| 1. |
- Schrire, David, et al.
(författare)
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Fission Gas Release in ABB SVEA 10x10 BWR Fuel
- 1997
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Ingår i: Proceedings from the International Topical Meeting on LWR Fuel Performance, Portland, Oregon, USA, march 2-5, 1997. ; , s. 8-, s. 9-
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 2. |
- Senis, Lorenzo, et al.
(författare)
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Feasibility study of gamma-ray micro-densitometry for the examination of nuclear fuel swelling
- 2021
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Nuclear fuel undergoes several thermo-mechanical changes during irradiation in a nuclear reactor, such as change of density, caused by solid and gaseous swelling. This affects the heat transport within the pellet and, when leading to the pellet-cladding gap closure, it also affects the gap conductance, causing stress in the cladding. The density of irradiated fuel pellets can be measured in post-irradiation examination using several methods. In this work, a feasibility study was made using the gamma-ray transmission micro-densitometry technique. This is based on the comparison of two intensity measurements, with and without a sample with well-characterized thickness. Using a collimated source, a local examination of the density can be performed, scanning a pellet slice radially. The proposed technique aims to obtain a spatial resolution of cca. 100 microns. In this work, the parameters of the setup, such as the source activity, detector counting time, slit dimensions, collimator length, and sample thickness, are used to predict detector efficiency and expected count rates. The obtainable precision of the density is assessed by first-order uncertainty propagation of counting errors in the gamma-ray detection to the density estimate. A collimator design was presented that achieves a reasonable compromise between time requirements, precision, and spatial resolution. The sensitivity of the performance to set-up parameters was investigated. In addition, a realistic setup was modeled in MCNP6 for validation of the peak count-rate, and to ensure that the total spectrum count-rate is within typical throughput capabilities of HPGe detectors. The MCNP model was also used to confirm that the assumed attenuation law is valid in a relevant geometry, and to assess the spatial resolution, using the 10-90% edge spread of an Edge Spread Function. It is concluded that fuel density can be determined with <1 % precision, using a 100-micron wide slit, and 1 hour of measurement.
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| 3. |
- Senis, Lorenzo, et al.
(författare)
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Performance evaluation of a novel gamma transmission micro-densitometer for PIE of nuclear fuel
- 2023
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Ingår i: Annals of Nuclear Energy. - : Elsevier. - 0306-4549 .- 1873-2100. ; 187
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Tidskriftsartikel (refereegranskat)abstract
- Collimated Gamma Transmission Micro-Densitometry (GTMD) is a novel technique proposed to investigate local density variations of nuclear fuel in PIE, with a high spatial resolution. In this work, the first experimental tests of a gamma micro-densitometer are presented and the performance is characterized. The experimental procedures are described, including the aligning process and the calibration methodology. The results demonstrated that for the calibration samples with a thickness above 5 mm, a local density was obtained with a maximum discrepancy of about 2% and a spatial resolution of about 280 µm. The setup was used for the first test on an irradiated ADOPTTM fuel pellet slice. From the measurement, an average bulk density of about 9.58 g/cm3 was calculated and local density features were observed, possibly related to rim effects or the presence of local cracks. The information acquired also presented valuable information for possible improvements in the setup’s performance.
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