Radiation detection with the Gamma Scout Geiger Counter
While preparing for our trip to Japan by the end of March 2012, we were getting all kinds of information about safety in regards to radiation levels from family (fretting), friends (dissuading) and media (confusing). It was just about one year after the Fukushima accident in March 2011 and Europe, traumatized by the Chernobyl nuclear reactor blast in 1986, rather alarmed about travelling towards the catastrophe.
WHY WE HAVE THE GAMMA SCOUT
To find out about radiation, we would actually be exposed to in Japan, we bought a Geiger counter to see for ourselves. We looked at various models and decided on a professional piece of equipment, the Gamma Scout, which is a fully featured radiation detector, made in Germany, that took 350 Euros out of our pockets. It is very light and portable, the size of a remote control.
WHAT IS A GEIGER COUNTER
I was introduced to the Geiger counter as a kid, by watching Scooby-Doo, an old cartoon series with apparently some educational value. I learned that cool kids have cool equipment and recently that the Geiger counter detects the emission of nuclear radiation. It picks up alpha, beta, gamma and x-ray radiation through a Geiger-Mueller tube, which gives its name to the instrument.
The Gamma Scout measures background radiation and is no good for testing food.
The display indicates the exposure rate in µSv/h (micro sievert per hour), which is an internationally used unit. Applied in medical, nuclear, mining, metal scrap and foundry industries, it is just the right kind of professional equipment for amateur users like us. Holding that bright yellow coloured counter with the radiation symbol on top, is like possessing the power of scientists. My precious, let me hold you…
WHAT IS ‘NORMAL RADIATION’
The natural environment in Heidelberg/ Germany has a radiation level of about 0.1 – 0.2 μSv/h (micro sievert/hour). So when looking at the Gamma Scout display I was evaluating levels of radiation to whether values exceeded this.
People working with radioactive sources professionally are classified into two groups with two legal upper limits in the EU, assuming 2,000 working hours per year:
- Dose rate limit is 6 mSv (milli sievert) per year = 3 μSv/h for people classified as category B.
- Dose rate limit is 20 mSv per year = 10 μSv/h for people classified as category A.
- Dose rate limit is 5 mSv per year for the general public – people not exposed to radiation occupationally.
HOW MUCH RADIATION AM I EXPOSED TO DAILY AND DURING FLIGHTS
DAILY RADIATION. I am exposed to the average rate of 0.2 micro sievert/ hour, every day. That would be a total dose of 1753 micro sievert annually, which is 1.7 mSv per year. I am not exceeding the rate limit of 5 mSv. All is good.
Maths: 0.2 microsievert * 24 h * 365 days = 1753 microsievert per year = 1.753 millisievert per year
DURING FLIGHTS. Let’s say I am going on 10 long distance flights (two-way tickets) in one year, each flight lasting about 10 hours, with an average radiation of 3 micro sievert/hour on the plane.
That is an extra dose of radiation of 600 micro sievert annually, which is 0.6 mSv per year. Even if I add that to the rate of everyday radiation, I am still doing fine, staying under the rate limit of 5 mSv.
Maths: 10 flights * 2 ways * 10 hours * 3 microsievert/h = 600 microsievert extra, per year (0.6 millisievert)
Radiation levels fluctuate bound to the altitude of the plane. Here are our dramatic Geiger pics during flights.
I am sure that the x-ray of my broken elbow during our ski trip added another dose but I do not know how much, so I left doctors’ treatments out of the equation.
OUR GAMMA SCOUT
You can see that the value on the display is 0.115 micro sievert/hour and therefore lies within the Heidelberg-norm. Picture taken in Poland/Szczecin upon arrival of the Gamma Scout from Germany on the 17th March 2012.
The cover of the box. Very low radiation levels on the display. Where did they measure that?
WHAT IS RADIATION
Radiation is composed of charged particles that travel through space. They are generated through nuclear reactions, such as on the sun, lightning or supernova explosions.
There is natural radiation which consists of solar and galactic radiation, coming from outer space and terrestrial radiation coming from the ground. Natural radiation is also emitted by building materials. In case you ever wondered, why radiation levels are pretty high at home, check for granite, cement, limestone concrete or sandstone. Additionally, there is internal radiation that we take in with food that contains radioactive substances, such as minerals.
In our modern civilization we are also exposed to artificial radiation due to coal and nuclear plants, or when undergoing x-ray examination in medicine and dentistry.
We are exposed to radiation early on, basically from the moment of conception, to as long as we live on earth. Radiation surrounds and penetrates us all the time, which is somewhat fascinating and horrifying.
Or maybe ‘radiation is simply overrated’ – as suggested by bionerd23, an inspiring ‘mad scientist’ nurturing a close relationship with radioactive sources.
OUR GEIGER DATA
The pictures of our measurements are not systematic, rather sporadic radiation checks since March 2012.