Nuclear Events Research Articles

Thermal Stress and Nuclear Transport.

Nuclear transport is the basis for the biological reaction of eukaryotic cells, as it is essential to coordinate nuclear and cytoplasmic events separated by nuclear envelope. Although we currently understand the basic molecular mechanisms of nuclear transport in detail, many unexplored areas remain. For example, it is believed that the regulations and biological functions of the nuclear transport receptors (NTRs) highlights the significance of the transport pathways in physiological contexts. However, physiological significance of multiple parallel transport pathways consisting of more than 20 NTRs is still poorly understood, because our knowledge of each pathway, regarding their substrate information or how they are differently regulated, is still limited. In this report, we describe studies showing how nuclear transport systems in general are affected by temperature rises, namely, thermal stress or heat stress. We will then focus on Importin α family members and unique transport factor Hikeshi, because these two NTRs are affected in heat stress. Our present review will provide an additional view to point out the importance of diversity of the nuclear transport pathways in eukaryotic cells.

Microstructure and high-temperature oxidation behaviour of anti-oxidation coating on zirconium alloys: An overview

Due to the rapid development of the nuclear industry, zirconium alloys have received more and more attention as accident-tolerant fuel for nuclear reactors. However, the oxidation rate of zirconium alloy fuel coating will increase rapidly in the high-temperature environment above 1000 °C, which leads to a catastrophic nuclear leakage event. The corrosion resistance of zirconium alloy can be significantly improved through the surface coating technology. In this work, the microstructure and phase composition evolutions of chromium coating, composite coating, multilayer coating and MAX phase coating before and after oxidation are introduced. In addition, the oxidation behaviour and failure mechanism of the surface coating of zirconium alloy were analysed and summarised. Finally, the main problems and challenges of coating on the zirconium alloy surface are summarised and prospected.

History of the impact of radiation on the environment: Hiroshima bomb

The history of the impact of nuclear radiation on the environment, as illustrated by the Hiroshima bombing, reveals a multifaceted interplay of scientific, ecological, and ethical dimensions. From the historical context and immediate environmental consequences to long-term ecological effects and human health implications, the effects of nuclear radiation are pervasive. Comparatively analyzed with other nuclear incidents, case studies of affected ecosystems, and through education, ongoing challenges and opportunities toward nuclear technology are revealed. Moreover, it is through the echoes of past nuclear events that lessons were learned which until today guide current efforts on striking a balance between technological advancement and environmental preservation plus ethical responsibility. The development of nuclear weapons, the instant horror of the bomb, and its lasting environmental effects underline how vital it is to have an all-embracing appreciation of nuclear technology's implications. While coming to terms with the legacy of Hiroshima, issues such as environmental conservation and public health should be placed at the forefront when discussing nuclear energy and weapons. It is through applying these historical lessons that we can work towards reducing such technological negatives to ensure a more environmentally viable future.

Short-term urban resilience estimation after a hypothetical nuclear event

<abstract> <p>In the event of a hypothetical tactical nuclear device being detonated in a densely populated urban area, the first responders must be well-prepared to make immediate decisions with limited information. To aid in this preparation, a computer simulation using the HotSpot Health Physics code was conducted to model the detonation of a tactical nuclear device in an international airport and its surroundings, considering different yields ranging from 1 to 10 kilotons. The simulation was conservative and applied to a time window of 4 days in the initial phase of the response to the event. The simulation findings allow for assessing the immediate effects of the electromagnetic pulse (EMP) and the radioactive contamination plumes on an inhabited area. This assessment includes data on the size of impacted zones, compromise of critical local infrastructure, radiological risk to potentially affected populations, and estimation of urban resilience and its temporal dynamics. This information helps raise levels of protection and optimize available resources.</p> </abstract>

Pathway Planning of Nuclear Power Development Incorporating Assessment of Nuclear Event Risk

Pathway Planning of Nuclear Power Development Incorporating Assessment of Nuclear Event Risk

Recent Advances in Computational Convective Heat Transfer Study in a Sub-Channel for Nuclear Power Reactor and Future Directions

A nuclear power reactor's primary use is to generate thermal energy, which in turn produces electricity. The primary heat source is a nuclear fission event occurring inside the fuel rod. The convection heat is transmitted through the coolant by the heat energy generated at the fuel rod wall boundary. Better heat transfer is produced in the flow area by turbulence and irregularity. As a result, turbulent flow heat transfer may present a significant challenge when predicting and assessing the thermal performance of nuclear power reactors. Computational techniques in convective heat transfer have become indispensable for solving challenging issues in the fields of science and engineering thanks to the development of current sophisticated numerical methods and high-performance computer hardware. The development of novel computational techniques and models for complicated transport and multi-physical phenomena is constantly in demand throughout applicable disciplines. This chapter's objective is to provide some recent developments in computational techniques for convective heat transfer, taking into account research interests in the community of mass and heat transfer, and to showcase relevant applications in nuclear power plant engineering domains including future directions. This study describes the most recent advancements in nuclear reactor convective heat transfer research utilizing the computational fluid dynamics (CFD) method, particularly at Ansys Fluent. This work examines the convective heat transfer and fluid dynamics fluid dynamics for turbulent flows across three rod bundle sub-channels that are typical of those employed in the PWR-based VVER type reactor. In this paper, CFD analysis is carried out using the software tool Ansys Fluent. Temperature distribution profile, velocity profile, pressure drop, and turbulence properties were investigated in this study. Boundary conditions i.e. temperature, velocity, pressure, heat flux, and heat generation rate were applied in the sub-channel domain. The main obstacles and bright spots for the CFD methods in nuclear reactor engineering are discussed, which helps to further its further uses. We intend to research a full-length fuel bundle model for VVER-1200 in the future to gather specific fluid characteristic data and use the findings to analyze safety and operate nuclear power facilities in Bangladesh. This paper presents a thorough analysis of the sub-channel thermal hydraulic codes used in nuclear reactor core analysis. This review discusses several facets of previous experimental, analytical, and computational work on rod bundles and identifies potential future directions based on those earlier studies.

The Roles of IL-18 in a Realistic Partial Body Irradiation with 5% Bone Marrow Sparing (PBI/BM5) Model.

IL-18 has been shown to play important roles in response to total body irradiation. However, homogenous total body irradiation is not a realistic model to reflect the radiation exposure in a real nuclear event. To further study the roles of IL-18 in a real nuclear scenario, we developed a mouse partial body irradiation with 5% bone marrow sparing (PBI/BM5) model to mimic the inhomogeneous radiation exposure. We established the dose response curves of PBI/BM5 using different radiation doses ranging from 12 to 16 Gy. Using the PBI/BM5 model, we showed that IL-18 knockout mice were significantly more radiation resistant than the wild-type mice at 14.73 Gy. We further studied the hematopoietic changes using a complete blood count, bone marrow colony-forming assays, and serum cytokine assays on the mice exposed to PBI/BM5 with IL-18BP treatment and wild-type/IL-18 knockout mice. In conclusion, our data suggest that IL-18 plays important roles in mouse survival in a realistic nuclear exposure model, potentially through the IL-18/IFNγ pathway.

Apoptosis-resistant megakaryocytes produce large and hyperreactive platelets in response to radiation injury

BackgroundThe essential roles of platelets in thrombosis have been well recognized. Unexpectedly, thrombosis is prevalent during thrombocytopenia induced by cytotoxicity of biological, physical and chemical origins, which could be suffered by military personnel and civilians during chemical, biological, radioactive, and nuclear events. Especially, thrombosis is considered a major cause of mortality from radiation injury-induced thrombocytopenia, while the underlying pathogenic mechanism remains elusive.MethodsA mouse model of radiation injury-induced thrombocytopenia was built by exposing mice to a sublethal dose of ionizing radiation (IR). The phenotypic and functional changes of platelets and megakaryocytes (MKs) were determined by a comprehensive set of in vitro and in vivo assays, including flow cytometry, flow chamber, histopathology, Western blotting, and chromatin immunoprecipitation, in combination with transcriptomic analysis. The molecular mechanism was investigated both in vitro and in vivo, and was consolidated using MK-specific knockout mice. The translational potential was evaluated using a human MK cell line and several pharmacological inhibitors.ResultsIn contrast to primitive MKs, mature MKs (mMKs) are intrinsically programmed to be apoptosis-resistant through reprogramming the Bcl-xL-BAX/BAK axis. Interestingly, mMKs undergo minority mitochondrial outer membrane permeabilization (MOMP) post IR, resulting in the activation of the cyclic GMP-AMP synthase-stimulator of IFN genes (cGAS-STING) pathway via the release of mitochondrial DNA. The subsequent interferon-β (IFN-β) response in mMKs upregulates a GTPase guanylate-binding protein 2 (GBP2) to produce large and hyperreactive platelets that favor thrombosis. Further, we unmask that autophagy restrains minority MOMP in mMKs post IR.ConclusionsOur study identifies that megakaryocytic mitochondria-cGAS/STING-IFN-β-GBP2 axis serves as a fundamental checkpoint that instructs the size and function of platelets upon radiation injury and can be harnessed to treat platelet pathologies.

Temporal Trends and Spatial Relationships of Radioactive Isotopes (I-131, Cs-134, and Cs-137) in Response to Nuclear Events: A Comprehensive Analysis Using Time Series Graphs, Regression, and Multivariate Techniques

This research aims to comprehend the evolution of radioactive isotopes Iodine-131 (I-131), Cesium-134 (Cs-134), and Cesium-137 (Cs-137) over time in diverse locations and analyze their relationships with the independent variables Longitude and Latitude using Linear Regression, Principal Component Analysis (PCA), and Canonical Correlation Analysis (CCA). The data used in this study were processed from the "DE.xlsx" file, including the imputation of missing values with 0 and column transformation into factors. The results of the Linear Regression analysis indicate a significant association between these isotopes and Longitude and Latitude. Additionally, PCA and CCA analyses reveal complex relationships between the isotopes and independent variables. This research provides valuable insights into the historical trends of radioactive isotopes Iodine-131 (I-131), Cesium-134 (Cs-134), and Cesium-137 (Cs-137) in various locations. The novel aspect and uniqueness of this study lie in the utilization of a comprehensive analytical approach, combining Linear Regression, PCA, and CCA to comprehend the relationships between isotopes and specific environmental factors. Moreover, this study significantly contributes to understanding the phenomena of radioactive isotopes and can serve as a foundation for further research in this field. The findings of this research are expected to support efforts in preventing and managing potential environmental and human health impacts of radioactive isotopes in the future.

Management of Casualties from Radiation Events

Radiation events such as nuclear war, nuclear reactor incidents, and the deployment of a radioactive dispersal device (dirty bomb) are all significant threats in today’s world. Each of these events would bring significant challenges to clinicians caring for patients with burns and traumatic injuries who are also contaminated or irradiated. The result of a nuclear exchange in a densely populated area could result in thousands of patients presenting with trauma, burns, and combined injury (trauma and burn in an irradiated patient). In this review, we will discuss the three major types of ionizing radiation: alpha, beta, and gamma, and their respective health hazards and biological effects. Additionally, we will discuss the types of burn injuries in a nuclear disaster, caring for the contaminated patient, and managing the combined injury of burn trauma with acute radiation syndrome. The reader will also be left with an understanding of how to prioritize lifesaving interventions, estimate the absorbed dose of radiation, and predict the onset of acute radiation syndrome. While some animal models for morbidity and mortality exist, there is limited modern day human data for patients with combined injury and burns associated with a nuclear disaster due to the infrequent nature of these events. It is extremely important to continue multidisciplinary research on the prevention of, preparedness for, and the response to nuclear events. Furthermore, continued exploration of novel treatments for radiation induced burns and the management of combined injury is necessary.

Characterization of TREM-1 Signaling in Human Neutrophils By Kinome Array and RNA-Seq

The Triggering Receptor Expressed on Myeloid Cells (TREM)-1 is a member of the Immunoglobulin superfamily and an activating receptor mainly expressed on myeloid cells. TREM-1 ligation leads to immediate activation of polymorphonuclear neutrophils (PMN) resulting in degranulation and release of reactive oxygen species as well as various effector molecules. Beyond its role in acute and chronic inflammatory processes, TREM-1 is also involved in cancer emergence and progression probably by alteration of the tumor associated neutrophils (TAN) and macrophages (TAM). Advanced information about the TREM-1 signaling cascade may reveal novel therapeutic approaches, as various kinases can specifically be targeted with kinase inhibitors. Therefore, we investigated the protein tyrosine kinome (PTK) and serine threonine kinome (STK) of human PMN after TREM-1 activation. To gain further insights beyond the signaling cascade, we performed RNAseq to validate the TREM-1 mediated activation and to reveal the TREM-1 mediated transcriptome. Purified PMN from healthy donors were stimulated with a monoclonal TREM-1 antibody compared to an isotype matched control for 20 minutes (kinome activity) or 60 minutes (RNAseq). For kinomics, PamChip arrays (PamGene) were used to quantify the kinome activity and upstream kinase analysis (UKA) was used to predict the kinase activity. The final data analysis and the UKA was performed by PamGene. A median final score (depending on the significance and the specificity of the kinase activity compared to the control group) > 1.2 was defined as specific kinase activity according to the manufacturer's recommendations. For transcriptomics, Novogene performed library preparation and sequencing, and data analysis was performed with CLC. Differentially expressed genes were defined as FDR adjusted p value ≤ 0.05 and fold change ≥2. Gene set enrichment analysis was performed with Enrichr using the libraries Reactome 2022, WikiPathway 2021 Human, and GO Biological Process 2023 and significance was defined as adjusted p value ≤ 0.05. We identified the activation of 31 PTKs and 38 STKs upon TREM-1 ligation. The kinase statistic revealed changes in the activation state of the kinases present in the TREM-1 treated cells compared to the untreated control group ranging from 2.4 to 5.5 (PTK) and from 1.2 to 1.6 (STK) suggesting more TREM-1 mediated activity alteration of the PTKs. Interestingly, there were no downregulated kinase activities after receptor ligation. Out of the PTK family, we identified ten Src family kinases as well as the Syk family member ZAP70 and other kinases such as BTK, already previously shown to abrogate TREM-1 mediated PMN activation. The RNAseq after TREM-1 ligation revealed 542 differentially expressed genes from which 102 genes were upregulated and 440 genes were downregulated. Gene set enrichment analysis revealed upregulation of genes related to nuclear events (kinase and transcription factor activaton, R-HSA-198725) and cell chemotaxis (GO:0060326) validating the activation of several kinases after TREM-1 ligation. We found increased expressions of genes involved in adipogenesis (WP236) and lung fibrosis (WP3624) suitably to the observed increased activity of Src family kinases that are described to be involved in lung fibrosis. Moreover, some upregulated genes related to NGF-stimulated transcription (R-HSA-9031628) or regulation of transcription in response to stress (GO:0043618) in which the MAPK are known to be involved. However, we did not observe clearly increased MAPK activity. Besides upregulation, TREM-1 ligation led to decreased expression of several genes involved in (positive) regulation of cytokine production involved in inflammatory response (GO:1900017 and GO:1900015) and signaling by interleukins (R-HSA-449147). Taken together, the results contribute to the knowledge about TREM-1 in inflammatory disorders and reveal approaches of its role in cancer. This study revealed various kinases possibly involved in early TREM-1 signaling of neutrophils that may be suitable targets to inhibit TREM-1 mediated cell activation. Moreover, we linked the TREM-1 mediated kinase activity to the resulting gene expression. Further studies are needed to validate the results in vitro and in vivo and and to identify suitable pharmacological inhibitors to modulate TREM-1 mediated activities in inflammatory conditions and cancer.

Electron scattering and neutrino physics

A thorough understanding of neutrino–nucleus scattering physics is crucial for the successful execution of the entire US neutrino physics program. Neutrino–nucleus interaction constitutes one of the biggest systematic uncertainties in neutrino experiments—both at intermediate energies affecting long-baseline deep underground neutrino experiment, as well as at low energies affecting coherent scattering neutrino program—and could well be the difference between achieving or missing discovery level precision. To this end, electron–nucleus scattering experiments provide vital information to test, assess and validate different nuclear models and event generators intended to test, assess and validate different nuclear models and event generators intended to be used in neutrino experiments. Similarly, for the low-energy neutrino program revolving around the coherent elastic neutrino–nucleus scattering (CEvNS) physics at stopped pion sources, such as at ORNL, the main source of uncertainty in the evaluation of the CEvNS cross section is driven by the underlying nuclear structure, embedded in the weak form factor, of the target nucleus. To this end, parity-violating electron scattering (PVES) experiments, utilizing polarized electron beams, provide vital model-independent information in determining weak form factors. This information is vital in achieving a percent level precision needed to disentangle new physics signals from the standard model expected CEvNS rate. In this white paper, we highlight connections between electron- and neutrino–nucleus scattering physics at energies ranging from 10 s of MeV to a few GeV, review the status of ongoing and planned electron scattering experiments, identify gaps, and lay out a path forward that benefits the neutrino community. We also highlight the systemic challenges with respect to the divide between the nuclear and high-energy physics communities and funding that presents additional hurdles in mobilizing these connections to the benefit of neutrino programs.

Nuclear Fusion in Yeast and Plant Reproduction.

Nuclear fusion is essential for the sexual reproduction of various organisms, including plants, animals, and fungi. During the life cycle of flowering plants, nuclear fusion occurs three times: once during female gametogenesis and twice during double fertilization, when two sperm cells fertilize the egg and the central cell. Haploid nuclei migrate in an actin filament-dependent manner to become in close contact and, then, two nuclei fuse. The nuclear fusion process in plant reproduction is achieved through sequential nuclear membrane fusion events. Recent molecular genetic analyses using Arabidopsis thaliana showed the conservation of nuclear membrane fusion machinery between plants and the budding yeast Saccharomyces cerevisiae. These include the heat-shock protein 70 in the endoplasmic reticulum and the conserved nuclear membrane proteins. Analyses of the A. thaliana mutants of these components show that the completion of the sperm nuclear fusion at fertilization is essential for proper embryo and endosperm development.

Hierarchical task analysis as a systems mapping tool in complex health care environments: Emergency department response to chemical, biological, radiological, and nuclear events

AbstractThe emergency department (ED) is at the forefront of the chemical, biological, radiological, and nuclear (CBRN) response. This study adopted a multilevel systems approach using the human factors/ergonomics (HFE) method of hierarchical task analysis (HTA) with document analyses of CBRN plans to represent work‐as‐Imagined. Work‐as‐imagined was compared with data from semistructured interviews using prompt cards for CBRN scenarios (n = 57) representing work‐as‐done. The aim was to provide methodological evidence for the use of HTA with an empirical synthesis of the ED in response to CBRN events. HTA was the preferred systems mapping tool because it aligns with a systems thinking approach, allows multiple‐level comparisons, highlights variability, and has an established usability track record. This study demonstrates the usability of HTA in the context of the ED responding to a CBRN event. The findings for core CBRN concepts included (1) liaise and communicate, (2) isolate and contain, and (3) personal protective equipment.

Evaluating transport conditions of conventional, widely used EDTA blood tubes for gene expression analysis in comparison to expensive, specialized PAXgene tubes in preparedness for radiological and nuclear events

Purpose Gene expression (GE) analysis of a radio-sensitive gene set (FDXR, DDB2, WNT3, POU2AF1) has been introduced in the last decade as an early and high-throughput prediction tool of later developing acute hematologic radiation syndrome (H-ARS) severity. The use of special tubes for RNA extraction from peripheral whole blood (PAXgene) represent an established standard in GE studies, although uncommonly used in clinics and not immediately available in the quantities needed in radiological/nuclear (R/N) incidents. On the other hand, EDTA blood tubes are widely utilized in clinical practice. Material and Methods Using blood samples from eleven healthy donors, we investigated GE changes associated with delayed processing of EDTA tubes up to 4 h at room temperature (RT) after venipuncture (simulating delays caused by daily clinical routine), followed by a subsequent transport time of 24 h at RT, 4 °C, and −20 °C. Differential gene expression (DGE) of the target genes was further examined after X-irradiation with 0 Gy and 4 Gy under optimal transport conditions. Results No significant changes in DGE were observed when storing EDTA whole blood samples up to 4 h at RT and subsequently kept at 4 °C for 24 h which is in line with expected DGE. However, other storage conditions, such as −20 °C or RT, decreased RNA quality and/or (significantly) caused changes in DGE exceeding the known methodological variance of the qRT-PCR. Conclusion Our data indicate that the use of EDTA whole blood tubes for GE-based H-ARS severity prediction is comparable to the quality of PAXgene tubes, when processed ≤ 4 h after venipuncture and the sample is transported within 24 hours at 4 °C.

PEGylated thrombopoietin mimetic, JNJ‑26366821 a novel prophylactic radiation countermeasure for acute radiation injury

Thrombopoietin (TPO) is the primary regulator of platelet generation and a stimulator of multilineage hematopoietic recovery following exposure to total body irradiation (TBI). JNJ‑26366821, a novel PEGylated TPO mimetic peptide, stimulates platelet production without developing neutralizing antibodies or causing any adverse effects. Administration of a single dose of JNJ‑26366821 demonstrated its efficacy as a prophylactic countermeasure in various mouse strains (males CD2F1, C3H/HeN, and male and female C57BL/6J) exposed to Co-60 gamma TBI. A dose dependent survival efficacy of JNJ‑26366821 (− 24 h) was identified in male CD2F1 mice exposed to a supralethal dose of radiation. A single dose of JNJ‑26366821 administered 24, 12, or 2 h pre-radiation resulted in 100% survival from a lethal dose of TBI with a dose reduction factor of 1.36. There was significantly accelerated recovery from radiation-induced peripheral blood neutropenia and thrombocytopenia in animals pre-treated with JNJ‑26366821. The drug also increased bone marrow cellularity and megakaryocytes, accelerated multi-lineage hematopoietic recovery, and alleviated radiation-induced soluble markers of bone marrow aplasia and endothelial damage. These results indicate that JNJ‑26366821 is a promising prophylactic radiation countermeasure for hematopoietic acute radiation syndrome with a broad window for medical management in a radiological or nuclear event.

THREATS AND RISKS RESEARCH METHODS

The work systematizes knowledge in the field of threat and risk research when solving applied problems. To achieve the set goal, the following scientific tasks must be solved: analyze the main concepts of threat and risk research; give a description of the tasks to be solved regarding threats and risks; consider the main methods of threat and risk analysis from the standpoint of the technocratic concept; from the standpoint of the technocratic concept, consider the main methods of risk assessment, their advantages and disadvantages. A threat is understood as a potentially possible event that can lead to harm (catastrophic event), and risk - determines the degree of danger of occurrence or impact of a threat (or a set of threats - a set of catastrophic events) on a specific object (resource, process or system). At the same time, for a specific dangerous (for example, a nuclear) object, the concepts of a certain type of threat and the risk of its occurrence are interconnected. This strict triangular dependence requires a unified (inseparable, interrelated) consideration of these concepts in relation to solving various applied problems. A systematic approach to ensuring their safety is applied to all complex man-made objects, which includes the identification of objective dangers, the definition and ranking of threats, the assessment of the risk of their manifestation and the preparation of a forecast, which is done in favor of preventing catastrophic events caused by objective dangers. The most effective methods of threat and risk assessment are methods integrated into monitoring systems, decision support systems, and other automated management systems. The events of recent years in Ukraine require the definition of a terrorist threat as the primary and most important one, because in relation to nuclear facilities, under a positive man-made environment, it creates an avalanche-like emergency situation caused by nuclear, radiation, environmental and other catastrophic events. In turn, this will require the systematization of existing and the development of new methods, algorithms and protocols for assessing and countering terrorist threats at man-made objects. Keywords: emergency situation, catastrophic event, man-made object, danger, threat, risk.

Seizure enhances SUMOylation and zinc-finger transcriptional repression in neuronal nuclei

A single episode of pilocarpine-induced status epilepticus can trigger the development of spontaneous recurrent seizures in a rodent model for epilepsy. The initial seizure-induced events in neuronal nuclei that lead to long-term changes in gene expression and cellular responses likely contribute toward epileptogenesis. Using a transgenic mouse model to specifically isolate excitatory neuronal nuclei, we profiled the seizure-induced nuclear proteome via tandem mass tag mass spectrometry and observed robust enrichment of nuclear proteins associated with the SUMOylation pathway. In parallel with nuclear proteome, we characterized nuclear gene expression by RNA sequencing which provided insights into seizure-driven transcriptional regulation and dynamics. Strikingly, we saw widespread downregulation of zinc-finger transcription factors, specifically proteins that harbor Krüppel-associated box (KRAB) domains. Our results provide a detailed snapshot of nuclear events induced by seizure activity and demonstrate a robust method for cell-type-specific nuclear profiling that can be applied to other cell types and models.

A Methodology for Calculating Inhalation Dose to Public Health Personnel Exposed to Material Resuspended from Evacuees Following the Detonation of a Fission Device.

Following a nuclear fission event, there likely would be a large number of contaminated persons who would seek assistance at community reception centers to be established outside the affected area. This paper provides a methodology for calculating inhalation doses to public health and other response personnel at such facilities who would be receiving and assisting potentially contaminated persons from whom particles can be resuspended. Three hypothetical facilities were considered: the Base Case is a rather small room with no forced air ventilation. The Preferred Case, which is more realistic, is a mid-sized room with an operating HVAC system with air being recirculated through a filter. The Gymnasium Case has only fresh air intake. Initial bounding calculations for the Base Case indicated the need for pre-screening of arrivals to avoid unacceptable doses to staff. The screening criterion selected was 1.67 × 10 6 Bq m -2 . Calculations are presented for radionuclide concentrations in air, dose to staff from inhalation, and how exposures and the resulting doses can be altered by air-turnover rates and the use of filters with varying efficiency. Doses are presented for various arrival times and for both plutonium- and uranium-fueled detonations. The highest calculated dose via inhalation with no respiratory protection was 0.23 mSv for the Base Case. The more important radionuclides contributing to dose with exposure starting at day D + 1 were 239 Np and 133 I. At day D + 30, 131 I and 140 Ba were the more important dosimetrically. The variable creating the highest uncertainty was the slough-off factor for resuspension of contamination from people arriving at the reception center.

First Dark Matter Search with Nuclear Recoils from the XENONnT Experiment.

We report on the first search for nuclear recoils from dark matter in the form of weakly interacting massive particles (WIMPs) with the XENONnT experiment, which is based on a two-phase time projection chamber with a sensitive liquid xenon mass of 5.9ton. During the (1.09±0.03) ton yr exposure used for this search, the intrinsic ^{85}Kr and ^{222}Rn concentrations in the liquid target are reduced to unprecedentedly low levels, giving an electronic recoil background rate of (15.8±1.3) events/ton yr keV in the region of interest. A blind analysis of nuclear recoil events with energies between 3.3 and 60.5keV finds no significant excess. This leads to a minimum upper limit on the spin-independent WIMP-nucleon cross section of 2.58×10^{-47} cm^{2} for a WIMP mass of 28 GeV/c^{2} at 90% confidence level. Limits for spin-dependent interactions are also provided. Both the limit and the sensitivity for the full range of WIMP masses analyzed here improve on previous results obtained with the XENON1T experiment for the same exposure.