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Kiselev, A. N.; Checherov, K. P.

doi:10.1023/a:1014851218238

Cited by 12 publications

(4 citation statements)

References 2 publications

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“…Burnthrough observed in the subinstrumentation room below suggests there were brief and sharply directed streams of high-temperature plasma entering from above. 25 This strongly supports the hypothesis of a much stronger plasma jet aimed in the opposite direction where because of the refueling tubes through the 4-m-thick upper plate, there was substantially less resistance. Outside the southeastern quadrant the bottom plate was relatively intact, but it had dropped about 4 m into the subinstrumentation room.…”

Section: Corroborating Evidence Va Observations At the Bottom Of The Reactor Tanksupporting

confidence: 71%

“…Outside the southeastern quadrant the bottom plate was relatively intact, but it had dropped about 4 m into the subinstrumentation room. 25 This probably occurred during the subsequent steam explosion, which did not create temperatures high enough to melt the plate but generated sufficient pressure to push the bottom plate down nearly 4 m and throw the top lid some 20 to 30 m above the floor of the central hall. The top lid weighed some 2000 tons.…”

Section: Corroborating Evidence Va Observations At the Bottom Of The Reactor Tankmentioning

confidence: 99%

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A Nuclear Jet at Chernobyl Around 21:23:45 UTC on April 25, 1986

2017

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The nature of two explosions that were witnessed within 3 s at the Chernobyl-4 reactor less than a minute after 21:23:00 UTC on April 25, 1986, have since then been the subject of sprawling interpretations. This paper renders the following hypothesis. The first explosion consisted of thermal neutron mediated nuclear explosions in one or rather a few fuel channels, which caused a jet of debris that reached an altitude of some 2500 to 3000 m. The second explosion would then have been the steam explosion most experts believe was the first one. The solid support for this new scenario rests on two pillars and three pieces of corroborating evidence. The first pillar is that a group at the V. G. Khlopin Radium Institute in then Leningrad on April 29, 1986, detected newly produced, or fresh, xenon fission products at Cherepovets, 370 km north of Moscow and far away from the major track of Chernobyl debris ejected by the steam explosion and subsequent fires. The second pillar is built on state-of-the-art meteorological dispersion calculations, which show that the fresh xenon signature observed at Cherepovets was only possible if the injection altitude of the fresh debris was considerably higher than that of the bulk reactor core releases that turned toward Scandinavia and central Europe. These two strong pieces of evidence are corroborated by what were manifest physical effects of a downward jet in the southeastern part of the reactor, by seismic measurements some 100 km west of the reactor, and by observations of a blue flash above the reactor a few seconds after the first explosion.

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Section: Corroborating Evidence Va Observations At the Bottom Of The Reactor Tanksupporting

confidence: 71%

Section: Corroborating Evidence Va Observations At the Bottom Of The Reactor Tankmentioning

confidence: 99%

A Nuclear Jet at Chernobyl Around 21:23:45 UTC on April 25, 1986

2017

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“…The accident that occurred at the 4 th reactor of the Chernobyl Nuclear Power Plant on April 28 th 1986 resulted in complete melting of the reactor core with severe consequences. It generated large amounts of highly radioactive nuclear fuel-containing materials, including so-called lava-like fuel-containing materials (LFCMs), [1][2][3][4] which have also been identied at the Fukushima Daiichi nuclear power plant. LFCM, a mixture of nuclear fuel and melted reactor components (stainless steel, concrete etc.…”

Section: Introductionmentioning

confidence: 99%

Safely probing the chemistry of Chernobyl nuclear fuel using micro-focus X-ray analysis

et al. 2021

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“…In this contribution, we describe the development of methods to quantitatively estimate U oxidation states, in micrometre-sized pixels, within m-XRF maps collected at multiple energies over the U L 3 absorption edge. For the purpose of method development, we apply these methods to investigate representative low-activity simulant Chernobyl LFCMs, that closely approximate the composition and microstructure of the core melt down product formed in the Chernobyl nuclear accident (Kiselev & Checherov, 2001;Ushakov et al, 1996;Burakov et al, 1997;Borovoi et al, 1998), but without the inclusion of short-lived fission product nuclides (Barlow et al, 2017(Barlow et al, , 2020Ding et al, 2021). Previous investigation of simulant LFCMs by analysis of bulk U L 3 XANES demonstrated a narrow range of average oxidation states of 4.0-4.5+ (Barlow et al, 2017(Barlow et al, , 2020.…”

mentioning

confidence: 99%

Chemical state mapping of simulant Chernobyl lava-like fuel containing material using micro-focused synchrotron X-ray spectroscopy

Ding¹,

Wilkins²,

Mottram³

et al. 2021

J Synchrotron Radiat

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Uranium speciation and redox behaviour is of critical importance in the nuclear fuel cycle. X-ray absorption near-edge spectroscopy (XANES) is commonly used to probe the oxidation state and speciation of uranium, and other elements, at the macroscopic and microscopic scale, within nuclear materials. Two-dimensional (2D) speciation maps, derived from microfocus X-ray fluorescence and XANES data, provide essential information on the spatial variation and gradients of the oxidation state of redox active elements such as uranium. In the present work, we elaborate and evaluate approaches to the construction of 2D speciation maps, in an effort to maximize sensitivity to the U oxidation state at the U L 3-edge, applied to a suite of synthetic Chernobyl lava specimens. Our analysis shows that calibration of speciation maps can be improved by determination of the normalized X-ray absorption at excitation energies selected to maximize oxidation state contrast. The maps are calibrated to the normalized absorption of U L 3 XANES spectra of relevant reference compounds, modelled using a combination of arctangent and pseudo-Voigt functions (to represent the photoelectric absorption and multiple-scattering contributions). We validate this approach by microfocus X-ray diffraction and XANES analysis of points of interest, which afford average U oxidation states in excellent agreement with those estimated from the chemical state maps. This simple and easy-to-implement approach is general and transferrable, and will assist in the future analysis of real lava-like fuel-containing materials to understand their environmental degradation, which is a source of radioactive dust production within the Chernobyl shelter.

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Cited by 12 publications

References 2 publications

A Nuclear Jet at Chernobyl Around 21:23:45 UTC on April 25, 1986

A Nuclear Jet at Chernobyl Around 21:23:45 UTC on April 25, 1986

Safely probing the chemistry of Chernobyl nuclear fuel using micro-focus X-ray analysis

Chemical state mapping of simulant Chernobyl lava-like fuel containing material using micro-focused synchrotron X-ray spectroscopy

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