Medical importance of Petten
Apart from its function as a research centre, Petten is also a large producer of radioactive material for the purpose of medical diagnosis and the treatment of cancer and contrast agents (Radiopharmaceuticals). The nuclear facilities at Petten supply 60% of the European demand for medical isotopes. Also at the high flux reactor, one of the neutron beam channels, which was originally installed for performing fundamental research, has been specially modified for the direct irradiation of patients. This allows use of neutrons for the treatment of tumors after saturation of these tumors with a pharmaceutical containing boron. When hit by a weak neutron beam, boron will locally emit radiation that will destroy the tumor. This technique is mainly suitable for the treatment of brain tumors.
As of 2006[update], only low-enriched uranium fuel was used at the facilities in Petten. As a result of political pressure from the United States and the International Atomic Energy Agency (IAEA), research reactors are no longer allowed to use highly enriched uranium fuel because of its potential use for the production of nuclear weapons. The use of highly enriched uranium targets for the production of medical isotopes was discontinued in January 2018.
The high flux reactor
The high flux reactor in Petten has been in use since 1961. The first criticality was obtained on 9 November 1961. The reactor was furnished by Allis-Chalmers.
From August 2008 the reactor was shut down due to corrosion of the pipes in its primary cooling circuit. The operator is expecting to bring the plant back on-line in February 2009.
The low flux reactor
The low flux reactor was first used in 1960 and permanently shut down in 2010. It had a capacity of 30 kW. The reactor was property of the Nuclear Research and Consultancy Group (NRG) and mainly used for the production of neutrons for biological and physical research.
In 2009 the Argentine company INVAP (teamed with Spanish group Isolux) was pre selected in the international tender for the PALLAS project, for the procurement of an 80 MW nuclear reactor for the Dutch village of Petten  but on February 2010, the Dutch radiopharmaceutical producer Nuclear Research and Consultancy Group (NRG) extended the preparatory phase up to end of the year for financing 
In mid-May 2014, NRG, the company that operates the reactor, asked for a bridging loan at the Dutch Ministry of Economic Affairs, because of the financial losses in the previous years. A bankruptcy could not be ruled out, if the credit would be refused. In addition, there were negotiations with the banks, because of the estimated 80 million euros, needed for the upcoming maintenance of the 50-year-old reactor.
In 2002, the High Flux Reactor was shut down for a few weeks because of two unrelated issues. There were indications of a weld defect in the reactor vessel and there were some concerns about the safety culture within the company. After completion of extensive research and the announcement of a series of additional measures, the reactor was put back into use.
Frans W. Saris, former director of ECN Petten, and former professor of physics and dean of mathematics and natural Sciences at the University of Leiden published in November his book "Darwin meets Einstein". In his book Saris mentioned two previously not noted incidents which he gives as the reason for his resigning from ECN. Saris says the following
- "In the summer of 2001 I discovered that our nuclear research and consultancy group in Petten had secretly initiated the building of their own reprocessing plant, because the highly enriched uranium remnants from the Mo99 production could not be sent to Dounreay anymore. Issues of environmental impact and the non-proliferation treaty were waved aside by referring to the medical applications. I could block this development in time, but only after seeking the support from ECN's Supervisory Board.
- "On a winter night in December 2001 there was a power failure in North Holland, where Petten is located. The nuclear reactor is a research reactor, not a power reactor; it needs electricity to operate, for instance to pump cooling water. The reactor has a back-up cooling system to prevent meltdown of the core in case of a power failure. But this evening the back-up cooling system failed to come into action and the operators did not know what to do. There is an extra safety system by convection cooling for which the operators had to open a valve, but the control room was dark. When they reached for a torch that should have been there, it had been taken away by a colleague to work under his car. Trying their luck the operators put the valve of the convection cooling in what they thought was the 'open' position. But then the lights came back on and the operators discovered they had actually closed the back-up convection cooling system. Had the power failure lasted longer it would have meant meltdown and a major disaster. When I learned about this some months later - they thought they could keep it secret - I did not think I could take responsibility any longer and I resigned from the ECN."
There have been a number of issues raised in reports stating protocol breaches and insufficient safety culture in the reactor as well as requests from parliament members to shut down the reactor. The reactor has been shut down a number of times since 2012 with different issues including radioactive waste leaking, tritium leaking into the surrounding underground waters and control rod problems. New allegations from Frans Saris and 3 INES2 scale incidents in 2013 in an article in 2016 arose.
- Chalk River Laboratories, a nuclear reactor in Ontario that produces North America’s supply of isotopes for nuclear medicine
- "Petten reactor back after major repair". World Nuclear News. World Nuclear Association. 9 September 2010. Retrieved 15 August 2019.
- Herderschee, Roselien; Hogervorst, Marjolein (27 December 2016). "Artsen willen besluit over medische isotopen". NOS (in Dutch).
- Sauerwein, Wolfgang A G; Moss, Ray L (2009). Requirements for Boron Neutron Capture Therapy (BNCT) at a Nuclear Research Reactor (PDF). Joint Research Centre. ISBN 978-92-79-12431-0.
- NRG (8 May 2006). "HEU-LEU conversion reactor Petten completed". Archived from the original on 14 November 2006.
- Dalton, David (31 January 2018). "Breakthrough As Petten Becomes First Mo-99 Production Facility In Europe To Stop Using HEU In Medical Isotope Production". NUCNET.
- Joint Research Centre (2005). "High Flux Reactor (HFR) Petten - Characteristics of the Installation and the Irradiation Facilities" (PDF). European Communities.
- CEA; NCBJ; NRG; PALLAS; RCR; SCK•CEN; TUM (15 June 2018). "European Research Reactor Position Paper" (PDF). European Observatory on the Supply of Medical Radioisotopes.
- http://www.world-nuclear-news.org/RS_Date_set_for_Petten_reactor_s_return_1510081.html[needs update]
- Wereldprimeur voor kerncentrale Petten
- "LFR fuel removed from Petten". World Nuclear News. 6 December 2013.
- Argentina, a un paso de venderle un reactor nuclear a Holanda
- (Dutch) Nu.nl (14 may 2014) Company behind nuclear reactor Petten almost bankrupt
- (Dutch) KRO brandpunt reporter (15 May 2014) nuclear reactor Petten almost bankrupt Archived 2014-05-14 at the Wayback Machine
- "Archived copy". Archived from the original on 2011-07-16. Retrieved 2009-11-30.CS1 maint: archived copy as title (link)
- 'Bijna-meltdown in Petten in 2001' (in Dutch)
- quotes from "Darwin Meets Einstein: On the Meaning of Science", Frans Saris, November 2009, Amsterdam University Press, p. 73
- LAKA: Summary of 2009 events, incl. official reporting (in Dutch)
- "'Safety procedures ignored' at Petten nuclear reactor: investigation - DutchNews.nl". DutchNews.nl. 2014-10-18. Retrieved 2016-06-15.
- "Radioactive waste leak at Dutch reactor". RNW Media. Retrieved 2016-06-15.
- "De onverwachte drone-aanval op Petten". nrc.nl. Retrieved 2016-06-15.
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