Browsing by Author "Villarino, EA"

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    Calculation of the core parameters measured during the commissioning of the OPAL Reactor
    (American Nuclear Society, 2010-05-12) Villarino, EA; Hergenreder, DF; Braoudakis, G; Ersez, T
    The OPAL Research reactor is a multi-purpose open-pool type reactor. The nominal fission power of the reactor is 20 MW. It was commissioned during the second half of the year 2006. The reactor has several nuclear safety related design criteria that have to be experimentally verified during Stage B of the commissioning of the reactor. The present work presents the measurements carried out during the Stage B of the commissioning of the OPAL reactor, and the numerical verification of the calculated values using the design calculation methodology against these measured values. A brief description of the OPAL reactor, its commissioning plan, its nuclear safety related design criteria and the calculation and the experimental methodology are presented. The measured values and a comparison with the calculated is also given.
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    Contract performance demonstration tests in the OPAL
    (International Atomic Energy Agency, 2007-11-08) Hergenreder, DF; Lecot, CA; Lovotti, O; Villarino, EA; Braoudakis, G; Ersez, T
    This paper will describe the measurements and calculations that were done in the OPAL Reactor to demonstrate compliance against contractual Design Features and Performance Acceptance Criteria. The contract specifies several neutronic aspects to be fulfilled by the core, the irradiation and the beam facilities design, which have to be verified during the commissioning tests. Guaranteed flux values will be taken as being for equilibrium core conditions. The relationship between values measured during commissioning (First Core) and the guaranteed values is largely based on calculations. The calculated values are obtained modelling with full detail the measurement conditions using the INVAP traditional calculation lines: CITVAP and MCNP calculation lines. © The Authors
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    Conversion of OPAL from U3Si2 to High Density U–Mo Fuel. Annex III
    (International Atomic Energy Agency, 2021-04) Braoudakis, G; Villarino, EA
    The ongoing development of high density low enriched uranium (LEU) fuels to replace the current application of highly enriched uranium (HEU) fuels, in accordance with the non‑proliferation and security objectives of the Global Threat Reduction Initiative (GTRI), offers an opportunity to assess the impact of such fuels on performance and reactor core parameters. The performance of the current 4.8 gU/cm3 U3Si2 fuel in the Open Pool Australian Lightwater (OPAL) reactor is compared against that estimated for a variety of potential U–Mo high density fuels that range in density from 6.0 to 8.0 gU/cm3. The comparison includes cycle length, fuel usage, shutdown system performance, neutron fluxes in irradiation positions, kinetic parameters and reactivity feedback coefficients.High performance research reactors depend on a compact core design to maximize the neutron flux available for irradiation and beam facilities. The most readily available technology to achieve this goal is the use of HEU fuels. The extensive experience and demonstrable reliability and performance of such fuels makes them a clear choice for most of the high performance research reactors around the world. In addition, there are gains in fuel economy through maximization of fuel burnup and minimization of parasitic neutron absorption, which is present in some of the LEU fuels. In the spirit of GTRI, new high density LEU fuels are being developed with the intention of providing a non‑proliferation option while maintaining much of the performance expected from HEU fuels. One of the most promising high density LEU fuels is a uranium–molybdenum (U–Mo) alloy dispersion type fuel in an aluminium matrix. The addition of Mo stabilizes the uranium during irradiation and several different densities of uranium and alloy compositions are considered in this study, as no qualified fuel exists at this time.The current core design is optimized for the use of 4.8 gU/cm3 U3Si2 fuel. This study was performed while maintaining the core and fuel dimensions (specifically the fuel meat, fuel plate and coolant channel thicknesses) and only the fuel meat composition was modified. The estimated performance parameters were calculated using the same codes and methods that were used for the U3Si2 calculations. In this way a direct comparison can be made to assess the impact of using high density U–Mo fuel. © The Author