Position statement by the college in relation to the production of radioisotopes for medical use: The risk of shortages of radioisotopes for medical use must not be allowed to compromise the safety of the reactors in which they are produced
While the reactors supplying most of the worldwide production of radioelements for medical use have now been in operation for over forty years, the French nuclear safety authority (ASN) wishes to alert stakeholders to the need to avoid any conflicts between public health and nuclear safety in the production of these radioelements. ASN believes that the solution is not to extend the operation of these old reactors, but rather to adopt a new concerted approach at an international scale.
Radioisotopes, or radioactive markers, are used in the diagnosis and treatment of a number of pathologies. Metastable technetium 99 (Tc-99m) is the most widely used radioelement in medical imaging with over 35 million examinations being carried out each year throughout the world. It is manufactured from molybdenum 99 (Mo-99) obtained by the neutron irradiation of enriched uranium targets in a reactor. It is the production of this radioelement that is causing at present the most concern.
The majority of world production currently comes from five ageing research reactors:
- NRU at Chalk River in Canada commissioned in 1957 (~40%)
- HFR at Petten in the Netherlands commissionedin 1961 (~30%)
- Safari at Pelindaba in South Africa commissionedin 1965 (~10%)
- BR2 at Mol in Belgium commissioned in 1961 (~9%)
- OSIRIS at Saclay in France commissioned in 1965 (~ 5%).
The safety of these research reactors is supervised by the nuclear safety authorities in each of the countries concerned. In France, ASN is responsible for supervising the safety of the OSIRIS reactor. Given the advanced age of this reactor, ASN decided on the 16 September 2008 that the operation of this reactor would not be permitted beyond 2015 at the latest and required a major programme to improve safety.
In 2007, a prolonged shutdown of the Canadian NRU reactor, recently re-started up under authorization of the Canadian Parliament and against the advice of the Canadian safety authority, resulted in a worldwide severe shortage of technetium that lasted for several weeks. A new shortage occurred in 2008 due to the unplanned shutdown of the Dutch HFR reactor. In view of this situation, medical services were obliged to curtail their programmes of examinations.
ASN believes that similar situations are bound to recur in the short and medium term. Situations in which two or more of these reactors are shut down at the same time are indeed unavoidable for the following reasons:
- These reactors are subject to programmed shutdowns of varying durations to allow maintenance or modification operations to be carried out. The OSIRIS reactor will be shut down for this reason between March and September 2010.
- After forty years of operation, the aging of materials and structures within these reactors is likely to result in the development of failures. The Canadian NRU reactor was shut down in mid-May 2009 until at least the Spring of 2010, while the Dutch HFR reactor requires extensive repair works following the discovery of leaks.
- There are no reactor available to replace the existing reactors in the short term. The two Maple reactors built in Canada to replace the NRU reactor are not yet in operation, and the French RJH reactor may not be ready to enter service before OSIRIS shut down in 2015.
In this context, ASN organised a seminar on the 7 and 8 of January 2009 on the ‘Safety and availability of radioisotope production facilities’ bringing together the nuclear safety authorities from the main radioisotopes producing countries, the AFSSAPS, the Nuclear Energy Agency (NEA) and the Association of Imaging Producers and Equipment Suppliers (AIPES). One of the main conclusions of this seminar was the need to strengthen the exchange of information between safety authorities on the problems of safety and availability of these reactors. A seminar was also organised by the NEA on the 29 and 30 of January 2009 on the supply of radiopharmaceuticals. One of the measures identified to improve the security of supply in the short term was to strengthen coordination between the operators of the various reactors when planning their maintenance programmes.
ASN has proposed to establish an exchange network between safety authorities devoted to supply security issues (including maintenance schedules and breakdowns) of radioisotopes nuclear-reactor produced.
ASN notes that, unlike reactors used to generate electrical power, there is currently no work being carried out at international level with the aim of harmonising the safety of facilities, research reactors and radioisotopes production facilities, both ageing and under construction. ASN considers that such harmonisation is a major issue and supports this idea in its bilateral and multilateral exchanges with its national counterparts.
In view of the risk of long term shortages in supply of radioisotopes for medical use, ASN believes that the solution is not to extend the operation of these old reactors as this could jeopardize the safety of these facilities. For ASN, the solution lies in the dialogue, cooperation and discussion at nternational level aiming at:
- The optimization of the use of Tc-99m, the research into alternative methods of production (e.g. by accelerators) and the investigation of other methods of medical imaging.
- The construction of a robust economic model for the production of these radioisotopes as the current model does not take account of the total cost of manufacture of the radioisotopes, especially the cost of manufacturing the molybdenum produced in state-owned research reactors.
The ASN Commission,
André-Claude LACOSTE Marie-Pierre COMETS Jean-Rémi GOUZE