RA-3 reactor power increase at 10 MW

Full text: The RA-3 Reactor. The production and research reactor RA-3 was designed by Argentina in the 60's (first criticality in 1967) to operate at the power of 3 MW, then it underwent several upgrading changes that allowed its operation along the time to fulfil the ever growing needs of its users and to comply with the evolution of safety regulations. It is worthwhile mentioning that in the period 1988/1989 some internal structure elements of the tank were replaced, the core reconverted to low enrichment, the instrumentation upgraded, the bridge and control mechanism replaced, apart from some other changes to the refrigeration systems that allowed the reactor to increase the power to 5 MW. Even though the RA-3 is a multi-purpose reactor, different activities are carried out. They include: radiation damage studies, activation analysis, detectors assays, fuel element qualifications, etc. But the main activity has been the radioisotopes production which sustains the extended schedule operation (approximately 120 h/week, 11 month/year). The ever growing demand on radioisotopes production and the need to incorporate some other products of highly specific activity, made CNEA develop a new project, in 1997, to increase the nominal power of RA-3 reactor to 10 MW. This project to increase RA-3 power involved, among other changes, activities such as: Engineering and Licensing: Thermos hydraulic Analyses (Operations of Irradiation Plates for the Production of Mo-99, etc.); Neutron Calculus; Fuel Elements Management; Postulated Accidents Analyses; Safety Report Updating. Refrigeration System Adaptation: Primary Circuit: An additional branch was added (Pump and Heat Exchanger); Secondary Circuit: Pumps and Cooling Towers were adapted. Auxiliary and Safety Systems Adaptation: Continual Demineralization: The Resins Column of Ion Exchanger was replaced, a physical filter was added, the shielding was improved and on-line Instrumentation was placed (Conductivity gauges). Ventilation System: the sensor/controller of the depression control area and the flow gauge were replaced. The by-pass to the activated carbon filters was equipped and an on-line gas detector in the chimney is being implemented; Sample Irradiation: A Pneumatic System of Samples Irradiation was implemented. Instrumentation Adaptation: Conventional Instrumentation: new Delta P Core gauge, Conductivity gauges and on-line PH, Flow and Pressure sensors. Nuclear Instrumentation: A third Start up Canal was added, the logic of the Chamber movements was modified and the implementation of a fine control bar associated to an automatic pilot is being worked on. Data Record System: A system of Date Acquisition and Operation Parameters were implemented through a PC and its respective software and Data Acquisition Plate. (author)