Showing papers by "Sophie Grape published in 2010"

Modeling of the Cherenkov Light Emission from Nuclear Fuel Assemblies with Partial Defects

Abstract: The International Atomic Energy Agency poses requirements on the detection and verification of partial defects of nuclear fuel assemblies before being placed in difficult-to-access storage. One instrument being considered for such detection is the Digital Cherenkov Viewing Device, with which images of the Cherenkov light from fuel assemblies in storage pools can be recorded and analyzed. This paper accounts for a software toolkit for simulating the Cherenkov photon distribution in the fuel using GEANT4. The toolkit enables the user to access information on individual photon emission coordinates and their momentum vectors, as well as to take into account the expected rod-by-rod burnup distribution at different axial levels. An example of this modeling is demonstrated.

Modelling Cherenkov light from irradiated nuclear fuel assemblies using GEANT4

Abstract: The Digital Cherenkov Viewing Device (DCVD) is currently used by International Atomic Energy Agency (IAEA) inspectors for gross defect verification of spent nuclear fuel assemblies in storage pools. A Cherenkov light image is obtained from the spent fuel and the verification is made by the detection of unique Cherenkov characteristics of spent fuel. To take further advantage of its quantitative capabilities, the DCVD’s ability to detect partial defects down to the 30% level is now being investigated. To evaluate the performance of the DCVD, simulations of the emitted and recorded light can be very useful. This presentation describes how the software toolkit GEANT4 is used to gain better understanding of the light contributions from the fuel and its environment by means of Monte Carlo simulations. The toolkit allows the user to access information on individual photon emission coordinates and their momentum vectors and it is also possible to take the expected rod-by-rod burnup distribution at different axial levels into account. Investigations have shown that the Cherenkov light production about the fuel is dominated by gamma radiation from the fuel material interacting with the water surrounding the fuel. A study of the range of the Cherenkov photon production from individual fuel rods, which is of relevance for partial-defect verification, is presented. In addition, emission distributions of Cherenkov light are presented for simulated PWR fuel assemblies with different configurations of replaced rods. Simulated light intensities in guide tubes are presented, showing variations depending on whether fuel rods nearby have been substituted or not.

Statistical grounds for determining the ability to detect partial defects using the Digital Cherenkov Viewing Device (DCVD)

Abstract: The DCVD (Digital Cherenkov Viewing Device), and its predecessor the CVD (CherenkovViewing Device), has been used by the IAEA to inspect gross defects in spent fuel. The time has now come to also write a report on the instrument’s ability to detect partial defects at the 50% level. Before this report can be finalized, the capabilities of the DCVD must of course be investigated and quantified. Discussions have arisen within the DCVD-group how this can and should be done.

Safeguards Licensing Aspects of a Future Gen IV Test Facility : A Case Study

Abstract: The scope of this study covers safeguards licensing aspects of a possible future Gen IV demonstration facility. As a basis for the investigation, the facility was assumed to be located in Sweden, comprising a lead-cooled fast reactor and a reprocessing plant with fuel fabrication. The aim has been to identify safeguards requirements that may be set by the IAEA and the Swedish Radiation Safety Authority, and also to suggest how the safeguards system could be implemented in practice. The changed usage and handling of nuclear fuel, as compared to that of today, has been examined in order to determine how today’s safeguards measures can be modified and extended to meet the needs of the demonstration facility. This work is part of GENIUS, the Swedish Gen IV research and development programme, which emphasizes lead-cooled fast reactors.