| 1. |
- Martinik, Tomas, et al.
(författare)
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Characterization of Spent Nuclear Fuel with a Differential Die-Away Instrument
- 2014
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The Differential die-away instrument (DDA) is currently being investigated within the Next Generation Safeguards Initiative Spent Fuel project as one of the non-destructive assay techniques for spent nuclear fuel characterization and verification. In this paper we report on the progress of designing the first prototype to be deployed at Swedish central interim storage facility (CLAB) where a first set of measurements of 25 PWR and 25BWR spent fuel assemblies is proposed. We also present several working concepts of how the instrument can be customized for dedicated purposes, be it a light weight instrument for portable applications, a minimalist design for reliable and economic operations or a so-called “defectoscope” design for detailed inspection of spent nuclear fuel assemblies.
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| 2. |
- Martinik, Tomas, et al.
(författare)
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Design of a Prototype Differential Die-Away Instrument proposed for Swedish Spent Nuclear Fuel Characterization
- 2016
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 821, s. 55-65
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Tidskriftsartikel (refereegranskat)abstract
- As part of the United States (US) Department of Energy’s Next Generation Safeguards Initiative Spent Fuel (NGSI-SF) project, the traditional Differential Die-Away (DDA) method that was originally developed for waste drum assay has been investigated and modified to provide a novel application to characterize or verify spent nuclear fuel (SNF). Following the promising, yet largely theoretical and simulation based, research of physics aspects of the DDA technique applied to SNF assay during the early stages of the NGSI-SF project, the most recent effort has been focused on the practical aspects of developing the first fully functional and deployable DDA prototype instrument for spent fuel. As a result of the collaboration among US research institutions and Sweden, the opportunity to test the newly proposed instrument’s performance with commercial grade SNF at the Swedish Interim Storage Facility (Clab) emerged. Therefore the design of this instrument prototype has to accommodate the requirements of the Swedish regulator as well as specific engineering constrains given by the unique industrial environment. Within this paper, we identify key components of the DDA based instrument and we present methodology for evaluation and the results of a selection of the most relevant design parameters in order to optimize the performance for a given application, i.e. test-deployment, including assay of 50 preselected spent nuclear fuel assemblies of both pressurized (PWR) as well as boiling (BWR) water reactor type.
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| 3. |
- Martinik, Tomas
(författare)
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Development of Differential Die-Away Instrument for Characterization of Swedish Spent Nuclear Fuel
- 2016
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Next Generation Safeguards Initiative Spent Fuel (NGSI-SF) project was established in 2009 by the U.S. Departmentof Energy with main objective to investigate, and potentially develop and test new technologies for spent nuclearfuel (SNF) characterization. In Sweden the SNF is currently being considered to be verified and encapsulated in canistersand deposited into a geological repository. The need for an independent instrument for SNF verification by theSwedish operator turned into the collaborative effort with NGSI-SF to develop an instrument for future deployment inSweden.One of the techniques investigated within this project is the differential die-away (DDA) technique, which followingthe theoretical investigation by means of high fidelity Monte Carlo simulations indicated the potential to be applied fordetermining of various spent fuel assembly (SFA) parameters.This work introduces the first deployable DDA instrument which was designed to be used for characterizing ofSwedish SFAs currently stored in the Central Interim Storage Facility for Spent Nuclear Fuel (Clab). All the instrumentcomponents relevant for DDA design functionality were evaluated to ensure reliable operation in Clab. Although mostof the components were tuned with special consideration given to concerns from the operator (The Spent Nuclear FuelandWaste Management Company) , several post-simulation modification of the design were made. These modificationsare described in this work.A complementary study of the detector responses to asymmetrically burned SFAs indicated a different detector responses,depending on which of the four different orientations was used to assay individual SFAs. This study illustratedthe sensitivity of detectors with respect to the SFA orientation if there is a strong burn-up gradient across the SFA andhence a strong asymmetry in isotopic distribution in the SFA. In addition, the study of asymmetry provided the informationon different operational scenarios of the DDA instrument. The DDA instrument may provide general informationabout the complete SFA as well as give local information about certain parts of the SFA.
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| 4. |
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| 5. |
- Martinik, Tomas, et al.
(författare)
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Simulation of differential die-away instrument's response to asymmetrically burned spent nuclear fuel
- 2015
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 788, s. 79-85
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Tidskriftsartikel (refereegranskat)abstract
- Previous simulation studies of differential die-away (DDA) instrument's response to active interrogation of spent nuclear fuel from a pressurized water reactor (PWR) yielded promising results in terms of its capability to accurately measure or estimate basic spent fuel assembly (SFA) characteristics, such as multiplication, initial enrichment (IE) and burn-up (BU) as well as the total plutonium content. These studies were however performed only for a subset of idealized SFAs with a symmetric BU with respect to its longitudinal axis. Therefore, to complement the previous results, additional simulations have been performed of the DDA instrument’s response to interrogation of asymmetrically burned spent nuclear fuel in order to determine whether detailed assay of SFAs from all 4 sides will be necessary in real life applications or whether a cost and time saving single sided assay could be used to achieve results of similar quality as previously reported in case of symmetrically burned SFAs.The results of this study suggest that DDA instrument response depends on the position of the individual neutron detectors and in fact can be split in two modes.The first mode, measured by the back detectors, is not significantly sensitive to the spatial distribution of fissile isotopes and neutron absorbers, but rather reflects the total amount of both contributors as in the cases of symmetrically burned SFAs. In contrary, the second mode, measured by the front detectors, yields certain sensitivity to the orientation of the asymmetrically burned SFA inside the assaying instrument. This study thus provides evidence that the DDA instrument can potentially be utilized as necessary in both ways, i.e. a quick determination of the average SFA characteristics in a single assay, as well as a more detailed characterization involving several DDA observables through assay of the SFA from all of its four sides that can possibly map the burn-up distribution and/or identify diversion or replacement of pins.
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