REPORT FROM THE COMMISSION TO THE COUNCIL AND THE EUROPEAN PARLIAMENT Operation of the High Flux Reactor in the period 2020-2023
Date: 2025-09-18
Institutions: European Commission, Joint Research Centre
Subjects: EAEC, EU research policy, Joint Research Centre, Netherlands, North Holland, nuclear reactor, nuclear research, nuclear safety, nuclear technology, research programme

EN 

  EN 

   EUROPEAN COMMISSION  Brussels, 18.9.2025  COM(2025) 505 final  REPORT FROM THE COMMISSION TO THE COUNCIL AND THE EUROPEAN PARLIAMENT Operation of the High Flux Reactor in the period 2020-2023 {SWD(2025) 265 final}  
 
 
OPERATION OF THE HIGH FLUX REACTOR IN THE 2020-2023 REPORTING 
PERIOD 

On  29 June  2020,  the  Council  adopted  a  four-year  (2020-2023)  supplementary 
the  high  flux  reactor  (HFR)  (Council  Decision 
research  programme  for 
2020/960/Euratom) (1) to be implemented by the Joint Research Centre (JRC) on the 
operation  of  the  HFR  located  in  Petten,  the  Netherlands.  Under  Article 5  of  the 
Council  Decision,  the  Commission  must  keep  the  European  Parliament,  and  the 
Council informed by producing a final report of the implementation of this Decision 
when the programme has ended. This report addresses this obligation. 

The  HFR  has  been  in  operation  since  1961  and  provides  a  variety  of  irradiation 
location possibilities (reactor core, reflector region and in the poolside). 

The main objectives of the supplementary research programme are: 

•  to  ensure  the  safe  and  reliable  operation  of  the  HFR  in  order  to  guarantee  the 

availability of the neutron flux for experimental purposes, 

•  to  allow  an  efficient  use  of  the  HFR  by  research  institutes  in  a  broad  range  of 
disciplines: (i) improvement of the safety of nuclear reactors, (ii) applications in 
the  health  sector,  including  the  development  of  medical  isotopes,  (iii)  nuclear 
fusion,  (iv)  fundamental  research  and  training,  and  (v)  waste  management 
including  the  possibility  to  study  the  safety  issues  of  nuclear  fuels  for  reactor 
systems that are of interest to Europe. 

The HFR is used for the commercial production of radioisotopes and acts as a training 
facility  for  doctoral  and  post-doctoral  fellows,  allowing  them  to  perform  research 
activities through national or European programmes. 

1.  SAFE OPERATION OF THE HFR 

The European Atomic Energy Community (Euratom) is the owner of the HFR (for a 
lease of 99 years). The HFR is run by the Nuclear Research and Consultancy Group 
(NRG) which operates and maintains  the plant and manages  commercial  activities 
around the reactor. It has an operating licence granted by the Dutch national regulator 
ANVS (Authority for Nuclear Safety and Radiation Protection). The HFR is subject 
to legally required 10-year periodic safety reviews under the same conditions as for 
nuclear plants, which are carried out by the NRG. 

In  the  2020-2023  reporting  period,  the  HFR  was  operational  above  90%  of  the 
scheduled operation time (which was set to be approximately 70% of a calendar year). 
In total, the HFR was operational for 991 days during 2020-2023. 

(1)  OJ L211 of 3.7.2020, p. 14. 

 
 
 
      
 
 
Regarding the safety operation of the reactor, in 2020, five notifications were sent to 
the regulator. Two of them related to higher collective exposure doses than expected 
during molybdenum (Mo-99) production and cell-dismantling activities. 

In 2021, two notifications were sent to the regulator on temporary unavailability of 
the  secondary-activity  monitor  and  a  longer-than-approved  irradiation  period  in  a 
production facility. 

In 2022, three notifications were sent to the regulator, the first one on contamination 
in a pump cellar, the second on a temporary breach of reactor containment (during 
outage  because  of  maintenance  activities)  and  the  last  one  on  the  inadequate 
performance of two activity monitors. 

In 2023, only one notification was sent to the Dutch nuclear regulator on a leakage in 
the reactor pool liner. A safety assessment was drawn up and submitted to the Dutch 
regulator. 

All  events  that  occurred  during  2020-2023  were  classified  as  INES  0  (i.e.  events 
without safety  significance and/or below scale) in  INES (international  nuclear  and 
radiological event scale). 

In terms of radiation protection of workers during HFR operations from 2020 to 2023, 
the individual and collective exposure doses were kept within the expected and legal 
limits. 

Maintenance activities comprise preventive, corrective and regular maintenance of all 
systems, structures and components. These were carried out with the aim of ensuring 
the  HFR’s  safe  and  reliable  operation.  The  main  activities  carried  out  during  the 
maintenance period were the following: 

(1) 

scheduled regular preventive and corrective maintenance, 

(2) 
requirements), 

periodic  leak  testing  of  the  containment  building  (as  one  of  the  licence 

in-service  inspection  of  the  safety-related  parts  of  the  primary  system 
(3) 
(reactor vessel, outlet reducers, bottom plug and primary piping in the primary pump 
building), 

(4) 

(5) 

(6) 

cleaning of the secondary cooling system, 

revamp of the emergency power diesels, 

two-week training for the HFR operator staff. 

2.  RESEARCH AND ISOTOPE PRODUCTION 

2.1.  Research 

The following scientific activities were carried out in 2020-2023: 

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improving nuclear safety through online measurement of fuel creep: two 
experiments were performed during the period, 

nuclear  fuel  being  crucial  to  all  nuclear  systems  and  essential  to  their 
performance and safety, a better understanding of the properties of the fuel 
and of the mechanisms underlying the changes under irradiation is key to 
developing more accurate and predictive codes for the simulation of fuel 
elements, 

research  on  molten  salt  reactor  (MSR)  technology:  a  molten  salt  reactor 
(MSR)  is  a  generation  IV  fission  reactor  in  which  the  primary  nuclear 
reactor  coolant  and/or  the  fuel  is  a  mixture  of  molten  salt  with  a  fissile 
material.  Molten  salt  reactors  have  higher  efficiency  and  less  waste 
generation, 

the  overall  aim  of  the  experimental  molten  salt  programme  is  to  gain 
experience  with  the  handling,  irradiation,  post-irradiation  research  and 
waste treatment of molten salts, 

conducting materials irradiation experiments on graphite degradation (key 
to determining the remaining service life of advanced gas-cooled reactors), 

aluminium  alloy  samples  of  structural  materials  of  the  Jules  Horowitz 
reactor  (JHR)  have  been  irradiated  to  provide  input  to  the  future 
surveillance programme of the JHR. 

From  2024  onwards,  Euratom  stakeholders  have  continued  to  collaborate  on 
developing  irradiation  facilities  for  fuel  and  materials  as  a  new  setting  for 
experimental  work  at  the  HFR.  Four  new  irradiation  devices  (experimental 
installations) are being set up to conduct research on molten salt reactors (two 
irradiation installations), a device for alloys and another for accelerated testing 
materials  in  capsules  (as  a  series  of  joint  experimental  programme  (JEEP) 
experiments  operating  within  the  Nuclear  Energy  Agency’s  framework  for 
irradiation experiments (FIDES) second triennial). 

2.2. 

Isotope production 

Approximately 30 000 patients worldwide per day depend on medical radioisotopes 
produced in the HFR in Petten for diagnosis and therapy. 

Molybdenum-99 is by far the most important of these isotopes. It plays a critical role 
in  heart  disease  diagnosis  and  cancer  diagnosis  through  bone  and  organ  scans.  In 
addition, new treatment methods are being developed, leading to an ever-increasing 
demand for new isotopes. Given the half-life of the isotopes produced and the high 
demand for related treatments, an efficient and just-in-time logistics infrastructure is 
essential. 

The HFR is one of the largest molybdenum-99 producers in the world.  It provides 
molybdenum-99 isotopes for 30 000 patient doses per day, which amounts to more 

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than 40 million patient doses in the 991 full-power days of operation in the 2020-2023 
reporting period. 

Other medicines also play an important role in the demand of isotopes. In addition to 
molybdenum-99  and  lutetium-177,  the  HFR  is  a  major  supplier  of  terbium-161, 
yttrium-90, iridium-192 and holmium-166 for various types of medical indications. 

The  HFR  is  proactively  producing  medical  isotopes  and  contributing  to  the 
development of new therapies and of the nuclear medicines market. In the 2020-2023 
reporting period, new clinical trials with lutetium-177 were started or announced, and 
the  HFR  delivered  more  lutetium-177  to  the  market,  allowing  for  more  patient 
treatments. 

In addition to the production of medical isotopes, NRG|PALLAS, the operator of the 
high  flux  reactor  is  also  focusing  on  nuclear  medical  innovation.  In  the  reporting 
period,  great  progress  has  been  made  in  developing  skills  in  the  field  of  medical 
isotope processing and the required infrastructure. The FIELD-LAB was set up for 
this purpose. The FIELD-LAB is an important innovation facility that helps accelerate 
the development and launch of new nuclear medicines. With the help of this facility, 
medical isotopes produced by the HFR will be made available for clinical trials. This 
innovative infrastructure will further increase the positive impact of the HFR on the 
health sector. 

3.  FINANCIAL CONTRIBUTIONS TO IMPLEMENT THE PROGRAMME 

During  2020-2023,  Member  States  made  the  following  financial  contributions  to 
implement the supplementary research programme: 

•  the Netherlands: EUR 26 654 000 

•  France: EUR 1 200 000 

Note  that  these  contributions  cover  the  expenses  related  to  the  operation  and 
decommissioning  of  the  HFR.  The  Commission  does  not  cover  any  operational 
deficits, including potential costs of maintenance or repair. 

The  annual  contribution  of  the  supplementary  research  programme  to  the 
decommissioning  fund  is  EUR 800 000  per  year.  This  amount  is  taken  from  the 
regular budget of the supplementary research programme. As of 31 December 2023, 
the total amount in the decommissioning fund was EUR 23 639 000. 

In  accordance  with  the  mandate  laid  down  by  Council  Regulation  (Euratom) 
2021/100,  the  JRC  appointed  an  independent  panel  of  experts  to  review  the  2022 
decommissioning plan for the high flux reactor at Petten. The objective was to assess 
the  plan’s  completeness,  feasibility  and  cost  estimates,  evaluate  implementation 
scenarios and support strategic decisions on funding and potential liability transfer to 
the  Dutch  State.  The  review (2)  concludes  that  the  total  decommissioning  cost  is 

(2)  Final  Report:  Review  of  the  HFR  decommissioning  plan,  cost  estimates  and  its  implementation 

(JRC/IPR/2023/RP/1498 – Rev. C, February 2025). 

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estimated at approximately EUR 244 million. However, this remains the best possible 
estimate subject to a number of uncertainties, including waste volumes, scheduling 
risks and site end-state criteria, which could lead to higher final costs. Against this 
backdrop, the amount of approximately EUR 23.6 million currently set aside under 
the  supplementary  programme  falls  well  short  of  covering 
the  expected 
decommissioning liabilities (to be borne by Euratom). 

Other expenditure incurred by the JRC during the  2020-2023  reporting period and 
paid from the supplementary research programme budget includes (i) direct staff costs 
(e.g.  HFR  supplementary  research  programme  management)  of  EUR 281 000  (ii) 
support  costs  (e.g.  legal  advice)  and  utilities  (e.g.  electricity,  water,  heating)  of 
EUR 2 585 000, and (iii) spent fuel management costs of EUR 5 719 000. 

The staff working document enclosed presents in more detail the results of the HFR’s 
operation in the 2020-2023 reporting period. 

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