Is the current isotope business sustainable?

For the last few days I’ve been putting down top soil and mulch in our garden and in addition to cursing the scientific illiterates responsible for the Ontario pesticide ban, I’ve been thinking more about the latest isotope supply crisis at NRU.

 

I’ve already written a couple of pieces in this blog about NRU and its problems but I’d like to come back to a theme that I first introduced in my January 2 post. Namely, that the current level of medical isotope use is not sustainable.

 

Do we really need to produce and use medical isotopes at the current level? It seems nobody has stepped back to consider this key question in a serious way. Instead all sorts of expedients to maintain the current production level are under consideration.

 

The first but least likely solution is to fix NRU. If it is possible to repair it in a reasonable time (doubtful), it’s only a short-term fix. There’s a reported rumour that some “nuclear engineers” want to restart the MAPLE project.  After the laughter died down, I have to concede there is something in the idea at least in terms of regulation. Given the present climate in government, CNSC would only pretend to regulate a MAPLE redux probably by making appropriate noises of no substantive content. The likely consequence would be that these apocryphal engineers would be enabled to do some “light dusting” of the existing MAPLEs all the time waving the banner of isotope production and then start them up. I suppose that if there was a good containment structure around the MAPLEs, the consequences of an accident (the MAPLES were infamous for control rods that wouldn’t engage reliably) would not be so severe.  But is there anything left to dust? Can the project be revived at this stage or are they too far down the decommissioning road?

 

There is also an innovative scheme to make some isotopes by photo-neutron methods at TRIUMF in Vancouver but it is only in the conceptual stage. I read that the University of Missouri wants to get into isotope production in a big way about five years from now. If that means they plan to irradiate enriched uranium targets (requiring heavy security) and store the highly radioactive fission product liquid waste, it’s a totally inappropriate activity for a university campus in my opinion. A criticality accident in the fission product storage tanks would result in many casualties in a densely populated area like a campus. Large scale isotope production should only be undertaken at an isolated nuclear reservation such as Chalk River or one of the US national labs such as Oak Ridge.

 

The few isotope production reactors in other countries are also old and in bad shape. It’s a good time to seriously consider whether society can or indeed needs to continue the present system of isotope supply. The current and future shortage mostly concerns technicium-99 which is extensively used in diagnostic tests. Do we really need so much technicium-99? The supply of the main therapeutic isotope, cobalt-60, is assured from power reactors and many other diagnostic and therapeutic isotopes with longer half lives are not so seriously affected.  

 

Before we go running off to implement desperate measures such as reviving the MAPLEs or embarking on intensive isotope production on university campuses, we should have an authoritative and objective assessment by an independent internationally respected institution (e.g. the Harvard School of Public Health) that spells out what technecium-99 tests are essential in the sense that there are no other tests that can be reasonably substituted. This would tell us what production level is really needed as distinct from what is desired by the specialists in the field and would form the basis for a sustainable plan for isotope production.

 

It’s clear that the old days of abundant supplies of cheap isotopes are over and the former altruistic attitude that the Canadian taxpayer should subsidize the world isotope supply (or more accurately the middlemen in the value chain) is hopefully long gone. Rather we must insist on a realistic price for isotopes that reflects their real cost, doing so will also serve to regulate demand.

9 Responses to “Is the current isotope business sustainable?”

  1. Randal Leavitt Says:

    I wish the universe would answer questions clearly. What technecium-99 are essential? No one knows, and neither does the universe. The patient will do anything to stay alive – if technecium-99 helps, then use it! But we just dont know until we get a statistical picture and that takes decades. Even then, the overall statistics dont tell us what will happen to a specific individual. So what can a doctor do – look patients in the eye and them that they cannot have the same test that appeared to save five of their relatives? Because a committee somewhere wrote a report! Medicine just is not that straightforward. The only morally justified reason for removing a test from the doctor’s tool kit is proof that it does harm – and again this takes decades to document and even then will be ambiguous and subject to lots of subjective interpretation.

    I think the Maple reactors should be put into use now, and upgraded as we learn how to make them better as a result of real experience. That is how we learned how to use fire. We should have three of them in operation so we can always be upgrading one while the other two are providing redundant reliability. What morally justified reason does a rich country like Canada have for not doing this?

  2. Don Jones Says:

    We don’t need new specialized isotope reactors. We need a new NRU type reactor for CANDU R&D support and to supply neutron beams for material research as well as isotope production. Government should have funded this years ago. How can we continue CANDU development without a new NRU.

  3. Steve Aplin Says:

    How about a compromise: build a new NRU and de-mothball one or both of the Maples. Unless they can figure out how to build a new NRU that uses low enriched uranium (i.e., less than 20 percent) targets for medical isotope production.

  4. Dr Singh Says:

    It always comes back to MAPLE…
    The first went critical in 2000. FYI that is 9 years ago. Back then the project was already a little overbudget. But, what did AECL and the government spend hundreds of million on since then?

    In 2000 we had a multi-purpose research reactor that also made isotopes that was deemed unsafe since empirical measurements didnt match calculations. In 2009, hundreds of millions of dollars later, we still have no NRU replacement…

    where did all that money and time go? Surely you could have built a duplicate of NRU in a small fraction of time and money…

  5. Sami Says:

    Tc-99 is the best option as medical diagnostic isotope. The reason is its short effective half life (i.e. combining radiological and biological half life) of almost 6 hours. Thus, following the diagnosis it leaves the body in almost 2 days. Accordingly, the cost in terms of radiological dose to the patient is minimal. You can’t beat that. Co-60 is not a diagnostic tool because of its long half life (5.27 Yrs), and it causes significantly high dose (for the purpose of diagnosis). Co-60 is used as “radiotherapy” following cancer operations (the benefit justifies the radiation dose risk). In summary, there isn’t much alternative to fixing the NRU or licensing the Maple reactor. BTW; the difference, between calculation and measurement, that is holding off the license can be reassessed by the CNSC. Ideally, the license requires “negative or “Zero” reactivity void coefficient. We already operate all CANDU s under positive coefficient. Some medium engineering modifications could have opened the door for the Maple license considering the wasted time doing nothing.

  6. Sami Says:

    For the sake of clarity, I think I should elaborate a bit to my above stated comment. Tc-99m medical isotope is typically purchased as Mo-99 (T1/2 of 2.7days) decays to Tc-99m (T1/2 of 6 hrs) . The nuclear medicine lab “milk” the Tc-99m for short term use. The hospital Mo-99 supply last 2-3 weeks and new supply is normally staged. That is why it is complicated story with the NRU. Production of Mo-99 from HEU is not easy or secure for most countries.

    Co-60 is produced in many reactors via activation of stable Co-59. Co-60 supply lasts long time at the hospital. Its radiological half life (5.27 yrs),and its biological (also effective) half life is ~9.5 days and it keeps irradiating the organs for over 3 months.

    So, in summary it is not easy to find alternative except fixing the NRU or fixing the licensing engineering problem with the Maple

  7. Dr Singh Says:

    Yes, positive void coefficient and build up of metal particles (friction) on control rods that *might* be problem in unusual circumstances, are amongst the main issues cited to licensing MAPLEs.

    But, these are not the first of their kind. A slightly different MAPLE was built in Korea and its been working perfectly for a decade (Korea is also home of the often cited very high capacity factor Wolsong CANDU E6s).

    I suspect the problem is similar to that encountered in NRU fiasco – although “riskier”, despite 1 in millions, CNSC is probably digging in its heels that MAPLE should operate exactly to design specification (which were off), and refuses leeway. Once again this is guessing on my part.

  8. Sami Says:

    Yes, Dr Singh this exactly what I meant by re-examining the MAPLE issue by reassessing the risk based on factual engineering parameters ,determine if engineering acceptable changes can be made to reduce identified risks (either in terms of probability or consequences) ,then we can determine its license-ability based on engineering not political bases. That is what the Probabilistic Risk Assessment (PRA) licensing concept was introduced for. I don’t know to what extent this process was followed. This is an issue shouldn’t have taken 9 years to solve, except of course when politics enter the game.

  9. FRG Says:

    It appears to me that the medical isotope business is mostly about making big bucks for the medical isotope supply companies such as Nordion. According to the US National Academy of Science one gram of Mo-99 is worth $46 million and millions of medical isotope tests are carried out each year – 80 % of which use Tc-99m derived from Mo-99. Having had a myocardial perfusion test myself – which found NOTHING – you have to ask how many of these diagnostic tests are really necessary and actually find anything of concern. Now add to this the fact that making 1 curie of Mo-99 generates about 100 curies of unwanted long-lived fission product waste that has to be safely stored for many decades and you start to question the wisdom of the whole radiopharmaceutical business. So to all you fans of medical isotopes out there I say: wake up people – you are being taken for a very expensive ride!


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