Following the post Understanding the Lynas Rare Earth Plant in 13 Questions, which featured answers by Dr. Lee Chee Hong, Chemical Engineering Expert on Metals, LoyarBurokker Eric Choo sought the views of Nick Tsurikov.
Mr Tsurikov is an expert in Mining Radiation Hazards. He is a director of Calytrix Consulting Pty Ltd which provides advice on the management of Naturally Occurring Radioactive Materials (NORM). Many of his replies relating to NORM can be obtained from his website. He does not work for Lynas Corporation but he has been independently advising Lynas on the management of radiation protection issues. He had on 29 August 2011 wrote a letter to reply to the technical comments made by YB Fuziah Salleh on TV PAS on issues relating to Lynas. More info of Nick can be obtained here. He is also a member of the Western Australia Radiation Council.
His response to Eric is reproduced below:
My apologies for the delay in replying — I will try to answer the questions and comment on the answers below. Questions from 1 to 9 I cannot answer — they are not relevant to radiation protection, Questions 10-13 I will.
Question 10
The points in the answer are generally correct. It is, however, important to note two things: the radon generated in the decay of thorium is different to the one generated in decay of uranium (I will address this below) and it is not ‘introduced’ by Lynas — the natural background in Malaysia in accordance with United Nations Scientific Committee on Effects of Atomic Radiation (UNSCEAR) [Table 24 of the Annex B of the 2000 Report to the UN General Assembly] specifies in that the background level of radon in Malaysia is 14 Becquerels per cubic meter.
Which means that in each cubic meter of air inside your home, your workplace, in the restaurant, etc — fourteen atoms of radon disintegrate every second, producing radioactive lead.
Question 11
The points in the answer are generally correct as well. Important thing to note, however, is that the wet(!) material will be transported in double-layered plastic bags that are placed inside containers, so there will be no spillage of any kind. Theoretically, radioactivity may be detected in plant stacks (chimneys) and in the waste water — it has been, however, scientifically proven that the concentrations of radioactive materials would be quite close to undetectable levels in the stack and the limit set by AELB for the waste water is of the same order as World Health Organisation sets for the drinking(!) water.
In fact, of course you can detect radiation everywhere; the main point that it is not expected that there will be any measurable increase in the background levels due to the operation of the plant.
Question 12
The first point is generally correct — there will be no external (gamma) radiation detectable at a distance of 100 meters from the plant, in fact probably not even at a 40-50 meter distance.
The second point (about radon and lead travelling hundreds of kilometers and being generally ‘deadly’). The unfortunate error was made here — most likely due to applying the criteria for uranium decay products to thorium decay products. I do understand that the answer is not entirely suitable to the question “I’m just a layman, I read the paper I saw the news, but I want to know more…”, however there is simply no other way but to get a little bit into the ‘scientific side’, making it as easy to understand as possible.
As we all know, there will be some very minimal amount of uranium present in the concentrate (but not more than in ilmenite and about 6-7 times less than in zircon — that are usual parts of tin/amang concentrate), and as everyone says the issue is with thorium. Now, if we compare the decay products of uranium and thorium, namely — radon and lead: Uranium-238: Radon (Rn-222), half-life=3.8 days – decaying into Lead (Pb-210), half-life=22 years Thorium-232: Radon (Rn-220), half-life=56 seconds – decaying into Lead (Pb-212), half-life=11 hours.
Clearly, the statements in the answer to Q12 appear to be more or less correct, but only for radon and lead generated by the decay of uranium. It is obvious from the comparison above that if any radon is emitted from any materials on site (thorium) — its concentration will be half of the original one in less than a minute.
And if we assume, for example, that the wind is blowing at a velocity of 5 meters per second, this will happen at a distance of about 300 meters from the ‘source’. Naturally, at a distance of, say, 3 kilometers (where the nearest houses are, as I understand) it will be less than one tenth of the original — thus pretty much ‘unmeasurable’ and ‘undetectable’ at distances over 1 kilometer.
Now to lead. Even if any lead from thorium (Pb-212) will be carried out anywhere and be detected (unlikely, but say it can be) — it is important to note that:
(a) in 24 hours there will be only about 20% of the original left; and (b) is is much less harmful than the one from uranium (Pb-210). There are established dose coefficients for the inhalation of both Pb-212 and Pb-210, and Pb-212 (from thorium) is three times less dangerous than Pb-210 (from uranium).
Therefore, the statements about radon and lead ‘getting into food chain’, ‘released inside the body’ and causing ‘very serious consequences’ are obviously incorrect.
It will be very much appreciated if this information is corrected anywhere where it was published.
Question 13
The answer to the Q12 above and a lot of information presented on my website clearly show that “it is safe”. Of course, no one has reported the consequences of consuming radioactive materials — as, even if there will be any — in theory, any increase in the background levels will be undetectable and increase in people’s exposure to radiation — unmeasurable.
And, lastly, anyone should decide for him/herself to whom they should listen to. I agree to this, of course.
If I’ve made any mistakes above or missed something — please let me know.
Kind regards
Nick Tsurikov