Technetium (Tc-99m) is the most widely used radioisotope in nuclear medicine. It accounts for 80% of all diagnostic nuclear medicine procedures. This amounts to 7 million diagnoses per year in Europe and 8 million per year in the USA. The present world demand for molybdenum (Mo-99), the parent radioisotope of Tc-99m, is estimated at 10.000 to 12.000 Ci per week (reference: 6 days after production day). Most of the world’s supply of Mo is produced by fissioning of U-235 in highly enriched uranium targets.

opal1ANSTO’s Open Pool Australian Lightwater (OPAL) reactor is a state-of-the-art 20 Megawatt reactor that uses low enriched uranium fuel and is cooled by water.
Opened by the Prime Minister in 2007, OPAL is one of a small number of reactors with the capacity for the commercial production of radioisotopes. This capacity, combined with the open pool design and operating utility, places OPAL among the best research reactors in the world.

While OPAL is the centerpiece of ANSTO’s research facilities, the suite of neutron beam instruments housed next to the reactor building represent a significant addition to ANSTO’s research capabilities.

These facilities, operated by the Bragg Institute, are supported by the Minister for Innovation, Industry, Science and Research, Senator Kim Carr, who recently described ANSTO’s contribution to Australian science by saying: "Having started out as a specialist organization tied to this site at Lucas Heights, ANSTO is now driving innovation in nuclear science and technology right around the country. The Government is very aware of how important this work is."

While virtually every reactor is unique, OPAL is one of a number of similar production facilities around the world, including the Safari-1 reactor in South Africa, the HFR reactor at Petten in the Netherlands and the NRU reactor at Chalk River in Canada.

These reactors play a vital role in society by helping us understand the world at the atomic level. They function as ’neutron factories’ producing isotopes for several important purposes, including the production of radioisotopes for cancer detection and treatment.

OPAL’s operation staff cooperates with their international colleagues in sharing information and knowledge both directly through formal collaboration agreements and via various international organizations and forums.

The heart of the reactor is a compact core of 16 fuel assemblies arranged in a 4x4 array, with five control rods controlling the reactor power. OPAL uses low enriched uranium fuel with just under 20 per cent uranium-235. In terms of security and nuclear safeguards, this is a distinct advantage over earlier research reactors; some of which required as much as 95 per cent enriched uranium (weapons grade).

OPAL’s fuel assemblies are cooled by demineralised light water (ordinary water) and are surrounded by a zirconium alloy ’reflector’ vessel which contains heavy water. It is positioned at the bottom of a 13-metre-deep pool of light water. The open pool design makes it ease to see and manipulate items inside the reactor pool. The depth of the water ensures effective radiation shielding of staff working above the pool.

HFR HOLLANDHFR Petten, The Netherlands
The High Flux Reactor (HFR) at Petten is owned by the Institute for Energy (IE) of the Joint Research Centre (JRC) of the European Commission (EC). Its operation has been entrusted since 1962 to the Netherlands Energy Research Foundation Nuclear Research and consultancy Group (NRG). Since February 2005, NRG became also the license holder of the HFR. Together with the hot cells of NRG at the Petten site, the HFR has provided for over four decades, an integral and full complement of irradiation and post-irradiation examination services as required by current and future R&D for nuclear energy, industry and research organisations. Since 1963, the HFR has a recognized record of consistency, reliability and high availability with more than 280 days of operation per year. The HFR operates at a constant power of 45 MW. The HFR is a tank in pool type reactor which has 20 in-core and 12 poolside irradiation positions, plus 12 horizontal beam tubes.

The High Flux Reactor is the most prominent nuclear facility in Petten. It is an indispensible facility for the production of radio-isotopes for the medical sectors, covering some 60% of European demand. In addition it plays a key role in international (nuclear) research projects, among which are projects on materials for fusion reactors.

NRU CANADANRU, Chalk River, Canada
The National Research Universal (NRU) reactor at Chalk River Laboratories is one of the largest and most versatile research reactors in the world. An elegant machine, NRU is a multipurpose reactor designed and constructed for three primary roles: to provide engineering research and development support for power reactor programs; to support materials research led by industry, academia and government scientists from across Canada and abroad; and as a supplier of industrial and medical radioisotopes.

The NRU reactor is one of the few research reactors in the world available for a wide variety of commercial irradiations. The applications include nuclear reactor fuels and materials testing, and research sample irradiations. The NRU provides world-leading expertise and facilities for analyzing stress and texture deep inside engineering materials, structural chemistry of materials, and magnetism in quantum materials.

As one of the world’s most versatile research reactors, NRU also produced the fundamental knowledge required to develop, maintain and evolve Canada’s fleet of CANDU power stations. While NRU doesn’t produce electricity, it is Canada’s only major materials and fuel testing reactor used to support and advance the CANDU design.

The NRU reactor operates at power levels up to 135 megawatts (thermal). It operates consistently at an annual capacity factor of 80 per cent. NRU is scheduled to cease operation in March, 2018.

SAFARI 1Safari-1, Pelindaba Site (near Pretoria), South Africa
SAFARI-1 is a tank in pool type reactor of Oak Ridge design which has a design power of 20 MW. The reactor’s 9 x 8 core matrix contain 28 MTR type fuel elements and six control rods.

The remaining lattice positions are either aluminium or beryllium reflector elements. The locally produced fuel elements consist of 19 flat plates constructed from uranium-aluminium alloy clad with aluminium A five-week operational cycle, which includes one shutdown week, is followed. In-core irradiation positions have neutron fluxes of 2 x 1014 at 20 MW and are primarily used for isotope production.

lvr15 CzechRepLVR 15 Reactor - Rez Czech Republic
The reactor LVR-15 is a light water tank type reactor with the thermal power 10 MW. The reactor uses IRT-4M fuel enriched to 19% of 235U and combined water-beryllium reflector. This core composition provides in the core maximum thermal neutron flux of 1.5x1018 n.m-2s-1 and maximum fast neutron flux of 3x1018 n.m-2s-1. LVR-15 operates in three-week cycles, usually 9-10 cycles per year.

The main research projects are aimed to material testing. 5 water loops and several irradiation rigs are used for this purpose. Water loops simulate conditions similar to those existing in reactors of nuclear power stations, such as temperature, pressure, doses and water chemistry. Another significant use of the reactor is irradiation of samples for medical purposes and radio-pharmaceutical production.

LVR-15 is also used for irradiation of silicon single monocrystals, activation analysis and experiments at beam tubes. Some experiments, including clinical tests, were also done at the thermal column in the field of neutron capture therapy.

osirisThe OSIRIS Reactor, Saclay, France
OSIRIS is an experimental reactor with a thermal power of 70 megawatts. It is a light-water reactor, open-core pool type, the principal aim of which is to carry out tests and irradiate the fuel elements and structural materials of nuclear power plants under a high flux of neutrons, to produce radioisotopes and semiconductors for the industry.

Located within the French Atomic Energy Commission (CEA) centre at Saclay, it is close to many research teams and inspection laboratories and has a large-scale technological infrastructure. The SACLAY centre (certified ISO 14001) is one of the 9 research sites of the French Atomic Energy Commission (CEA). It is a top-ranking innovation and research centre at the European level. More than 5000 people work in the centre. It plays a major role in the regional economic development. The centre is multidisciplinary, with activities in fields such as nuclear energy, life sciences, material sciences, climatology and the environment, technological research and teaching.

Main Features
In order to maintain direct access to the core, the reactor does not comprise a pressurization vessel, resulting in a high level of flexibility for laying out experiments and handling operations. The fact that the configuration of the core can be changed also means considerable ease of experimentation from a neutronic point of view.
The reactor started operation in 1966 and functions on average 200 days a year, in cycles of varying lengths from 3 to 5 weeks. A shutdown of about 10 days between two cycles is necessary to reload the core with fuel, carry out light maintenance operations and the handling operations required for the experiments. More consequential maintenance operations are carried out during dedicated shutdowns of longer duration.

The gradual conversion of the reactor to using U3Si2 Al fuel enriched to 19.75% began in January 1995 and was completed in April 1997. An on-going refurbishment program has been established to avoid the ageing of the components in the flux and the obsolescence of the materials.

The following major operations have been undertaken to maintain the degree of reliability and improve the safety level of the reactor: rebuilding of the effluent tanks and the de-activation tanks, the overhaul of the control/command system, the replacement of the core housing which maintains the fuel elements, and the replacement of the core vessel surrounding the fuel.

Radio-Isotopes Production
Radio-isotopes used in imagery for medical diagnoses: this involves the use of gamma cameras to examine the operation of organs onto which a radioactive molecule has been fixed. The product most frequently used is 99mTc obtained from targets made of enriched 235U. The targets are in tube form, 160 mm high and 22 mm in diameter.

Production is part of a joint program with the other European reactors in order to ensure a regular supply for hospitals. About 1000 tubes or targets are irradiated each year in the OSIRIS reactor for French and European industrials.

mariaMARIA Reactor, Otwock, Poland
The multipurpose high flux research reactor MARIA operated by National Centre for Nuclear Research in Otwock-Świerk site, Poland. It is a water and beryllium moderated reactor of a pool type with graphite reflector and pressurised channels containing concentric six-tube assemblies of fuel elements. It has been designed to provide high degree of flexibility.
The fuel channels are situated in a matrix containing beryllium blocks and enclosed by lateral reflector made of graphite blocks in aluminium cans. The MARIA reactor is equipped with vertical channels for irradiation of target materials, a rabbit system for short irradiations and six horizontal neutron beam channels.

BR2 MOLBR2 Reactor, Mol, Belgium
The BR2 nuclear reactor became operational in 1961. It works on highly enriched uranium and is moderated and cooled by water. The BR2 is still one of the most powerful research reactors in the world. The reactor is used for the testing of fuels and materials for different reactor types, and for the production of radioisotopes. It is a100 MWth high-flux materials testing reactor and one of the most powerful research reactors in the world. BR2 is operated within the framework of programmes aimed at promoting the development of structural materials and nuclear fuels for fission and fusion reactors.
Together with four other reactors BR2 is responsible for the production of 90% of the radioisotopes that are used worldwide as part of nuclear medicine’s diagnostic and treatment capability. The BR2-reactor is also a major supplier worldwide of isotopes for use in industry and of Neutron Transmutation Doped (NTD) silicon. BR2’s present annual operating regime is based on six irradiation cycles, i.e. 140 operating days per year. The reactor uses 93 % 235U-enriched uranium as fuel and is moderated by light water and beryllium. A serious effort has also been made to perform the above-mentioned commercial activities in accordance with a ’Quality System’ that has been certified to the requirements of the "EN ISO 9001:2000".

FRMIIForschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II)
The Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II) is the most powerful neutron source in Germany and reaches due to its compact fuel assembly concept the highest neutron flux (8·10 14 n/cm2s) relative to its thermal power (20 MW) worldwide. It is a beam tube reactor designed to provide neutrons for scientific experiments as well as for industrial and medical applications. The facility is operated as an integrative research centre by the Technische Universität München (TUM) in Garching near Munich, Germany. Its first criticality was achieved in March 2004.

The FRM II is equipped with cold, thermal, hot and fast fission neutron sources and covers a broad range of applications, including experiments with positrons. An ultra-cold neutron source is under construction. Today, 26 instruments are operational.

Furthermore, 7 irradiation systems for isotope production, silicon doping and analytical purposes are in service. An irradiation facility for the production of the medical isotope 99Mo is under construction. For research purposes, a second neutron guide hall is being connected to the reactor building offering even more high-performance neutron scattering instruments in future.

The FRM II is a user facility, which is organized under the name “Heinz Maier-Leibnitz Zentrum (MLZ)”. The MLZ represents the cooperation between the Technische Universität München (TUM) and two research centres of the Helmholtz Association, namely Forschungszentrum Jülich and Helmholtz-Zentrum Geesthacht (HZG) to exploit the scientific use of the FRM II. The MLZ is funded by the Bavarian State Ministry of Education, Science and the Arts (StMBW) and the German Federal Ministry of Education and Research (BMBF) as well as the partners themselves. By offering a unique suite of high-performance neutron scattering instruments, scientists are encouraged and enabled to pursue research in diverse fields such as physics, chemistry, biology, earth sciences, engineering, material science, or even cultural heritage.