Tag: Tritium in rainwater

When Quick Decisions Lead to Wrong Conclusions

The final step: making sure to put numbers in their right context. Are we looking at the whole picture? What works for some people may not work so well for others.

There is a tremendous amount of excellent technical information about radioactivity on the web, but it is often hard for anyone without that specific training to understand. There are also a lot of misleading statements and conclusions on the web. These even appear in peer-reviewed scientific journal articles such as the Chinese paper given as a link in my blog Tritium Trivia. This paper showed the results of modelling various releases of tritium water from Fukushima. Unfortunately, the last step was forgotten. Showing great expanses of red all over the Pacific Ocean would lead nearly everybody to say “How terrible! Japan is polluting the Pacific Ocean with radioactive material.” However, at the end of the document the background levels of tritium in the Pacific Ocean are quoted and this puts the release data into perspective. But nowhere in the paper was the context of the data given, that is that the levels of tritium were so low compared to normal background levels that they would be impossible to distinguish from the background variability.

I have made the decision that I will try to make my blogs as easy to read as I can so that they are suitable for most users of the web. This is not easy with technical information and my background of writing technical reports. Word has an editor function that allows you to calculate the readability of the document. Yesterday, for the very first time I managed to achieve my goal.

I was so excited that I quickly finished the blog and published it only to realize within minutes that I had forgotten a crucial step. I had jumped to the conclusion too quickly and not fully put the information into context. I rapidly edited the post and republished it. However, my subscribers received a set of comments that were not quite right. In my joy of finding a way to explain just how low tritium levels can be, I forgot just how many hydrogen atoms are in a little water. 18 g of water (one mole for the technocrats) contains 6*1023 molecules of water, 12*1023 hydrogen atoms and about a million tritium atoms.  This is still just as teeny in radiation terms but the numbers 1 and a million sound so different. 1TU is only 0.118 Bq/L. I will explain what this means in future blogs.

I apologize to my subscribers. At my age you are allowed to call it a senior moment. However, I suspect that in our current haste over climate change mitigation, we are all making similar mistakes. We do the first part of the work but then forget to really look at the big picture and put everything into context.

It’s Raining! I Might Get Tritium in My Hair?

True or false?

True, and this blog will tell you why it happens.

We all have trouble looking at very big or small numbers and understanding their size and importance. I am one of those lucky people who have less trouble than most. This has had its downsides too.  As a child I loved mathematics and algebra. I saw the patterns in numbers easily and it was all a big game to me until I was bullied at a small country school for being different. I was tied to a post, day after day, mocked at, spat at, and even pummeled with food scraps.

Now I am a senior, maths is not so easy, but I will try and make some numbers about radiation levels easier to understand.

Tritium is a natural substance.

Tritium is formed in minute quantities every day in our atmosphere. Cosmic rays from space hit the gases in the air, mainly nitrogen, forming tritium. Tritium is a type of hydrogen atom with 2 extra neutrons in its nucleus. Tritium quickly becomes part of a water molecule.  Instead of a water molecule with 2 atoms of ordinary common hydrogen with one atom of oxygen (H2O), a few molecules of water are HTO. The chemistry of both is virtually identical.  The mixture comes down as rain.

Just how many water molecules have tritium in them? Well, this is where the big and little numbers come in, making the situation hard to visualize. A new unit was created to help scientists assess the meaning of various concentrations.  1 TU or tritium unit equals 1 tritium atom in 1018 atoms of hydrogen. 1018 is 1 followed by 18 zeros. I find that hard to visualize. Let’s try. There are 8 billion people on Earth, that is 8,000,000,000 people. That is only 8 with 9 zeros. So, we have to imagine the same number of planets as there are people on the earth, with populations similar to earth to be in the right ballpark.  So TUs are like one tritium or one person out of all those people on all those planets put together.  I still find that hard to visualize, but it does tell me that finding 1 tritium atom in all those ordinary hydrogen atoms looks impossible.  Yet scientists around the world can and do measure tritium levels in rain, river and ocean water and ground water. In Australia, ANSTO publishes some of this data.

So how high are tritium levels in rain? It is seasonal and dependent on rainfall patterns. In Australia it is 2 to 3 TU. Most numbers vary from 1 to 10 TU.  Nuclear bomb testing increased tritium levels in rain for a time but still at levels in the same sort of range, definitely measurable but extremely small.

So, what does this actually mean? What are the chances of one tritiated water molecule falling on your head? 18 g of water (3 big teaspoons) contain 6 *1023 molecules of water. There would be a million tritium atoms in this rainwater.

Yes, if it rains on your hair, you will get natural tritium in your hair.

So the answer is TRUE.