BELGONUCLEAIRE has been operating the Dessel MOX plant at an industrial scale between 1986 and 2006. During this period, 40 metric tons of plutonium (HM) have been processed into 90 reloads of MOX fuel for commercial light water reactors. The decision to stop the production in 2006 and to decommission the MOX plant was the result of the shrinkage of the MOX fuel market due to political and commercial factors. As a significant part of the decommissioning project of the Dessel MOX plant, about 170 medium-sized glove-boxes and about 1.200 metric tons of structure and equipment outside the glove-boxes are planned for dismantling. The license for the dismantling of the MOX plant was granted by Royal Decree in 2008 and the dismantling started in March 2009. The dismantling works are carried out by an integrated organization under leadership and responsibility of BELGONUCLEAIRE; this organization includes 3 main contractors, namely Tecnubel N.V., the THV (‘Tijdelijke HandelsVereniging’) Belgoprocess / SCK•CEN and Studsvik GmbH and TRACTEBEL ENGINEERING as project manager. In this paper, after having described the main characteristics of the project, the authors review the different organizational and technical options considered for the decommissioning of the glove-boxes; thereafter the main decision criteria (qualification of personnel and of processes, confinement, cutting techniques & radiation protection, safety aspects, alpha-bearing waste management) are analyzed as well. Finally the progress, the feedback and the lessons learned at the end of August 2013 are presented, giving the principal’s and contractors point of view.

Decommissioning of nuclear facilities is a complex process involving operations such as detailed surveys, decontamination and dismantling of equipment’s, demolition of buildings and management of resulting waste and nuclear materials if any. This process takes place in a well-developed legal framework and is controlled and followed-up by stakeholders like the Safety Authority, the Radwaste management Agency and the Safeguards Organism. In the framework of its nuclear waste and decommissioning program and more specifically the decommissioning of the BR3 reactor, SCK•CEN has developed different software tools to secure the waste and material traceability, to support the sound management of the decommissioning project and to facilitate the control and the follow-up by the stakeholders. In the case of Belgium, it concerns the Federal Agency for Nuclear Control, the National Agency for radioactive waste management and fissile material and EURATOM and IAEA. In 2005, BELGONUCLEAIRE decided to shutdown her Dessel MOX fuel fabrication plant and the production stopped in 2006. According to the final decommissioning plan (“PDF”) approved by NIRAS, the decommissioning works should start in 2008 at the earliest. In 2006, the management of BELGONUCLEAIRE identified the need for an integrated database and decided to entrust SCK•CEN with its development, because SCK•CEN relies on previous experience in comparable applications namely already approved by authorities such as NIRAS, FANC and EURATOM. The main objectives of this integrated software tool are: • simplified and updated safeguards • waste & material traceability • computerized documentation • support to project management • periodic & final reporting to waste and safety authorities. The software called DASAO (Database for Safeguards, Waste and Decommissioning) was successfully commissioned in 2008 and extensively used from 2009 to the satisfaction of BELGONUCLEAIRE and the stakeholders. SCK•CEN is now implementing a simplified release of the software for the management of the decommissioning of the THETIS reactor. Its decommissioning will start in March 2013 and will be completed by the end of 2014.

BELGONUCLEAIRE has been operating the Dessel MOX plant at industrial scale between 1986 and 2006. In this period, 40 metric tons of plutonium (HM) has been processed into 90 reloads of MOX fuel for commercial light water reactors. The decision to stop the production in 2006 and to decommission the MOX plant was the result of the shrinkage of the MOX fuel market owing to political and customer’s factors. As a significant part of the decommissioning project of the Dessel MOX plant, about 170 medium-sized glove boxes and about 1.300 metric tons of structure and equipment outside the glove boxes are planned for decommissioning. The license for the decommissioning of the MOX plant was granted by Royal Decree in 2008 and the decommissioning works started in March 2009; the decommissioning works are executed by an integrated organization under leadership and responsibility of BELGONUCLEAIRE with 3 specialized contractors, namely TECNUBEL N.V., the joint venture (THV) BELGOPROCESS / SCK·CEN and STUDSVIK GmbH. In this paper, after having described the main characteristics of the project, the authors introduce the different organisational and technical options considered for the decommissioning of the glove boxes, and the main decision criteria (qualification of personnel and of processes, confinement, cutting techniques & radiation protection, safety aspects, alpha-bearing waste management) are analyzed as well. The progress, the feedback and the lessons learned mid 2011 are presented, giving the principal’s and contractors point of view as well.

BELGONUCLEAIRE has been operating the Dessel plant from the mid-80’s at industrial scale. In this period, over 35 metric tons of plutonium (HM) has been processed into almost 100 reloads of MOX fuel for commercial west-european light water reactors. In late 2005, the decision was made to stop the production because of the shortage of the MOX fuel market remaining accessible to BELGONUCLEAIRE. As a significant part of the decommissioning project of this Dessel plant, about 170 medium-sized glove boxes and about 1.300 metric tons of structure and equipment outside the glove boxes are planned for dismantling. The dismantling works are expected to start in the second quarter of 2009. On account of stringent internal rules of alpha-containment during over 25 years of operation, there is no significant contamination of the plant, outside the glove boxes; that assumption has been confirmed by radiological surveys performed by independent bodies in 2001 and 2008. Therefore most of the materials outside the glove boxes that were not a priori destined for radioactive waste will be released without restriction on the basis of the applicable legal regulations in Belgium (ARBIS), along with the buildings and the plant site. In this paper, after having reviewed the different regulations in Belgium, the authors introduce the different options considered for release of materials, and the main decision criteria (process, safety aspects, radiological, etc) for the different expected types of materials (inert materials, metals, plastics, electrical cabinets and cables and electronics) are analysed. Besides the regulatory aspects, the technological and economical aspects are considered (as an example, comprehensive metal smelting is implemented, as a favourite solution because it provides with decontamination, homogeneization and volume characterization).

The multistep direct TUL model has been extended in order to account for nuclear deformation. The new formalism was tested in calculations of neutron emission spectra from the $^{232}\mathrm{Th}$($n$, $\mathit{xn}$) reaction. These calculations include vibration-rotational coupled channels for the inelastic scattering to low-lying collective levels, ``deformed'' multistep direct (MSD) for inelastic scattering to the continuum, multistep compound, and Hauser-Feshbach with advanced treatment of the fission channel. Prompt fission neutrons were also calculated. The comparison with experimental data shows clear improvement over the ``spherical'' MSD calculations and JEFF-3.1 and JENDL-3.3 evaluations. Similar calculational results have been obtained of neutron emission spectra from the stable deformed nuclei $^{181}\mathrm{Ta}$ and $^{184}\mathrm{W}$.

EMPIRE is a modular system of nuclear reaction codes, comprising various nuclear models, and designed for calculations over a broad range of energies and incident particles. A projectile can be a neutron, proton, any ion (including heavy-ions) or a photon. The energy range extends from the beginning of the unresolved resonance region for neutron-induced reactions (∽ keV) and goes up to several hundred MeV for heavy-ion induced reactions. The code accounts for the major nuclear reaction mechanisms, including direct, pre-equilibrium and compound nucleus ones. Direct reactions are described by a generalized optical model (ECIS03) or by the simplified coupled-channels approach (CCFUS). The pre-equilibrium mechanism can be treated by a deformation dependent multi-step direct (ORION + TRISTAN) model, by a NVWY multi-step compound one or by either a pre-equilibrium exciton model with cluster emission (PCROSS) or by another with full angular momentum coupling (DEGAS). Finally, the compound nucleus decay is described by the full featured Hauser-Feshbach model with γ-cascade and width-fluctuations. Advanced treatment of the fission channel takes into account transmission through a multiple-humped fission barrier with absorption in the wells. The fission probability is derived in the WKB approximation within the optical model of fission. Several options for nuclear level densities include the EMPIRE-specific approach, which accounts for the effects of the dynamic deformation of a fast rotating nucleus, the classical Gilbert-Cameron approach and pre-calculated tables obtained with a microscopic model based on HFB single-particle level schemes with collective enhancement. A comprehensive library of input parameters covers nuclear masses, optical model parameters, ground state deformations, discrete levels and decay schemes, level densities, fission barriers, moments of inertia and γ-ray strength functions. The results can be converted into ENDF-6 formatted files using the accompanying code EMPEND and completed with neutron resonances extracted from the existing evaluations. The package contains the full EXFOR (CSISRS) library of experimental reaction data that are automatically retrieved during the calculations. Publication quality graphs can be obtained using the powerful and flexible plotting package ZVView. The graphic user interface, written in Tcl/Tk, provides for easy operation of the system. This paper describes the capabilities of the code, outlines physical models and indicates parameter libraries used by EMPIRE to predict reaction cross sections and spectra, mainly for nucleon-induced reactions. Selected applications of EMPIRE are discussed, the most important being an extensive use of the code in evaluations of neutron reactions for the new US library ENDF/B-VII.0. Future extensions of the system are outlined, including neutron resonance module as well as capabilities of generating covariances, using both KALMAN and Monte-Carlo methods, that are still being advanced and refined.

Abstract. The flux of energetic light ions at low altitude is both an important input and output for self-consistent calculations of albedo particles resulting from the interaction of trapped and cosmic ray particles, with the upper atmosphere. In addition, data on the flux of light ions are needed to evaluate radiation damages on space-borne instruments and on space mission crews. In spite of that, sources of data on the flux of energetic ions at LEO are roughly limited to the AP-8 model, CREME/CREME96 codes and the SAMPEX, NOAA/TIROS satellites. The existing and operational European SAC-C/ICARE and PROBA-1/SREM instruments could also be potential sources for proton data at LEO. Although AP-8 and SAMPEX/PSB97 may be publicly accessed through the SPENVIS, they exhibit an order of magnitude difference in low altitude proton fluxes and they do not contain helium fluxes. Therefore, improved light ion radiation models are still needed. In this paper we present a procedure to identify and measure the energy of ions that are not stopped in the NINA-2 instrument. Moreover, problems related to particles that cross the instrument in the opposite direction are addressed and shown to be a possible cause of particle misidentification. Measuring fluxes of low abundance elements like energetic helium ions requires a good characterisation of all possible sources of backgrounds in the detector. Hints to determine the several contributions to the background are presented herein and may be applied to extract an order of magnitude of energetic ions fluxes from existing data sets, while waiting for dedicated high performance instruments.

The alpha-contaminated solid waste generated in Belgium results from past activities in the fuel cycle (R&D + Reprocessing and MOX fabrication pilot plants) and operation of BELGONUCLEAIRE’s MOX fuel fabrication plant. After the main steps in the management of alpha-contaminated solid waste were established, BELGONUCLEAIRE, with the support of BELGOPROCESS and ONDRAF/NIRAS, started the design and construction of the T & C and interim-storage facilities for this alpha waste. The accumulated solid alpha radwaste containing a mixture of combustible and non-combustible material must be sorted and characterized. After sorting, both the accumulated and recently-generated alpha waste will be compacted and the pellets will be embedded in a cement matrix in a 400-1 drum. The commissioning of the sorting unit which includes glove boxes was completed at BP, at the beginning of year 2005; the sorting campaign of 30-1 cans has been achieved in March 2007. The paper describes the project environment and gives a short description of the used facilities; the lessons learned from the sorting campaign and from the first T/C period, will be presented, as well.

The Waste Drum Characterization installation was originally developed for the assay of alpha-bearing waste in standard 200 l (55 gallons) drums during the dismantling operations of the Siemens mixed-oxide (MOX) facility in Hanau (Germany). That installation was validated and qualified by the German authorities, its main performances being: - Counting efficiency for coincident neutrons: app. 1%; - Lowest Limit of Detection (LLD): 75 mg 240Pueq; - Pu content per drum: up to 100 g tot. (35 g 240Pueq); - Measurement duration: app. 20 minutes. The success of this system, a passive neutron coincidence counter combined with a high resolution gamma spectrometer, led to the radiological characterization and qualification of about 1,700 drums during the period 2001 – 2004. In 2005, after completion of the dismantling operations of the Siemens MOX facility, Tecnubel took over the WDC installation which could be used in the frame of the future dismantling of the Belgonucleaire’s MOX plant in Dessel (Belgium), which can be comparable to the Siemen’s one. This second (and new) life for the WDC means that it must be rigorously retested and validated against the Belgian authorities requirements. Furthermore, and additionally to the future use in the Belgonucleaire’s facility, Tecnubel was faced with new challenges, namely: - Assay of 400 l drums together with the 200 l packages; - Determination of the real LLD taking into account the background in different Belgian nuclear facilities, the determination of a value of ∼5 mg 240Pueq being an objective; - Assay of mixed alpha/beta-gamma wastes; - Transportability of the WDC from one plant to another; - Assistance to different nuclear operators for the licensing of the WDC for their own waste types. This paper describes the installation itself and its performances, presents the difficulties encountered during the new challenge and the results of the performed revalidation tests; it gives the perspectives and objectives on short time as well.