The VENUS reactor is an experimental low-power reactor of the “zero-power critical facility” type. It was critical for the first time in 1964 with a water-moderated core. Being a flexible installation, after the first start the VENUS reactor was modified several times in order to better meet the needs in nuclear research.
VENUS has been used for the validation of reactor physics calculation codes. These codes are applied to make more efficient use of the core loading during the exploitation of nuclear installations. They have proven their usefulness for the determination of the optimum nuclear fuel configuration with regard to parameters like power distribution, neutron economy and neutron irradiation of the reactor vessel. If, however, one wants to deviate from the standard configuration and enter new domains, the codes must be revalidated. The critical VENUS facility was particularly fit for this purpose: the flexibility of the installation enables the development of realistic simulations.
In 1968 VENUS was modified to carry out neutron studies of new reactor configurations. Large power reactor cores were reproduced on a small scale (about 50 x 50 x 50 cm3).
The VENUS reactor was modernised in 1991 and in 2000-2001, the internal parts of the reactor vessel were modified in order to enable to load fuel of 1 m instead of 50 cm for new application areas.
In June 2003, SCK•CEN carried out a unique experiment in VENUS. For the first time a fuel assembly, irradiated in a power reactor like Doel or Tihange, was loaded. Because of burning in the nuclear reactor, irradiated fuel contains less uranium than non-irradiated fuel. The difference is called the “burn-up credit”. Since spent fuel can still attain a critical mass, the more accurate the knowledge of the "burn up credit" is, the better and safer the storage and transport of the spent fuel can be designed. The codes have been validated in VENUS for the calculation of the “burn-up credit”.
In 2008 the reactor has known a major modification. From a water moderated core the reactor was transformed into a fast lead reactor to support the R&D of the future GEN-IV reactor and ADS systems.
The GUINEVERE project at the VENUS-F installation
In 2008 the GUINEVERE (Generator of Uninterrupted Intense NEutrons at the lead VEnus REactor) project was started within the EUROTRANS Integrated Project of the 6th EURATOM Framework Programme. During 2008 and 2009, the VENUS facility was modified in order to allow the experimental programme to start in 2010. These experiments aim to provide an answer to the questions of online reactivity monitoring, subcriticality determination and operational procedures in an Accelerator Driven System (ADS).
The execution of the GUINEVERE project consisted of coupling a subcritical fast lead core with a particle accelerator that acts as external neutron source. Two major modifications were then necessary at the SCK•CEN site. First of all, there were the modifications required for the installation of the new GENEPI-3C accelerator at the VENUS critical facility and its coupling to the core. The second main modification was the adaptation of the VENUS critical facility to host a fast lead core. Since then the reactor is known as VENUS-F. In October 2011 for the very first time a lead-based subcritical reactor was coupled with a particle accelerator in continuous mode.
In 2011 a new project called FREYA (Fast Reactor Experiments for hYbrid Applications) was started within the 7th Framework Programme of EURATOM. The main objectives of FREYA are the further development and validation of a technique for online reactivity monitoring, as a continuation of the GUINEVERE project, and the validation of computer codes for ADS studies.
Contact: Guido Vittiglio