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The Jamaican SLOWPOKE HEU-LEU Core Conversion

The 2014–2015 academic year was a pivotal year for ICENS, after 31 years of operation of the SLOWPOKE-II research reactor the US Department of Energy agreed to convert the core reactor from Highly Enriched Uranium (HEU) to Low enriched Uranium (LEU). The 17th of July, 2015 marked the last day of operation of the SLOWPOKE-II reactor with HEU fuel. The new fuel will arrive in Jamaica in September, with installation to be completed by mid-October. The removal of HEU (weapons grade material) from civilian use is in line with Jamaica’s firm commitment to the three pillars of the Non-Proliferation Treaty: Nuclear disarmament, nuclear non-proliferation and peaceful uses of nuclear technology. The removal is also in line with the growing international consensus to eliminate civil uses of HEU. 

Slowpoke History

  • 1970 a prototype unit was designed and built at Chalk River Laboratories.
  • 1971 SLOWPOKE-1 prototype, moved to University of Toronto
  • 1976 University of Toronto to SLOWPOKE-2 (first commercial unit, decommissioned 2001)
  • 1976 Dalhousie University
  • 1976 École Polytechnique core converted to LEU in 1997 - Present
  • 1978 University of Alberta SLOWPOKE 2
  • 1981 Saskatchewan Research Council
  • 1985 the first low-enriched Uranium (LEU) fuelled SLOWPOKE-2 reactor was commissioned at the Royal Military College of Canada (RMC) in Kingston
  • Scaled-up version (2-10 MWth) called SLOWPOKE-3 for district heating (shutdown in 1989)

The Slowpoke Reactor

The SLOWPOKE-2 reactor at the International Centre for Environmental and Nuclear Sciences (ICENS) formerly CNS is the only nuclear research reactor in the Caribbean. It is mainly used for Neutron Activation Analysis . The reactor achieved criticality for the first time in March 1984.

Peaceful Uses of the Atom (Slowpoke)

  • National Development
  • Human Health
  • Clinical Analysis
  • Medicine
  • Environment
  • Forensics
  • Mining
  • Animal health
  • Nutrition
  • Soils
  • Geochemistry
  • Food Analysis
  • Agriculture

Basic Safety Features of the Slowpoke-2 Reactor

  • Core designed to have a negative temperature and void coefficient
  • Self-limiting power Excursion
  • Maximum excess reactivity is ≤ 0.4% mk, adjusted by top beryllium reflector loading.
  • Start-up of SLOWPOKE to preset power level is totally automatic
  • No automatically actuated SCRAM. Apart from manual shutdown, or remote shutdown, shutdown achieved by auxiliary shutdown with cadmium capsules
  • The neutron flux is measured by a Reuter-Stokes welf-powered cadmium flux detector with a nominal sensitivity of 1x10 ^(-20) amps per unit flux. 

Reactivity Adjustments

  • Fuel Life – 3.395 x 10 5 kWh
  • Lifetime Core
  • By agreement handling and shipping of spent fuel will be the responsibility of the Reactor Vendor/Supplier (AECL) and will be shipped back to Canada unless otherwise arranged.
  • No spent fuel elements removed from site or discharged
  • Changing Beryllium Reflectors ~ 5-6 years
  • Reactivity adjustment team June 2009 

Slowpoke Core Conversion Project

Why Convert?

  • Non-proliferation 
  • Better Performance with LEU Core

The conversion of the core of the SLOWPOKE reactor in Jamaica is in keeping with the spirit the global threat reduction initiative and Reduced Enrichment for Research and Test Reactors (RERTR) program. The actual core conversion for the SLOWPOKE reactor in Jamaica is to be contracted to Atomic Energy of Canada Limited (AECL). Fuel manufacture dependent on bid.  Documentation for process to completed by ICENS.  HEU core to sent to Savannah River for final disposal.

  •  IAEA Technical cooperation Project
  •  Funding by US DOE
  • Radiation monitoring to be provided in-house, ICENS is regional (English speaking) provider for radiation monitoring services
  • Specifications for replacement core already exist (Ecole/RMC)


  •  TC (Funding provided by the DOE)
  •  Documentation Provide by ICENS / Subcontractors
  •  Defueling/Refueling preferably contracted to AECL
  •  Legislation moving in the right direction
  •  No major legal or physical obstacles
  •  A firm timetable only when LEU fuel manufacturer has been selected
  •  Conversion process from shutdown to startup can be completed in a six week window


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