IRSN, Institut de radioprotection et de sûreté nucléaire

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Enhancing Nuclear Safety


Research programs

The ARCHER project

Last update in September 2012

The aim of the ARCHER European project- Advanced High-Temperature Reactors for Cogeneration of Heat and Electricity R&D – is to get further knowledge relative to the technology of very high temperature reactors  (V-HTR) and, in particular, to demonstrate the safety of the concept.  It also aims to contribute to demonstrating the feasibility of the cogeneration of electricity and heat by a nuclear reactor.



Context of the project

Launched in February 2011 for a four year period, ARCHER is continuing the work of the RAPHAEL project (completed in April 2010) on graphite-moderated, helium-cooled V-HTR reactors. With funding from the 7th EURATOM Framework Research and Development Programme (FRDP), the project ties in with the objectives of the European SNETP (Sustainable Nuclear Energy Technology Platform).

The consortium set up for ARCHER is composed of 33 partners, including representatives from conventional and nuclear industry, public services, TSOs, research organisations and universities. 


Bise facility © IRSN



Topics studied


The work will cover the following main topics (IRSN is particularly involved in the 2nd topic, cf. below):

  • Integration studies of a nuclear cogeneration unit coupled to industrial processes.
  • Critical safety aspects of V-HTR (integrity of the containment system, behaviour of graphite dust, air and water ingress accidents, etc.).
  • Modelling of the behaviour of the fuel and improvement of its performance in the core.
  • Development of components necessary for coupling with an industrial facility (heat exchangers, steam generators).
  • Evaluation and qualification of materials capable of operating at high temperature.
  • Definition of data useful for the design of the graphite components of the core. 
  • Training on the V-HTR concept.

VESTA software - example of an evolution chain for actinides © IRSN



IRSN’s involvement


IRSN is contributing to R&D on the critical safety aspects of V-HTR by participating in three working groups of the ARCHER project:

  • The study of water ingress accidents ; 
IRSN is working on the flammability limits of the gaseous mixtures created during the reaction of steam with graphite in the core. This research work is being carried out in collaboration with CNRS ICARE laboratory in Orleans.

  • The analysis of the safety of the fuel under the aspect of the potential release of fission products ;
The quantification of the actinides produced during irradiation is necessary for the evaluation of the radioactive inventory that may be released in the event of an accident. These species also have an important role on the residual power of the irradiated fuel (which is in particular useful for the behaviour of the stored fuel). IRSN will evaluate the capacities of its VESTA calculation software platform (moreover used to quantify the evolution under irradiation of the composition of the fuel of pressurised water reactors) by comparison with the results of the HFR-EU1bis and HFR-EU1 irradiation examinations performed in Petten (Netherlands). Following this validation action, VESTA will be used to predict the quantities produced of certain isotopes (americium isotopes in particular).

  •  The calculation of the radioactive source term ;
The calculation of the radioactive inventory (or source term) released immediately after a depressurisation accident in a V-HTR depends, among other things, on the quantity of dust present in the primary circuit and released into the reactor vessel. IRSN will carry out experiments in its BISE facility to characterise the mechanisms of re-suspending dust from the primary circuit (essentially dust from the graphite). These experiments will enable physical modelling capable of evaluating the source term to be developed.

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Dates: 2011-2015

Pilot: Nuclear Research and Consultancy Group
Funding: FP7 Euratom

Involved IRSN laboratories



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