A Review of Root Causes of SCC Phenomena in BWR/RBMK: Issues, Approaches, and Proposals

2004 ◽  
Author(s):  
Genn Saji
Keyword(s):  
Current Approach ◽  
Long Distance ◽  
Electric Conductor ◽  
Soil Corrosion ◽  
Electrolytic Corrosion ◽  
Radiation Induced ◽  
Hypothetical Mechanism ◽  
Local Cell ◽  
Corrosive Environments ◽  
Autocatalytic Growth

The author looked for potential mechanisms deemed insignificant in the early stages of SCC research and the current approach used in SCC studies were selected. The basis for those mechanisms was in non-nuclear corrosive environments as well as analyses of redox potential data measured under radiation. Three possible mechanisms were identified; ‘long cell action (which suppresses local cell cathodic activities and accelerates remote local cell anodic activities),’ ‘autocatalytic growth of cracks in crevice water chemistry,’ and ‘transpassive corrosion of stainless steel.’ The ‘long cell action’ has been identified as a key mechanism of soil corrosion which is induced by a difference in the availability of oxygen inside the soil. In this mechanism, conduction of electrons through an electric conductor over a long distance plays a significant role. This author proposes a hypothetical mechanism that states; ‘radiation-induced ‘long cell action’ causing electrolytic corrosion.’

A Review of Root Causes of SCC Phenomena in BWR/RBMK: An Overview of Radiation-Induced Long Cell Action Relevant to SCC

2004 ◽  
Author(s):  
Genn Saji
Keyword(s):  
Nuclear Reactor ◽  
Basic Mechanism ◽  
Companion Paper ◽  
Metallic Ions ◽  
Long Distance ◽  
Electric Conductor ◽  
Radiation Induced ◽  
Hypothetical Mechanism ◽  
Water Reactors ◽  
Underground Corrosion

In a review of recent occurrences of Stress Corrosion Cracking (SCC) in Japanese Boiling Water Reactors (BWRs) and Russian High Power Channel-type Reactors (RBMKs), the author proposes a hypothetical mechanism which states; ‘radiation-induced ‘long cell action’ causing electrolytic corrosion.’ This article provides the currently available technical bases for the proposed mechanism which was introduced in a companion paper also presented at this conference [1]. There is some experimental evidence indicating that long cell action may not be negligible in nuclear reactor environments, when induced by the radiolysis of water. There are also some surprising similarities between SCC in the reactor systems and the basic mechanism of underground corrosion by long cell action. In this mechanism, the ‘long cell action’ is induced by a difference in availability of oxygen inside the soil. Conduction of electrons through an electric conductor over a long distance plays a significant role as they are released by dissolution of metallic ions and sucked up from the metal surface.

Radiation-Induced Electrolytic Corrosion of LWRS: (Part 2) — Verification of In- and Out-Core Redox Potential Differences

2016 ◽  
Author(s):  
Genn Saji
Keyword(s):  
Dielectric Property ◽  
Redox Potential ◽  
Single Point ◽  
Ionic Species ◽  
Nernst Equation ◽  
Radiation Chemical ◽  
Potential Shift ◽  
Reactor Water ◽  
Electrolytic Corrosion ◽  
Radiation Induced

The author recently identified that there should exist a “differential radiation cell” mechanism in the reactor water, prompting “radiation-induced electrolytic (RIE)” phenomena. This mechanism was identified while trying to theoretically reconstruct the potential differences observed in two in-pile test loops; NRI-Rez in Czech Republic and INCA Loop in Sweden. Part 2 of this series focuses on the theoretical reconstruction of the observed potential differences. Assuming a state of equilibrium, the author tried to develop a formalism by extending the Nernst equation to reproduce the observed redox potential differences. The radiological potential shift term is separated from the Nernst equation where the latter deals only with stable molecular and ionic species. The radiological effect is described as a perturbation term to the Nernst equation representing a potential shift due to radiation-chemical reactions which should diminish to zero without radiation. The theory generally reproduced the experimental results after fitting the theoretical curve at a single point of the potential for both PWR and BWR-NWC water chemistry environments. This discrepancy is likely due to the “conductive-dielectric property” of the reactor water.

scholarly journals International tuberculosis contact-tracing notifications in Germany: Analysis of national data from 2010-2018 and implications for efficiency

2020 ◽  
Author(s):  
Saskia Glasauer ◽  
Stefan Kröger ◽  
Walter Haas ◽  
Nita Perumal
Keyword(s):  
National Level ◽  
Current Approach ◽  
Air Travel ◽  
International Travel ◽  
International Standards ◽  
Contact Tracing ◽  
Sputum Smear ◽  
Long Distance ◽  
Robert Koch Institute ◽  
International Contact

Abstract Background International contact-tracing (CT) following exposure during long-distance air travel is resource-intensive, whereas evidence for risk of tuberculosis (TB) transmission during international travel is weak. In this study, we systematically analyzed the information from international requests for CT received at the national level in Germany in order to evaluate the continued utility of the current approach and to identify areas for improvement. Methods An anonymized archive of international CT notifications received by the Robert Koch Institute between 2010 and 2018 was searched for key parameters for data collection. A total of 31 parameters, such as characteristics of TB patients and their identified contacts, were extracted from each CT notification and collated into a dataset. Descriptive data analysis and trend analyses were performed to identify key characteristics of CT notifications, patients, and contacts over the years. Results 192 CT notifications, each corresponding to a single TB index case were included in the study, increasing from 12 in 2010 to 41 in 2018. The majority of notifications (N=130, 67.7%) concerned international air travel, followed by private contact (N=39, 20.3%) and work exposure (N=16, 8.3%). 159 (82.8%) patients had sputum smear results available, of which 147 (92.5%) were positive. Of 119 (62.0%) patients with drug susceptibility testing results, most (N=92, 77.3%) had pan-sensitive TB, followed by 15 (12.6%) with multi-drug resistant TB. 115 (59.9%) patients had information on infectiousness, of whom 99 (86.1%) were considered infectious during the exposure period. 7 (5.3%) patients travelled on long-distance flights despite a prior diagnosis of active TB. Of the 771 contact persons, 34 (4.4%) could not be reached for CT measures due to lack of contact information. Conclusion The high variability in completeness of information contained within the international CT requests emphasizes the need for international standards for reporting of CT information. With the large proportion of TB patients reported to have travelled while being infectious in our study, we feel that raising awareness among patients and health professionals to detect TB early and prevent international long-distance travel during the infectious disease phase should be a cornerstone strategy to safeguard against possible transmission during international travel.

Effect of vacancies on the nucleation of Cr precipitates at grain boundary in α-Fe

2019 ◽  
Vol 97 (8) ◽  
pp. 842-846
Author(s):  
Y.Y. Dai ◽  
L. Yang ◽  
J.L. Nie ◽  
S.M. Peng ◽  
X.G. Long ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundary ◽  
Model Potential ◽  
Nucleation Mechanism ◽  
Atomic Model ◽  
Long Distance ◽  
Vacancy Clusters ◽  
Vacancy Migration ◽  
Migration Mechanism ◽  
Radiation Induced

Effect of local vacancies on the nucleation of Cr precipitates at Σ3 ⟨110⟩ {112} grain boundary (GB) in α-Fe has been studied using molecular dynamics with a two-band embedded atomic model potential. Radiation-induced vacancies and Cr atoms were directly introduced into the GB core. The local vacancies affect the accumulation of Cr atoms and the evolution of the GB. It is of interest to find that high vacancy concentrations enhance the long-distance migration of Cr, which is mainly correlated to the vacancy migration mechanism, thus leading to the formation of large vacancy-diluted Cr precipitates near the GB plane. Also, the large vacancy clusters are found to be depleted by Cr atoms during relaxation. The accumulation of vacancies and nucleation of Cr precipitates at the GB lead to significant deformation of the GB structure, resulting in the displacement and broadening of the GB. Without vacancies, the GB tends to climb perpendicular to the GB axis. The current research could help in understanding the nucleation mechanism of Cr precipitates at the GB in α-Fe.

Current Approach to Planning Angiography and MAA Administration

2021 ◽  
Vol 38 (04) ◽  
pp. 397-404
Author(s):  
Clayton W. Commander ◽  
David M. Mauro
Keyword(s):  
Optimal Dose ◽  
Current Approach ◽  
Medicine Department ◽  
Transarterial Radioembolization ◽  
Adjacent Structures ◽  
Diagnostic Angiography ◽  
Radiation Induced ◽  
Diseased Liver ◽  
Hepatic Malignancies ◽  
Yttrium 90

AbstractTransarterial radioembolization of primary and secondary hepatic malignancies utilizing yttrium-90 microspheres is a commonly performed treatment by interventional radiologists. Traditionally performed as a two-part procedure, a diagnostic angiography is performed 1 to 3 weeks prior to treatment with the injection of technetium-99m-macroaggregated albumin followed by planar scintigraphy in the nuclear medicine department. Careful attention must be paid to the details during the diagnostic angiography to ensure the delivery of a safe and optimal dose to the diseased liver and to minimize radiation-induced damage to both unaffected liver and adjacent structures. In this article, we will review the steps and considerations that must be made during the angiography planning and discuss current and future areas of research.

The Time Course of Long-Distance Signaling in Radiation-Induced Bystander EffectIn VivoinArabidopsis thalianaDemonstrated Using Root Micro-Grafting

2011 ◽  
Vol 176 (2) ◽  
pp. 234-243 ◽  
Author(s):  
Ting Wang ◽  
Fanghua Li ◽  
Shuyan Xu ◽  
Po Bian ◽  
Yuejin Wu ◽  
...  
Keyword(s):  
Time Course ◽  
Long Distance ◽  
Radiation Induced

scholarly journals Myocardial Disease and Long-Distance Space Travel: Solving the Radiation Problem

2021 ◽  
Vol 8 ◽  
Author(s):  
Manon Meerman ◽  
Tom C. L. Bracco Gartner ◽  
Jan Willem Buikema ◽  
Sean M. Wu ◽  
Sailay Siddiqi ◽  
...  
Keyword(s):  
Cardiovascular Disease ◽  
Cardiovascular System ◽  
Space Radiation ◽  
Space Travel ◽  
Long Distance ◽  
Radiation Problem ◽  
Microvascular Damage ◽  
Different Types ◽  
Radiation Induced ◽  
Underlying Mechanisms

Radiation-induced cardiovascular disease is a well-known complication of radiation exposure. Over the last few years, planning for deep space missions has increased interest in the effects of space radiation on the cardiovascular system, as an increasing number of astronauts will be exposed to space radiation for longer periods of time. Research has shown that exposure to different types of particles found in space radiation can lead to the development of diverse cardiovascular disease via fibrotic myocardial remodeling, accelerated atherosclerosis and microvascular damage. Several underlying mechanisms for radiation-induced cardiovascular disease have been identified, but many aspects of the pathophysiology remain unclear. Existing pharmacological compounds have been evaluated to protect the cardiovascular system from space radiation-induced damage, but currently no radioprotective compounds have been approved. This review critically analyzes the effects of space radiation on the cardiovascular system, the underlying mechanisms and potential countermeasures to space radiation-induced cardiovascular disease.

Radiation-Induced Electrolytic Corrosion of LWRS: (Part 1) — Basic Mechanism and Implications in Degradation Phenomena

2016 ◽  
Author(s):  
Genn Saji
Keyword(s):  
Water Chemistry ◽  
High Purity ◽  
Basic Mechanism ◽  
Core Region ◽  
Reactor Water ◽  
Pile Test ◽  
Electrolytic Corrosion ◽  
Radiation Induced ◽  
High Concentrations ◽  
Solute Species

The author recently found that there should exist a “radiation-induced electrolytic (RIE)” mechanism in the reactor water inducing severe interaction between structural materials and their environments in aged LWRs. This mechanism was identified while trying to theoretically reconstruct the potential differences observed in two in-pile test loops; NRI-Rez in Czech Republic and INCA Loop in Sweden. These results are indicating that the in-core potential is approximately 0.1/0.4volt higher, in BWR(NWC)/PWR water chemistry respectively, when compared to the out-core regions. Through modeling studies, it was found that the concentrations of (DH)/(DO) for PWR/BWR(NWC) are higher/lower respectively, in the in-core region compared with the out-of-core region. These solute species in high concentrations should spontaneously decompose at the out-of-core region, enabling control of their water chemistry. This mode of corrosion cell has been dismissed in the nuclear community considering that the transport of ions with flow is insignificant due to high purity of reactor water. Part 1 of this paper focuses on how the RIE phenomena are prompted although the reactor water is kept in high purity. The stable molecular species in the reactor water flow transport the valence electrons. They are released at the cathodic in-core region and are recovered at the anodic out-of-core region. Thus estimated potential differences have been benchmarked with the published in-pile test results for both PWR- and BWR water chemistry environments as explained in Part 2 of this series (1).

Radiation‐induced Changes in Stimulant Pharmacokinetics Relevant to Long‐distance Space Travel

2020 ◽  
Vol 34 (S1) ◽  
pp. 1-1
Author(s):  
Michael D. Hambuchen ◽  
Anna Mazur ◽  
David L. Findley ◽  
Mitchell R. McGill
Keyword(s):  
Space Travel ◽  
Long Distance ◽  
Radiation Induced ◽  
Induced Changes
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