Maple Reactors

The Maple-1 and Maple-2 reactors are 10-MWt pool-type dedicated medical isotope production reactors fueled with LEU. When operated at their design capacities, the output of Mo-99 from one of the two reactors would have been roughly equal to current worldwide demand.

These reactors were designed to operate with HEU targets. The decision to use HEU targets was controversial because at the time the construction of the Maples was initiated, there was an international push, led by the United States. and supported by IAEA, to eliminate the civilian use of HEU (see Chapter 11).

AECL discovered that the reactor had a positive power coefficient of reactivity in June 2003, after the Maple-1 reactor had been operated at a reactor power of 8 MW. This behavior was unanticipated and, because its origin could not be identified, it was deemed by the regulator (the Canadian Nuclear Safety Commission) to be a safety issue. AECL engaged the services of organizations such as Brookhaven National Laboratory, Idaho National Laboratory, and INVAP, an Argentinian company that designs research reactors, from 2005 to 2008 for computer simulations and development of a test program to identify the cause of the discrepancy between the predicted negative and measured positive coefficient of reactivity of the reactor, but a cause was never determined. In May 2008, AECL halted work on Maple-1 and announced that it was discontinuing the project.

transfer of ownership of the DIF from MDS Nordion to AECL, assumption by AECL of all future capital and operating costs, and a $25 million cash payment to MDS Nordion. In return, AECL agreed to supply medical isotopes to MDS Nordion under a 40-year revenue-sharing arrangement.

As noted in Sidebar 10.1, work to understand and correct the technical problems with the Maple reactors continued until May 2008, when AECL announced that it was discontinuing that work.4 AECL also announced that it intended to seek a 5-year extension of the operating license for NRU (from 2011 to 2016) to maintain production of Mo-99 for the intermediate term. As noted in Chapter 4, this life extension will reportedly cost several hundreds of millions of dollars. Natural Resources Canada, a Canadian federal department, has been charged by the Canadian government with developing contingency plans for medical isotope production by AECL. The goals of this planning are to (1) avoid unplanned outages at NRU, (2) help


Following this decision, AECL was served with a notice of arbitration proceedings. MDS Nordion is seeking to compel AECL to meet its contractual obligations under the 2006 agreement. MDS Nordion has also filed a $1.6 billion lawsuit against AECL and the government of Canada for breach of contract and interference with economic relations.

The National Academies of Sciences, Engineering, and Medicine
500 Fifth St. N.W. | Washington, D.C. 20001

Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement