COMMISSION STAFF WORKING DOCUMENT […] Accompanying the document Report from the Commission to the Council and the European Parliament “Operation of the High Flux Reactor in the period 2020-23”
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  SWD(2025) 265 final  COMMISSION STAFF WORKING DOCUMENT […] Accompanying the document Report from the Commission to the Council and the European Parliament “Operation of the High Flux Reactor in the period 2020-23” {COM(2025) 505 final}  
 
 
TABLE OF CONTENTS 

INTRODUCTION ................................................................................................... 2 

1.  HFR OPERATION .......................................................................................... 3 

1.1.  Operating Schedule and maintenance ................................................... 3 

1.2.  Safety of the HFR .................................................................................. 4 

2.  HFR AS  A TOOL FOR RESEARCH ON REACTOR MATERIALS AND 
FUEL CYCLES ............................................................................................... 5 

2.1.  Advances in nuclear safety – on-line measurement of fuel creep ......... 5 

2.2.  Molten Salt Reactor technology ............................................................ 7 

2.2.1.  SAGA ...................................................................................... 7 

2.2.2.  ENICKMA .............................................................................. 8 

2.3.  Materials irradiations ........................................................................... 10 

2.3.1.  BLACKSTONE ..................................................................... 10 

2.3.2.  Graphite irradiations for HTR application............................. 11 

2.3.3. 

Irradiation of aluminium-based reactor materials ................. 11 

2.4.  Outlook 2024 and onwards .................................................................. 12 

2.4.1.  ENICKMA-HTC ................................................................... 12 

2.4.2.  SALIENT-03 ......................................................................... 12 

2.4.3.  MIDI ...................................................................................... 13 

2.4.4.  ATOMIC ............................................................................... 13 

2.4.5. 

INCREASE-HFR .................................................................. 13 

3. 

ISOTOPE PRODUCTION ............................................................................ 13 

3.1. 

Isotope production ............................................................................... 13 

3.2.  Facilities and capacity ......................................................................... 14 

4.  FINANCIAL 

PROGRAMME’S 
IMPLEMENTATION ................................................................................... 15 

CONTRIBUTIONS 

THE 

TO 

ANNEX A 

GLOSSARY AND ACRONYMS ......................................... 17 

 
 
 
 
 
INTRODUCTION 

This staff working document is a companion document to the Commission’s report 
on ‘Operation of the High Flux Reactor in the years 2020-23, sent to the Council and 
the European Parliament. 

The high flux reactor (HFR), located in Petten (The Netherlands), is one of the most 
powerful multi-purpose materials-testing reactors in the world. The reactor is of the 
tank-in-pool type, light water cooled and moderated, which is operated at 45 MW. 
The HFR is used by the Commission in accordance with the Petten Site agreement 
between Euratom and The Netherlands of 25 July 1961.  

The  reactor  provides  a  variety  of  irradiation  location  possibilities  (reactor  core, 
reflector region and in the poolside). Horizontal beam tubes are available for research 
with neutrons as well as gamma irradiation facilities. Furthermore, fully equipped on-
site hot cell laboratories make it possible to carry out post irradiation examinations 
(PIEs). 

The research fields are nuclear materials and fuel science with the aim to improve the 
safety of nuclear reactors (both fission and fusion), investigations on reactor ageing 
and life management, research on advanced fuel cycles and waste management. The 
HFR acts also as a training facility hosting doctoral and post-doctoral fellows which 
perform  their  research  activities  through  national  or  European  Programmes.  The 
reactor is also used for the commercial production of radioisotopes. 

The  close  cooperation  between  the  European  Commission  Joint  Research  Centre 
(JRC) and the Dutch Nuclear Research and Consultancy Group (NRG) has led to a 
unique  system  of  managing  the  HFR,  involving  both  organizations.  The  European 
Atomic  Energy  Community  (Euratom)  owns  the  plant  (which  is  leased  from  the 
Dutch state for 99 years) but is operated by NRG. As of February 2005, the NRG has 
become the holder of the operation license granted under the Dutch Nuclear Energy 
Law. 

Over the last six  decades, the HFR has been operated and partly financed through 
Supplementary  Research  Programmes  which  were  regularly  discussed  and 
unanimously  approved  by  the  European  Council  based  on  Article  7  of  Euratom 
Treaty. On 29 June 2020, the Council adopted a four-year (2020-23) Supplementary 
Research Programme for the HFR (1)  to be implemented by the JRC. 

The  contribution  for  the  2020-2023  Supplementary  Research  Programme  was 
financed entirely out of contributions from France and the Netherlands, through the 
CEA and NRG, respectively, with a total budget of EUR 27,854,000 in the four-year 
period.  This  amount  included  the  provisions  for  the  annual  contributions  to  the 
decommissioning fund. 

(1)  OJ L211 of 3.7.2020, p. 14 

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This document reports on the operation, safety, financial contributions, and results of 
the scientific and technical work carried out in the period 2020-23. 

1.  HFR OPERATION 

1.1.  Operating Schedule and maintenance 

The HFR was scheduled to operate around 70% of the time (see table 1). Of 
this planned time, the HFR was  operational  around above 90% of the time 
each year, showing a robust operational capability and high reliability.  

Nominal power was 45 MW. During the reporting period the annual 30 MW 
reactor training for the operators and the yearly flux measurements have been 
carried out as scheduled. 

Table 1: HFR operating time 2020-2023 

2020 

2021 

2022 

2023 

"# full power days 
(operational/planned)" 

257/262 

258/271 

238/257 

238/256 

The main causes for the lost full power days each of the 4 years were: 

•  Year 2020: A delay in a mix of activities during a long maintenance outage 

was mainly responsible for the missed unplanned full power days. 

•  Year  2021:  Malfunctioning  equipment  before  reactor  start  caused  a  few 
delays and were mainly responsible for the missed unplanned full power 
days. 

•  Year 2022: Large part of one cycle missed due to a leakage in a primary 
facility  system  in  the  concrete.  A  new  system  has  been  designed  and 
commissioned to restore primary integrity. 

•  Year 2023: Two reasons provoked loss of full power days: 

•  Leakage  in  the  reactor  pool  liner.  Safety  assessment  (including 
inspections) has been made and submitted to regulator. After approval 
the HFR was started for safe and reliable operation. 

•  Replacement of heat exchanger plates took longer than expected. 

In the reported period 2020 to 2023, maintenance activities consisted of the 
preventive  and  corrective  maintenance  of  all  systems,  structures,  and 

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components  (SSC)  of  the  HFR,  as  described  in  the  annual  and  long-term 
maintenance plans. These activities were carried out to ensure the HFR’s safe 
and reliable operation and to prevent inadvertent scrams caused by insufficient 
maintenance. 

The following activities were successfully completed: 

•  Scheduled Regular preventive and corrective maintenance. 

•  Periodic  leak  testing  of  the  containment  building  as  one  of  the  license 

requirements (0.02 MPa overpressure for 24 h). 

•  In  Service  Inspection  of  the  safety  relevant  parts  of  the  primary  system 
(reactor vessel, the outlet reducers, the bottom plug, and primary piping in 
the Primary Pump Building). 

•  Cleaning of the secondary cooling system. 

•  Revision of the emergency power diesels. 

•  Two-week training for the HFR operator staff. 

1.2. 

Safety of the HFR 

During  the  reported  operational  period  2020-2023  there  has  been  several 
events,  all of them classified as Level 0 (without safety significance/below 
scale) in the INES (International Nuclear and radiological Event Scale) scale. 

(1) 

Year 2020: 

5  Notifications  to  the  regulator.  Two  related  to  higher  dose  than 
anticipated during molybdenum (Mo-99) production and Dismantling 
(DM) -cell activities, overfilling of tritium tanks, test failure of a coal 
filter and a leakage in a fuel element. All events were classified INES 
0. The individual and collective dose are well within expectations and 
legal limits. 

(2) 

Year 2021: 

2 Notifications to the regulator. Related to temporary unavailability of 
the secondary activity monitor and a larger than approved irradiation 
period in  one of the production facilities. All  events  were  classified 
INES  0.  The  individual  and  collective  dose  are  well  within 
expectations and legal limits. 

(3) 

Year 2022: 

3 Notifications to the regulator. Related to a contamination in a pump 
cellar,  temporary  breach  of  reactor  containment  (during  outage 
because of maintenance activities and a degraded functionality of two 
activity monitors. All events were classified INES 0. The individual 
and collective dose are well within expectations and legal limits. 

4 

 
(4) 

Year 2023: 

1 Notification to the Dutch regulator (ANVS) related to a leakage in 
the reactor pool liner. Safety assessment was made and submitted to 
the  Dutch  regulator.  It  was  classified  INES  0.  The  individual  and 
collective dose are well within expectations and legal limits. 

2.  HFR AS A TOOL FOR RESEARCH ON REACTOR MATERIALS AND FUEL 

CYCLES 

2.1.  Advances in nuclear safety – on-line measurement of fuel creep  

Fuel Creep II / INSPYRE irradiations 

Nuclear fuel is at the heart of all nuclear systems and constitutes an essential 
component  of  their  performance  and  safety.  A  better  understanding  of  the 
properties  of  fuel  and  of  the  mechanisms  underlying  their  changes  under 
irradiation is key to the development of more accurate and predictive codes 
for the simulation of fuel elements.  

These  codes  are  now  an  essential  tool  for  design,  qualification,  and 
independent  assessment  of  the  fuels.  INSPYRE  is  the  path  forward  to  cost 
effective  nuclear  fuel  licensing  and  improved  safety,  through  a  thorough 
understanding of fuel performance issues.  

In the previous reporting period, in September 2017, the Horizon2020 project 
INSPYRE (Investigations Supporting Mixed Oxide (MOX) Fuel Licensing in 
ESNII  Prototype  Reactors)  was  launched.  The  project  included  a  creep 
experiment bearing MOX discs. INSPYRE used a modified proof of principle 
irradiation that was performed in 2017, with added features to exert an axial 
load on the samples  and recording integral  stack lengths by using a Linear 
Variable  Differential  Transformer  (LVDT).  In  the  reporting  period  the 
experiment was built and assembled and subsequently irradiated. 

In parallel, a second, accompanying experiment (named Fuel Creep II) was 
built outside the scope of INSPYRE, bearing UO2 discs. The designs of Fuel 
Creep II and INSPYRE were identical, and irradiation conditions were to be 
as  similar  as  possible.  The  samples  of  both  experiments  were  produced  by 
JRC and tailored such that the expected power density was similar, for direct 
comparison of the data from the two experiments. 

The fuel discs were to be subjected to variable axial loads up to 100 MPa at 
average temperatures between 481°C and 1130°C. This range of temperatures 
can  be  achieved  by  carrying  out  the  irradiation  in  two  different  in-core 
positions in the HFR. By switching core position, both higher temperatures 
due to higher heating rates, as well as higher fission rate density are achieved, 
leading to higher creep rates. 

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Figure  1: INSPYRE/Fuel  Creep  II  irradiation  rig.  The  instrument  head 
allows simultaneous connection of three creep capsules. The head that is 
connected to the sample is still open in the figure (A). Two connectors on 
the other end of the blue hose carry the wiring and tubing to access panels 
in  the  HFR.  The  round  plug  head  (B)  has  the  coax  connectors  for  3x6 
capacitor plate sets (36 connectors). The rectangular plate (C) carries the 
gas lines and thermocouple wires. 

Source: JRC 

After design and assembly of the experiments the irradiation was started at the 
end of June 2020. Unfortunately, the UO2 experiment had a failure of the first 
containment in the first cycle. After discharging of the rig, the irradiation of 
the MOX experiment was continued. During the following irradiation cycles, 
parameters were kept as planned. Unfortunately, after four additional cycles a 
rapid  rise  in  sample  temperatures  along  with  a  drop  in  the  pressure  of  the 
second containment was observed, indicating a leak to the first containment. 
As this meant that the safety conditions were no longer met, this also brought 
the irradiation of the MOX experiment to a premature end in May 2021. Due 
to  the  seemingly  similar  failures  of  the  two  experiments,  it  was  decided  to 
assess the failure modes or root causes of these failures.  

An external, independent team was requested to perform root-cause analyses 
of the failed experiments, looking at all the phases of the project, as well as 
any other events or circumstances that could impact the proper functioning of 
the experiments. These root-cause analyses were finalized at the start of 2022. 
Even  though  no  definite  cause  for  failure  could  be  determined,  several 
preliminary causal factors were identified, such as the choice for the brazing 
alloy that was made as well as the centreless grinding method that was used 

6 

 
 
 
 
 
the  experiments’ 

to  produce 
tubing.  Additionally,  a  set  of 
thin 
recommendations  was  made  in  the  preliminary  root  cause  analysis,  which 
have been divided into pre-assembly recommendations and organizational / 
project management recommendations. The pre-assembly recommendations 
pertain  to  the  design  process,  acceptance  limits  and  inspection  and  testing 
(I&T), rather than directly to the design itself. 

2.2.  Molten Salt Reactor technology 

A molten-salt reactor (MSR) is a class of Generation IV nuclear 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 benefits in higher 
efficiencies and lower waste generation. The MSRs operate at atmospheric or 
low  pressures,  significantly  reducing  the  risk  of  pressure-related  accidents. 
MSRs also incorporate passive safety features, such as passive cooling and 
the potential for defueling in response to accidents which enhance the reactor's 
safety profile without requiring active intervention. 

Molten salt fuel forms have received a significantly growing interest in the 
past  decade.  NRG  has  started  a  collaboration  with  JRC  and  the  Delft 
University  of  Technology  (TU  Delft)  with  the  aim  to  develop  molten  salt 
technology  and investigate the  feasibility  of molten salt  reactors, under the 
program  name  LUMOS  (Learning  to  Understand  MOlten  Salts).  For  these 
purposes  specific  agreements  under  the  umbrella  of  the  JRC-NRG 
Cooperation Agreement have been drawn up. In addition, NRG has initiated 
supporting  activities  within  the  domain  of  Molten  Salt  Reactors  (MSR) 
outside this Cooperation Agreement. 

The overall aim of the experimental molten salt program is to gain practical 
experience with the handling, irradiation, post-irradiation research and waste 
treatment of molten salts, and then use this experience to: 

•  improve  insight  into  the  behaviour  of  fission  products  in  molten  salt  in 

relation to accident scenarios and decommissioning. 

•  qualify materials and components for use in an MSR. 

•  develop  a  technique  for  the  (partial)  on-line  removal  of  fission  products 

("helium bubbling"). 

•  test  and  qualify  measurement  and  control  techniques  required  to  drive 

MSRs. 

•  design, build and operate a facility for the HFR that can serve as a prototype 

for future first-of-a-kind reactors (a so-called "MSR loop"). 

2.2.1. 

SAGA 

The objective of Salt spraying off-Gas systems experiment (SAGA) is to study 
the gas formation that can take place when molten salt waste (fuel waste from 
Molten Sal Reactors) is temporarily stored before waste treatment and final 
disposal. 

7 

 
Low temperature radiolytic fluorine gas production at room temperature and 
up to 150 ºC is an issue for future irradiation experiments in the HFR. SAGA 
has been designed with the objective to measure the amount of F2 gas released 
from salt samples in a gamma field and to study the mechanism of radiolytic 
gas  production  for  several  salt  species.  The  idea  of  the  experiment  is  to 
continuously measure pressure in sealed salt-filled capsules during high-dose 
gamma irradiation using HFR spent fuel (at an average gamma dose rate of 
~30 kGy/hour). Energy absorption is registered by ionization chambers, and 
temperature in the system is monitored by thermocouples (45-60 °C).  

The SAGA irradiation facility is reloadable. For the first experiments, it has 
been  loaded  with  samples  of  LiF,  BeF2,  UF4,  ThF4  and  a  LiF-BeF2  -UF4 
mixture and one empty reference capsule is present as well. A collaboration 
with the Nuclear Research Institute Rez in Czech Republic was established 
for the fabrication of the fuel salts. In the previous reporting the first SAGA 
irradiation was started (last quarter of 2019). 

The observed pressure build-up confirms the idea that heavier (higher-Z) salts 
absorb  more  energy  and  therefore  generate  more  fluorine  gas.  In  2021, 
recombination  tests  were  carried  out  by  placing  the  irradiated  salt-filled 
capsules in a tube oven, with two goals: to recombine the fluorine gas with the 
salt  at  elevated  temperatures  to  ‘reset’  the  samples  and  allow  for  a  second 
round  of  gamma  irradiation  of  the  same  samples;  and  to  quantify  the 
recombination rate as a function of temperature. 

In 2022, the results from the first SAGA irradiation were analysed by an NRG 
-  TU  Delft  Ph.D.  student,  and  subsequently  published.  In  addition, 
preparations were made for a second round of gamma irradiations (SAGA-2) 
to  confirm  and  extend  measurements  from  SAGA-1 and include  a chloride 
salt sample (NaCl) to obtain first information on possible chlorine production, 
for comparison with the fluoride salts. This second irradiation was started in 
December 2023 and is foreseen to continue until May 2024. 

Figure  2: The  SAGA  facility  in  the  spent  fuel  pool  of  the  HFR  for 
irradiation (left) and the experimental set-up for recombination tests in a 
fume hood in a radiological laboratory (right). 

Source: JRC 

2.2.2. 

ENICKMA 

Nickel-based materials are foreseen to be used in MSR components for their 
high  corrosion  resistance.  Nickel  is  however  sensitive  to  thermal  neutron 

8 

 
 
irradiation, producing helium which may consequently weaken the material. 
The ENICKMA project  (Evaluation  of NICKel-based Materials  for Molten 
salt  reactor  Applications)  is  performed  to  study  the  effect  of  helium 
embrittlement  in  nickel-based  materials  such  as  Hastelloy  N,  that  are 
candidates for use in Molten Salt Reactors. 

100 tensile, stress relaxation and low cycle fatigue samples are irradiated at 
MSR-relevant temperatures. Test results for the irradiated materials are then 
compared with results for reference samples. 

Table 2 presents an overview of the various materials tested. 

Table 2: Overview of the various materials for the ENICKMA irradiation 
experiment. 

Material 

3166 L(N) 

Hastelloy N 

GH3535 

HN80MTY 

MONICR 

Hastelloy 242 

Supplier 

CEA (Fr) 

Haynes (US) 

SINAP (Ch) 

COMTES FHT (Cz) 

COMTES FHT (Cz) 

Haynes (US) 

In 2022, the irradiation of the ENICKMA was successfully completed after a 
total irradiation of 9 HFR cycles. The experiment was transported to the Hot 
Cell  Laboratories  (HCL)  for  dismantling.  All  planned  tensile  tests  on 
irradiated and annealed specimens were completed in 2022. Tensile tests were 
performed both at room temperature and at irradiation temperature (650 °C). 
Also,  an  extensive  pre-irradiation  microstructural  investigation  (optical  and 
electron  microscopy  including  element  analysis)  on  reference  material  and 
material annealed at 800°C was completed. 

Figure 3: ENICKMA dismantling in the D cell (left) and the 10 ENCIKMA 
drums during the dismantling procedure (right). 

Source: JRC 

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Figure  4: Instrumentation  head  of  a  so-called  TRIO  facility  with  the 
ENICKMA experiment in one of the three channels. The instrumentation 
head,  which  is  positioned  a  few  meters  above  the  reactor  core  during 
operation, contains the drive for vertical displacement. 

Source: JRC 

2.3.  Materials irradiations 

2.3.1. 

BLACKSTONE 

The United Kingdom’s EdF (Electricité de France) Energy operates a fleet of 
advanced gas cooled reactors (AGRs) using graphite as the neutron moderator 
and carbon dioxide as coolant.  

Graphite  degradation  is  one  of  the  key  issues  that  determine  the  remaining 
service life of an AGR.  

Data  on  graphite’s  behaviour  at  high  irradiation  doses  and  weight  loss  is 
required  to  make  it  possible  to  predict  and  assess  the  behaviour  of  AGR 
graphite  cores  beyond  their  currently  estimated  lifetimes,  thus  ensuring 
continued safe operation and lifetime extension. Phase 3 of BLACKSTONE 
focuses  on  the  graphite  from  the  Heysham  2  and  Torness  reactors  and  is  a 
follow-up of Blackstone Phases 1 and 2, in which graphite from other AGRs 
was successfully characterized to support lifetime extension. As part of the 
project, graphite material extracted from AGRs has been irradiated in the High 
Flux  Reactor  During  the  HFR  irradiation  both  the  in-core  neutron  and 
oxidation damage mechanisms that take place in an AGR are simulated and 
accelerated  under  representative  conditions.  Following  the  irradiation, 
graphite specimens are characterized in the NRG Hot Cell Laboratories (HCL) 
to provide high quality material behaviour data, providing essential input to 
graphite  property  models  which  are  used  to  assess  the  future  structural 
integrity of AGR cores. Phase 3, started in 2016 include 2 irradiations in C7 
irradiation 
position,  BLACKSTONE-5  and  BLACKSTONE-6.  Post 

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examinations of BLACKSTONE 5, irradiated from 2017-C05 to 2018-C06, 
were done in HCL. After this campaign the graphite samples were irradiated 
in BLACKSTONE-6. This irradiation started in 2019-07 and was completed 
after  2020-05.  All  characterization  of  specimens  is  completed,  and  the 
program was finalized in 2022. 

2.3.2. 

Graphite irradiations for HTR application 

A  high-temperature  reactor  (HTR)  is  a  type  of  nuclear  reactor  which  uses 
uranium fuel and graphite moderation to produce very high reactor core output 
temperature. The high operating temperatures of HTGR reactors potentially 
enable applications such as process heat or hydrogen production. 

Around the world, multiple initiatives are undertaken to deploy Generation IV 
High Temperature Reactors (HTR).  

Building on the experience of previous graphite irradiation programs, graphite 
(creep)  irradiations  at  high  temperature  are  performed  to  characterize  and 
qualify  graphite  grades.  An  inert  graphite  irradiation  was  performed  for 
Terrestrial Energy’s Integral Molten Salt Reactor. In this irradiation, 12 cycles 
were  completed  between  cycles  2020-07  and  2022-02,  with  a  range  of 
graphite grades that are of interest for application in the IMSR. The graphite 
specimens were characterized in the Hot Cell Laboratories in a campaign that 
completed in 2023. 

Another activity is the qualification of a nuclear graphite grade provided by 
SIAMC Advanced Materials Co. Both an inert high temperature irradiation 
(SAINT-01 with start 2022-08 and end 2023-04) and a first creep irradiation 
(SINOGRAPH-I with start 2021-06 and end 2021-09) were performed. The 
graphite  specimens  from  these  irradiations  are  characterized  and  follow-up 
irradiations are scheduled for the coming years. 

2.3.3. 

Irradiation of aluminium-based reactor materials 

The Jules Horowitz Reactor (JHR) Material Test Reactor project will provide 
the means needed to explore an essential scientific and technical field: testing 
the  behaviour  of  materials  and  fuels  under  irradiation  in  order  to  support 
current and future nuclear reactors. 

The  JHR  Material  Test  Reactor  is  currently  under  construction  at  the  CEA 
(Commissariat  à l'énergie atomique et  aux énergies  alternatives) Cadarache 
site.  The  reactor  is  being  built  under  the  framework  of  an  international 
consortium of research institutes It is leaded by France's CEA which provides 
45% of the project's funding and includes another 9 research institutions from 
EU member states and the participation of European Commission with a 6% 
contribution to the project. 

In January 2016 the Jules Horowitz Reactor (JHR) SURP project started. The 
JHR-SURP  irradiation  formed  part  of  the  French  contribution  to  the 
Supplementary  Program  of  the  High  Flux  Reactor  (HFR)  2016-2019  and 
2019-2023. In the JHR SURP facility aluminium alloy samples of structural 
materials of the Jules Horowitz Reactor have been irradiated providing input 

11 

 
to the (future) surveillance program of the JHR. The irradiation forms part of 
the support to the industrial manufacturer of the reactor.  

The irradiation started in the previous reporting period, in January 2017, and 
was continued in the period 2020-2023. The samples were irradiated in the 
HFR  in  a  core  position.  The  irradiation  was  successfully  completed  in 
December  2023.  With  1764  full  power  days  this  irradiation  is  amongst  the 
most longest running experiments in the history of the HFR. After irradiation 
the rig with the samples was removed from the HFR core and transported to 
the hot cells. In April 2024 the samples were transported to France for future 
research. 

2.4.  Outlook 2024 and onwards 

Euratom  stakeholders  continue  to  collaborate  on  the  development  of 
irradiation facilities for fuel and materials as new set up for experimental work 
at  the  High  Flux  reactor.  At  the  time  of  writing,  the  following  irradiation 
devices are in preparation. 

2.4.1. 

ENICKMA-HTC 

ENICKMA-HTC is a follow-up irradiation to ENICKMA (section 2.2). It also 
assesses the mechanical performance of Molten Salt Reactor (MSR) structural 
materials  but  focuses  on  in-pile  measurement  of  creep  behaviour  at  high 
temperatures (~650ºC). A concept design for the in-pile irradiation was made 
in  collaboration  with  IFE.  The  design  of  the  ‘creep  unit’  was  supplied  by 
Institute  for  Energy  Technology,  Norway  (IFE)  and  incorporated  into  the 
concept design of the full irradiation rig. 

2.4.2. 

SALIENT-03 

The  interest  for  Molten  Salt  Reactor  (MSR)  technologies  is  increasing 
worldwide. The MSR is operated at low (atmospheric) pressure in the primary 
circuit  and  in  the  event  of  overheating,  the  fuel  would  be  drained  into  an 
emergency dump tank assuring subcriticality and natural removal of the decay 
heat. 

The  irradiation  experiments  SALIENT-03  is  being  carried  out  within 
collaboration between the Nuclear Research and Consultancy Group (NRG) 
and the Joint Research Centre (JRC). The main goal of the experiment is to 
assess the corrosion mechanism of selected Ni-based alloys in molten fluoride 
salt considered as one of the candidates for MSR fuel salt. The corrosion test 
will be carried out during irradiation of the fuel salt in the High Flux Reactor 
in Petten (The Netherlands). 

SALIENT-03 is the successor of the SALIENT-01 experiment. Whereas the 
objective  of  SALIENT-01  was  to  acquire  knowledge  and  experience  with 
performing  an  MSR-type  irradiation,  including  the  design  of  a  rig  and  the 
handling of irradiated fuel salts, SALIENT-03 has a more dedicated objective: 
the determination of corrosion rates of candidate containment materials. 

Lessons  learned  from  the  SALIENT-01  experiment  are  incorporated  in  the 
design. SALIENT-03 is the second capsule irradiation of molten fluoride fuel 

12 

 
salt and is being executed in collaboration between JRC and NRG. SALIENT-
03 focuses on salt corrosion of alloys used for MSR construction under known 
redox  conditions.  The  design  also  includes  a  pressure  sensor  for  noble  gas 
release  measurements  and  nickel  electrodes  for  generating  current-voltage 
plots. Start of the irradiation is scheduled for the last quarter of 2024. 

2.4.3. 

MIDI 

The MIDI irradiation facility is a follow-up of the LYRA-facilities that have 
previously been used to irradiate structural materials in the pool-side-facility 
(PSF) of the High Flux Reactor (HFR). The facility is a reloadable device that 
can be used to study the irradiation performance of alloys to irradiation doses 
and temperatures that are representative of reactor pressure vessel conditions. 

2.4.4. 

ATOMIC 

The  Accelerated  Testing  of  Materials  in  Capsules  (AToMiC)  irradiation 
project  is  a  series  of  Joint  ExpErimental  Program  (JEEP)  experiments 
operating  within  the  Nuclear  Energy  Agency’s  (NEA’s)  Framework  for 
IrraDiation Experiments (FIDES) second triennial. 

AToMiC is dedicated to the understanding of microstructural evolution of fuel 
materials  for  use  in  higher  temperature  (HTR,  section  2.3),  Generation  IV 
(GenIV)  type  reactors  (notionally  referred  to  as  advanced  reactors).  This 
project  is  executed  by  a  core  group  with  that  includes  NRG/JRC,  Idaho 
National Laboratory (INL), CEA and Westinghouse. The design for a High 
Flux  Reactor irradiation  facility is  performed to  allow irradiation  of Mixed 
Oxyde (MOX) fuels under controlled temperature conditions. 

2.4.5. 

INCREASE-HFR 

The  In-Core  Real-Time  Mechanical  Testing  of  Structural  Materials 
(INCREASE-HFR)  irradiation  project  is  a  series  of  Joint  ExpErimental 
Program (JEEP) experiments operating within the Nuclear Energy Agency’s 
(NEA’s) Framework for IrraDiation Experiments (FIDES-II) second triennial.  

INCREASE-HFR is a continuation of an irradiation starting at MITR Material 
Test  Reactor  in  collaboration  with  Idaho  national  Laboratory  (INL).  The 
experiment  is  dedicated  to  the  quantitative  evaluation  of  in-core  real-time 
stress relaxation data for stainless steels in current light-water reactor (LWR). 
This  project  is  executed  by  a  core  group  that  includes  NRG/JRC,  Idaho 
National Laboratory (INL), CEA and EPRI. 

3. 

ISOTOPE PRODUCTION  

3.1. 

Isotope production 

Worldwide,  approximately  25.000  patients  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  is  a 
precursor of Technetium-99m which represents the most widely used medical 

13 

 
isotope for imaging, accounting for 80% of nuclear diagnostic procedures. It 
performs a critical role in the diagnosis of heart disease and is also used in 
cancer diagnosis  through bone and organ scans.  In addition,  new treatment 
methods are being developed thus leading to ever increasing demand for (new) 
isotopes. Obviously, given the half-life of the produced isotopes and the high 
demand  for  treatment,  a  well-oiled  just-in-time  logistic  infrastructure  is 
essential. 

The HFR provides isotopes for 30.000 patient doses per day of Molybdenum-
99.  With  991  full  power  days,  this  equals  the  production  of  more  than  40 
million patient doses in the reporting period 2020 – 2023.  

The HFR is one of the largest molybdenum-99 producers in the world. With 
increasing prosperity in larger parts of the world, ever better diagnostics and 
the ageing population, the demand for nuclear medicine is growing, especially 
due to the increased use of therapeutic isotopes like lutetium-177. This growth 
is reflected by an increasing number of clinical trials and the registration of 
new therapeutic drugs. 

Other medicines play an important role in the supply of isotopes as well. 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 constantly anticipates the developments within the field of medical 
isotopes  by  contributing  to  the  development  of  new  therapies  and  the 
development of the market for nuclear medicines. In the reporting period 2020 
- 2023, new clinical trials with lutetium-177 were started and/or announced, 
and the HFR delivered more lutetium-177 activity to the market, allowing for 
more patient treatments. The registration of the first PSMA lutetium-177 drug 
in 2022 has started the expected growth spurt. NRG|PALLAS invested in HFR 
production  capacity  in  2022  to  accommodate  this  growth  and  gain  a  large 
market share in irradiation service. 

Next to the production of medical isotopes NRG|PALLAS, the operator of the 
High Flux Reactor, is focusing on nuclear medical innovation. In the reporting 
period  great  progress  has  been  made  in  the  development  of  competences 
within  the  field  of  processing  of  medical  isotope  and  the  required 
infrastructure. For this  purpose, the  FIELD-LAB has  been  established. The 
FIELD-LAB is an important innovation facility, that helps to accelerate the 
development  of  new  nuclear  medicines  to  shorten  the  time  to  market.  The 
facility was opened in December 2023. With this facilities, medical isotopes 
produced by the HFR, will be made available for clinical trials. In other words, 
the new innovation-infrastructure will further enlarge the health impact of the 
HFR.  

The  continuation  of  the  important  production  function  of  the  HFR  will  be 
taken over by the PALLAS reactor in the future. In the year 2023, a decision 
for full financing of the PALLAS reactor was taken by Dutch Government. 

14 

 
3.2. 

Facilities and capacity 

The  HFR  has  various  production  facilities  available  to  produce  medical 
isotopes:  

•  3 in core facilities for molybdenum-99, 

•  2 in core facilities for therapeutic isotope (lutetium-177, lutetium-177 no 

carrier added (n.c.a.) etc.), 

•  5 pool side facilities for molybdenum-99, 

•  a pneumatic rabbit system for holmium-166. 

With  the  increasing  demand  for  isotopes,  NRG|PALLAS  is  preparing  to 
expand  the  production  capacity  to  produce  medical  isotopes.  This  capacity 
expansion  for  the  period  2022-2026  is  included  in  the  CONNECT  '26 
program. The objective is to develop capabilities to meet the market demand 
for therapeutic isotopes during the remainder of the HFR operational period 
and to connect as closely as possible to the (larger) production capacity of the 
PALLAS reactor. The approach is achieved by optimization of the irradiation 
process to increase the volume while maintaining the reliability of the current 
production chain. 

In 2023, technical improvements were implemented in irradiation facilities, 
which increases capacity and specific activity. Together with several logistical 
improvements,  this  means  that  the  capacity  is  in  order  for  the  anticipated 
growth. 

4.  FINANCIAL 

CONTRIBUTIONS 

TO 

THE 

PROGRAMME’S 

IMPLEMENTATION 

In 2020-23, the following financial contributions were received from Member States 
for the implementation of the Supplementary Research Programme:  

•  Netherlands: EUR 26.654.000  

•  France: EUR 1.200.000  

Note that these contributions cover the expenses specified under Annex II of Council 
Decision  2020/960/Euratom.  The  Commission  does  not  cover  any  operational 
deficits, including potential costs of maintenance or repair.  

Since 2004, due to a re-evaluation of decommissioning costs, the annual contribution 
of the Supplementary Research Programme to the decommissioning fund is EUR 800 
000/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 is EUR 23.639.000.  

This fund will contribute to the future decommissioning costs of the HFR (to be borne 
by Euratom).   

15 

 
Other expenditure incurred by the JRC during the reporting period and paid from the 
Supplementary  Research  Programme  budget  includes  direct  staff  costs  (e.g.  HFR 
Supplementary Research Program  management)  EUR  281.000 HFR;  support costs 
(e.g. legal advice) and utilities (e.g. electricity, water, heating) EUR 2.585.000, and 
spent fuel management costs EUR 5.719.000. 

16 

 
 
 
 
 
 
 
 
 
 
 
 
Annex A 

Glossary and Acronyms 

AGR           Advance Gas Cooled Reactor 

AToMiC     Accelerated Testing of Materials in Capsules  

ANVS         Dutch Nuclear regulator 

CEA            Commissariat a l’énergie atomique (France) 

EdF             Electricité de France 

Euratom      European Atomic Energy Community 

ENICKMA   Evaluation of NICKel-based Materials for Molten salt reactor Applications 

FIDES         Framework for IrraDiation ExperimentS 

HCL            Hote Cell Laboratories 

HFR            High Flux Reactor 

HTR            High Temperature Reactors 

IFE              Institute for Energy Technology, Norway 

INES           International Nuclear and radiological Event Scale 

INL             Idaho National Laboratory 

INSPYRE    INvestigations SuPporting MOX Fuel Licensing in ESNII Prototype REactors 

JEEP            Joint ExpErimental Program 

JRC  

         European Commission Joint Research Centre 

JHR              Jules Horowitz Reactor 

LUMOS        Learning to Understand MOlten Salts 

LVDT           Linear Variable Differential Transformer 

MOX             Mixed Oxide 

MSR             Molten Salt Reactors 

NRG 

          Dutch Nuclear Research and consultancy Group 

SAGA           Salt sprAyin off-GAs systems 

SSC               Systems, Structures, and Components 

TU Delft        Delft University of Technology 

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