Editing SCK CEN (section)

== Reactors ==
=== BR1 ===
''The Belgian Reactor 1'' (BR1) is the first [[research reactor]] to have been built and commissioned in [[Belgium]]. This [[natural uranium]] air-cooled [[graphite]]-[[neutron moderator|moderated]] reactor was commissioned in 1956. Its maximal thermal power is 4&nbsp;MW, but it is presently only operated at 700&nbsp;kW. Its natural uranium inventory could allow the reactor to run without refueling during several centuries (~&nbsp;300 years). At first, this [[research reactor]] was used primarily for research into reactor and neutron physics, for [[neutron activation analysis]], and for a minor production of [[radionuclide]]s. Now, it is being used for the irradiation of components, the calibration of measuring instruments, and for performing analyses and training nuclear students. BR1 operates by order of other research centres, universities and the industry.

=== BR2 ===
Commissioned in 1962'', The Belgian Reactor 2'' (BR2) is a [[materials testing reactor]]. It is a high-flux reactor (~&nbsp;10{{sup|15}} neutron・cm{{sup|-2}}・s{{sup|-1}}) in which [[neutron]]s are [[Neutron moderator|moderated]] by a [[beryllium]] matrix and cooled by light water pumped at low pressure (12-15&nbsp;bar). Its core is very compact due to the particular shape of its beryllium matrix ([[paraboloid]] of revolution) allowing to install the [[Nuclear fuel|fuel rods]], the [[control rod]]s, and the experiments in a very small volume (~ 1m{{sup|3}}). One reports that its very compact core architecture was quickly drawn on a [[Drink coaster|beer mat]] during a discussion between nuclear physicists in a bar in [[New York City|New York]] during a very creative night at the end of the 1950s, or beginning 1960. At the demand of the US authorities, its [[nuclear fuel]] is presently based on [[Enriched uranium#Low-enriched uranium (LEU)|low-enriched uranium]] (LEU) to minimize the risk of [[nuclear proliferation]]. Its thermal power (100&nbsp;MW) is dissipated in the environment by water heated at modest temperature (40-48 °C). This research reactor is also used for the production of [[Radiopharmacology|medical radio-isotopes]]. The BR2 research reactor produces on an annual basis more than 25% of the worldwide demand for [[molybdenum-99]] and in peak periods even up to 65%.

=== BR3 ===
''The Belgian Reactor 3'' was the first [[pressurised water reactor]] (PWR) in Europe. The reactor served as a prototype for the reactors in [[Doel]] and [[Tihange]].  It was taken into service in 1962 and permanently shut down in 1987.

==== Decommissioning ====
[[Nuclear decommissioning|Decommissioning]] started in 2002.<ref name="sckcen-br3">[https://web.archive.org/web/20190401060959/https://science.sckcen.be/en/Facilities/BR3 ''Belgian Reactor 3 - BR3'']. SCK•CEN (archived Apr 2019, no update)</ref> The [[European Commission]] selected BR3 as a pilot project to show the technical and economic feasibility of the dismantling of a reactor under real conditions.<ref>[https://www.world-nuclear.org/information-library/country-profiles/countries-a-f/belgium.aspx ''Nuclear Power in Belgium'']. World Nuclear Association, update Feb 2023</ref>

=== VENUS ===
The research reactor VENUS, which stands for ''Vulcan Experimental Nuclear Study'' was commissioned in 1964. VENUS is used as an experimental installation for nuclear reactor physics studies of new reactor systems and for testing reactor calculations. The installation was re-built and modernised several times. As part of the GUINEVERE project, SCK CEN decided to re-build the VENUS reactor into a scale model of Accelerator Driven Systems (ADS). The particle accelerator was first connected in 2011. VENUS is a "[[zero power critical|zero power]] reactor": it has a power consumption of only 500 Watt.

=== MYRRHA ===
{{Main|MYRRHA}}
MYRRHA is a design of a ''Multi-purpose HYbrid Research Reactor for High-tech Applications''. MYRRHA is the world's first research reactor driven by a particle accelerator.<ref>{{cite web|url=http://www.euronuclear.org/e-news/e-news-21/myrrha.htm|title=MYRRHA a new future for nuclear research|publisher=}}</ref>

===INES incidents===
After a leak in the hot cell of BR2 reactor, [[selenium-75]] was released in the atmosphere on 15 May 2019. The event was classified by FANC at the level 1 of the international nuclear and radiological events scale ([[INES scale]]).<ref name="FANC_2019_05_16">{{Cite web |title=Rejet limité de sélénium-75 au SCK-CEN |trans-title=Limited release of selenium-75 at SCK-CEN |author=FANC |work=FANC – Federal Agency for Nuclear Control |date=16 May 2019 |access-date=8 July 2021 |url= https://afcn.fgov.be/fr/actualites/rejet-limite-de-selenium-75-au-sck-cen |language=fr}}</ref> <sup>75</sup>Se (half-life = 119.8 days) was detected at low concentrations on aerosol filters from several air monitoring stations belonging to [[IRSN]] (Institut de Radioprotection et de Sûreté Nucléaire, France), in the [[Lille]] area and in the northwestern part of [[France]]. IRSN also performed an atmospheric dispersion modeling analysis. The dose assessment showed very low exposure levels (< 1 microsievert) without concern for public health in France.<ref name="IRSN_2019_05_28">{{Cite web |title=Release of selenium-75 from the SCK-CEN facilities, in Mol (Belgium) |author=IRSN |work=irsn.fr |date=28 May 2019 |access-date=8 July 2021 |url= https://www.irsn.fr/EN/newsroom/News/Documents/IRSN_NI-Incident-Belgium-Selenium75-Release_20190528.pdf |language=English}}</ref>

The power of the BR2 reactor was insufficiently measured on January 27, 2021, because two of the three measuring chains were not functioning in accordance with the regulations and the third was defective. Since the installation had two independent sets of three measuring chains, any power variations could still be detected.<ref name="FANC_2021_01_27">{{Cite web |title=Évènements classés sur l'échelle INES en Belgique durant les 12 derniers mois |trans-title=Events classified on the INES scale in Belgium during the last 12 months |author=FANC |work=FANC – Federal Agency for Nuclear control |date=27 January 2021 |access-date=8 July 2021 |url= https://afcn.fgov.be/fr/situations-durgence/echelle-ines/evenements-classes-sur-lechelle-ines-en-belgique-durant-les-12 |language=fr}}</ref>

FANC has classified this incident at level 2 on the [[INES scale]], not only because the operating conditions were not respected, but also because a similar incident had already occurred at SCK CEN in 2019. These two incidents were related to a lack of safety culture from the licensee leading to inappropriate operations.<ref name="FANC_2021_02_02">{{Cite web |title=Incident at the SCK CEN nuclear research center classified at level 2 on the INES scale |author=FANC |work=fanc.fgov.be |date=2 February 2021 |access-date=8 July 2021 |url= https://fanc.fgov.be/nl/system/files/2021-02-02-incident-sck-cen-niveau-2-ines-schaal.pdf |language=Dutch}}</ref>