Speaker: Albert Lee
Manager, Analysis - MMIR Project, AECL
Director, Nuclear Studies and Analysis, AECL Office of the Chief Engineer
Topic: MAPLE Reactors: From Concept to Product
Location: J.L. Gray Centre
Deep River, Ont.
Date: Thursday, December 13, 2001 (8:00 pm)
Albert Lee photo

Summary published in North Renfrew Times, January 2, 2002:

Scientist Provides History of Maple Reactors

by Bryan White

Dr. Albert Lee, Director of Nuclear Studies of AECL's Chief Engineer's Office presented a seminar entitled "MAPLE Reactors: From Concept to Product" to the Chalk River Branch of the Canadian Nuclear Society at the J.L Gray Engineering Centre on December 13. Dr. Lee has been the Analysis Manager for the MAPLE Medical Isotope Reactors since 1997 and has been involved with the development of this research reactor technology since 1981. He presented a personal view of the development of this technology.

When AECL found its bid to supply a 30 MW reactor to Indonesia was not competitive in 1981, the need for a new approach was recognized. The international market prospects were encouraging for research reactors ranging in power from 1 to 10 MW that were larger than the successful 20 kW SLOWPOKE 2 reactors. AECL entered into a feasibility study with Korea for a 30 MW reactor. Plans were being developed for a 20 MW reactor to replace NRX.

The international promotion of low-enrichment (less than 20% uranium-235) as an aid to nuclear non-proliferation and the development of uranium silicide-aluminum fuel at CRL for NRU was a key element of the development. Low capital cost and the virtues of "passive safety" attributes lead to choosing a pool-reactor design (as were the SLOWPOKES). These features with the Canadian regulatory requirements for 2 shutdown systems lead to the MAPLE concept. The marketing group were enthralled with the name, which Dr. Lee termed an acronym in search of an application. This light water moderated reactor's dense hexagonal lattice fuel geometry, with the core surrounded by a heavy water reflector results in a high neutron flux that extends out into the reflector to provide a large volume for isotope production and research applications.

Dr. Lee outlined the progression of the MAPLE design starting from a 20 MW design that was proposed to be installed in a pool inserted into the biological shielding structure of the NRX reactor, to a MAPLE-X20 reactor in a separate building that ultimately became MAPLE-X10, the forerunner to the current MMIR reactors. During this period, the Korean MAPLE Research Reactor (KMRR) 30 MW design was developed and ultimately renamed HANARO. AECL and Korean teams developed the reactor systems and facility. HANARO was first critical in February 1995 and entered its operational phase in 1996. Presently operation of this reactor is restricted by regulatory issues to 26 MW. The validation of computer software programs used for safety analysis and critical heat flux data for the fuel are related to the similar activities still in progress for the MMIR reactors.

There was a series of MAPLE reactor designs proposed that failed either to secure funding or to be chosen as the winning bid for international contracts. These included a 10 MW reactor to replace the 5 MW pool reactor at McMaster University in Hamilton, a similar reactor for Thailand, and the ANSTO replacement reactor in Australia. General Atomics of the US won the Thailand bid and INVAP of Argentina were chosen for Australia.

Meanwhile, AECL developed the concept for the 20 MW MAPLE Materials Test Reactor. Ultimately this was changed to the 40 MW Irradiation Research Facility that was renamed the Canadian Neutron Facility as a successor to NRU.

In response to questions following his presentation, Dr. Lee agreed that the delay in the development of regulatory requirements for new research reactors in Canada impeded this work. Moreover, Dr. Lee observed that the MMIR reactors are built and licensed following the protocols for CANDU power reactors despite their small size and low risk for harm to the public or workers. He observed that international practice is tending toward applying power reactor criteria to research reactors. When asked about the market opportunities for such reactors, Dr. Lee stated that recently three groups expressed interest but that the current economic conditions has delayed these initiatives. He noted that of the 45 research reactors with power levels greater than 10 MW, 42 have an average age in excess of 30 years. He believes that one new opportunity should arise approximately every 4 years.