Academic literature on the topic 'Fuel element shell'

Until recently, many of America's ethnic poets remained underrepresented in classrooms and literary anthologies. This volume, celebrating the lives and works of 75 significant poets, testifies to the power of poetry to change perspectives. These poets produce works that display the range of human experiences and expression, with an added element of intensity from being both American and ethnic. This book presents the lives and literary contributions of famous and unfamiliar poets alike. Offering concise personal and professional information, including awards, coverage includes such poets as Maya Angelou, N. Scott Momaday, Leslie Marmon Silko, Rita Dove, Gary Soto, Pat Mora, Derek Walcott, and more. Readers are also introduced to the major works and thematic concerns of such lesser-known poets as Luci Tapahonso, Li-Young Lee, and Jimmy Santiago Baca. A dozen different ethnic backgrounds are represented, including Asian American, African American, Jewish American, American Indian, Latino/a, and Palestinian American. Full bibliographic information following each entry will help users locate the collections and anthologies where the cited poems can easily be found. Instead of having to turn to a number of different sources for information on diverse poets, users will find here a wealth of information to satisfy their individual needs and interests. Introduced with an inspiring essay on multi-cultural poetry, this multi-use guide follows standard A-to-Z reference format for direct access to all biographical and bibliographic content. Set up to aid librarians and educators, additional components allow users to search for information in a number of different ways. Readers interested in poets of a particular ethnicity will find two helpful guides: an appendix listing poets by ethnic background and a supplementary list of additional poets, not covered in the text, also organized by ethnicity. For student assignments, a thematic guide identifies which poets have written about important topics such as ancestry, nature, family, lesbianism, immigration, and internment. Whether used a collection development tool or a research guide, this valuable reference will earn its place on the reference shelf.

AbstractWith the emergence of various novel fuel elements, traditional X-ray test technologies refer to national standards that have gradually been unable to meet the non-destructive testing (NDT) requirements for these novel fuel elements. As a new NDT technology, industrial computed tomography (CT) has great potential for NDT of nuclear fuel elements. In this paper, through a personalized transformation of self-developed X-ray equipment, we carried out CT scanning imaging experiments up to more than 400 kV on pellet-shell gap in rod-shaped fuel elements, a high-density annular component, and a tungsten-based workpiece. Not only that, after three-dimensional reconstruction and image analysis, it was found that sub-millimeter internal void defects could be detected. Furthermore, size measurements were carried out through image analysis which achieved a relative error of 5%. A conservative conclusion can be drawn from this research: industrial CT, including but not limited to micro-CT, high-energy X-ray CT, etc., has an optimistic future in testing internal defects and measuring internal dimensions of novel fuel elements.

Uninterrupted transportation of bulk fuel and lubricant cargoes is one of the main tasks facing the railway transport of Ukraine. At the same time, the nomenclature (light and dark petroleum products, fuel oils) of bulk cargoes and the limited number (due to the obsolescence of the existing fleet of tank cars and the inability to renew them in military conditions) of the corresponding rolling stock require constant and high-quality cleaning of tank car boilers. This is due to the need for prompt use of tank cars for the transportation of various types of cargo. Modern boiler cleaning technologies are associated with the application of temperature loads to their boilers, namely with washing and steaming operations. This directly affects the stress-deformed state of tank car boilers. Which, in turn, determines the need for scientific research to determine the temperature effect on the stressed-deformed state of the tank car boiler during washing and steaming operations. It was the solution of such a scientific and applied task that became the goal of research, the results of which are presented in this section of the monograph. To achieve the set goal, the following scientific and applied tasks were defined and solved. The existing information sources on the relevant topic were analyzed. Next, the technical description and requirements for modern designs of tank cars and their boilers are presented. Then, the used and adapted moment theory of shells is presented. On the basis of this mathematical theory, the load values at the control points of the tank car boiler are determined. Based on these results, the calculation model built in a modern computer computing and software complex was adjusted. Which was calculated using the finite element method and brought to an adequate level. The developed adequate finite element model includes the optimal number of finite elements and nodes: 10 182 768 elements and 18 655 084 nodes. Tetrahedrons and triangles are used as finite elements. With the use of the developed adequate finite-element model, temperature load calculations and simulation of the application of hot steam were carried out. At the same time, the temperature of hot steam is 160 °C, and the calculation period is 20 minutes. As a result of the calculations, it was found that the maximum heating temperature of the boiler is 71.3 °C when the temperature is loaded with steam. On the basis of the obtained results of temperature simulations, the input data for determining the stress-strain state of the tank car boiler were formed. The results of the calculations made it possible to establish that the maximum stress values are 173 MPa and do not exceed the permissible values. That is, when washing and steaming operations are carried out, the strength condition is fulfilled. The obtained results of simulations of temperature loads and the stress-strain states corresponding to them will be useful in conducting further research and development works on the selected topic. In addition, the obtained results and achievements can be used in educational activities in the preparation of students of various levels of education.

Continuously curved, full glass shells have a large potential for application in free-form façades or roofs. Glass elements needed for such a construction can be fabricated either by heat bending or cold lamination bending. But as the curvature and size of glass laminates are limited by manufacturing restrictions, structural joining is necessary for assembling large shells. Unfortunately, such joint discontinuities conflict with the desired membrane state of the shell. The joint pattern layout has a large influence on the load bearing behaviour, stability and appearance of glass shells. Hence, computational procedures have been used to optimise the joint geometry layout by targeting either at minimising particular joint forces or by following the principal membrane force trajectories of the shell.

Abstract For multi-electron atoms we cannot solve the Hamiltonian analytically, but by making appropriate approximations we can explain their structure in a physically meaningful way. To do this, we start by considering the elementary ideas of atomic structure underlying the periodic table of the elements. In the ground states of atoms the electrons have the configuration that minimises the energy of the whole system. The electrons do not all fall down into the lowest orbital with n = l (the K-shell) because the Pauli exclusion principle restricts the number of electrons in a given (sub-)shell-two electrons cannot have the same set of quantum numbers. This leads to the ‘building-up’ principle: electrons fill up higher and higher shells as the atomic number Z increases across the periodic table.1 Full shells are found at atomic numbers Z = 2, 10, ... corresponding to helium and the other inert gases.

‘The fundamentals’ investigates why the element carbon is so suited for the generation of so many compounds. Carbon has atomic number six, meaning it has six protons in its nucleus and six electrons around the nucleus, four of which are valence electrons held in the outer shell. Carbon achieves a stable, full outer shell of electrons by sharing electrons with other elements and other carbon atoms to form covalent bonds. The carbon–carbon bonds are one of the principle reasons why so many organic molecules are possible, including linear chains, branched chains, and rings. The naming of compounds and identification of structures is also explained along with stereochemistry, functional groups, and intermolecular and intramolecular interactions.

A proposition of 3D numerical model of light wood-framed structures is presented in the paper. To describe the behavior of fasteners, 6 degrees of freedom beam element was used. The model took into account the non-linear characteristics of the whole structure resulting from the non-linear behavior of individual connectors. There was made an assumption that only non-linear elements of the structure had sheathing-to-framing connectors. Sheathing and framing were described by shell elements and its stiffness matrixes had included orthotropic material characteristics of timber and chipboard. The function describing the P-Δ characteristics of fasteners was obtained on the basis of joint experimental researches. Verification of the proposed model was provided by comparative analyses of results obtained from the proposed model and full-scale experimental tests. The proposed model results have shown good agreement with the results of experimental studies, particularly in the range of destructive burden.

Abstract The conclusion from the analysis of the abiological material around us in Chapter 6 is that, in both its physical and chemical conditions, the variance of inanimate Earth became incalculably large due to the prevailing conditions that inhibited the generation of full chemical equilibria, thus giving rise to many components, and to the inability to maintain equilibrium transfer of components between phases. In effect, most systems on Earth broke down into compartments (Section 6.3) in and between which both failures to equilibrate were due to barriers to change produced by the rapid fall in temperature. However, we were able to treat most of these systems locally through the thermal equilibrium considerations described in Chapter 6. Now around us we see millions of living individuals in species, which are reproducible almost identical objects, closely, if not exactly, invariant in chemical composition as well as in physical appearance, even during growth. They can be compared with a set of identical single crystals. Our arguments in the previous chapters led us to conclude that internally individual living systems, organisms, are therefore effectively invariant in components and transfer between their compartments, which is the condition of equilibrium. Clearly, however, they are not at equilibrium since they are developing and expanding flow systems. It must then be to considerations of flow and development, that is, to rate of change of, first, components and, second, of compartments, to which we must turn to understand the nature of this constancy of living reproducible objects. We shall ask the question: is there any true parallel between the growth of living organisms with a fixed pattern and the expansion of phases of inanimate objects (crystals) that can occur on cooling at equilibrium? Throughout this enquiry we are seeking an explanation of the objects around us in terms of the natural selection of the chemical elements, now related to their ability to change at selected rates. We shall not attempt to come to any firm conclusion until Chapter 16.

Finite element models of spent fuel casks and canisters that are typically used in impact and impulse analyses may contain tens of thousands of nonlinear elements. These models use explicit time integration methods with small time steps. To achieve reasonable run times, fully integrated elements are replaced with under-integrated elements that use reduced integration procedures. When fully integrated these elements produce a linear strain distribution. Reduced integration, however, results in a constant strain distribution, which requires more elements through the thickness of the canister shell to achieve the same accuracy as fully integrated elements. This paper studies the effect of the number of reduced integration elements through the thickness of the canister shell and the ratio of element height to shell thickness on the accuracy of the strains in regions of high through-thickness bending, such as the junction between the shell and base plate. It is concluded that mesh refinement has a significant effect on the maximum plastic strain response in such regions and that a converged solution may not be attainable within practical limits of mesh refinement, if the results are based solely on the maximum plastic strain on a cross section at a structural discontinuity. The objective is not to chase the stress concentration with ever finer meshes, but rather the objective is to establish a mesh density within the discontinuity region that results in the stresses and strains that are associated with the bending moment that restores compatibility at the structural discontinuity. In this case a converged solution is obtained by investigating the response of other elements on the same cross section that are not located on the surface of the stress concentration at the structural discontinuity. Based on the results, a “rule of thumb” is proposed for mesh refinement in a region of severe structural discontinuity wherein reasonably proportioned reduced integration solid elements are used and plastic strains are evaluated.

To inhibit the infiltration of liquid fluoride salt and easy to load and unload, fuel element in molten salt reactor (MSR) was isostatically pressed with an innovative design: A fuel-free low density graphite core of ≤ 30 mm diameter embedded in fuel-zone shell of ≥ 2.5 mm thickness, and then enveloped in a high density graphite shell of ≥ 5 mm thickness. Bulk density of the spherical fuel element can be designed from the range of 1.65–1.80 g/cm3, which is lower than the density of the liquid fluoride salt to make sure the fuel element can float in the MSR to load and unload. Characteristics of mercury infiltration and molten salt infiltration in graphite shell were investigated and compared with A3-3 graphite to identify the infiltration behaviors. The results indicated that the graphite shell has a low porosity about 9%, and an average pore diameter of 100 nm. The fluoride salt occupation of A3-3 was 10 wt% under 6.5 atm, whereas the salt gain did not infiltrate in graphite shell even up to 6.5 atm. It demonstrated that the outside graphite shell could inhibit the infiltration of liquid fluoride salt effectively. At the operating temperature of MSR (700 °C), thermal conductivity of graphite shell was 13.61 W/m K. The coefficient of thermal expansion (CTE) of outside graphite shell lied in 6.01×10−6 K−1 (α⫽) and 6.15×10−6 K−1 (α⊥) at the temperature range of 25–700 °C. The anisotropies factor of graphite shell calculated by CTE maintained below 1.12, which could meet the requirement of the spherical fuel element (below 1.30). The constant isotropic properties of graphite shell are beneficial for the integrity and safety of the spherical fuel element for a MSR.

Abstract An improved moving deformable barrier (MDB) model was developed for simulation of fuel system performance tests. This MDB model was designed to replace a bullet vehicle model for the vehicle-to-vehicle impact simulations where a bullet vehicle impacts a target vehicle at 50mph. This study included three crash modes, rear-inline, rear-50% offset, and side impact-centerline of fuel filler, required in the fuel system integrity test. The MDB model is composed of a barrier facial, same as the FMVSS (Federal Motor Vehicle Safety Standards) 214 [1] side impact barrier facial, and a movable cart on which the barrier facial is mounted. The main block and bumper block in the barrier facial are modeled by using solid elements while aluminum plates are represented by using shell elements. The movable cart is modeled by using beam elements with four air-bag tires. Two dynamic component tests were adopted to calibrate the barrier facial properties. To assure the model is applicable to all vehicle lines and different test modes, extensive validation was conducted. The full system validation contained a car, a mini-van, a van, and a pick-up truck. Three different test modes were all included in this study. Both accuracy and numerical stability of the model were examined carefully in each simulation. For accuracy, the deformation modes and responses of the MDB were compared to those of the tests. Time steps were monitored in each simulation to investigate the degradation of numerical stability. Through calibration and validation, the MDB model was found to be robust and numerically stable.

A method has been developed to incorporate the local three-dimensional shell behavior of two concentric tubes in the two-dimensional beam modeling of the problem. The two dimensional modeling of fuel channels in CANDU pressurized heavy water nuclear reactors is used in lieu of a more accurate three dimensional finite element approach in order to reduce the on-line simulation time which greatly affects the SLAR (Spacer Location And Repositioning) maintenance operation cost during outage. However, effort must be made to include the three-dimensional shell behavior of these channels into the two-dimensional modeling. In recent studies a nonlinear force-dependent model for contact stiffness between the calandria tube and pressure tube has been developed. However, local deformation of calandria the tube at spacer locations due to in-reactor creep leads to settling of the spacer into the calandria tube that consequently reduces the gap between the two tubes. In this work, the effect of local deformation (elastic and creep) of calandria tubes on modeling of contact at spacer locations is assessed using a three dimensional finite element code. The result is incorporated into a two-dimensional beam model of the problem as a reduction in size of the spacers that separate the two tubes. It is shown that the proposed method increases the accuracy of prediction of contact time and the spacer. In general, the method described in this paper suggests a way to incorporate local shell deformation into beam models of slender shell structure.

Abstract. Bipolar plates are the essential components of a Proton Exchange Membrane Fuel Cell. Lightweight bipolar plates can be micro-stamped from an ultrathin metallic foil. A major concern is the manufacturability of the foil in the micro-stamping process. The typical stamped micro-channels have end cavities or corners where the deformation mode can be different from the two-dimensional plane strain conditions that occur at the straight sections of the micro-channels. The thin foil has a large ratio of length (or width) to thickness, and shell elements were often used for three-dimensional models. Currently, it is unknown if the shell elements available in commercial software packages are able to predict the ultrathin material behaviour correctly. In addition, the deformation behaviour and forming limits of titanium foil in the micro-stamping process are not well understood. The current study uses a micro-stamping tool to produce straight micro-channels from commercially pure titanium foil. The experimental data are used to validate a two-dimensional and a three-dimensional finite element model of the process. It is shown that there are deviations between the experimental and the numerical thinning results. Material thinning is different between the straight and the cavity end sections suggesting that three-dimensional process models are required to accurately analyze forming.

<title>ABSTRACT</title> <p>Lithium-ion (Li-ion) batteries have become an important energy storage solution for a wide range of applications from consumer electronics to automobiles. In particular, the automotive industry’s push for improved fuel efficiency has led to the development of electric and hybrid-electric vehicles, many of which use Li-ion batteries. In addition to these fuel-saving motivations for Li-ion batteries, the US Army has its own unique mission requirements for onboard energy storage and available power, which could potentially be addressed at least in part, by Li-ion batteries. However, military ground vehicles are also subject to harsh operating conditions and abuse conditions that can cause failures of onboard equipment. Due to complex nature of the batteries, it is numerically challenging to capture the behavior of these batteries under abuse conditions such as a high-energy impact event. Each battery cell is made up of several layers and sub-layers of different materials. If a finite element model is created by meshing each sub-layer with sufficient detail to perform a ballistic simulation, even a single battery cell will have millions of degrees of freedom (DOF). In a hybrid-electric vehicle battery there are typically tens of cells in a module and hundreds of cells in a full pack. Therefore, the computational challenge associated with using finite element analysis (FEA) for ballistic simulations becomes daunting. In this work, a new method is proposed that employs a Thick Shell Composite (TSC) representation of Li-ion batteries using the commercially available FEA software, LS-DYNA. This approach shows promise for modeling the battery at the module or full-pack level with significantly reduced computational cost compared to a more traditional modeling approach. Individual layers are embedded into this TSC in order to reduce the number of finite elements in each cell significantly. Several of these cells are then assembled either in series or parallel to represent the module and the full battery pack. The TSC numerical model is validated by running a simulation of a bullet impact test and comparing the results to the equivalent physical test. The TSC model predictions show good agreement with the experimental results. In addition, three different impact angle scenarios (oblique, vertical, and horizontal) are simulated for one module of a generic Li-ion battery using the new approach. The extent of the predicted battery damage due to these different impact loading conditions are compared both qualitatively and quantitatively.</p>

Metal matrix microencapsulated (M3) fuel is one of the research directions on Accident Tolerant Fuel (ATF). In this article, it provides one of ATF design which consists of BISO (Bistructural ISOtropic) particles embedded in a zirconium alloy matrix, and the cladding coating with silicon carbon (SiC). The temperature distribution of the ATF element has been built, and then the center temperature has also been calculated based on the operation parameters of the large-scale pressurized-water reactor. Simultaneity, the several factors of fuel failure is preliminary analyzed and calculated, especially the pressure shell failure mechanism.

Abstract A composite container for the retention and disposal of used CANDU™ nuclear fuel was structurally analyzed. The design employs an inner steel vessel for support against external pressure and a close-fitting outer copper vessel for corrosion resistance. The container is deposited in an underground disposal vault in granitic rock and is surrounded by a clay-based buffer that swells when contacted by groundwater. It must withstand the swelling pressure of the buffer plus the hydrostatic pressure of the groundwater at a minimum 500-m depth. The case was analyzed in which a small manufacturing defect penetrates the copper shell, allowing groundwater to seep between the vessels and gradually convert the steel of the inner vessel to magnetite. Because the specific volume of magnetite is approximately twice that of steel, the outer surface of the steel vessel progressively swells while the remaining (uncorroded) shell thins. Outward deformation of the copper vessel is resisted by the buffer and surrounding rock, therefore pressure on the steel vessel gradually increases as it corrodes. The finite element code, ANSYS, was used to predict the minimum corrosion that would produce plastic collapse of the steel vessel. Knowledge of the rate of conversion of steel to magnetite under disposal-vault conditions could then allow an estimate of the time-to-collapse following the initial ingress of groundwater.

Efficient and cost-effective thermal energy storage system plays an important role in energy conservation. Elemental sulfur, the thirteenth most abundant element on earth, is actively being researched as a potential thermal storage medium due to its high energy storage density and low cost. The present work investigates the heat transfer behavior of elemental sulfur at temperatures between 50 degree Celsius and 250 degree Celsius. A shell and tube heat exchanger configuration with sulfur stored inside the tubes and heat transfer fluid flowing over the tubes through the shell is considered. A detailed computational model solving for the conjugate heat transfer and solid-liquid phase change dynamics of the sulfur based thermal energy storage system is developed to elucidate the complex interplay between the governing heat transfer and fluid flow phenomena during charge and discharge operations. The developed numerical model is compared with experimental results and a systematic parametric analysis of the effects of various design parameters on the performance of the thermal storage system is reported.

Spent fuel pool and storage racks are important nuclear security structures and components. In order to prevent it from structural failure, which includes the loss of the structural integrity of the spent fuel pool and stability of the spent fuel storage racks, also includes the possibility of fallen down of storage racks under seismic loading. Besides the necessary static analysis of structures, the influence of seismic loading on the interaction between water and structure should be fully considered, Especially concerned the analysis of the shaking effect of water sloshing on the storage racks, the displacement and the possibility of fallen down of the storage racks. The present paper is concerned with the problem of modeling the fluid-structure interaction (FSI) in filled liquid and filled with spent fuel pool. The study focuses on the sloshing phenomena and on the coupling computational fluid dynamic (CFD) analysis with the finite element stress analysis (FEA) code LS-DYNA. By the results of the response of seismic, such as the displacement of the storage racks, pressure exerted on the plate of racks and the walls of the pool. This paper also evaluates the seismic performance of the structure and the safety margin. Various numerical methods can be used for analysis of liquid storage pools, among these we mention explicit finite element, implicit Lagrangian-Eulerian, hybrid finite element, Smoothed Particle Hydrodynamics volume of fluid. In this article the coupled sloshing dynamics in a rectangle pool were studied using a model developed in LS-DYNA environment. The main solution methodology is based on explicit time integration. In order to demonstrate the FSI results of the FEA models of the spent fuel pool on seismic analysis, a 3D FEA models were developed. The Finite element model composed of the spent fuel pool (steel plate concrete), spent fuel storage racks, cushion block, water and air. Solid element modeling is used in concrete, cushion block, water and air. Steel plate and storage racks employ the shell element. The constitutive model of solid element is linear elastic. And the constitutive model of fluid element is described by the Gruneisen equation. Arbitrary Lagrangian-Eulerian (ALE) formulation is thought of as algorithms that perform automatic rezoning. It realized the advection of water and air in the ALE multi-material group.

Buried pipelines subjected to non-continuous ground movement such as frost heave, thaw settlement, slope instability and seismic movement experience high compressive strains that can cause local buckling (or wrinkling), in which the pipe wall buckles like a thin cylindrical shell in axial compression. In a strain-based design and assessment framework, excessive local buckling deformation that may cause loss of serviceability, or even pressure containment in some cases, is managed by limiting the strain demand below the strain limit. The determination of compressive strain limit is typically performed by full-scale structural testing or nonlinear finite element analysis that takes into account material and geometric non-linearity associated with the inelastic buckling of cylindrical shells. Before performing testing and numerical analysis (or when such options do not exist), empirical equations are used to estimate the strain limit. In this report a number of representative equations were evaluated by comparing strain limit predictions to full-scale test results. Work prior to this study has identified the importance of key variables that have the greatest impact on the local buckling behaviour. Examples of these variables include the diameter-to-thickness (D/t) ratio, internal pressure and shape of the stress strain curve. The evaluation focused on how existing equations address these key variables, and the performance with respect to key variables and in different ranges.

Banco de la República is celebrating its 100th anniversary in 2023. This is a very significant anniversary and one that provides an opportunity to highlight the contribution the Bank has made to the country’s development. Its track record as guarantor of monetary stability has established it as the one independent state institution that generates the greatest confidence among Colombians due to its transparency, management capabilities, and effective compliance with the central banking and cultural responsibilities entrusted to it by the Constitution and the Law. On a date as important as this, the Board of Directors of Banco de la República (BDBR) pays tribute to the generations of governors and officers whose commitment and dedication have contributed to the growth of this institution.1 Banco de la República’s mandate was confirmed in the National Constitutional Assembly of 1991 where the citizens had the opportunity to elect the seventy people who would have the task of drafting a new constitution. The leaders of the three political movements with the most votes were elected as chairs to the Assembly, and this tripartite presidency reflected the plurality and the need for consensus among the different political groups to move the reform forward. Among the issues considered, the National Constitutional Assembly gave special importance to monetary stability. That is why they decided to include central banking and to provide Banco de la República with the necessary autonomy to use the instruments for which they are responsible without interference from other authorities. The constituent members understood that ensuring price stability is a state duty and that the entity responsible for this task must be enshrined in the Constitution and have the technical capability and institutional autonomy necessary to adopt the decisions they deem appropriate to achieve this fundamental objective in coordination with the general economic policy. In particular, Article 373 established that “the State, through Banco de la República, shall ensure the maintenance of the purchasing power of the currency,” a provision that coincided with the central banking system adopted by countries that have been successful in controlling inflation. In 1999, in Ruling 481, the Constitutional Court stated that “the duty to maintain the purchasing power of the currency applies to not only the monetary, credit, and exchange authority, i.e., the Board of Banco de la República, but also those who have responsibilities in the formulation and implementation of the general economic policy of the country” and that “the basic constitutional purpose of Banco de la República is the protection of a sound currency. However, this authority must take the other economic objectives of state intervention such as full employment into consideration in their decisions since these functions must be coordinated with the general economic policy.” The reforms to Banco de la República agreed upon in the Constitutional Assembly of 1991 and in Act 31/1992 can be summarized in the following aspects: i) the Bank was assigned a specific mandate: to maintain the purchasing power of the currency in coordination with the general economic policy; ii) the BDBR was designatedas the monetary, foreign exchange, and credit authority; iii) the Bank and its Board of Directors were granted a significant degree of independence from the government; iv) the Bank was prohibited from granting credit to the private sector except in the case of the financial sector; v) established that in order to grant credit to the government, the unanimous vote of its Board of Directors was required except in the case of open market transactions; vi) determined that the legislature may, in no case, order credit quotas in favor of the State or individuals; vii) Congress was appointed, on behalf of society, as the main addressee of the Bank’s reporting exercise; and viii) the responsibility for inspection, surveillance, and control over Banco de la República was delegated to the President of the Republic. The members of the National Constitutional Assembly clearly understood that the benefits of low and stable inflation extend to the whole of society and contribute mto the smooth functioning of the economic system. Among the most important of these is that low inflation promotes the efficient use of productive resources by allowing relative prices to better guide the allocation of resources since this promotes economic growth and increases the welfare of the population. Likewise, low inflation reduces uncertainty about the expected return on investment and future asset prices. This increases the confidence of economic agents, facilitates long-term financing, and stimulates investment. Since the low-income population is unable to protect itself from inflation by diversifying its assets, and a high proportion of its income is concentrated in the purchase of food and other basic goods that are generally the most affected by inflationary shocks, low inflation avoids arbitrary redistribution of income and wealth.2 Moreover, low inflation facilitates wage negotiations, creates a good labor climate, and reduces the volatility of employment levels. Finally, low inflation helps to make the tax system more transparent and equitable by avoiding the distortions that inflation introduces into the value of assets and income that make up the tax base. From the monetary authority’s point of view, one of the most relevant benefits of low inflation is the credibility that economic agents acquire in inflation targeting, which turns it into an effective nominal anchor on price levels. Upon receiving its mandate, and using its autonomy, Banco de la República began to announce specific annual inflation targets as of 1992. Although the proposed inflation targets were not met precisely during this first stage, a downward trend in inflation was achieved that took it from 32.4% in 1990 to 16.7% in 1998. At that time, the exchange rate was kept within a band. This limited the effectiveness of monetary policy, which simultaneously sought to meet an inflation target and an exchange rate target. The Asian crisis spread to emerging economies and significantly affected the Colombian economy. The exchange rate came under strong pressure to depreciate as access to foreign financing was cut off under conditions of a high foreign imbalance. This, together with the lack of exchange rate flexibility, prevented a countercyclical monetary policy and led to a 4.2% contraction in GDP that year. In this context of economic slowdown, annual inflation fell to 9.2% at the end of 1999, thus falling below the 15% target set for that year. This episode fully revealed how costly it could be, in terms of economic activity, to have inflation and exchange rate targets simultaneously. Towards the end of 1999, Banco de la República announced the adoption of a new monetary policy regime called the Inflation Targeting Plan. This regime, known internationally as ‘Inflation Targeting,’ has been gaining increasing acceptance in developed countries, having been adopted in 1991 by New Zealand, Canada, and England, among others, and has achieved significant advances in the management of inflation without incurring costs in terms of economic activity. In Latin America, Brazil and Chile also adopted it in 1999. In the case of Colombia, the last remaining requirement to be fulfilled in order to adopt said policy was exchange rate flexibility. This was realized around September 1999, when the BDBR decided to abandon the exchange-rate bands to allow the exchange rate to be freely determined in the market.Consistent with the constitutional mandate, the fundamental objective of this new policy approach was “the achievement of an inflation target that contributes to maintaining output growth around its potential.”3 This potential capacity was understood as the GDP growth that the economy can obtain if it fully utilizes its productive resources. To meet this objective, monetary policy must of necessity play a countercyclical role in the economy. This is because when economic activity is below its potential and there are idle resources, the monetary authority can reduce the interest rate in the absence of inflationary pressure to stimulate the economy and, when output exceeds its potential capacity, raise it. This policy principle, which is immersed in the models for guiding the monetary policy stance, makes the following two objectives fully compatible in the medium term: meeting the inflation target and achieving a level of economic activity that is consistent with its productive capacity. To achieve this purpose, the inflation targeting system uses the money market interest rate (at which the central bank supplies primary liquidity to commercial banks) as the primary policy instrument. This replaced the quantity of money as an intermediate monetary policy target that Banco de la República, like several other central banks, had used for a long time. In the case of Colombia, the objective of the new monetary policy approach implied, in practical terms, that the recovery of the economy after the 1999 contraction should be achieved while complying with the decreasing inflation targets established by the BDBR. The accomplishment of this purpose was remarkable. In the first half of the first decade of the 2000s, economic activity recovered significantly and reached a growth rate of 6.8% in 2006. Meanwhile, inflation gradually declined in line with inflation targets. That was how the inflation rate went from 9.2% in 1999 to 4.5% in 2006, thus meeting the inflation target established for that year while GDP reached its potential level. After this balance was achieved in 2006, inflation rebounded to 5.7% in 2007, above the 4.0% target for that year due to the fact that the 7.5% GDP growth exceeded the potential capacity of the economy.4 After proving the effectiveness of the inflation targeting system in its first years of operation, this policy regime continued to consolidate as the BDBR and the technical staff gained experience in its management and state-of-the-art economic models were incorporated to diagnose the present and future state of the economy and to assess the persistence of inflation deviations and expectations with respect to the inflation target. Beginning in 2010, the BDBR established the long-term 3.0% annual inflation target, which remains in effect today. Lower inflation has contributed to making the macroeconomic environment more stable, and this has favored sustained economic growth, financial stability, capital market development, and the functioning of payment systems. As a result, reductions in the inflationary risk premia and lower TES and credit interest rates were achieved. At the same time, the duration of public domestic debt increased significantly going from 2.27 years in December 2002 to 5.86 years in December 2022, and financial deepening, measured as the level of the portfolio as a percentage of GDP, went from around 20% in the mid-1990s to values above 45% in recent years in a healthy context for credit institutions.Having been granted autonomy by the Constitution to fulfill the mandate of preserving the purchasing power of the currency, the tangible achievements made by Banco de la República in managing inflation together with the significant benefits derived from the process of bringing inflation to its long-term target, make the BDBR’s current challenge to return inflation to the 3.0% target even more demanding and pressing. As is well known, starting in 2021, and especially in 2022, inflation in Colombia once again became a serious economic problem with high welfare costs. The inflationary phenomenon has not been exclusive to Colombia and many other developed and emerging countries have seen their inflation rates move away from the targets proposed by their central banks.5 The reasons for this phenomenon have been analyzed in recent Reports to Congress, and this new edition delves deeper into the subject with updated information. The solid institutional and technical base that supports the inflation targeting approach under which the monetary policy strategy operates gives the BDBR the necessary elements to face this difficult challenge with confidence. In this regard, the BDBR reiterated its commitment to the 3.0% inflation target in its November 25 communiqué and expects it to be reached by the end of 2024.6 Monetary policy will continue to focus on meeting this objective while ensuring the sustainability of economic activity, as mandated by the Constitution. Analyst surveys done in March showed a significant increase (from 32.3% in January to 48.5% in March) in the percentage of responses placing inflation expectations two years or more ahead in a range between 3.0% and 4.0%. This is a clear indication of the recovery of credibility in the medium-term inflation target and is consistent with the BDBR’s announcement made in November 2022. The moderation of the upward trend in inflation seen in January, and especially in February, will help to reinforce this revision of inflation expectations and will help to meet the proposed targets. After reaching 5.6% at the end of 2021, inflation maintained an upward trend throughout 2022 due to inflationary pressures from both external sources, associated with the aftermath of the pandemic and the consequences of the war in Ukraine, and domestic sources, resulting from: strengthening of local demand; price indexation processes stimulated by the increase in inflation expectations; the impact on food production caused by the mid-2021 strike; and the pass-through of depreciation to prices. The 10% increase in the minimum wage in 2021 and the 16% increase in 2022, both of which exceeded the actual inflation and the increase in productivity, accentuated the indexation processes by establishing a high nominal adjustment benchmark. Thus, total inflation went to 13.1% by the end of 2022. The annual change in food prices, which went from 17.2% to 27.8% between those two years, was the most influential factor in the surge in the Consumer Price Index (CPI). Another segment that contributed significantly to price increases was regulated products, which saw the annual change go from 7.1% in December 2021 to 11.8% by the end of 2022. The measure of core inflation excluding food and regulated items, in turn, went from 2.5% to 9.5% between the end of 2021 and the end of 2022. The substantial increase in core inflation shows that inflationary pressure has spread to most of the items in the household basket, which is characteristic of inflationary processes with generalized price indexation as is the case in Colombia. Monetary policy began to react early to this inflationary pressure. Thus, starting with its September 2021 session, the BDBR began a progressive change in the monetary policy stance moving away from the historical low of a 1.75% policy rate that had intended to stimulate the recovery of the economy. This adjustment process continued without interruption throughout 2022 and into the beginning of 2023 when the monetary policy rate reached 12.75% last January, thus accumulating an increase of 11 percentage points (pp). The public and the markets have been surprised that inflation continued to rise despite significant interest rate increases. However, as the BDBR has explained in its various communiqués, monetary policy works with a lag. Just as in 2022 economic activity recovered to a level above the pre-pandemic level, driven, along with other factors, by the monetary stimulus granted during the pandemic period and subsequent months, so too the effects of the current restrictive monetary policy will gradually take effect. This will allow us to expect the inflation rate to converge to 3.0% by the end of 2024 as is the BDBR’s purpose.Inflation results for January and February of this year showed declining marginal increases (13 bp and 3 bp respectively) compared to the change seen in December (59 bp). This suggests that a turning point in the inflation trend is approaching. In other Latin American countries such as Chile, Brazil, Perú, and Mexico, inflation has peaked and has begun to decline slowly, albeit with some ups and downs. It is to be expected that a similar process will take place in Colombia in the coming months. The expected decline in inflation in 2023 will be due, along with other factors, to lower cost pressure from abroad as a result of the gradual normalization of supply chains, the overcoming of supply shocks caused by the weather, and road blockades in previous years. This will be reflected in lower adjustments in food prices, as has already been seen in the first two months of the year and, of course, the lagged effect of monetary policy. The process of inflation convergence to the target will be gradual and will extend beyond 2023. This process will be facilitated if devaluation pressure is reversed. To this end, it is essential to continue consolidating fiscal sustainability and avoid messages on different public policy fronts that generate uncertainty and distrust. 1 This Report to Congress includes Box 1, which summarizes the trajectory of Banco de la República over the past 100 years. In addition, under the Bank’s auspices, several books that delve into various aspects of the history of this institution have been published in recent years. See, for example: Historia del Banco de la República 1923-2015; Tres banqueros centrales; Junta Directiva del Banco de la República: grandes episodios en 30 años de historia; Banco de la República: 90 años de la banca central en Colombia. 2 This is why lower inflation has been reflected in a reduction of income inequality as measured by the Gini coefficient that went from 58.7 in 1998 to 51.3 in the year prior to the pandemic. 3 See Gómez Javier, Uribe José Darío, Vargas Hernando (2002). “The Implementation of Inflation Targeting in Colombia”. Borradores de Economía, No. 202, March, available at: https://repositorio.banrep.gov.co/handle/20.500.12134/5220 4 See López-Enciso Enrique A.; Vargas-Herrera Hernando and Rodríguez-Niño Norberto (2016). “The inflation targeting strategy in Colombia. An historical view.” Borradores de Economía, No. 952. https://repositorio.banrep.gov.co/handle/20.500.12134/6263 5 According to the IMF, the percentage change in consumer prices between 2021 and 2022 went from 3.1% to 7.3% for advanced economies, and from 5.9% to 9.9% for emerging market and developing economies. 6 https://www.banrep.gov.co/es/noticias/junta-directiva-banco-republica-reitera-meta-inflacion-3

A broadly based research program to determine the remaining strength of pipe with corrosion defects with complex geometries and combined pressure] and axial loads was conducted to develop engineering guidelines to assess the remaining strength or pressure limitation of corrosion defects. A broadly based research approach has been applied including full-scale experiments, finite element investigations, and shell models. This research has resulted in an improved understanding of and theory for the behavior of corrosion defects. The understanding and theory are merged in a fundamentally based modeling tool for analysis for use by the industry. The detailed results of this investigation are presented in this report and its appendices.