nuclear-news

Still more information about Tritium

Many citizens do not realize that SMNRs (Small Modular Nuclear Reactors) produce all of the same kinds of radioactive wastes that traditional larger reactors do – high-level waste (irradiated nuclear fuel), medium-level waste (e.g. decommissioning waste resulting from the dismantling of reactor structures), and low-level waste. This particular post is about tritium.

by Gordon Edwards, 9 Aug 23

By far the most radioactive objects produced by any nuclear reactor, large or small, are the intensely radioactive used nuclear fuel elements. A used nuclear fuel bundle is one of the most dangerous objects on Earth. It can give a lethal gamma radiation dose to any unshielded human being in a short time, even after “cooling off” for several decades.

But even after all the irradiated nuclear fuel (high-level radioactive waste) has been removed from the reactor there is still a large volume of dangerous radioactive waste left behind – including the activation products that are created in the core area of the reactor. Two of the most biologically and environmentally mobile radioactive activation products are  tritium (radioactive hydrogen) and carbon-14 (radioactive carbon). 

(1) Tritium is radioactive hydrogen. A tritium atom is three times heavier than a normal hydrogen atom, but the two are otherwise chemically identical. Any chemical compounds formed with ordinary hydrogen can equally well use tritium instead. The only fundamental difference is that tritium atoms disintegrate (explode), while other hydrogen atoms do not disintegrate. When a tritium atom explodes it gives off a beta particle, but there are no gamma rays. It is a “pure” beta emitter.

(2) For example, a normal water molecule H2O is not radioactive. Tritiated water is radioactive because one or both of the hydrogen atoms in H2O has been replaced by a tritium atom. So when you drink or inhale or otherwise absorb tritiated water, the tritium atoms are disintegrating inside your body. Your cells are being bombarded with beta particles from disintegrating tritium atoms.

(3) Chemically, radioactive water molecules are no different than ordinary water molecules. It is not possible to separate out the tritiated water molecules by filtration or any normal chemical processes. Tritiated water is chemically identical to ordinary water. Municipal water treatment plants cannot remove tritium from drinking water. You can’t filter water from water.

(4) Evaporation of tritiated water will produce radioactive water vapour. Tritiated water vapour will condense to form radioactive dew drops, and can precipitate as radioactive raindrops or radioactive snowflakes. To contain tritiated water therefore it is important to prevent evaporation. Sealed drums or water tanks are suitable for the task. 

At Fukushima Daiichi there are about 1.3 million tonnes of tritiated water stored in over 1000 large steel tanks. This inventory is constantly growing because of the continual cooling of the molten cores with ordinary water which becomes heavily contaminated with two dozen radioactive waste materials on contact with the molten core material, including tritium.  The main reason that TEPCO has given for dumping this huge amount of stored tritiated water into the Pacific Ocean is simply because the site is running out of space to accommodate more tanks. This is a lame excuse – more space can be found if needed. The tritiated water at Fukushima is also contaminated with other radioactive materials, even though much of these other varieties has been greatly reduced by decontamination equipment called ALPS — which in no way reduces the tritium content. Since no removal process is 100%, other radionuclides remain in the tritiated water, in some cases to a very significant degree.

This problem of a growing inventory of tritiated water will not occur at Indian Point or any other shut down nuclear reactor. In such a situation, the  volume of tritiated water is a constant and can be stored for many decades in drums. These drums would have to be inspected and repaired or replaced when necessary. 

(5) All organic molecules (including DNA) incorporate carbon atoms and hydrogen atoms. Tritium atoms can and do replace some of the non-radioactive hydrogen atoms in the organic molecules in your body. This is called “organically bound tritium” or OBT. Whereas tritiated water, like ordinary water, passes through the body easily, OBT stays around for a lot longer. The “biological half-life” is how long it takes the body to get rid of half of the tritium; evidently it depends a lot on whether it is OBT or not. Tritium and carbon-14 are unique in their ability to become a part of our very own DNA molecules; most radionuclides do not have this possibility.

(6) It has been shown in animal experiments that tritium causes genetic damage of almost all kinds, both chromosomal and non-chromosomal. Tritium ingested by a pregnant female passes through the umbilical cord to the embryo and the developing fetus in fact gets a larger radiation dose than the mother. Tritium has been shown to cause physical deformities and more subtle developmental abnormalities in embryos of experimental animals – for example, loss of the “righting reflex” in mammalian juveniles. 

(7) Tritium gives off a non-penetrating form of beta radiation and so it is relatively harmless outside the body – unless it is in contact with bare skin. It can be absorbed directly through the skin. However once inside the body it goes everywhere (all organs) and is known to be at least 2-3 times more biologically damaging (per unit of absorbed energy) than gamma radiation. IMPORTANT: Although this “discrepancy” has been known for decades, and is not disputed, NONE of the regulatory bodies take it into account! After careful study, the UK Committee Examining Radiation Risks of Internal Emitters (CERRIE) published a report showing that the biological damage of tritium (per unit of absorbed energy) may be as much as 15 times greater than the damage from gamma radiation. See www.ccnr.org/tritium_paper_CERRIE.pdf .

(1) Resources on tritium can be found at “Troubles with Tritium” www.ccnr.org/#tr For general background on tritium, this article is easy to read: http://www.ccnr.org/GE_ODWAC_2009_e.pdf(2) Other resources can be found at Tritium Awareness Project (TAP Canada) http://tapcanada.orgHere is a brief reference to OBT (organically-bound tritium) from TAP Canada.

August 11, 2023 - Posted by Christina Macpherson | radiation, Reference