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At least 1,063 records · Page 59

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DOE OSTI2022

Application of the Continuum Damage Mechanics Wilshire-Cano-Stewart (WCS) Model

In this study, the applications of the continuum damage mechanics-based Wilshire-Cano-Stewart (WCS) model are explored to predict rupture time, minimum-creep-strain-rate (MCSR), damage, damage evolution, and creep deformation. Increase knowledge in manufacturing methods has pushed the limit of material science and the development of new materials. Conventional testing is required to qualify materials against creep which according to the ASME B&PV III code, 10,000+ hours of experiments are necessary for each heat before materials are put into service. This process is costly and not feasible for new materials. As an alternative, models have been employed to predict creep behaviors and reduce the amount of time necessary for material qualification. Many models have been developed to predict distinct creep behaviors and the question of which model is best remains. Amongst current models, the WCS model has emerge with the ability to predict multiple behaviors using an explicit analytical approach with the ability to predict long-term creep. In this study the novel continuum damage mechanics WCS is employed in multiple applications. The goals of the study are (a) to discuss and determine the framework of the WCS model and validated it mathematically and using parametric simulations, (b) applied the model to accelerated creep data to show the capabilities of the model with non-conventional data, and (c) applied a novel numerical method, the datum temperature method (DTM) to show the model extrapolations and interpolations capabilities with limited and reduce data sets. To accomplish these goals, data is gathered for alloy P91 and Inconel 718 to develop and post-audit validate the model. The benefits of using the WCS model is that it provides an explicit stress and temperature dependency ideal for extrapolations, the coupled equations are suitable for finite element analysis (FEA) implementation, and it follows an explicit calibration approach. The model also proves that it can be applied to accelerated testing data and using the DTM.

Cano, Jaime A↗

DOE OSTI2016

CASTOR V casks: quiver for damaged fuel rods

After the accident at Fukushima in 2011, 8 nuclear power plants (NPPs) in Germany were shut down immediately and parliament decided a phase-out of nuclear energy by 2022. As prerequisite for a quick dismantling of the shut-down NPPs, all fuel has to be removed from the spent fuel pools as soon as possible. For over 20 years, spent fuel assemblies from German NPPs have already been stored in CASTOR dual purpose casks by GNS. Already more than 1200 CASTOR casks are stored in dry interim storage facilities worldwide, and there is an additional demand for several hundred more casks for the remaining spent fuel assemblies in Germany until the final phase-out. Furthermore the phase-out decision has triggered the demand for a complementary solution for the damaged fuel rods that have been collected separately in the pools for disposal after the NPP shut-down. In 2011, GNS started to develop a disposal concept for these damaged fuel rods. For that purpose, GNS designed 2 quivers for damaged fuel rods to fit into square tubes of the basket of the CASTOR V/19 (PWR) and the CASTOR V/52 (BWR) respectively. The customisable internal baskets of the quivers facilitate the disposal of a large variety of nuclear inventory. Furthermore, the quiver features a robust design and a welded closure system. This design has been affirmed by a series of tests and qualification processes, supervised by the German authorities. This first of its kind solution ensures the dry interim storage of damaged fuel rods. The package design approval for the quiver for CASTOR V/19 is expected for 2016. This presentation will focus on the design of the Quivers in combination with the CASTOR V casks and describe the challenges during the licensing procedures. We will show the components of the Quiver and explain their mechanical characteristics during accident conditions of transport as well as the drying and welding process necessary to enable the long term storage of the Quivers. (authors)

42 ENGINEERING↗

DOE OSTI2016

A Frozen Soil Barrier to Control Groundwater Inflow into Damaged Reactors at the Fukushima Daiichi Nuclear Power Station - 16613

Reactor buildings and support facilities at the Fukushima Daiichi Nuclear Power Station (F1 Site) were damaged by a March 2011 tsunami. In response, the Tokyo Electric Power Company (TEPCO) is implementing a number of countermeasures to limit the releases and impacts of contaminated water to the surrounding environment. The diverse countermeasures work together in an integrated manner to provide different types, and several levels, of environmental protection. In general, the strategy represents an example of a 'defense in depth' concept that is used for nuclear facilities around the world. One of the key countermeasures is a frozen soil barrier encircling the damaged reactor facilities. The frozen barrier is intended to limit the flow of water into the area, reduce the amount of water entering damaged reactors, and reduce the resulting volume of contaminated water that requires treatment and storage. The frozen soil barrier was designed and installed by a team from TEPCO and Kajima Corporation. A group of scientists and engineers from US Department of Energy National Laboratories provided independent evaluation of the frozen barrier design and operational plans along with technical recommendations to the TEPCO team. The frozen soil barrier design extends to about 30 m depth; the bottom of the barrier is in a low permeability interval, and the total barrier length around the reactors is just over 1.5 km. The barrier required 1927 total boreholes: 1568 for freeze pipes plus 359 for temperature monitoring arrays. Drilling of all of the boreholes was completed November 9, 2015. Construction of the refrigeration plant is complete and all of the above ground piping/manifolds are in the final stages of construction. The DOE laboratory independent assessment of the frozen soil barrier concluded that the technical characteristics of a frozen barrier are relatively well suited to Fukushima-specific hydrogeologic conditions and the need for reducing the inflow of water into damaged reactors at the F1 Site. The scale of the Fukushima barrier is bounded by industry experience and the equipment and infrastructure proposed for the ground freezing is well understood. The on-site pilot test at Fukushima indicated predictable ground freezing and supported the full scale design parameters. These factors increase the confidence in the frozen soil barrier project underway at Fukushima. TEPCO is currently working with the Japanese Nuclear Regulatory Authority (NRA), providing operational plans/strategies for the frozen soil barrier and modeling results of the projected performance. Full scale frozen soil barrier operations are to begin after authorization from NRA. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2018

Radioactivity and neutron damage calculators for research and test reactor neutron-activated materials - 25652

The Idaho National Laboratory Nuclear Science User Facilities program is proposing to launch a new online expert system that will assist users in planning experiments and writing proposals. The Combined Materials Experimentation Toolkit (CoMET) will include two nuclear calculators. The first of these, the Neutron Damage Calculator, will assist users in selecting reactor positions in order to obtain desired material damage in Damage Per Atom (DPA) and provide the required irradiation time to reach the damage levels. The second, the Radioactivity Calculator, will estimate the post-irradiation radioactivity levels of sample materials, which will inform technical staff of examination facility requirements and any potential scheduling delays. Both of these calculators were designed to simplify the information needed from users in order to properly plan and execute awarded proposals. This paper presents the primary purpose and methodologies implemented by these two calculators. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

DOE OSTI2016

Combined effects of radiation damage and He accumulation on bubble nucleation in Gd2Ti2O7

Pyrochlores have long been considered as host phases for long-term immobilization of radioactive waste nuclides that would undergo ..alpha..-decay for hundreds of thousands of years. This work utilizes ion-beam irradiations to examine the combined effects of radiation damage and He accumulation on bubble formation in Gd2Ti2O7 over relevant waste-form timescales. Helium bubbles are not observed in pre-damaged Gd2Ti2O7 implanted with 2 x 1016 He/cm2, even after post-implantation irradiations with 7 MeV Au3+ at 300, 500, and 700 K. However, He bubbles with average diameters of 1.5 nm and 2.1 nm are observed in pre-damaged (amorphous) Gd2Ti2O7 and pristine Gd2Ti2O7, respectively, after implantation of 2 x 1017 He/cm2. The critical He concentration for bubble nucleation in Gd2Ti2O7 is estimated to be 6 at.% He.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2022

DCIF (Directional Cooling-Induced Fracturing) Westerly Granite AE Borehole Damage Effect Test (Task 3-0)

Directional Cooling-Induced Fracturing (DCIF) experiments were conducted on three rectangular Westerly granite blocks (width=depth=4.0", height=2.0") which were preheated to 200, 400, and 600 degree C to induce damage (microcracks) with varying degrees. Liquid nitrogen was poured in a small, 1"-diameter copper cup attached to the top of the sample, and the resulting acoustic emissions (AEs) and temperature changes on the surface of the sample were monitored. The experiments were conducted under one selected biaxial stress (5.8MPa). The obtained AEs were used to determine the microcracking source locations and amplitude, and the associated moment tensors. The onset time of the AEs was correlated with the cooling temperature, which was used to show that the temperature at the onset of microcracking is not affected significantly by the preexisting damage, compared to the impact of the stress in the sample. Included in this submission are the animations of the AE locations and graphics displaying the measured temperature-AE activity changes for samples with different degrees of microcrack damage.

15 GEOTHERMAL ENERGY↗

NASA NTRS2005

Fatigue Crack Growth Database for Damage Tolerance Analysis

The objective of this project was to begin the process of developing a fatigue crack growth database (FCGD) of metallic materials for use in damage tolerance analysis of aircraft structure. For this initial effort, crack growth rate data in the NASGRO (Registered trademark) database, the United States Air Force Damage Tolerant Design Handbook, and other publicly available sources were examined and used to develop a database that characterizes crack growth behavior for specific applications (materials). The focus of this effort was on materials for general commercial aircraft applications, including large transport airplanes, small transport commuter airplanes, general aviation airplanes, and rotorcraft. The end products of this project are the FCGD software and this report. The specific goal of this effort was to present fatigue crack growth data in three usable formats: (1) NASGRO equation parameters, (2) Walker equation parameters, and (3) tabular data points. The development of this FCGD will begin the process of developing a consistent set of standard fatigue crack growth material properties. It is envisioned that the end product of the process will be a general repository for credible and well-documented fracture properties that may be used as a default standard in damage tolerance analyses.

Metallic materials↗

NASA NTRS2017

Compendium of Current Total Ionizing Dose and Displacement Damage Results from NASA Goddard Space Flight Center and NASA Electronic Parts and Packaging Program

Total ionizing dose and displacement damage testing was performed to characterize and determine the suitability of candidate electronics for NASA space utilization. Devices tested include optoelectronics, digital, analog, linear bipolar devices, and hybrid devices. Displacement Damage, Optoelectronics, Proton Damage, Single Event Effects, and Total Ionizing Dose.

Proton Damage↗

NASA NTRS2021

Damage Tolerance of Candidate Sandwich Structure for the Space Launch System (SLS) Payload Adapter Fitting (PAF)

This Technical Memorandum presents results from a damage tolerance study undertaken in support of the payload adapter fitting (PAF) for the Space Launch System (SLS) program at NASA’s Marshall Space Flight Center (MSFC). The study consisted of determining the compression-after-impact (CAI) strength of candidate carbon/epoxy face sheet sandwich structure that has been identified for potential use to manufacture the PAF hardware. Two types of core material that have been considered for use on the PAF structure were used in this study. One was an aluminum honeycomb and the other was a Rohacell foam. Levels of barely visible impact damage (BVID) were determined for the types of sandwich structure tested in this study and this level of damage was used for CAI strength testing. It was found that the honeycomb core sandwich structure failed by face sheet failure and the foam core sandwich structure failed by core shear failure. CAI strength values were normalized by weight of the sandwich structure since lower mass is desirable for this structure.

sandwich structure↗

DOE OSTI2024

Quantum Simulations of Radiation Damage in a Molecular Polyethylene Analog

Abstract An atomic‐level understanding of radiation‐induced damage in simple polymers like polyethylene is essential for determining how these chemical changes can alter the physical and mechanical properties of important technological materials such as plastics. Ensembles of quantum simulations of radiation damage in a polyethylene analog are performed using the Density Functional Tight Binding method to help bind its radiolysis and subsequent degradation as a function of radiation dose. Chemical degradation products are categorized with a graph theory approach, and occurrence rates of unsaturated carbon bond formation, crosslinking, cycle formation, chain scission reactions, and out‐gassing products are computed. Statistical correlations between product pairs show significant correlations between chain scission reactions, unsaturated carbon bond formation, and out‐gassing products, though these correlations decrease with increasing atom recoil energy. The results present relatively simple chemical descriptors as possible indications of network rearrangements in the middle range of excitation energies. Ultimately, the work provides a computational framework for determining the coupling between nonequilibrium chemistry in polymers and potential changes to macro‐scale properties that can aid in the interpretation of future radiation damage experiments on plastic materials.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗

DOE OSTI2019

Genotoxic Damages and Bioaccumulation of Cadmium in Geophagus Brasiliensis (Quoy & Gaimard, 1824)

The toxic effects of cadmium (Cd) in Geophagus brasiliensis was investigated in the present study. For this, 32 specimens of G. brasiliensis were exposed in individual aquaria to Cd concentrations (0.00, 0.01, 0.07, and 0.67 mg/L) for 14 days. The micronuclei test did not detect the genotoxic damage at the studied concentrations and time of exposure. However, the comet assay proved to be more efficient, as DNA damage was found in the animals exposed to the higher Cd concentrations. Finally, exposure of G. brasiliensis to Cd was associated with Cd accumulation in the gills, while only the animals exposed to 0.67 mg/L of Cd exhibited muscle accumulation. These results demonstrate that Cd concentrations over 0.07 mg/L caused genotoxic damage, as well as Cd accumulation in G. brasiliensis individuals after a 14 days exposure.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2015

Characterisation of radiation damage in W and W-based alloys from 2MeV self-ion near-bulk implantations

The displacement damage induced in bulk W and W-5 wt.% Re and W-5 wt.% Ta alloys by 2 MeV W + irradiation to doses 3.3×10 17 - 2.5×10 19 W + /m 2 at temperatures ranging from 300 to750°C has been characterized by transmission electron microscopy. An automated sizing and counting approach based on Image J has been proposed and performed for all irradiation data. In all cases the damage comprised dislocation loops, mostly of interstitial type, with Burgers vectors b = ½<111> (> 60%) and b = <100>. The diameters of loops did not exceed 20 nm, with the majority being ≤ 6 nm. The loop number density varied between 10 22 and 10 23 loops/m 3 . With increasing irradiation temperature, the loop size distributions shifted towards larger sizes, and there was a substantial decrease in loop number densities. The damage microstructure was less sensitive to dose than to temperature. Under the same irradiation conditions, loop number densities in the alloys were higher than in pure W but loops were smaller. In grains with normals close to z = <001>, loop strings developed in W at temperatures ≥ 500°C and doses ≥ 1.2 dpa, but such strings were not observed in the W-Re or W-Ta alloys. However, in other grain orientations complex structures appeared in all materials and dense dislocation networks formed at higher doses.

36 MATERIALS SCIENCE↗

DOE OSTI2023

Damage-free X-ray spectroscopy characterization of oxide thin films

Thin polymer or oxide films are ubiquitous components in many devices, including membranes for filtration or electrodes in electrochemical energy storage. High energy electron or x-ray probes for microscopy and spectroscopy are useful to characterize and understand these materials. However, irreversible damage by the probe radiation remains a challenge. Here, we show that graphene serves as an x-ray and electron transparent substrate that substantially reduces radiation damage of an oxide thin film. We demonstrate this using highly focused x-ray beams, which show that compared to oxide thin films supported on a substrate, graphene-supported regions show minimal changes in the x-ray spectra as a function of x-ray dose. Further, these results pave the way for the development of experimental setups that allow for long exposure time measurements with limited sample damage and substrate-directed radiation patterning.

36 MATERIALS SCIENCE↗

DOE OSTI2014

Implications of caspase-dependent proteolytic cleavage of cyclin A1 in DNA damage-induced cell death

Highlights: • Caspase-1 mediates doxorubicin-induced downregulation of cyclin A1. • Active caspase-1 effectively cleaved cyclin A1 at D165. • Cyclin A1 expression is involved in DNA damage-induced cell death. - Abstract: Cyclin A1 is an A-type cyclin that directly binds to CDK2 to regulate cell-cycle progression. In the present study, we found that doxorubicin decreased the expression of cyclin A1 at the protein level in A549 lung cancer cells, while markedly downregulating its mRNA levels. Interestingly, doxorubicin upregulated caspase-1 in a concentration-dependent manner, and z-YAVD-fmk, a specific inhibitor of caspase-1, reversed the doxorubicin-induced decrease in cyclin A1 in A549 lung cancer and MCF7 breast cancer cells. Active caspase-1 effectively cleaved cyclin A1 at D165 into two fragments, which in vitro cleavage assays showed were further cleaved by caspase-3. Finally, we found that overexpression of cyclin A1 significantly reduced the cytotoxicity of doxorubicin, and knockdown of cyclin A1 by RNA interference enhanced the sensitivity of cells to ionizing radiation. Our data suggest a new mechanism for the downregulation of cyclin A1 by DNA-damaging stimuli that could be intimately involved in the cell death induced by DNA damage-inducing stimuli, including doxorubicin and ionizing radiation.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2015

NDR1 modulates the UV-induced DNA-damage checkpoint and nucleotide excision repair

Nucleotide excision repair (NER) is the sole mechanism of UV-induced DNA lesion repair in mammals. A single round of NER requires multiple components including seven core NER factors, xeroderma pigmentosum A–G (XPA–XPG), and many auxiliary effector proteins including ATR serine/threonine kinase. The XPA protein helps to verify DNA damage and thus plays a rate-limiting role in NER. Hence, the regulation of XPA is important for the entire NER kinetic. We found that NDR1, a novel XPA-interacting protein, modulates NER by modulating the UV-induced DNA-damage checkpoint. In quiescent cells, NDR1 localized mainly in the cytoplasm. After UV irradiation, NDR1 accumulated in the nucleus. The siRNA knockdown of NDR1 delayed the repair of UV-induced cyclobutane pyrimidine dimers in both normal cells and cancer cells. It did not, however, alter the expression levels or the chromatin association levels of the core NER factors following UV irradiation. Instead, the NDR1-depleted cells displayed reduced activity of ATR for some set of its substrates including CHK1 and p53, suggesting that NDR1 modulates NER indirectly via the ATR pathway. - Highlights: • NDR1 is a novel XPA-interacting protein. • NDR1 accumulates in the nucleus in response to UV irradiation. • NDR1 modulates NER (nucleotide excision repair) by modulating the UV-induced DNA-damage checkpoint response.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2016

TGF-β1 accelerates the DNA damage response in epithelial cells via Smad signaling

The evidence suggests that transforming growth factor-beta (TGF-β) regulates the DNA-damage response (DDR) upon irradiation, and we previously reported that TGF-β1 induced DNA ligase IV (Lig4) expression and enhanced the nonhomologous end-joining repair pathway in irradiated cells. In the present study, we investigated the effects of TGF-β1 on the irradiation-induced DDRs of A431 and HaCaT cells. Cells were pretreated with or without TGF-β1 and irradiated. At 30 min post-irradiation, DDRs were detected by immunoblotting of phospho-ATM, phospho-Chk2, and the presence of histone foci (γH2AX). The levels of all three factors were similar right after irradiation regardless of TGF-β1 pretreatment. However, they soon thereafter exhibited downregulation in TGF-β1-pretreated cells, indicating the acceleration of the DDR. Treatment with a TGF-β type I receptor inhibitor (SB431542) or transfections with siRNAs against Smad2/3 or DNA ligase IV (Lig4) reversed this acceleration of the DDR. Furthermore, the frequency of irradiation-induced apoptosis was decreased by TGF-β1 pretreatment in vivo, but this effect was abrogated by SB431542. These results collectively suggest that TGF-β1 could enhance cell survival by accelerating the DDR via Smad signaling and Lig4 expression. -- Highlights: •TGF-β1 pretreatment accelerates γ-radiation-induced DNA damage response. •TGF-β1-accelerated DNA damage response is dependent on Smad signaling and DNA Ligase IV. •TGF-β1 pretreatment protects epithelial cells from γ-radiation in vivo.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2017

Antibiotic tigecycline enhances cisplatin activity against human hepatocellular carcinoma through inducing mitochondrial dysfunction and oxidative damage

Targeting mitochondrial metabolism has been recently demonstrated to be a promising therapeutic strategy for the treatment of various cancer. In this work, we demonstrate that antibiotic tigecycline is selectively against hepatocellular carcinoma (HCC) through inducing mitochondrial dysfunction and oxidative damage. Tigecycline is more effective in inhibiting proliferation and inducing apoptosis of HCC than normal liver cells. Importantly, tigecycline significantly enhances the inhibitory effects of chemotherapeutic drug cisplatin in HCC in vitro and in vivo. Mechanistically, tigecycline specifically inhibits mitochondrial translation as shown by the decreased protein levels of Cox-1 and -2 but not Cox-4 or Grp78, and increased mRNA levels of Cox-1 and -2 but not Cox-4 in HCC cells exposed to tigecycline. In addition, tigecycline significantly induces mitochondrial dysfunction in HCC cells via decreasing mitochondrial membrane potential, complex I and IV activities, mitochondrial respiration and ATP levels. Tigecycline also increases levels of mitochondrial superoxide, hydrogen peroxide and ROS levels. Consistent with oxidative stress, oxidative damage on DNA, protein and lipid are also observed in tigecycline-treated cells. Importantly, antioxidant N-acetyl-L-cysteine (NAC) reverses the effects of tigecycline, suggesting that oxidative stress is required for the action of tigecycline in HCC cells. We further show that HCC cells have higher level of mitochondrial biogenesis than normal liver cells which might explain the different sensitivity to tigecycline between HCC and normal liver cells. Our work is the first to demonstrate that tigecycline is a promising candidate for HCC treatment and highlight the therapeutic value of targeting mitochondrial metabolism in HCC. - Highlights: • Tigecycline selectively targets HCC in vitro and in vivo. • Tigecycline enhances HCC cell response to chemotherapeutic drug. • Tigecycline inhibits mitochondrial translation and functions in HCC cells. • Tigecycline induces oxidative stress and damage in HCC cells. • Mitochondrial biogenesis and respiration is higher in HCC than normal liver cells.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2017

Ku70 inhibits gemcitabine-induced DNA damage and pancreatic cancer cell apoptosis

The current study focused on the role of Ku70, a DNA-dependent protein kinase (DNA-PK) complex protein, in pancreatic cancer cell resistance to gemcitabine. In both established cell lines (Mia-PaCa-2 and PANC-1) and primary human pancreatic cancer cells, shRNA/siRNA-mediated knockdown of Ku70 significantly sensitized gemcitabine-induced cell death and proliferation inhibition. Meanwhile, gemcitabine-induced DNA damage and subsequent pancreatic cancer cell apoptosis were also potentiated with Ku70 knockdown. On the other hand, exogenous overexpression of Ku70 in Mia-PaCa-2 cells suppressed gemcitabine-induced DNA damage and subsequent cell apoptosis. In a severe combined immune deficient (SCID) mice Mia-PaCa-2 xenograft model, gemcitabine-induced anti-tumor activity was remarkably pontificated when combined with Ku70 shRNA knockdown in the xenografts. The results of this preclinical study imply that Ku70 might be a primary resistance factor of gemcitabine, and Ku70 silence could significantly chemo-sensitize gemcitabine in pancreatic cancer cells. - Highlights: • Ku70 knockdown sensitizes gemcitabine-induced killing of pancreatic cancer cells. • Ku70 knockdown facilitates gemcitabine-induced DNA damage and cell apoptosis. • Ku70 overexpression deceases gemcitabine's sensitivity in pancreatic cancer cells. • Ku70 knockdown sensitizes gemcitabine-induced anti-tumor activity in vivo.

60 APPLIED LIFE SCIENCES↗