#29 Jun 9, 2012
ADSORPTION AND SOLUBILITY
"Thorium-232 is strongly bound (adsorbed) by soil especially clay soil. The Thorium concentration in the clay particles is about 500,000 % higher than in the water between the clay particles.
So, it cannot be leached out by water and pollute the rivers. Even if the clay soil is washed into the rivers and sea it will not do any harm as the thorium will still be strongly attached (adsorbed) to the clay and will not dissolve into the water."
"Lynas' snake-oil salesman forgot to tell you that the WLP waste will be roasted in concentrated acid. And in that form, thorium is highly soluble. Unquote
The SOLUBILITY of a substance in a solute like water and ADSORPTION of the substance are 2 separate properties and not the same.
In nature Thorium-232 is found in the form of Monazite (Ce,La,Nd,Th)PO4 i.e. the phosphate of Thorium-232. This is completely insoluble in water.
The next most common ore is Thorite (ThSiO4) which has a gram molecular weight of 324.12 gm. This is also completely insoluble in water.
Practically most of the other thorium compounds are artificially created in the laboratory. The most famous is Thorium dioxide (ThO2) which was used as a radiological contrast media and because it is also insoluble, it is administered intravenously as a colloidal dispersion of thorium-232 dioxide (Thorotrast)
Huge doses of 25cc to 50 cc of a 25%solution of Thorium dioxide (Thorotrast) was injected into the vein or artery in the contrast radiological studies.
The other Thorium salts like the fluorides, chlorides, Iodides, sulfides, selenides, tellurides, nitrides, nitrates, sulphates and other complexes are all artificially synthesized.
All of these have varying degrees of solubility in water. The most soluble will be the nitrates, chlorides and to a lesser degree sulphates. As mentioned above, the oxides, silicates and phosphates are insoluble.
Metallic Thorium-232 is of course totally insoluble in water.
However, whether Thorium-232 is in the SOLUBLE OR INSOLUBLE FORM, IT IS STILL STRONGLY ADSORPED BY CLAY AND CANNOT BE LEACHED OUT BY WATER.
The extremely dangerous herbicide Paraquat is a liquid and is extremely soluble in water. Although it is extremely soluble and dangerous, IT IS NOT LEACHED OUT OF THE SOIL and pollute the rivers because it is STRONGLY ADSORPED BY CLAY SOIL JUST LIKE THORIUM-232.
So Lynas can continue their acid roasting of the ore and with the usual procedures taken, it should not be a problem.
Dato' Dr Looi Hoong Wah.
FAMM, MB., ChB(Manchester), MRCS(England), MRCP(UK), MRCP(London).
#30 Jun 23, 2012
What is the "safe" level of radiation?
Public dose limits for exposure from uranium mining or nuclear plants are usually set at 1 mSv per year above background.
The figures below are given by the National Council on Radiation Protection and Measurement (NCRP) and its international counterpart, the International Commission on Radiological Protection (ICRP). Both of these organizations offer recommendations for the maximum permissible dose (MPD) of radiation.
General Public annual MPD by both NCRP and ICRP is 1 mSv.
For Radiation Workers, the annual MPD is 50 mSv (NCRP) and 20 mSv (ICRP), with a cumulative MPD of 10 mSv x Age.
MPD during pregnancy is 5 mSv (NCRP) and 2 mSv (ICRP).
This is over and above background exposure, and excludes medical exposure.
However, experts including Professor Wade Allison of Oxford University argue that the dose limit can safely be raised to 100 millisieverts, based on current health statistics.
Compare this with the dose of 0.002 millisieverts/year of exposure for people living within 1 km of the Lynas plant in the worst case scenario (estimated by Lynas).
This level of 0.002 mSv/yr is actually grossly overestimated because the low energy gamma rays from the Thorium-232 decay chain is able to travel less than 300 metres in air.
Note, the average energy of most abundant emission is only 0.059 MeV, though the gamma ray from Thallium-208 decay to stable Lead-208 has a higher energy of 2.62 MeV.
The radon-220 has a very short half life of only 55 seconds and as such cannot travel far and do not accumulate in confined spaces like the radon-222 from the Uranium decay series.
So the actual radiation dose at a distance greater than 300 metres from the plant is approaching 0 mSv/year !
Comparative Dosages in Biological Effect in mSv.
Dose from natural radiation in the human body: 0.40 mSv per year
Sleeping next to someone for 8 hours 0.02 mSv/yr (10x Lynas worst case)
Sleeping in wooden house = 0.20 mSv/yr (100x Lynas worst case)
Smoking a pack of cigarettes daily 0.20 mSv/yr (100x Lynas worst case)
Slag brick and granite house = up to 2.0 mSv/yr (1,000x Lynas worst case)
Chest X-ray = 0.10 mSv
Medical or dental X-ray 0.39 mSv
CT Scan (Chest)= 10 mSv
CT Fluoroscopy of abdomen and pelvis 6 to 90 mSv (median=31 mSv)
Average individual background radiation dose: 2 mSv per year (1.5 mSv per
year for Australians and 3.0 mSv per year for Americans)
Dose from atmospheric sources (mostly radon): 2 mSv per year
Total average radiation dose for Americans: 6.2 mSv per year
Current average dose limit for nuclear workers: 20 mSv per year
Dose from background radiation in parts of Iran, India and Europe: 50 mSv per year
(Source: UNSCEAR and EPA and IAEA)
All the potassium that we eat everyday in our food contains potassium-40 and the normal dietary potassium would give a total of about 80 Bq per day.
Compare this with the Lynas waste which produces only 6 Bq/gm
Even your wife or husband is radioactive, with a radioactivity of 4,000 Bq from Potassium-40 and another 3,000 Bq from Carbon-14 giving a total of about 7,000 Bq!
Sleeping next to someone (i.e. your wife or husband) for 8 hours a day will lead to an exposure of 0.02 mSv/year (Source: UNSCEAR and EPA).
Since all living cells contain potassium, all types of meat, flesh, fruits, nuts and vegetables are radioactive because of the potassium-40 content.
The so-called sodium free salt recommended by health experts to combat high blood pressure is nothing more than just highly radioactive potassium salt! Even a lot of doctors, specialists and professors do not know this!
The message here is that more radioactive substances are freely sold in the shops and used as a fertilizer or eaten by us than you would otherwise thought.
Seri Kembangan, Malaysia
#32 Nov 16, 2012
Are you saying that thorium will not cause cancer ? Or are you saying that YOU DON'T REALLY KNOW, because at the end of the day science is BLIND ?
Seri Kembangan, Malaysia
#33 Nov 16, 2012
I think you misunderstood Dr.Chan's contention. He is referring to internal and external emitters. If it is outside then the harm would be less as the energy would have been dissipated over a short distance. But inside the body where the thorium is in close proximity to the cells the damage would be significant.
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