scholarly journals Aircraft Impact Effects on an Aged NPP

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 816
Author(s):  
Rosa Lo Frano
Keyword(s):  
Nuclear Power ◽  
Military Aircraft ◽  
Residual Resistance ◽  
Plant Safety ◽  
Need To Evaluate ◽  
Target Wall ◽  
Impact Area ◽  
Wall Perforation ◽  
The Impact ◽  
Loss Of Strength

The impact of an aircraft is widely known to be one of the worst events that can occur during the operation of a plant (classified for this reason as beyond design). This can become much more catastrophic and lead to the loss of strength of/collapse of the structures when it occurs in the presence of ageing (degradation and alteration) materials. Therefore, since the performance of all plant components may be affected by ageing, there is a need to evaluate the effect that aged components have on system performance and plant safety. This study addresses the numerical simulation of an aged Nuclear Power Plant (NPP) subjected to a military aircraft impact. The effects of impact velocity, direction, and location were investigated together with the more unfavorable conditions to be expected for the plant. The modelling method was also validated based on the results obtained from the experiments of Sugano et al., 1993. Non-linear analyses by means of finite element (FE) MARC code allowed us to simulate the performance of the reinforced concrete containment building and its impact on plant availability and reliability. The results showed that ageing increases a plant’s propensity to suffer damage. The damage at the impact area was confirmed to be dependent on the type of aircraft involved and the target wall thickness. The greater the degradation of the materials, the lower the residual resistance capacity, and the greater the risk of wall perforation.

Human Factor Data in Nuclear Power Plant Applications

1980 ◽  
Vol 24 (1) ◽  
pp. 123-123
Author(s):  
Linda O. Hecht
Keyword(s):  
Nuclear Power ◽  
Nuclear Regulatory Commission ◽  
The United States ◽  
Reliability Modeling ◽  
Plant Safety ◽  
Modeling Techniques ◽  
Nuclear Systems ◽  
Factor Data ◽  
Regulatory Commission ◽  
The Impact

Due to the concern for safety the nuclear power industry in the United States has fostered the use of reliability analysis to assess system performance and the impact of system failure on overall plant safety. The need for system and component failure rate data has been recognized and has spurred such efforts as NPRDS (Nuclear Power Research Data System) and IEEE's Std 500 (The Reliability Data Manual). Reliability modeling techniques have been developed for application to nuclear systems and are presently being considered by the Nuclear Regulatory Commission for licensing purposes.

Probability of a High-Speed Military Aircraft Falling at a Nuclear Power Plant and Setting of Design Loads on Building Structures

2020 ◽  
pp. 10-26
Author(s):  
Adolf N. Birbraer ◽  
George D. Kostrov
Keyword(s):  
High Speed ◽  
Nuclear Power ◽  
Power Plants ◽  
Impact Load ◽  
Terrorist Attack ◽  
Building Structures ◽  
Military Aircraft ◽  
Aviation Accidents ◽  
Design Loads ◽  
The Impact

The article is devoted to issues related to the probabilistic justification of the safety of nuclear power plants (NPP) when a high-speed military aircraft falls. The random parameters are the recurrence of falls and the direction of the aircraft's trajectory. The conservative value of the recurrence of falls, given in the IAEA documents, was used, which ensures a high degree of NPP safety. The aircraft approach is assumed to be equally probable from either side. The trajectory slope is specified taking into account the IAEA documents and statistics of aviation accidents. The aircraft impact load is applied to one of the structures, therefore the impact probability must be determined independently for each of them. It is proportional to the equivalent area of the building structure, depending on its size, shape, position in space and in relation to other structures. Expressions are given for the equivalent areas of structures of various shapes, typical for NPP. It is shown that if the aircraft crash is unintentional (accident), then with the usual dimensions of structures, the probability of an impact in them is less than the value, starting from which, according to Russian standards, it must be taken into account in the design basis of the NPP, i.e. it can be ignored. Dependencies are given for calculating the probability of an aircraft strike in the case of a deliberately organized accident (terrorist attack), in which the aircraft will surely fall on the territory of “Nuclear Island” of the NPP. The procedure for setting the design loads on the building structures of a NPP in the case of a deliberate aircraft fall based on the allowed probability of their realization is described. It is shown that this method of setting the loads makes it possible to substantiate their significant reduction, which leads to a reduction in the cost of the NPP while guaranteeing its safety. A probabilistic assessment of structures safety of existing NPP in the event of an aircraft impact is discussed.

Considerations for the Use of Probabilistic Assessments in Regulatory Decision Making Related to Pressure Boundary Component Aging

2017 ◽  
Author(s):  
Blair Carroll ◽  
John C. Jin
Keyword(s):  
Decision Making ◽  
Boundary Component ◽  
Nuclear Power ◽  
Structural Integrity ◽  
Informed Decision ◽  
Informed Decision Making ◽  
Regulatory Decision ◽  
Plant Safety ◽  
Unintended Effect ◽  
The Impact

Within the current Canadian regulatory framework, the structural integrity of pressure boundary components with detected service-induced degradation must be demonstrated using deterministic evaluation techniques. However, Canadian Nuclear Safety Commission staff has recognized that the inherent conservatism in these deterministic assessment approaches may generate overly conservative conclusions when they are applied to assess the impact of postulated service-induced degradation to establish aging management requirements for nuclear power plant pressure boundary components. This may have the unintended effect of reducing the effectiveness of aging management programs by directing resources towards activities that will have minimal benefit on improving plant safety and could result in unnecessary dose to personnel. With this in mind, CNSC staff has accepted the limited use of probabilistic assessments prepared by licensees to support aging management activities for pressure boundary components. These probabilistic assessments form a part of risk-informed decision making strategies intended to reduce excess conservatism that could arise if decisions are based solely on the results of deterministic assessments. This paper provides an overview of CNSC staff’s experiences with the review and acceptance of licensee submissions incorporating probabilistic assessments of pressure boundary component aging for risk informed decision making.

scholarly journals The Impact of a Reentry and Aftercare Program on Recidivism

2020 ◽  
pp. 003464462097393
Author(s):  
Colin Cannonier ◽  
Monica Galloway Burke ◽  
Ed Mitchell
Keyword(s):  
Sample Selection ◽  
Cost Savings ◽  
Social Program ◽  
Recidivism Rates ◽  
Criminal Justice Reform ◽  
Heterogeneous Effects ◽  
Need To Evaluate ◽  
Reducing Recidivism ◽  
Aftercare Service ◽  
The Impact

In this article, we explore the impact of a reentry and aftercare service program on the likelihood of returning to prison by ex-offenders. Using administrative data within a difference-in-differences design, we find that this social program is associated with a reduction in recidivism rates. Benchmark estimates show that the program was associated with estimated reductions in the probability of recidivating of 6.0 to 8.7 percentage points. The estimate appears to be economically significant as it implies an estimated treated effect in the 15.8% to 19.2% range. We consider the heterogeneous effects of the program on reducing recidivism according to race, age group, and program type. The program helped to reduce recidivism among Whites but not Blacks; older participants were the main beneficiaries while the effectiveness of the program was observed among older participants. Back-of-the-envelope cost-savings analysis is incorporated to estimate the potential savings to the state arising from the reduction in recidivism rates likely attributable to the program. The findings are robust to sample selection bias, alternative specifications, and estimation techniques. Our results offer some implications for the role of faith-based social programs within the context of criminal justice reform to combat reentry of former inmates. They also provide a cautionary tale about the need to evaluate programs not just based on their overall effect.

scholarly journals Water Influence on the Uniaxial Tensile Behavior of Polytetrafluoroethylene-Coated Glass Fiber Fabric

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 846
Author(s):  
Hastia Asadi ◽  
Joerg Uhlemann ◽  
Natalie Stranghoener ◽  
Mathias Ulbricht
Keyword(s):  
Mechanical Properties ◽  
Glass Fiber ◽  
Operation Time ◽  
Uniaxial Tensile ◽  
Membrane Structures ◽  
Strength Deterioration ◽  
Coated Glass ◽  
Reversible Loss ◽  
The Impact ◽  
Loss Of Strength

Polytetrafluoroethylene (PTFE)-coated glass fiber fabrics are used for long-lasting membrane structures due to their outstanding mechanical properties, chemical stabilities, and satisfying service life. During their operation time, different environmental impacts might influence their performance, especially regarding the mechanical properties. In this contribution, the impact of water on the tensile strength deterioration was assessed experimentally, providing evidence of considerable but partially reversible loss of strength by up to 20% among the various types of investigated industrially established fabrics.

scholarly journals The Environmental Effects of the April 2020 Wildfires and the Cs-137 Re-Suspension in the Chernobyl Exclusion Zone: A Multi-Hazard Threat

Atmosphere ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 467
Author(s):  
Rocío Baró ◽  
Christian Maurer ◽  
Jerome Brioude ◽  
Delia Arnold ◽  
Marcus Hirtl
Keyword(s):  
Air Quality ◽  
Nuclear Power ◽  
Transport Model ◽  
Atmospheric Transport ◽  
Point Of View ◽  
Plume Dispersion ◽  
Exclusion Zone ◽  
Fire Plume ◽  
Mean Values ◽  
The Impact

This paper demonstrates the environmental impacts of the wildfires occurring at the beginning of April 2020 in and around the highly contaminated Chernobyl Exclusion Zone (CEZ). Due to the critical fire location, concerns arose about secondary radioactive contamination potentially spreading over Europe. The impact of the fire was assessed through the evaluation of fire plume dispersion and re-suspension of the radionuclide Cs-137, whereas, to assess the smoke plume effect, a WRF-Chem simulation was performed and compared to Tropospheric Monitoring Instrument (TROPOMI) satellite columns. The results show agreement of the simulated black carbon and carbon monoxide plumes with the plumes as observed by TROPOMI, where pollutants were also transported to Belarus. From an air quality and health perspective, the wildfires caused extremely bad air quality over Kiev, where the WRF-Chem model simulated mean values of PM2.5 up to 300 µg/m3 (during the first fire outbreak) over CEZ. The re-suspension of Cs-137 was assessed by a Bayesian inverse modelling approach using FLEXPART as the atmospheric transport model and Ukraine observations, yielding a total release of 600 ± 200 GBq. The increase in both smoke and Cs-137 emissions was only well correlated on the 9 April, likely related to a shift of the focus area of the fires. From a radiological point of view even the highest Cs-137 values (average measured or modelled air concentrations and modelled deposition) at the measurement site closest to the Chernobyl Nuclear Power Plant, i.e., Kiev, posed no health risk.

scholarly journals Fire Resistance Behaviour of Geopolymer Concrete:An Overview

Buildings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 82
Author(s):  
Salmabanu Luhar ◽  
Demetris Nicolaides ◽  
Ismail Luhar
Keyword(s):  
Compressive Strength ◽  
Thermal Resistance ◽  
Building Materials ◽  
Elevated Temperatures ◽  
Construction Materials ◽  
Flexural Behavior ◽  
Thermal Shrinkage ◽  
Physico Chemical ◽  
The Impact ◽  
Loss Of Strength

Even though, an innovative inorganic family of geopolymer concretes are eye-catching potential building materials, it is quite essential to comprehend the fire and thermal resistance of these structural materials at a very high temperature and also when experiencing fire with a view to make certain not only the safety and security of lives and properties but also to establish them as more sustainable edifice materials for future. The experimental and field observations of degree of cracking, spalling and loss of strength within the geopolymer concretes subsequent to exposure at elevated temperature and incidences of occurrences of disastrous fires extend an indication of their resistance against such severely catastrophic conditions. The impact of heat and fire on mechanical attributes viz., mechanical-compressive strength, flexural behavior, elastic modulus; durability—thermal shrinkage; chemical stability; the impact of thermal creep on compressive strength; and microstructure properties—XRD, FTIR, NMR, SEM as well as physico-chemical modifications of geopolymer composites subsequent to their exposures at elevated temperatures is reviewed in depth. The present scientific state-of-the-art review manuscript aimed to assess the fire and thermal resistance of geopolymer concrete along with its thermo-chemistry at a towering temperature in order to introduce this novel, most modern, user and eco-benign construction materials as potentially promising, sustainable, durable, thermal and fire-resistant building materials promoting their optimal and apposite applications for construction and infrastructure industries.

scholarly journals Influence of the Spatial Pressure Distribution of Breaking Wave Loading on the Dynamic Response of Wolf Rock Lighthouse

2021 ◽  
Vol 9 (1) ◽  
pp. 55
Author(s):  
Darshana T. Dassanayake ◽  
Alessandro Antonini ◽  
Athanasios Pappas ◽  
Alison Raby ◽  
James Mark William Brownjohn ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Pressure Distribution ◽  
Distinct Element ◽  
Breaking Waves ◽  
Breaking Wave ◽  
Wave Loading ◽  
Wave Impact ◽  
Pressure Distributions ◽  
Impact Area ◽  
The Impact

The survivability analysis of offshore rock lighthouses requires several assumptions of the pressure distribution due to the breaking wave loading (Raby et al. (2019), Antonini et al. (2019). Due to the peculiar bathymetries and topographies of rock pinnacles, there is no dedicated formula to properly quantify the loads induced by the breaking waves on offshore rock lighthouses. Wienke’s formula (Wienke and Oumeraci (2005) was used in this study to estimate the loads, even though it was not derived for breaking waves on offshore rock lighthouses, but rather for the breaking wave loading on offshore monopiles. However, a thorough sensitivity analysis of the effects of the assumed pressure distribution has never been performed. In this paper, by means of the Wolf Rock lighthouse distinct element model, we quantified the influence of the pressure distributions on the dynamic response of the lighthouse structure. Different pressure distributions were tested, while keeping the initial wave impact area and pressure integrated force unchanged, in order to quantify the effect of different pressure distribution patterns. The pressure distributions considered in this paper showed subtle differences in the overall dynamic structure responses; however, pressure distribution #3, based on published experimental data such as Tanimoto et al. (1986) and Zhou et al. (1991) gave the largest displacements. This scenario has a triangular pressure distribution with a peak at the centroid of the impact area, which then linearly decreases to zero at the top and bottom boundaries of the impact area. The azimuthal horizontal distribution was adopted from Wienke and Oumeraci’s work (2005). The main findings of this study will be of interest not only for the assessment of rock lighthouses but also for all the cylindrical structures built on rock pinnacles or rocky coastlines (with steep foreshore slopes) and exposed to harsh breaking wave loading.

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