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Emerging nonvolatile memories (eNVMs) have demonstrated satisfactory accuracy on various applications in deep learning. Characterized by high density and low leakage power consumption, resistive random access memory (RRAM) becomes very attractive in synaptic devices for deep neural networks (DNNs). RRAM-based synaptic devices include both analog and discrete versions. Unlike analog RRAM synapses which suffer from nonlinearity, discrete but multistate RRAM synapses are better suited for neural network hardware implementation. In this article, the multistate operation in RRAM arrays has been proposed as a synaptic device for DNN inference. Four-state conductance has been achieved in HfO x -based RRAM synaptic arrays. The impact of total ionizing dose (TID) on the multistate behavior of HfO x -based RRAM is investigated by irradiating a one-transistor–one-resistor (1T1R) 64-kb array with CMOS peripheral decoding circuitry fabricated at the 90-nm technology node with Co-60 gamma rays (60Co $\gamma $ -ray irradiation).

Total ionizing dose response of 14-nm bulk-Si FinFETs has been studied with a specially designed test chip. The radiation testing shows evidence of interface trap build-up on 14-nm Bulk FinFET technologies. These defects created in the isolation layer give rise to a new radiation-induced leakage path which might lead to a reliability issue in CMOS technologies at or below the 14-nm node. TCAD simulations are performed and an analytical model for TID-induced leakage current is presented to support analysis of the identified TID mechanism. TCAD simulation and analytical model results are consistent with the experimental data.

Atmospheric nitrous oxide (N2O) is a potent greenhouse gas thought to be mainly derived from microbial metabolism as part of the denitrification pathway. Here, we report that in unexplored peat soils of Central and South America, N2O production can be driven by abiotic reactions (≤ 98 %) highly competitive to their enzymatic counterparts. Extracted soil iron positively correlated with in-situ abiotic N2O production determined by isotopic tracers. Moreover, we found that microbial N2O reduction accompanied abiotic production, essentially closing a coupled abiotic-biotic N2O cycle. Anaerobic N2O consumption occurred ubiquitously (pH 6.4-3.7), with proportions of diverse clade II N2O-reducers increasing with consumption rates. Our findings show denitrification in tropical peat soils is not a purely biological process, but rather a “mosaic” of abiotic and biotic reduction reactions. We predict hydrological and temperature fluctuations differentially affect abiotic and biotic drivers and further contribute to the high N2O flux variation in the region.

Atmospheric nitrous oxide (N

Chemodenitrification – the non-enzymatic process of nitrite reduction – may be an important sink for fixed nitrogen in tropical peatlands. Rates and products of chemodenitrification are dependent on O2, pH, Fe2+ concentration, and organic matter composition, which are variable across peat soils. Assessing abiotic reaction pathways is difficult because sterilization and inhibition agents can alter the availability of reactants by changing iron speciation and organic matter composition. We compared six commonly used soil sterilization techniques – γ irradiation, chloroform, autoclaving, and the use of three different chemical inhibitors (mercury, zinc, and azide) – for their compatibility with chemodenitrification assays for tropical peatland soils (organic-rich, low-pH soil from the eastern Amazon). Out of the six techniques, γ irradiation resulted in soil treatments with the lowest cell viability and denitrification activity and the least effect on pH, iron speciation, and organic matter composition. Nitrite depletion rates in γ-irradiated soils were highly similar to untreated (live) soils, whereas other sterilization techniques showed deviations. Chemodenitrification was a dominant process of nitrite consumption in tropical peatland soils assayed in this study. Nitrous oxide (N2O) is one possible product of chemodenitrification reactions. Abiotic N2O production was low to moderate (3 %–16 % of converted nitrite), and different sterilization techniques lead to significant variations on production rates due to inherent processes or potential artifacts. Our work represents the first methodological basis for testing the abiotic denitrification and N2O production potential in tropical peatland soil.

Greenhouse gas emissions from fossil power plants contribute significantly toward climate change. Simultaneously, the increase in ambient air and water temperatures reduces thermal power generation. Coal, nuclear and natural gas plants experience a 0.25%-0.72% reduction in power output for a 1°C increase in the ambient temperature. As ambient temperatures increase, generation losses from coal, nuclear and natural gas together are predicted to increase at an average rate of around 700 GWh/y. At this rate, average annual generation losses could add up to around 29 TWh for coal, nuclear and natural gas combined in 2050. Approximately ten additional 600 MW power plants might be needed to replace this lost electricity by 2050. Concurrently, average losses in generation income could total $1400 million for these thermal plants in 2050. Changes in solar and hydro power are also briefly compared. Finally, the importance of water availability and the effects of extreme climate events on thermal power plants are discussed.

With the growing interest to explore Jupiter’s moons, technologies with +10 Mrad(Si) tolerance are now needed, to survive the Jovian environment. Conductive-bridging random access memory (CBRAM) is a nonvolatile memory that has shown a high tolerance to total ionizing dose (TID). However, it is not well understood how CBRAM behaves in an energetic ion environment where displacement damage (DD) effects may also be an issue. In this paper, the response of CBRAM to 100-keV Li, 1-MeV Ta, and 200-keV Si ion irradiations is examined. Ion bombardment was performed with increasing fluence steps until the CBRAM devices failed to hold their programed state. The TID and DD dose (DDD) at the fluence of failure were calculated and compared against tested ion species. Results indicate that failures are more highly correlated with TID than DDD. DC cycling tests were performed during 100-keV Li irradiations and evidence was found that the mobile Ag ion supply diminished with increasing fluence. The cycling results, in addition to prior 14-MeV neutron work, suggest that DD may play a role in the eventual failure of a CBRAM device in a combined radiation environment.

Cu–SiO2 and Ag–Ge30Se70 conductive bridging random access memory (CBRAM) resistive memories are shown to be susceptible to ionizing radiation effects during neuromorphic pulse programming. in situ measurements were performed to evaluate the response of CBRAM devices during 60Co irradiation. DC current–voltage ( $I$ – $V$ ) sweeps and pulse testing were performed. No total ionizing dose (TID) effects were observed during the in situ $I$ – $V$ measurements; however, the conductance change caused by pulsed programming was shown to decrease with increasing TID. Both device types were tested beyond 1 Mrad.

This chapter reveals that nuclear energy can be utilized to supply power in specialized cases. First, nuclear-powered ships and submarines were the inspiration of today’s commercial pressurized water reactors. Second, reactors can be employed for the propulsion and powering of space vehicles. Besides reactors, radioisotopes have been placed into service for heating and electric power generation in both terrestrial and space borne platforms. Future extraterrestrial applications include power for interplanetary exploration and terraforming.

This chapter explores the use of radioisotopes in extracting information. Radioisotopic tracers permit measurement of fluid velocities. Medical diagnosis and therapy routinely employ radiopharmaceuticals. To generate three-dimensional images, various tomography methods rely upon the signatures generated from the passage of radiation through matter. Although carbon-14 dating is well known, other radionuclides are better suited to dating items of greater age. The activation of samples exposed to neutrons allows quantification of the impurities present. Radiography uses photons and neutrons to study the internal composition of living organisms and inanimate objects. Portable nuclear gauges measure density and moisture content of the ground.

This chapter reviews the history related to nuclear energy beginning with scientific investigations in the late 1800s that led to the discovery of subatomic particles and both atomic and nuclear structure. Those research efforts spawned the discovery of fission. The Manhattan Project to develop an atomic bomb then accelerated the knowledge base of nuclear phenomena. After World War II, the Atomic Energy Commission was established and later the International Atomic Energy Agency. Research and development efforts led to the deployment of the first nuclear power plants. This chapter ends by addressing the controversies surrounding nuclear energy in the late twentieth century.

This chapter establishes a solid foundation for understanding nuclear reactions such as transmutation. Writing a nuclear reaction formula requires balancing nucleons, charge, momentum and total energy. Application of conservation of energy permits determination of the Q value from which a reaction is categorized as endothermic or exothermic. Additionally, conservation of momentum, a vector quantity, allows calculation of the product kinetic energies. Microscopic cross sections, which vary with the energy of the incident particle, quantify the likelihood of one of a multitude of different reactions occurring with a nucleus including scattering, capture, and fission. Reaction rates are the product of the particle flux and the macroscopic cross section. Neutron scattering is the key process to reduce neutron energy while they diffuse in a medium. Neutrons experience attenuation in a medium by an exponential law.

This chapter delves into the important heating processes within a nuclear power plant. Applying Fourier’s law of heat conduction permits determining temperature distributions within the nuclear fuel rods. In contrast, convective cooling occurs on the rod surface. The coolant, cladding and fuel temperature distributions through a reactor are determined. Besides heat transfer in the reactor core, some power plants employ heat exchangers to generate steam that is fed to a turbine-generator to produce electricity. As a consequence of the second law of thermodynamics, thermal power plants reject condenser heat to the environment through mechanisms such as cooling towers.

This chapter examines the interaction of various radiations with matter beginning at the atomic level and finally at the macroscopic level. Incident electrons, beta particles and heavy ions are stopped primarily by the orbital electrons through Coulombic interactions. Additionally, electrons and betas can produce bremsstrahlung. Heavy charged particles (ions) also may undergo nuclear reactions. Photons such as X-rays and gamma rays experience three major interactions, namely photoelectric effect, Compton scattering, and pair production, where the latter leads to annihilation radiation. The neutral radiations (photons and neutrons) are considered indirectly ionizing, while the charged particles (electrons and ions) are directly ionizing. Radiation causes changes in material macroscopic properties.

This chapter presents the physics behind a variety of particle accelerators, which are used in nuclear physics research and other applications. A brief review of the effects of electric and magnetic fields on charged particles is provided. Early approaches were the high-voltage machines such as the Van de Graaff electrostatic generator and the Cockroft-Walton voltage multiplier. The linear accelerator (LINAC) utilizes successive particle accelerations through a series of tubular electrodes. By employing a magnetic field, the cyclotron accelerates particles in a circular direction. Within the betatron, a changing magnetic field produces an electric field that accelerates electrons to relativistic speeds; whereas in the synchrotron, both radiofrequency and time-varying magnetic fields are used.

This chapter faces the realization that the same atoms that can produce life-saving electricity can also be used to construct weapons of mass destruction. Some facilities, such as enrichment and reprocessing, in the nuclear fuel cycle can also serve dual uses when considering proliferation. The original atomic bombs were constructed of highly enriched uranium and high-grade plutonium, but their development led to thermonuclear devices with much larger yields. Thus far, nuclear war has been avoided by policies such as mutual assured destruction and international agreements such as the Non-Proliferation Treaty. The International Atomic Energy Agency (IAEA) is charged with performing worldwide nuclear material safeguards inspections. The legacy of the nuclear weapons arms race has left considerable weapons-grade materials that must be dealt with.

This chapter presents various beneficial uses of radiation, such as crop mutations and insect control. Most people are cognizant of the use of radiation for treating cancer, but less well-known applications include food preservation through elimination of pathogens, bacteria, and other contaminants. Sterilization via radiation exposure is performed on medical instruments and products. Local energy deposition can stimulate chemical reactions and transform the structure of plastics and semiconductors. Neutrons and X-rays are used to investigate basic physical and biological processes.

This chapter explores the breeding of fissile material within a reactor in order to extract greater amounts of energy in uranium and thorium resources. From neutronic considerations, fast reactors are found to be more appropriate to serve as a breeder reactor. Differential equations describing the buildup of plutonium in a U-238 fueled reactor are solved. Several liquid metal fast breeder reactors have been built worldwide with two basic configurations: pool and loop systems. The economics of breeders is linked with the cost, and therefore available resources, of uranium. The interrelationship between breeder reactors and reprocessing is explained.

This chapter describes the biological effect of radiation on cells, tissues, organs, and individuals. Quantifiers for radiation dose and units such as rad, rem, gray, and sievert are identified. Some radiations, namely ions and neutrons, are found to have a more detrimental impact on biological entities for the same dose. Radioactive decay and biological elimination of radionuclides lead to an effective decay constant. Related concepts addressed include radiation sickness, lethal dose, chronic and acute exposures, and hormesis. The philosophy and practice of setting limits on exposure are reviewed with special attention given to regulations related to the nuclear power industry.

Climate change is affecting power generation globally. Increase in the ambient temperature due to the emission of greenhouse gases, caused mainly by burning of fossil fuels, is the most prominent reason for this effect. Climate change has encouraged the shift of power generation from burning of fossil fuels to more sustainable generation techniques from renewable sources such as hydro, wind and solar energy. Outcomes of climate change affect the power generation from these sources. Increase in the temperature and evaporation and decrease in the snow levels have decreased the hydropower generation in the Colorado River Basin. The maximum decrease in wind power generation, only due to the effect of increasing temperatures, in the U.S. is 0.6-1.0% by mid-century and 0.8-1.9% by end of the century. Change in solar radiation and precipitation affect the solar power generation. This paper analyzes various factors of climate change and the extent to which they impact the power generation from hydro, wind and solar energy sources.