Jan Wagemans

MYRRHA, a Multipurpose hYbrid Research Reactor for High-end Applications

One of the major challenges that our society faces is the increasing demand for energy in general and electricity in particular. During the last century our energy supply was based on fossil fuels. Nowadays, we are confronted with decreasing hydrocarbon reserves and excessive CO2 emissions. At the same time renewable energy sources cannot satisfy the complete demand. For this reason the European Union, Japan, the United States, Korea, Russia, China, India, and other countries recognize that nuclear energy needs to be part of the “energy basket” of the future.

The BR1 reactor: a versatile irradiation facility for fundamental research and industrial applications

The BR1 reactor located at the Belgian Nuclear Research Centre SCK·CEN in Mol, Belgium, is a research reactor with a variety of irradiation possibilities. Thanks to its large reactor core, its flexible operation and its different irradiation facilities, this reactor is particularly suited for in-core and ex-core neutron physics experiments and industrial applications. As an MCNP model of the BR1 reactor exists, the experimental work can be supported by MCNP calculations if required.

Experimental determination of the 14 N ( n , p ) 14 C reaction cross section for thermal neutrons

The 17O(n_th,alpha)14C reaction cross section was determined at the high flux reactor of the ILL in Grenoble relative to the known 14N(n_th,p)14C cross section. The 17O(n_th,alpha)14C measurements were performed with several highly enriched oxygen gas samples and the flux calibration was done with 14N_2 from the air. This resulted in a precise value of (244+/-7)mb for the 17O(n_th,alpha)14C cross section.

Effective delayed neutron fraction measurement in the critical VENUS-F reactor using noise techniques

This paper present the measurements of VENUS-F kinetic parameters using the Rossi-Alpha methods. The VENUS-F reactor is a zero-power reactor based in Mol, Belgium at SCK-CEN [1]: its fuel is made of metallic enriched uranium with pure lead in order to simulate the behavior of a lead fast reactor. The reactor can be operated in a sub-critical state when it is coupled with the GENEPI-3C neutron source [2]. At the beginning of 2014, a measurement campaign was performed in the critical state in order to estimate the kinetic parameters of the reactor. In this paper, two measurements are analyzed at two different powers (approximately 2W and 30W) with 7 different fission chambers (with a 235-U deposit that varies from 1g to 10mg). All the correlation functions needed for the Rossi-Alpha method have been built for each possible set of two detectors for the two power levels and values of the effective delayed neutron fraction obtained are then compared. Experimental results show the importance to operate at a very low power. The final value for the effective delayed neutron fraction is finally estimated to be (730 ±11) pcm and the prompt neutron generation time is estimated to be equal to (0.41 ± 0.04) μsec.

Experimental results from the VENUS-F critical reference state for the GUINEVERE Accelerator Driven System project

The GUINEVERE (Generation of Uninterrupted Intense NEutron pulses at the lead VEnus REactor) project was launched in 2006 within the framework of FP6 EUROTRANS in order to validate online reactivity monitoring and subcriticality level determination in accelerator driven systems (ADS). Therefore, the VENUS reactor at SCK-CEN in Mol, Belgium, was modified towards a fast core (VENUS-F) and coupled to the GENEPI-3C accelerator built by CNRS. The accelerator can operate in both continuous and pulsed mode. The VENUS-F core is loaded with enriched Uranium and reflected with solid lead. A well-chosen critical reference state is indispensable for the validation of the online subcriticality monitoring methodology. Moreover, a benchmarking tool is required for nuclear data research and code validation. In this paper, the design and the importance of the critical reference state for the GUINEVERE project are motivated. The results of the first experimental phase on the critical core are presented. The control rods worth is determined by the positive period method and the application of the Modified Source Multiplication (MSM) method allows the determination of the worth of the safety rods. The results are implemented in the VENUS-F core certificate for full exploitation of the critical core.

Preparation and characterisation of an 39Ar sample and study of the 39Ar(nth, α)36S reaction

Abstract The 39 Ar ( n th , α ) 36 S reaction has been studied for the first time. A sample containing 2.85×10 14 39 Ar atoms was produced at the ISOLDE facility at CERN. The number of 39 Ar atoms in the layer was determined by measuring the 39 Ar β -activity using a primary standardisation method. Subsequently, the sample was irradiated with thermal neutrons at the High Flux Reactor of the Institut Laue–Langevin. An upper limit of 0.29 b was obtained for the 39 Ar ( n th , α ) 36 S reaction cross-section.

High resolution measurement of the 234U(n, f) cross section in the neutron energy range from 0.5 eV to 100 keV

Abstract The 234U(n,f) cross section has been measured in the energy range from 0.5 eV to 100 keV at the GELINA neutron time-of-flight facility of the Institute for Reference Materials and Measurements in Geel using highly enriched 234U samples. Two independent measurements were performed: one in a low detection geometry (15% of 2π) and another in a 2π detection geometry. A 235U(n,f) cross-section measurement was performed under the same experimental conditions, allowing a reliable correction for the 235U(n,f) contribution to the yield. Special attention has been given to the strongest resonance at 5.16 eV and to the fission resonance integral If, for which large discrepancies are reported in the literature.

High resolution measurement of the 36Cl(n,p)36S and 36Cl(n,α)33P reactions

Abstract New high resolution measurements of the 36 Cl(n,p) 36 S and 36 Cl(n,α) 33 P reaction cross sections are reported. Some 20 resonances have been identified in the neutron energy region from 0.1 keV to 350 keV.

Thermal neutron induced (n, p) and (n, alpha) reactions on Ar-37

The 37Ar(n_th,alpha)34S and 37Ar(n_th,p)37Cl reactions were studied at the high flux reactor of the ILL in Grenoble. For the 37Ar(n_th,alpha_0) and 37Ar(n_th,p) reaction cross sections, values of (1070+/-80)b and (37+/-4)b, respectively, were obtained. Both values are about a factor 2 smaller than results of older measurements. The observed suppression of the 37(n_th,alpha_1) transition could be verified from theoretical considerations. Finally, evidence was found for the two-step 37Ar(n_th,gamma-alpha) process. Comment: 11 pages, 5 figures, accepted for publication in Nuclear Physics A

Cross-Section Measurement of Thermal Neutron-Induced Fission on 243Cm

Abstract An experimental program was set up at SCK·CEN to determine the thermal neutron-induced fission cross section of curium isotopes. These transuranium nuclei are produced in nuclear reactors and are candidates for transmutation. This paper presents our 243Cm(n,f) measurement, yielding a cross-section value of (667 ± 26) b. A detailed analysis of the experimental results published by previous groups is performed, and the renormalized values are compared with our result. In general, a good agreement with old data is observed, questioning the values adopted by different nuclear data libraries.