 35.8 -1.2 10.2 36.2 10.3 -0.7 -1.0
04:00-05:00 37.3 +0.3 10.7 37.3 10.7 +0.4 +0.4
05:00-06:00 38.1 +1.1 10.9 37.5 10.7 +0.6 +0.9
06:00-07:00 36.9 -0.1 10.5 36.0 10.3 -0.9 -0.5
07:00-08:00 35.9 -1.1 10.3 37.2 10.6 +0.3 -0.4
08:00-09:00 37.8 +0.8 10.8 38.3 10.9 +1.4 +1.1
09:00-10:00 36.3 -0.7 10.4 37.2 10.6 +0.3 -0.2
10:00-11:00 37.0 0.0 10.6 35.8 10.2 -1.1 -0.6
11:00-12:00 37.1 +0.1 10.6 35.6 10.2 -1.3 -0.6
12:00-13:00 38.2 +1.2 10.9 36.3 10.4 -0.6 +0.3
13:00-14:00 36.5 -0.5 10.4 37.6 10.7 +0.7 +0.1
14:00-15:00 36.6 -0.4 10.6 38.4 11.0 +1.5 +0.6
15:00-16:00 39.8 +2.8 11.4 37.8 10.8 +0.9 +1.9
16:00-17:00 36.3 -0.7 10.4 37.2 10.6 +0.3 -0.2
17:00-18:00 36.4 -0.6 10.4 35.3 10.1 -1.6 -1.1
18:00-19:00 35.2 -1.8 10.1 37.0 10.6 +0.1 -0.9
19:00-20:00 36.8 -0.2 10.5 35.7 10.2 -1.2 -0.7
20:00-21:00 35.3 -1.7 10.1 36.8 10.5 -0.1 -0.4
21:00-22:00 36.9 -0.1 10.5 37.7 10.8 +0.8 +0.4
22:00-23:00 35.6 -1.4 10.2 35.4 10.1 -1.5 -1.5
23:00-24:00 38.2 +1.2 10.9 37.0 10.6 +0.1 +0.7
In search of:
* After a long period of adjustments, tests and learning to understand what my Medcom brand "Inspector" Geiger counter is telling me, I at first settled on doing long interior gamma counts for periods of the day, up to 8 hours each (essentially: morning, afternoon and night). That resulted in an over-all 24 hour spanning average with an estimated consistency of +/-0.16cpm (0.05uR/hr) plus some indication of how stable the background radiation had recently been. I noted on my graphs when the three 8-hour periods spanned 1cpm or more. From day to day, the background line on my graphs would commonly swing through a range of 35cpm to 37cpm.
* I've stopped doing the long monitoring periods --in favor of a less demanding record of randomly distributed 100 minute long counts, but centered on 3 periods of "Night", "Morning", and Afternoon (until 6pm).
* I try to sandwich the readings of any (10 cubic meter) outside air filter draws and other sample readings between a pair of these 100 minute counts --although it's possible that I could be fooled by a short term rise in the average background radiation during the sample count (an uncommon event). A person might simply monitor the sample count with a program like GeigerGraph (off-line, of course) --and discarding a series of counts if a significant spike/hump is seen in one of the graphs (of the background or sample runs).
~ During and between my background counts, my Geiger counter reports to the local GeigerGraph program, so any short term spikes over periods as short as one minute are recorded and can be seen at a glance.
* Once in a while I try to check food items for radiation, which is almost entirely beta: from naturally occurring potassium in food. I've stopped doing "paper towel wipe" tests from rained-upon surfaces because they seem so uncontrolled as to be meaningless. Instead I'll run a weather-capped, 1-hour long, 5 cubic meter air draw --through a fresh, 5/8" diameter N95 filter. While I note the initial radon daughter reading, what I'm on the look-out for is any long lasting gamma or alpha radiation.
This was at first an hour-long 5 cubic meter air draw, then a 2-hour, 10 cubic meter air draw, and now I'm going back to an hour-long draw. Of course, that makes little difference to the initial reading of short half-lived radon daughters. Since I've had zero detections of any residual radiation since September of 2011, I don't have to worry about breaking with a baseline on that account either.
It's important to note:
~ My methods are much more sensitive than is commonly assumed (for using a Geiger counter), but I'm still a factor of 10 or 100 away from the sensitivity one needs to "okay" food as being safe --plus: I'd still need someone to run confirming gamma spectrometry on any suspect samples.
~ Alpha and beta get stopped by water, so moist samples have to be thin sliced, crumbled, --and preferably dried and powdered --but then still Geiger counted as a thin or thinly spread sample, since the sample itself will block beta and alpha.
To prove this to yourself, put your Geiger counter in a thin plastic baggy and read a tablespoon of "salt substitute" (potassium chloride). The naturally occurring radio-isotope potassium-40 ("K-40") will significantly raise your Geiger count above the background level. Next: stir that same tablespoon of KCl into a few ounces of water and try to read anything off the water's surface: zilch. That's why, when you see a rain radiation video, the presenter soaks up (soaks out) the water with a paper towel --and maybe wrings the towel out as well. (At risk to your Geiger counter's delicate alpha window, you might be able to read the alpha associated with radon --in very close proximity to rain water or the moist air above it.)
~ The levels of "background" radiation we experience varies from place to place, but aside from (low to the ground) radon and other factors (like maybe a "plume" passing overhead), it's surprisingly constant in any given location (and as is implied in the Medcom Inspector manual:
~ From watching the excursions of my first (small tubed) Geiger counter, I once had the impression that "waves" of "background radiation" were moving over us. However, I was actually watching the randomness with which gamma rays happen to hit the little Geiger-Mueller tube in a Geiger counter. You can satisfy yourself of that by watching two Geiger counters placed side-by-side. As often as not, they'll swing in opposite directions, even though the average CPM for both tends to draw ever closer to the same value over a long period of time. (You have to use the Inspector's timer, total the count, then divide by the total number of minutes. The PRM-8000 and the new PRM-9000 pancake tube Geiger counter, or the GeigerGraph program will figure long term averages for you --plus log a record of CPM swings to either side of those averages.)
* I've seen background levels that were within +/- 0.5% for periods of several days, but the background level does change at times --which is why we keep track of it, and there are unstable periods as well.
* Consequently, when we do see a change in our averages, or when we take a longish count on a sample, we can usually detect fairly small changes in radiation.
In June of 2012 I read the "K-40" (radioactive component) of the potassium in a single 6.7 gram (1/4 oz) banana slice at 10.93 uR/hr (38.26 CPM using a Medcom Inspector Geiger counter, with its pancake window open only to gamma and beta). I'd previously pinned the background down to 10.43 +/- 0.05 uR/hr, so at all of 0.50 uR/hr (1.75 CPM) above that, the radioactivity in that slice of banana "stood out like a sore thumb".
* The same would go for reading residual radiation from (say) a 3 day old air filter --but with my Inspector GC's window open to alpha, beta and gamma in that case. (If you detect persistent radiation in a filter, you should carefully document, seal and protect the sample/filter, then find a lab willing to test it. For large air filters, try getting a ticket for sending it to www.radtest4u.com --for a free scan with their Berkeley Nucleonics spectrometer.)
* Because long term averages can produce very sensitive comparisons and detections, it's important to be on guard against false alarms due to natural radioactivity --from radon/daughters and potassium content in particular. Be advised that, like my banana chip --potatoes, mushrooms, flesh/meat and other foods contain potassium, the K-40 component of which might read twice as strong after being dried and crumbled. Potassium-40 has a strong radiation signature with up to 1.3 MeV beta (89% of the radiation) and 1.46 MeV gamma.
* If you use potassium chloride ("KCl", often sold as a salt substitute) for calibration, I suggest that you keep it in a very small "Ziploc" type bag and that you not transfer the stuff anywhere near your Geiger counter. KCl dust readily disperses into the air, such that I immediately start tasting and coughing it up (unless I wear a mask). Perhaps that's because its dust gets highly charged/ionized, but it officially dissolves into the humidity of the air.
* I also caution against exposing your Geiger counter to conditions which might leave it cold and/or damp. This is not only because it's a sensitive, high voltage, high impedance electronic device, but because the Medcom manual warns us that the light blocking coating on the mica window can wash off when it gets wet (page #21). (Symptom: your counts tend to go up at daybreak.) Instead of taking your GC outside, simply bring the outdoors inside, via samples and filters.
http://www.youtube.com/watch?v=YSb5FARMULo (Corbett Report)
http://www.youtube.com/watch?v=3Fq4teGzhTo&list=PLA7C3E509D78488EA (Gore Vidal)
http://www.youtube.com/watch?v=6GeTv4O_64E (Dr. David Ray Griffin)
http://www.youtube.com/watch?feature=endscreen&v=MAmJ9oAy1mc&NR=1 (Jessie Ventura)
http://www.youtube.com/watch?feature=player_embedded&v=hZEvA8BCoBw#! (Ed Asner)