“Here are some important facts about tritium…”
Please take a look at Gordon’s work. I belive what is here is true and sound and trust this information in a way I could never trust the NRC or the “administrative” standards that you are using David.
Greetings all –
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 email is about tritium.
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).
Here are some important facts about tritium , , , ,
(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 Tritiated water is radioactive because one or both of the hydrogen atoms in H2O has been replaced by a tritium atom.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 .
(8) The rad is a purely physical unit of measurement. In technical terms, the “absorbed energy” is measured in “rads” (rad = radiation absorbed dose). This quantity is cut and dried, no argument. The rem on the other hand (rem = “roentgen equivalent man”) is a somewhat murkier unit. In most cases the rem is used as a purely administrative unit for purposes of setting standards, in other cases it a carefully calibrated biomedical unit based on a great deal of experimental data. The actual biological hazard from a particular number of rads may depend on such things as gender, age, type of organ, and whether the dose is fractionated (spread out) or not. It also depends on the health effect being measured – cancer? genetic damage? or something else? Most countries use the international units Gray = 100 rads, and Sievert = 100 rems.
(9) A word about RBE (Relative Biological Effectiveness). It is a multiplicative factor used to convert rads into rems (or grays into sieverts). It is sometimes called a Quality Factor (QF).
(Dose in rems) = (RBE) times (dose in rads).
For most gamma radiation, RBE is chosen to be 1 whereas for alpha radiation, regulators have chosen RBE=20. Thus, for a regulator, 1 rad of gamma = 1 rem of gamma, whereas 1 rad of alpha = 20 rems of alpha. Nobody knows exactly why, but – per unit of energy absorbed by living tissue – alpha radiation is about 20 times more effective than gamma radiation in causing cancer and other kinds of biological harm.
If you look at the discussion in point 5 above, it appears that for tritium, the RBE should be at least 2 or 3, and possibly as high as 15, but in fact our nuclear regulators use ONLY an unrealistic and unscientific RBE = 1 for tritium, which is simply wrong. This arbitrariness is why the “rem” is often not so much a scientific unit but an administrative unit, as it is used by the authorities. The failure of authorities to use a realistic RBE for tritium reveals a flaw in their attitude: they just want to pretend that tritium is not really harmful because they cannot prevent it from getting out into the environment. (10) CANDU reactors use large volumes of expensive heavy water (deuterium oxide) as both moderator (to slow doen the neutrons) and as primary coolant (to transfer heat from the core to the boilers). Heavy water is NOT radioactive to begin with. Heavy water is D2O instead of H2O, where D=deuterium = a non-radioactive isotope of hydrogen, where each deuterium atom is twice as heavy as a normal hydrogen atom but is otherwise chemically identical to it.
During routine operation of a CANDU reactor, stray neutrons transform many of these deuterium atoms into tritium atoms. For this reason each CANDU reactor produces 30 to 100 times more tritium per unit of electricity generated, compared with American Light Water Reactors (LWRs). Because water is very difficult to contain 100% during the operation of a nuclear plant, large amounts of tritium (hundreds of trillions of becquerels per year) are released to the environment from every CANDU reactor. A lot of it is released as radioactive steam and a lot is released as liquid effluent.
(11) In 1980, the Select Committee on Ontario Hydro Affairs (an all-party committee of the legislature) issued a report on the Safety of Ontario’s Nuclear Reactors in which they wrote:
“Carbon-14 and tritium are of comparable and special concern for similar reasons.
- First, they each have long half-lives: 5 730 years for carbon-14 and 12.3 years for tritium. Long half-lives allow them to accumulate in the environment around a reactor and in the global biosphere.
- Second, they are easily incorporated into human tissue. Carbon-14 is incorporated into the carbon that comprises about 18 percent of total body weight, including the fatty tissue, proteins and DNA [molecules]. Tritium is incorporated into all parts of the body that contain water.
“Thus the radiological significance of both elements is not related to their inherent toxicity, as each is a very low energy form of radiation, but to their easy incorporation in the body.”
(12) Darlington Tritium Removal Facility (TRF) – this is an isotope separation facility in Ontario that extracts tritium from contaminated heavy water, using an expensive and technologically advanced process. Once separated from the tritiated heavy water, the very much smaller volume of tritium can be stored as a metallic hydride. But this would make no sense as a storage medium for tritium unless the tritium were first separated out from the non-radioactive water.
“Tritium can be safely stored as metal hydride (tritide). At room temperature certain metals take up hydrogen isotopes like a sponge, forming a stable metal hydride. When heated to elevated temperatures, the metal hydride is decomposed, thus making it a fully reversible storage medium.”
(13) Tritium is a very expensive commodity. It can be used in nuclear fission weapons to greatly enhance the explosive power of A-bombs. It can be used in paint to make glow-in-the dark instrument dials. It can be used to manufacture self-illuminating exit signs and landing lights for aircraft that do not depend on any external source of energy. The TRF (the removal facility) has large routine emissions of tritium to the environment. Two factories in Ontario (SSI in Peterborough, now shut down, and SRB in Pembroke, still in operation) have bought tritium from the Darlington TRF and used it to manufacture tritium lighted signs while emitting very large amounts of tritium to the local environment. Moreover, all the commercial radioactive waste from these “illuminated signs” are sent to Chalk River Ontario for permanent storage, on the unceded territory of 11 Algonquin communities.
Gordon Edwards.
(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.org
(3) Decades ago I produced a dossier on tritium for Mayor Marion Dewar of Ottawa citing several scientific reports: It is still a decent background with links to the 1977 UNSCEAR Report on teratogenic and mutagenic effects of tritium. http://www.ccnr.org/tritium_1.html
