Editing Open-pool Australian lightwater reactor

{{Short description|Research nuclear reactor in Australia}}
{{Use dmy dates|date=August 2020}}
{{Use Australian English|date=August 2011}}
{{Science with neutrons}}
The '''Open-pool Australian lightwater reactor''' ('''OPAL''') is a 20&nbsp;[[megawatt]] (MW) [[swimming pool reactor|swimming pool]] nuclear [[research reactor]]. Officially opened in April 2007, it replaced the [[High Flux Australian Reactor]] as Australia's only nuclear reactor, and is located at the [[Australian Nuclear Science and Technology Organisation]] (ANSTO) Research Establishment in [[Lucas Heights, New South Wales]], a suburb of [[Sydney]]. Both OPAL and its predecessor have been known simply as the '''Lucas Heights reactor'''.

==Uses==
The main reactor uses are:

* Irradiation of target materials to produce [[Radionuclide|radioisotopes]] for medical and industrial applications
* Research in the fields of [[materials science]] and [[structural biology]] using neutron beams and its sophisticated suite of experimental equipment
* Analysis of minerals and samples using the [[Neutron activation analysis|neutron activation technique]] and the delay neutron activation technique
* Irradiation of [[Boule (crystal)|silicon ingots]] in order to dope them with phosphorus and produce the basic material used in the manufacturing of semiconductor devices

The reactor runs on an operation cycle of 30 days non-stop at full power, followed by a stop of 5 days to reshuffle the fuel.

Typically the reactor runs for a total of 300 days at power per year.

==History==
The [[Argentina|Argentine]] company [[INVAP]] was responsible through a [[turnkey]] contract, signed in June 2000, for the delivery of the reactor, performing the design, construction and commissioning. Local civil construction was performed by INVAP's partner, [[John Holland Group|John Holland]]-[[Evans Deakin]] Industries.<ref>{{cite web |url=http://www.leighton.com.au/our-business/projects/completed-projects/ansto-replacement-research-reactor |archive-url=https://web.archive.org/web/20150318134231/http://www.leighton.com.au/our-business/projects/completed-projects/ansto-replacement-research-reactor |title=ANSTO Replacement Research Reactor |work=Leighton Holdings |archive-date=18 March 2015 |access-date=20 January 2016}}</ref> The facility features a large ({{convert|20|L|adj=on}}) liquid-deuterium cold neutron source,<ref name=":0">{{cite web |url=http://www.ansto.gov.au/AboutANSTO/OPAL/Capabilities/ColdNeutronSource/ |title=Cold Neutron Source |author=Australian Nuclear Science and Technology Organisation |work=ansto.gov.au |access-date=20 January 2016 |archive-url=https://web.archive.org/web/20160303233219/http://www.ansto.gov.au/AboutANSTO/OPAL/Capabilities/ColdNeutronSource/ |archive-date=3 March 2016 |url-status=dead }}</ref> modern [[supermirror]] guides, and a {{convert|35|x|65|m}} guide hall.  The cold source was designed by the Petersburg Nuclear Physics Institute,<ref>{{cite web |url=http://www.pnpi.spb.ru/ |title=Petersburg Nuclear Physics Institute. National Research Centre "Kurchatov Institute" |work=pnpi.spb.ru |access-date=20 January 2016}}</ref> the cryogenic system designed and supplied by [[Air Liquide]] and the initial set of four supermirror guides supplied by Mirrotron.<ref>{{cite web |url=http://www.mirrotron.kfkipark.hu/ |title=Mirrotron Multilayer Laboratory |author=Szimandl Béla |work=kfkipark.hu |access-date=20 January 2016 |archive-date=29 September 2017 |archive-url=https://web.archive.org/web/20170929104423/http://www.mirrotron.kfkipark.hu/ |url-status=dead }}</ref>

On 17 December 2001, 46 Greenpeace activists occupied the Lucas Heights facility to protest the construction of OPAL. Protestors gained access to the grounds, the HIFAR reactor, the high-level radioactive waste store and the radio tower. Their protest highlighted the security and environmental risks of the production of nuclear materials and the shipment of radioactive waste from the facility.<ref>{{Cite web|url=http://www.abc.net.au/science/articles/2001/12/18/443080.htm|title=Greenpeace raid on Australian nuclear reactor|date=2001-12-18|website=www.abc.net.au|language=en-AU|access-date=2017-09-01}}</ref>

OPAL was opened on 20 April 2007 by then [[Prime Minister of Australia|Australian Prime Minister]] [[John Howard]]<ref>{{cite press release |publisher=[[ANSTO]] |date=20 April 2007 |title=PM Opens Australia's New Nuclear Reactor |url=http://www.ansto.gov.au/__data/assets/pdf_file/0005/9662/OPAL_opening_release.pdf |access-date=2009-07-03 |archive-url=https://web.archive.org.au/awa/20070828202550mp_/http://www.ansto.gov.au/__data/assets/pdf_file/0005/9662/OPAL_opening_release.pdf |archive-date=2007-08-28}}</ref> and is the replacement for the [[HIFAR]] reactor.  ANSTO received an operating licence from the [[Australian Radiation Protection and Nuclear Safety Agency]] (ARPANSA) in July 2006, allowing commencement of hot commissioning, where fuel is first loaded into the reactor core. OPAL went [[Critical mass|critical]] for the first time on the evening of 12 August 2006 and reached full power for the first time on the morning of 3 November 2006.<ref>{{cite press release |publisher=[[INVAP]] |date=10 November 2006 |title=Sydney Opal reactor at full power |url=http://www.invap.net/news/novedades-e.php?id=20061110183244 |access-date=2009-07-03 |archive-date=14 July 2008 |archive-url=https://web.archive.org/web/20080714005407/http://www.invap.net/news/novedades-e.php?id=20061110183244 |url-status=dead }}</ref>

==Facility details==
[[File:OPAL reactorpools.jpg|right|thumb|The OPAL reactor pools. Made of stainless steel and {{convert|4.5|m|adj=on}} wide, it contains demineralised water used for shielding and cooling.]]

The [[Nuclear reactor core|reactor core]] consists of 16 low-enriched plate-type [[Nuclear fuel|fuel assemblies]] and is located under {{convert|13|m}} of water in an open pool. Light water (normal H<sub>2</sub>O) is used as the coolant and [[Neutron moderator|moderator]] while [[heavy water]] (D<sub>2</sub>O) 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 [[Radiopharmacology|radiopharmaceutical]] and [[radioisotope]] production, [[irradiation]] services (including neutron [[Nuclear transmutation|transmutation]] doping of silicon), [[neutron activation analysis]] and [[Particle beam|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|cold]] [[neutron source]] (CNS).<ref name=":0" />

The OPAL reactor already has received seven awards in Australia.<ref>{{cite press release |publisher=[[INVAP]] |date=14 November 2006 |title=The OPAL reactor already has received seven awards in Australia |url=http://www.invap.net/news/novedades-e.php?id=20061114194744 |access-date=2009-07-03 |archive-date=14 July 2008 |archive-url=https://web.archive.org/web/20080714005412/http://www.invap.net/news/novedades-e.php?id=20061114194744 |url-status=dead }}</ref>

==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===
[[File:ECHIDNA HRPD design.jpg|thumb|right|240px|Engineering drawing of the ECHIDNA High-Resolution Powder Diffractometer (August 2003)]]
[[File:NeutronMonochromatorBNL.jpg|thumb|right|240px|The Ge-115 monochromator has been acquired from the [[Brookhaven National Laboratory]].]]
'''ECHIDNA''' is the name of the high-resolution [[neutron diffraction|neutron]] [[powder diffraction|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 [[neutron temperature|thermal neutron]]s. 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.<ref>{{cite journal |last1=Liss |first1=L. |last2=Hunter |first2=B. |last3=Hagen |first3=M. |last4=Noakes |first4=T. |last5=Kennedy |first5=S. |year=2006 |title=Echidna—the new high-resolution powder diffractometer being built at OPAL |url=http://liss.freeshell.org/KDL/papers/LissEchidnaICNS2005.pdf |journal=[[Physica B]] |volume=385-386 |pages=1010–1012 |doi=10.1016/j.physb.2006.05.322 |bibcode=2006PhyB..385.1010L}}</ref>

====Components====
* Neutron guide
*: The instrument is located on the TG1 [[neutron temperature|thermal neutron]] guide of the OPAL reactor. The distance from the reactor is {{convert|58|m}}. The position is the second on the guide after the [[WOMBAT - High Intensity Powder Diffractometer|WOMBAT]] instrument. The size of the guide is {{convert|300|mm}} high by {{convert|50|mm}} wide, and it is plated with [[neutron supermirror|supermirror]] coatings.
* Primary [[collimator]]
*: There are Söller [[collimator]]s prior to the monochromator in order to reduce the divergence of the beam and to increase the angular resolution of the instrument. Since this is an intensity compromise, two items of [[Minute of arc|5']] and [[Minute of arc|10']], respectively, can be interchanged or fully removed by an automated mechanism. The collimators cover the full size of the beam delivered by the neutron guide.
* [[Crystal monochromator|Monochromator]]
*: The monochromator is made by slabs of [[Miller index|<nowiki>[115]</nowiki>]] oriented Germanium crystals which are inclined towards each other in order to focus down the Bragg reflected beam. The device has been acquired from the [[Brookhaven National Laboratory]] in the US after the shutdown of their neutron facility.
* Secondary collimator
*: Optionally a secondary collimator with [[Minute of arc|10']] angular acceptance and {{convert|200|x|20|mm}} can be placed in the monochromatic beam between the monochromator and the sample, which again influences the resolution function of the instrument.
* Slit system
*: Two automated sets of horizontal and vertical pairs of absorbing plates allow to cut down the size of the monochromatic beam prior to the secondary collimator and sample size. They remove unwanted neutrons and reduce the background near the detector. In addition, they allow selection of the sample position to be studied.
* Beam monitor
*: A [[Uranium-235|<sup>235</sup>U]] [[neutron detector|fission monitor]] measures the amount of neutrons incident to the sample. The efficiency is [[Orders of magnitude (numbers)|10<sup>−4</sup>]] and most neutrons traverse the device undisturbed. The monitor counts are important to correct for beam flux variations due to changes in the reactor or at the upstream instrument.
* Sample stage
*:The sample is supported by a heavy load [[goniometer]] consisting of a 360° vertical omega rotation axis, x-y translation tables and a chi-phi cross tilt stage of ±20° range. It can hold a few hundred kilograms in order to support heavier sample environments, such as cryostats, furnaces, magnets, load frames, reaction chambers and others. A typical powder sample is filled into vanadium cans which give little unstructured background. The mentioned sample environment allows measurement of changes in the sample as a function of external parameters, like temperature, pressure, magnetic field, etc. The goniometer stage is redundant for most powder diffraction measurements, but will be important for single crystal and texture measurements, where the orientation of the sample plays a role.
* Detector [[collimator]]s
*:A set of 128 detectors each equipped which a 5' collimator in front are arranged in a 160° sector focusing to the sample. The collimators select the scattered radiation into the well defined ranges of 128 angular positions. The whole collimator and detector setup is mounted on a common table which is scanned in finer steps around the sample, to be combined further into a continuous diffraction pattern.
* Detector tubes
*:The 128 linear position-sensitive [[Helium-3|<sup>3</sup>He]] gas detector tubes cover the full opening height of {{convert|300|mm}} behind the collimators. They determine the position of the neutron event by charge division over the resistive anode towards each end of the detector. Overall and local count rates lie in the several 10000&nbsp;Hz range.

===PLATYPUS===
PLATYPUS is a [[time-of-flight]] [[Neutron reflectometry|reflectometer]] built on the [[neutron temperature|cold neutron]] source. The instrument serves to determine the structure of interfaces using highly collimated [[neutron radiation|neutron beams]]. These beams are shone on to the surface at low angles (typically less than 2 degrees) and the intensity of the reflected radiation is measured as a function of angle of incidence.

It operates using cold neutrons with a wavelength band of 0.2–2.0&nbsp;nm.  Although up to three different angles of incidence are required for each reflectivity curve, the time-of-flight nature means that timescales of kinetic processes are accessible. By analysing the reflected signal one builds a picture of the chemical structure of the interface.  This instrument can be used for examining biomembranes, lipid bilayers, magnetism, adsorbed surfactant layers, etc.

It is named after [[Platypus|''Ornithorhynchus anatinus'']], the semi-aquatic monotreme mammal native to Australia.

===WOMBAT===
WOMBAT is a high-intensity [[neutron diffraction|neutron]] [[powder diffraction|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 [[wombat]], a [[marsupial]] indigenous to Australia.

It will operate with [[thermal neutron]]s. It has been designed for highest flux and data acquisition speed in order to deliver time resolved diffraction patterns in a fraction of a second. Wombat will concentrate on ''in-situ'' studies and time critical investigations, such as 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.

===KOWARI===
'''KOWARI''' is a [[neutron diffraction|neutron]] [[residual stress]] diffractometer. [[Strain (materials science)|Strain]] scanning using [[thermal neutron]]s is a [[powder diffraction]] technique in a polycrystalline block of material probing the change of atomic spacing due to internal or external [[Stress (physics)|stress]]. It is named after the [[kowari]], an Australian marsupial.

It provides a diagnostic non-destructive tool to optimise e.g. [[post weld heat treatment]] (PWHT, similar to [[tempering (metallurgy)|tempering]]) of welded structures. Tensile stresses for example drive crack growth in engineering components and compressive stresses inhibit crack growth (for example cold-expanded holes subject to fatigue cycling). Life extension strategies have high economic impact and strain scanning provides the stresses needed to calculate remaining life as well as the means to monitor the condition of components since it is non-destructive. One of the main features is the sample table that will allow examination of large engineering components while orienting and positioning them very accurately.{{citation needed|date=May 2020}}

===Others===

* TAIPAN - Thermal 3-Axis Spectrometer<ref>{{cite web |url=http://www.ansto.gov.au/ResearchHub/Bragg/Facilities/Instruments/Taipan/index.htm |title=Taipan - ANSTO |author=Australian Nuclear Science and Technology Organisation |work=ansto.gov.au |access-date=20 January 2016}}</ref>
* KOALA - Laue Diffractometer<ref>{{cite web |url=http://www.ansto.gov.au/ResearchHub/Bragg/Facilities/Instruments/Koala/index.htm |title=Koala - ANSTO |author=Australian Nuclear Science and Technology Organisation |work=ansto.gov.au |access-date=20 January 2016}}</ref>
* QUOKKA - Small-Angle Neutron Scattering<ref>{{cite web |url=http://www.ansto.gov.au/ResearchHub/Bragg/Facilities/Instruments/Quokka/index.htm |title=Quokka - ANSTO |author=Australian Nuclear Science and Technology Organisation |work=ansto.gov.au |access-date=20 January 2016}}</ref>
* PELICAN - Cold-Neutron Time-of-Flight Spectrometer<ref>{{cite web |url=http://www.ansto.gov.au/ResearchHub/Bragg/Facilities/Instruments/Pelican/index.htm |title=Pelican - ANSTO |author=Australian Nuclear Science and Technology Organisation |work=ansto.gov.au |access-date=20 January 2016 |archive-date=21 January 2016 |archive-url=https://web.archive.org/web/20160121134722/http://www.ansto.gov.au/ResearchHub/Bragg/Facilities/Instruments/Pelican/index.htm |url-status=dead }}</ref>
* SIKA - Cold 3-Axis Spectrometer<ref>{{cite web |url=http://www.ansto.gov.au/ResearchHub/Bragg/Facilities/Instruments/Sika/index.htm |title=Sika - ANSTO |author=Australian Nuclear Science and Technology Organisation |work=ansto.gov.au |access-date=20 January 2016 |archive-date=21 January 2016 |archive-url=https://web.archive.org/web/20160121130816/http://www.ansto.gov.au/ResearchHub/Bragg/Facilities/Instruments/Sika/index.htm |url-status=dead }}</ref>
* KOOKABURRA - Ultra-Small-Angle Neutron Scattering (USANS)<ref>{{cite web |url=http://www.ansto.gov.au/ResearchHub/Bragg/Facilities/Instruments/Kookaburra/index.htm |title=Kookaburra - ANSTO |author=Australian Nuclear Science and Technology Organisation |work=ansto.gov.au |access-date=20 January 2016}}</ref>
* DINGO - Neutron Radiography, Tomography and Imaging<ref>{{cite web |url=http://www.ansto.gov.au/ResearchHub/Bragg/Facilities/Instruments/Dingo/index.htm |title=Dingo - ANSTO |author=Australian Nuclear Science and Technology Organisation |work=ansto.gov.au |access-date=20 January 2016}}</ref>

==Performance==
During the initial testing and commissioning period, all the equipment and systems were tested individually, and then in an integrated manner. Initial tests were carried out without nuclear fuel loaded into the core, and then a careful plan was followed for loading nuclear fuel into the reactor core, and subsequently reaching a nuclear chain reaction for the first time. Power to the reactor was increased in successive stages to finally allow the reactor to run at its full output. Once commissioning was completed, Australia’s nuclear regulator, the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA), issued a licence that authorised OPAL’s operation at full power. During the first operation cycles, a typical teething period of a [[first of a kind design]] occurred.<ref>
{{cite news |publisher=[[ABC News (Australia)|ABC News]] |date=27 July 2007 |title=Sydney nuclear reactor to shut down |url=http://www.abc.net.au/news/stories/2007/07/27/1990090.htm |archive-url=https://web.archive.org/web/20070921212838/http://www.abc.net.au/news/stories/2007/07/27/1990090.htm |url-status=dead |archive-date=21 September 2007 |access-date=2009-07-03}}</ref><ref>
{{cite press release |publisher=[[ANSTO]] |date=27 July 2007 |title=Reactor to shut down for about eight weeks |url=http://www.ansto.gov.au/__data/assets/pdf_file/0010/16201/Reactor_shutdown.pdf |access-date=2007-10-25}}</ref>
The reactor has proven itself to be a reliable supplier of [[radiopharmaceutical]]s, while also serving as a neutron source to conduct material research.<ref>[https://www.ansto.gov.au/facilities/opal-multi-purpose-reactor Australian Nuclear Science and Technology Organisation. "OPAL Multipurpose reactor"]. ansto.gov.au. Retrieved 21 may 2023.</ref><ref>[https://www.ansto.gov.au/science/health/biosciences Australian Nuclear Science and Technology Organisation. "Biosciences at ANSTO"]. ansto.gov.au. Retrieved 21 may 2023.</ref>

Since commissioned the reactor has been running with a very high availability, during the term 2012-13 it operated 265 days at full power (including an extended routine maintenance period), during 2013-14 for 294 days at full power, and during 2014-15 it operated 307 days at full power.

As at September 2016 it has accumulated a total of 2200 equivalent Full Power Days. Each 30 days operating cycle more than 150 batches of Silicon are irradiated, Mo99 is produced on a regular basis for the nuclear medicine market. OPAL has delivered 4 million doses.  Regarding research with neutrons the Australian Centre for Neutron Scattering (formerly Bragg Institute) features more than 120 scientists and 13 neutron beam operational instruments, and has produced more than 600 scientific research papers using the neutrons coming from OPAL core.{{citation needed|date=May 2020}}

==See also==
* [[ANSTO]]
* [[INVAP]]
* [[Spallation Neutron Source]]
* [[Nuclear medicine]]

==References==
{{reflist|30em}}

==External links==
*[https://web.archive.org/web/20090307014952/http://www.ansto.gov.au/discovering_ansto/anstos_research_reactor OPAL]
*[http://www.ansto.gov.au/research/bragg_institute/facilities/instruments/kowari KOWARI]
*[http://www.ansto.gov.au/research/bragg_institute/facilities/instruments/echidna ECHIDNA]
*[http://www.ansto.gov.au/research/bragg_institute ''Bragg Institute'']
*[http://www.invap.net/ ''INVAP Nuclear Division designs'']
*[http://www.abc.net.au/news/newsitems/200501/s1287833.htm Announcement of the new reactor's name]
*[http://www.smh.com.au/news/national/nuclear-reactor-to-reopen-after-sixmonth-shutdown/2007/12/26/1198345080938.html Nuclear reactor to reopen after six-month shutdown]
*[https://web.archive.org/web/20080111063950/http://www.abc.net.au/news/stories/2008/01/10/2135942.htm Govt expects nuclear reactor to restart this month]
*[http://www.smh.com.au/news/national/reactor-ready-for-second-try/2008/11/06/1225561044319.html Reactor ready for second try]

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{{DEFAULTSORT:Opal}}
[[Category:Nuclear research reactors]]
[[Category:Light water reactors]]
[[Category:Neutron facilities]]
[[Category:Nuclear research institutes]]
[[Category:Research institutes in Australia]]
[[Category:Lucas Heights, New South Wales]]
[[Category:2007 establishments in Australia]]