scholarly journals QUANTOM® − Optimization of the online neutron flux measurement system

2020 ◽  
Vol 225 ◽  
pp. 06014
Author(s):  
Olaf J. Schumann ◽  
Theo Köble ◽  
Andreas Havenith ◽  
Bo Fu ◽  
Laurent Coquard
Keyword(s):  
Neutron Flux ◽  
Specific Activity ◽  
A Priori ◽  
Flux Measurement ◽  
Hazardous Substances ◽  
Nondestructive Methods ◽  
Spatially Resolved ◽  
Reconstruction Performance ◽  
Final Design ◽  
Gamma Neutron Activation

For the final disposal of radioactive waste, the waste packages have to meet the acceptance requirements defined by national licensing and supervisory authorities. Nondestructive methods are very much preferred over destructive methods for the qualification or re-qualification. Existing nondestructive methods as integral or segmented gamma scanning or neutron counting only determine the isotope specific activity but do not allow quantifying other non-radioactive hazardous substances. These should have been documented during creation, conditioning, and packaging of the waste. But especially for legacy waste, this documentation is often poor or even missing. This gap is to be filled by the QUANTOM® measurement device that will determine the mass fraction of elements within a 200-l-drum using the Prompt- and Delayed- Gamma-Neutron-Activation-Analysis. In order to obtain a spatially resolved characterization, it will employ a segmented scanning approach. For the determination of the absolute mass fractions, the neutron flux inside the drum has to be known accurately. As the waste itself will alter the neutron distribution and flux, it is not possible to calculate the latter a priori from the gamma measurement. Hence the neutron flux has to be measured simultaneously with the gamma radiation. In this presentation, we will introduce the system for measuring the thermal neutron flux surrounding the waste drum from which the flux within the waste package has to be reconstructed. We performed a simulation study to score several possible detector placements for an improved reconstruction performance. We will show the outcome of these calculations and present the final design of the detector arrangement.

Neutron flux measurement at the Baksan Underground Scintillation Telescope

2018 ◽  
Vol 49 (1) ◽  
pp. 97-100
Author(s):  
M. M. Kochkarov ◽  
M. M. Boliev ◽  
I. M. Dzaparova ◽  
R. V. Novoseltseva ◽  
Yu. F. Novoseltsev ◽  
...  
Keyword(s):  
Neutron Flux ◽  
Flux Measurement ◽  
Baksan Underground Scintillation Telescope

Possible Implementation of Ex-core Measurement in TEPLATOR Graphite Reflector

2021 ◽  
Author(s):  
Eva Vilimova ◽  
Tomas Peltan ◽  
Jana Jiricková
Keyword(s):  
Neutron Flux ◽  
District Heating ◽  
Flux Measurement ◽  
Heating System ◽  
Fast Response ◽  
Reactor Power ◽  
Measuring System ◽  
Monte Carlo Code ◽  
District Heating System ◽  
And Control

Abstract An ex-core neutron flux measurement is a crucial system for all common power reactors. It is necessary to monitor the neutron flux and control the chain reaction, therefore the ex-core neutron flux measurement is one of the main safety and control systems. The main advantage of this arrangement of detectors is a fast response to neutron flux change, which determines the reactor power change. Regarding to the new reactor concepts, it is important to deal with improved detection systems suitable for these reactors. Many of the modern reactor concepts are based on a graphite moderator or reflector, which is also the case of the TEPLATOR. The TEPLATOR is a solution of a district heating system based on heavy water as a moderator and graphite as a reflector. The TEPLATOR is designed to use irradiated fuel from the commercial PWR or BWR reactors, which has low to intermediate burnup. This article is focused on the verification of the possible use of the special neutron measuring system placed in the graphite reflector. The Monte Carlo code Serpent was used for the calculations performed in this article.

Methodological errors in radioisotope flux measurements

1988 ◽  
Vol 255 (5) ◽  
pp. G696-G699
Author(s):  
R. W. Egnor ◽  
S. G. Vaccarezza ◽  
A. N. Charney
Keyword(s):  
Specific Activity ◽  
Flux Measurement ◽  
Sampling Interval ◽  
Flux Chamber ◽  
Sources Of Error ◽  
Counting Time ◽  
Flux Measurements ◽  
The Absolute ◽  
The Difference ◽  
Serial Samples

We examined several sources of error in isotopic flux measurements in a commonly used experimental model: the study of 22Na and 36Cl fluxes across rat ileal tissue mounted in the Ussing flux chamber. The experiment revealed three important sources of error: the absolute counts per minute, the difference in counts per minute between serial samples, and averaging of serial samples. By computer manipulation, we then applied hypothetical changes in the experimental protocol to generalize these findings and assess the effect and interaction of the absolute counts per minute, the sampling interval, and the counting time on the magnitude of the error. We found that the error of a flux measurement will vary inversely with the counting time and the difference between the consecutive sample counts per minute used in the flux calculations and will vary directly with the absolute counts per minute of each sample. Alteration of the "hot" side specific activity, the surface area of the tissue across which flux is measured and the sample volume have a smaller impact on measurement error. Experimental protocols should be designed with these methodological considerations in mind to minimize the error inherent in measuring isotope flux.

Neutron flux measurement using activated radioactive isotopes at the Baksan underground scintillation telescope

2016 ◽  
Vol 47 (6) ◽  
pp. 980-985 ◽  
Author(s):  
M. M. Kochkarov ◽  
I. A. Alikhanov ◽  
M. M. Boliev ◽  
I. M. Dzaparova ◽  
R. V. Novoseltseva ◽  
...  
Keyword(s):  
Neutron Flux ◽  
Flux Measurement ◽  
Radioactive Isotopes ◽  
Baksan Underground Scintillation Telescope

scholarly journals Robust Acquisition of High Resolution Spatial Transcriptomes from Preserved Tissues with Immunofluorescence Based Laser Capture Microdissection

2021 ◽  
Author(s):  
Xiaodan Zhang ◽  
Chuansheng Hu ◽  
Chen Huang ◽  
Ying Wei ◽  
Xiaowei Li ◽  
...  
Keyword(s):  
Laser Capture Microdissection ◽  
Spatial Organization ◽  
Spatial Information ◽  
A Priori ◽  
Rna Degradation ◽  
Spatially Resolved ◽  
Mouse Small Intestine ◽  
Dissociated Cells ◽  
Laser Capture

The functioning of tissues is fundamentally dependent upon not only the phenotypes of the constituent cells but also their spatial organization in the tissue. However, obtaining comprehensive transcriptomic data based on established phenotypes while retaining this spatial information has been challenging. Here we present a general and robust method based on immunofluorescence-guided laser capture microdissection (immuno-LCM-RNAseq) to enable acquisition of finely resolved spatial transcriptomes with as few as tens of cells from snap-frozen or RNAlater-treated tissues, overcoming the long-standing problem of significant RNA degradation during this lengthy process. The efficacy of this approach is exemplified by the characterization of differences at the transcript isoform level between cells at the tip versus the main capillary body of the mouse small intestine lacteal. With the extensive repertoire of phenotype-specific antibodies that are presently available, our method provides a powerful means by which spatially resolved cellular states can be delineated in situ with preserved tissues. Moreover, such high quality spatial transcriptomes defined by immuno-markers can be used to compare with clusters obtained from single-cell RNAseq studies of dissociated cells as well as applied to bead-based spatial transcriptomics approaches that require such information a priori for cell identification.

scholarly journals A tissue atlas of ulcerative colitis to guide TNF inhibitor therapy

2021 ◽  
Author(s):  
Aaron Mayer ◽  
Derek Holman ◽  
Utkarsh Tandon ◽  
Salil Bhate ◽  
Sunil Bodapati ◽  
...  
Keyword(s):  
Ulcerative Colitis ◽  
A Priori ◽  
Cell Types ◽  
Underlying Disease ◽  
Mucosal Inflammation ◽  
Tnf Inhibitor ◽  
Spatially Resolved ◽  
Architectural Features ◽  
Immune Mediated ◽  
Inhibitor Resistance

Abstract Ulcerative colitis is a chronic-relapsing inflammatory disease of the large intestine with a complex, multifactorial pathogenesis. TNF inhibitors are widely used to suppress immune-mediated tissue damage in ulcerative colitis patients; however, therapy failures are common. Predicting TNF inhibitor response requires an understanding of the architectural features that underlie mucosal inflammation and those responsible for resistance. Here, we used highly multiplexed immunofluorescence to uncover the spatially resolved tissue architectures underlying disease progression and treatment response in 42 tissue regions from 34 individuals. We created a tissue atlas and performed spatial analysis to identify cell-cell contacts and cellular neighborhoods. We observed that cellular functional states depend on cellular neighborhood and that a subset of inflammatory cell types and cellular neighborhoods in ulcerative colitis patients persisted even during treatment with TNF inhibitor, indicating resistant niches. A computer vision model, with no a priori assumptions regarding cellular architectural features, was able to predict TNF inhibitor resistance. This spatial model significantly outperformed classification models based on single-cell data alone. Our results demonstrate the value of a spatial tissue atlas as a precision medicine tool to guide treatment of patients suffering from autoimmune diseases.

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