[en] The RA-6 is an open pool MTR type reactor with 500 Kw nominal power, using fuel elements enriched to 90 %. It was designed and constructed fully in Argentina and is owned and operated by the C.N.E.A. at the Bariloche Atomic Center. A design of the epithermal device was performed, analyzing different and relative sizes of the materials conforming the neutron filter to optimize the neutron spectrum and the absolute value of the epithermal flux at the beam port. This design was used also to make preliminary studies regarding the nuclear safety and solve potential licensing problems. A complete design of the internal filter was presented to the Regulatory Authority and after some feedback the filter was constructed and mounted. During this stage a very simple (without any geometry complexity) external port was used to test the free beam facility and to get a complete on phantom dosimetry. Using the previous results the new beam port was designed, built and mounted by november 1998. The final characterization of the facility was performed, obtaining a good agreement between calculated and measured values The irradiation room was designed and is being constructed to adequate the facility to irradiate patients. (author)

[en] The RA-6 research reactor is owned and operated by the National Atomic Energy Commission (CNEA) of Argentina. It is located at the Bariloche Atomic Center, Bariloche (Argentina). The reactor was entirely designed and built in Argentina and it has operated since October 1982. The main design goal was for a training reactor to support nuclear engineering education. Moreover, CNEA wanted to own a plant suitable for nuclear experiments to be performed for its Nuclear Engineering Department. To further support the role of the RA-6 as a plant comprehensively providing facilities for training and education and for experimental work, the irradiation facilities initially included in the reactor design were improved, focusing on specific interests. The appropriate personnel involvement together with student's cooperation allowed different grades of development and improvement to be achieved. Facilities involved in that process were: - Neutron Activation Analysis Laboratory (LAAN); - Boron neutron capture therapy (BNCT) facility; - Neutron radiography facility, which was designed as an academic tool mainly for teaching and training purposes, but also for industrial services; - Prompt gamma neutron activation analysis (PGNAA), designed for academic purposes and being upgraded in the framework of the current IAEA project 'New Applications on PGNAA'. The RA-6 will remain a plant capable of providing excellent capabilities and facilities for education and training

[en] The reactor RA-6 NCT system was improved during the last year mainly in two aspects: the facility itself getting lower contamination factors and using better measurements techniques to obtain lower uncertainties in its characterization. In this job we show the different steps to get the source to be used in the treatment planning code representing the NCT facility. The first one was to compare the dosimetry in a water phantom between the calculation using the entire facility including core, filter and shields and a surface source at the end of the beam. The second one was to transform this particle by particle source in a distribution one regarding the minimum spatial, energy and angular resolution to get similar results. Finally we compare calculation and experimental values with and without the water phantom to adjust the distribution source. The results are discussed. (author)

[en] This paper reviews the status and trends of the spent fuel storage and disposal in Argentina

[en] A hyperthermal beam has been developed at the RA-6 reactor Boron Neutron Capture Therapy (BNCT) facility in order to perform human clinical trials for the treatment of skin melanomas in extremities. Based on the previously developed epithermal beam, the objective was to modify it in order to improve its therapeutic gain for the treatment of skin melanomas up to 2 cm in depth. After finishing the beam set up and commissioning stage, a theoretical analysis of such beam performance has been completed, based on a clinical case of malignant melanoma in extremities. In spite of the complexity of the clinical case under review, results showed that only 4% of the tumour volume is under dosed in cases of mean blood ¹⁰B concentration values, even in the most unfavourable analysis. The overall results suggest that this BNCT facility is prepared to rigorously explore the clinical efficacy of the RA-6 beam and the BNCT treatment modality for peripheral melanomas. A special configuration was arranged for in vivo experiments with small animals like hamsters and mice. These experiments were successfully performed in order to analyze the potential of BNCT for the treatment of oral cancer in the hamster cheek pouch model and undifferentiated thyroid carcinoma. (author)

[en] The RA-6 reactor at the Bariloche Atomic Centre was designed mainly as a teaching tool. During its almost 21 years, after the first criticality, it was used as a support for several graduate and post graduate careers at the Balseiro Institute, depending on the Argentine National Atomic Energy Commission and the Cuyo National University. Besides these tasks, a big work was done in research and development using the synergy produced by the close relationship between the students and researchers. Main characteristics of the reactor are described. An outline of use for teaching and training is given. Research activities resulting from appropriate personnel management and students' cooperation that allowed achieving different grades of development are described. (author)

[en] In order to perform a beam-physical dosimetry characterization, fast neutron and gamma dose rates, and thermal neutron flux were measured along the central axis in a water-filled phantom in the RA-6 BNCT facility. Threshold activation detectors were also activated in a different approach to determine fast neutron dose. Comparison with MCNP4B calculation for the same geometry was made, in order to determine a surface source for Treatment Planning calculations. (author)

[en] Poster presentation

[en] A dual epithermal/mixed beam is available for BNCT applications at the RA-6 reactor facility. This switchable beam allows the selection of the best configuration in view of the tumour depth, optimizing the performance of the treatment. The mixed beam performance for skin melanomas has been exhaustively evaluated and the first human clinical trial has already been performed

[en] The RA-6 is an open pool MTR type reactor with 500 Kw nominal power, using fuel elements enriched to 90%. It was designed and constructed fully in Argentina and is owned and operated by the C.N.E.A. at the Bariloche Atomic Center. In this work the analysis of the different alternatives, depending on the main features of a research reactor (type, power, shielding, etc.), are showed to design a BNCT facility. After that, the different steps followed to produce the epithermal beam at the RA-6 are presented: Because only small modifications were required, the first stage was the arrangement of a thermal beam to test and validate our calculation methods and to gain expertise in the different experimental techniques to design and characterise the epithermal facility. A basic design of the epithermal device was performed, analysing different and relative sizes of the materials conforming the neutron filter to optimise the neutron spectrum and the absolute value of the epithermal flux at the beam port. This design was used also to make preliminary studies regarding the nuclear safety and solve potential licensing problems. A complete design of the internal filter was presented to the Regulatory Authority and after some feedback the filter was constructed and mounted. During this stage a very simple (without any geometry complexity) external port was used to test the free beam facility and to get a complete on phantom dosimetry. Using the previous results the new beam port was designed, built and mounted by November 1998, the final characterisation of the facility is being currently performed. Preliminary results of this job for the free beam are: φ_epithermal = 1.1 E9 n/cm² seg (0.5 eV < E < 10 KeV); D_fast/n_epi = 7.5 cGy cm²/n_epi; D_γ/n_epi 3.0 cGy cm²/n_epi5. The next goal will be to optimise the irradiation room to adequate the facility to irradiate patients. (author)