on the evening of 12 August 2006 and reached full power for the first time on the morning of 3 November 2006. Facility details The reactor core consists of 16 low-enriched plate-type fuel assemblies and is located under of water in an open pool. Light water (normal H2O) is used as the coolant and moderator while heavy water (D2O) is used as the neutron reflector. The purpose of the neutron reflector is to improve neutron economy in the reactor, and hence to increase the maximum neutron flux. OPAL is the centrepiece of the facilities at ANSTO, providing radiopharmaceutical and radioisotope production, irradiation services (including neutron transmutation doping of silicon), neutron activation analysis and neutron beam research. OPAL is able to produce four times as many radioisotopes for nuclear medicine treatments as the old HIFAR reactor, and a wider array of radioisotopes for the treatment of disease. The modern design includes a cold neutron source (CNS). The OPAL reactor already has received seven awards in Australia. Neutron scattering at OPAL The Bragg Institute at ANSTO hosts OPAL's neutron scattering facility. It is now running as a user facility serving the scientific community in Australia and around the world. New funding was received in 2009 in order to install further competitive instruments and beamlines. The actual facility comprises the following instruments: ECHIDNA ECHIDNA is the name of the high-resolution neutron powder diffractometer. The instrument serves to determine the crystalline structures of materials using neutron radiation analogous to X-ray techniques. It is named after the Australian monotreme echidna, as the spiny peaks of the instrument looks like an echidna. It operates with thermal neutrons. One of the main features is the array of 128 collimators and position sensitive detectors for rapid data acquisition. ECHIDNA allows for structure determinations, texture measurements and reciprocal space mapping of single crystals in most different sample environments serving the physics, chemistry, materials, minerals and earth-science communities. ECHIDNA is part of the Bragg Institute's park of neutron scattering instruments. Components Neutron guide The instrument is located on the TG1 thermal neutron guide of the OPAL reactor. The distance from the reactor is . The position is the second on the guide after the WOMBAT instrument. The size of the guide is high by wide, and it is plated with supermirror coatings. Primary collimator There are Söller collimators prior to the monochromator in order to reduce the divergence of the