Pebble Bed HTGR’s like the AVR in Ju¨lich have the advantage of continuous fuelling. However the multiple passes of the fuel pebbles through the core have the disadvantage that the pebble’s movement through the fuelling system and the core produces graphite dust. This dust is transported from the core to other parts of the primary circuit and deposits on components. Although previous experiments performed during AVR operation have given some insight into the dust particle size and activity, there is little information on the behaviour of the dust that was deposited in the system. The decommissioning of the AVR has provided the opportunity to sample and characterise such dust from a number of components and gauge the adhesion strength. From the side of PBMR Pty Ltd this opportunity is considered important to enhance the knowledge about dust characteristics before the PBMR Demonstration Power Plant (DPP) is operational and able to produce specific plant information through sampling and analysis. AVR GmbH has provided a number of pipes and joints for investigation of loose and bound dust. Phase 1 of the analysis was used to determine the best techniques to be used on larger items. No measurable loose dust could be collected. Thereupon rings were cut from a T-section and subdivided into eight segments. The surface of the untreated segments were photographed and documented by optical microscopy, the dose rates were measured and gamma-spectrometry performed. Following this a mechanical or chemical decontamination was carried out to remove and isolate the bound dust. The average isolated dust amount was about 2 mg/cm2. Both decontamination processes indicates a strong bonding of the dust surface layer. In the case of mechanical decontamination about 60% and by chemical decontamination about 95% of the radionuclide inventory could be removed. The contribution of removed metal needs to be investigated in more detail. The median number related particle size measured by optical microscopy was found to be in the range of 0.2 to 0.7 μm whereas the median weight related size is in the range of 0.8 to 1.5 μm. The initial results indicate that this dust sticks very strongly to the pipe surface. Phase 2 will concentrate on longer pieces of piping where hopefully more loose dust can be obtained and analysed. If the same strong bonding is observed the reason for this phenomenon needs to be explained and perhaps tested with non-active dust.
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Fourth International Topical Meeting on High Temperature Reactor Technology
September 28–October 1, 2008
Washington, DC, USA
Conference Sponsors:
- ASME
ISBN:
978-0-7918-4854-8
PROCEEDINGS PAPER
Examination of Dust in AVR Pipe Components
Johannes Fachinger,
Johannes Fachinger
Forschungszentrum Ju¨lich, Ju¨lich, North Rhine-Westphalia, Germany
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Heiko Barnert,
Heiko Barnert
Forschungszentrum Ju¨lich, Ju¨lich, North Rhine-Westphalia, Germany
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Alexander P. Kummer,
Alexander P. Kummer
Forschungszentrum Ju¨lich, Ju¨lich, North Rhine-Westphalia, Germany
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Guido Caspary,
Guido Caspary
Forschungszentrum Ju¨lich, Ju¨lich, North Rhine-Westphalia, Germany
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Manuel Seubert,
Manuel Seubert
Forschungszentrum Ju¨lich, Ju¨lich, North Rhine-Westphalia, Germany
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Albert Koster,
Albert Koster
Pebble Bed Modular Reactor (Pty.) Ltd., Centurion, Gauteng, South Africa
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Munyaradzi Makumbe,
Munyaradzi Makumbe
Pebble Bed Modular Reactor (Pty.) Ltd., Centurion, Gauteng, South Africa
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Lolan Naicker
Lolan Naicker
Pebble Bed Modular Reactor (Pty.) Ltd., Centurion, Gauteng, South Africa
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Johannes Fachinger
Forschungszentrum Ju¨lich, Ju¨lich, North Rhine-Westphalia, Germany
Heiko Barnert
Forschungszentrum Ju¨lich, Ju¨lich, North Rhine-Westphalia, Germany
Alexander P. Kummer
Forschungszentrum Ju¨lich, Ju¨lich, North Rhine-Westphalia, Germany
Guido Caspary
Forschungszentrum Ju¨lich, Ju¨lich, North Rhine-Westphalia, Germany
Manuel Seubert
Forschungszentrum Ju¨lich, Ju¨lich, North Rhine-Westphalia, Germany
Albert Koster
Pebble Bed Modular Reactor (Pty.) Ltd., Centurion, Gauteng, South Africa
Munyaradzi Makumbe
Pebble Bed Modular Reactor (Pty.) Ltd., Centurion, Gauteng, South Africa
Lolan Naicker
Pebble Bed Modular Reactor (Pty.) Ltd., Centurion, Gauteng, South Africa
Paper No:
HTR2008-58033, pp. 591-602; 12 pages
Published Online:
July 1, 2009
Citation
Fachinger, J, Barnert, H, Kummer, AP, Caspary, G, Seubert, M, Koster, A, Makumbe, M, & Naicker, L. "Examination of Dust in AVR Pipe Components." Proceedings of the Fourth International Topical Meeting on High Temperature Reactor Technology. Fourth International Topical Meeting on High Temperature Reactor Technology, Volume 1. Washington, DC, USA. September 28–October 1, 2008. pp. 591-602. ASME. https://doi.org/10.1115/HTR2008-58033
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