7-Years Leaching Tests of NPP Vitrified Radioactive Waste

1995 ◽  
Vol 412 ◽  
Author(s):  
A. S. Barinov ◽  
M. I. Ojovan ◽  
N. V. Ojovan
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Leaching Tests ◽  
Borosilicate Glasses ◽  
Real Character ◽  
Open Area ◽  
Natural Conditions ◽  
Testing Area ◽  
Radionuclide Leaching

AbstractLong term tests of vitrified intermediate level waste from nuclear power plants were performed in a shallow ground repository as well as on an open testing area. Borosilicate glasses were tested. Radionuclide leaching differs significantly in natural conditions in contrast to laboratory behaviour. Average leaching factors were obtained for open area tests as well as for repository tests. These factors should be used for long term predictions since they take into account the real character of leaching.

scholarly journals Simulation of MASPn Experiments in MISTRA Test Facility with COCOSYS Code

2008 ◽  
Vol 2008 ◽  
pp. 1-7 ◽  
Author(s):  
Mantas Povilaitis ◽  
Egidijus Urbonavičius
Keyword(s):  
Boundary Conditions ◽  
Nuclear Power ◽  
Power Plants ◽  
Volume Fraction ◽  
Characteristic Length ◽  
Initial Conditions ◽  
Test Facility ◽  
Work Package ◽  
Acceptable Agreement

An issue of the stratified atmospheres in the containments of nuclear power plants is still unresolved; different experiments are performed in the test facilities like TOSQAN and MISTRA. MASPn experiments belong to the spray benchmark, initiated in the containment atmosphere mixing work package of the SARNET network. The benchmark consisted of MASP0, MASP1 and MASP2 experiments. Only the measured depressurisation rates during MASPn were available for the comparison with calculations. When the analysis was performed, the boundary conditions were not clearly defined therefore most of the attention was concentrated on MASP0 simulation in order to develop the nodalisation scheme and define the initial and boundary conditions. After achieving acceptable agreement with measured depressurisation rate, simulations of MASP1 and MASP2 experiments were performed to check the influence of sprays. The paper presents developed nodalisation scheme of MISTRA for the COCOSYS code and the results of analyses. In the performed analyses, several parameters were considered: initial conditions, loss coefficient of the junctions, initial gradients of temperature and steam volume fraction, and characteristic length of structures. Parametric analysis shows that in the simulation the heat losses through the external walls behind the lower condenser installed in the MISTRA facility determine the long-term depressurisation rate.

scholarly journals Stochastic Optimization for Long Term Capital Structures, Systems, and Components Refurbishment and Replacement

2020 ◽  
Author(s):  
Congjian Wang ◽  
Diego Mandelli ◽  
Shawn St Germain ◽  
Curtis Smith ◽  
David Morton ◽  
...  
Keyword(s):  
Stochastic Optimization ◽  
Nuclear Power ◽  
Power Plants ◽  
Capital Investments ◽  
Priority List ◽  
Multi Stage ◽  
Plant Operations ◽  
Economic Constraints ◽  
Returns On Investment

Abstract As commercial nuclear power plants (NPPs) pursue extended plant operations in the form of Second License Renewals (SLRs), opportunities exist for these plants to provide capital investments to ensure long-term, safe, and economic performance. Several utilities have already announced their intention to pursue extended operations for one or more of their NPPs via SLR2. The goal of this research is to develop a risk-informed approach to evaluate and prioritize plant capital investments made in preparation for, and during the period of, extended plant operations to support decisions in NPP operations. In order to prioritize project selection via a risk-informed approach we developed a single decision-making tool that integrates safety/reliability, cost, and stochastic optimization models to provide users with data analysis capabilities to more cost effectively manage plant assets. Both stochastic analysis methods — such as Monte Carlo-based sampling strategies — and multi-stage stochastic optimization strategies are employed to provide priority lists to decision-makers in support of risk-informed decisions. We applied the proposed method to a trial application of projected replacement/refurbishment expenditures for plant capital assets (i.e., structures, systems, and components [SSCs]). The objective is to optimize the SSC replacement/refurbishment schedule in terms of economic constraints, data uncertainties, and SSC reliability data, as well to generate a priority list for maximizing returns on investment.

Experimental Study of Selected Properties of Heavyweight Concrete Based on Analysis of Chemical Composition and Radioactive Elements of its Components

2021 ◽  
Vol 321 ◽  
pp. 113-118
Author(s):  
Janette Dragomirová ◽  
Martin T. Palou ◽  
Katalin Gméling ◽  
Veronika Szilágyi ◽  
Ildikó Harsányi ◽  
...  
Keyword(s):  
Bulk Density ◽  
Nuclear Power ◽  
Power Plants ◽  
Concrete Strength ◽  
Prompt Gamma ◽  
Longitudinal Deformation ◽  
Heavyweight Concrete ◽  
Furnace Slag ◽  
Selection Of

Heavyweight concrete is mostly used for its shielding properties in the nuclear power plants. These properties can already be influenced by the selection of the input materials. In the present study, concrete samples comprised of four-component binders based on CEM I 42.5 R, blast furnace slag, metakaolin and limestone and a mixture of barite and magnetite aggregate, were investigated. Based on Energy Dispersive X-ray Fluorescence, Neutron Activation, and Prompt-Gamma Activation analyses, three concrete designs were prepared and tested. Mechanical, physical (namely cubic compressive strength, bulk density, longitudinal deformation, and dynamic modulus of elasticity) and thermal properties (thermal conductivity coefficient, specific heat capacity, and thermal diffusivity), which should be influenced by the long-term exposure to irradiation were investigated. Presented results confirmed that the prepared samples are heavyweight concrete with bulk density higher than 3400 kg.m-3 with a low level of longitudinal deformation (between 0.265 ‰ and 0.352 ‰). All the prepared samples belong to the C 35/45 concrete strength class.

Guided Waves as an Online Monitoring Technology for Long-Term Operation in Nuclear Power Plants: Experimental Results on a Steam Discharge Pipe

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Mauro Cappelli ◽  
Francesco Cordella ◽  
Francesco Bertoncini ◽  
Marco Raugi
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Guided Waves ◽  
Complex Structure ◽  
Theoretical Background ◽  
Guided Wave ◽  
Experimental Results ◽  
Term Operation

Guided wave (GW) testing is regularly used for finding defect locations through long-range screening using low-frequency waves (from 5 to 250 kHz). By using magnetostrictive sensors, some issues, which usually limit the application to nuclear power plants (NPPs), can be fixed. The authors have already shown the basic theoretical background and simulation results concerning a real steel pipe, used for steam discharge, with a complex structure. On the basis of such theoretical framework, a new campaign has been designed and developed on the same pipe, and the obtained experimental results are now here presented as a useful benchmark for the application of GWs as nondestructive techniques. Experimental measures using a symmetrical probe and a local probe in different configurations (pulse-echo and pitch-catch) indicate that GW testing with magnetostrictive sensors can be reliably applied to long-term monitoring of NPPs components.

Thermoelastoplastic Stress Analysis of a Thick-Walled Tube of Nonlinear Strain Hardening

1996 ◽  
Vol 118 (3) ◽  
pp. 340-346 ◽  
Author(s):  
S. Jahanian
Keyword(s):  
Strain Hardening ◽  
Nuclear Power ◽  
Power Plants ◽  
Rapid Heating ◽  
Numerical Procedure ◽  
Temperature Dependent ◽  
Nonlinear Strain ◽  
Elastic Approximation

In pressure vessel technology or nuclear power plants, some of the mechanical components are often subjected to rapid heating. If the temperature gradient during such process is high enough, thermoelastoplastic stresses may be developed in the components. These plastic deformations are permanent and may result in the incremental deformation of the structure in the long term. Accordingly, determination of thermoelastoplastic stresses during this process is an important factor in design. In this paper, a thick-walled cylinder of nonlinear strain hardening is considered for the thermoelastoplastic analysis. The properties of the material are assumed to be temperature dependent. The cylinder is subject to rapid heating of the inside surface while the outside surface is kept at the room temperature. A quasi-static and uncoupled thermoelastoplastic analysis based on incremental theory of plasticity is developed and a numerical procedure for successive elastic approximation is presented. The thermoelastoplastic stresses developed during this process are also presented. The effect of strain hardening and temperature dependency of material on the results are investigated.

The Need for Strategic Planning for Nuclear Power Plant I&C Upgrades

2002 ◽  
Author(s):  
J. Douglas Hill ◽  
Paul Moore
Keyword(s):  
Strategic Planning ◽  
Control Systems ◽  
Digital Technology ◽  
Nuclear Power ◽  
Power Plants ◽  
Short Term ◽  
Nuclear Plants ◽  
And Control ◽  
Plant Control

Nuclear power plants rely on Instrumentation and Control (I&C) systems for control, monitoring and protection of the plant. The original, analog designs used in most nuclear plants have become or soon will be obsolete, forcing plants to turn to digital technology. Many factors affect the design of replacement equipment, including long-term and short-term economics, regulatory issues, and the way the plant operates on a day-to-day basis. The first step to all modernization projects should involve strategic planning, to ensure that the overall long and short-term goals of the plant are met. Strategic planning starts with a thorough evaluation of the existing plant control systems, the available options, and the benefits and consequences of these options.

Life Beyond 60 Years: The Importance of Sustaining the Current Fleet of Light Water Reactors in the U.S. and the R&D Needs

2010 ◽  
Author(s):  
Ronaldo Szilard ◽  
Hongbin Zhang
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Superior Performance ◽  
Light Water Reactors ◽  
Economic Operation ◽  
Significant Interest ◽  
Water Reactors ◽  
The U.S

The current fleet of 104 nuclear power plants in the U.S. began their operation with 40 years operating licenses. About half of these plants have their licenses renewed to 60 years and most of the remaining plants are anticipated to pursue license extension to 60 years. With the superior performance of the current fleet and formidable costs of building new nuclear power plants, there has been significant interest to extend the lifetime of the current fleet even further from 60 years to 80 years. This paper addresses some of the key long term technical challenges and identifies R&D needs related to the long term safe and economic operation of the current fleet.

Research Activities in the European Union on Ageing Management for Long Term Operation of Nuclear Power Plants

2010 ◽  
Author(s):  
Oliver Martin ◽  
Antonio Ballesteros ◽  
Christiane Bruynooghe ◽  
Michel Bie`th
Keyword(s):  
Energy Supply ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Age Distribution ◽  
Term Operation ◽  
Research Activities ◽  
Ageing Management ◽  
The Eu

The energy supply of the future in the EU will be a mix of renewable, fossil and nuclear. There are 145 nuclear power reactors in operation in 15 out of the 27 EU countries, with installed power ∼132 GWe. The age distribution of current nuclear power plants in EU is such that in 2010 most of them will have passed 20-years and approximately 25% of them 30 years of age. The decrease of energy supply from nuclear generated electricity can not always be compensated in a reliable and economical way within a short time span. For this situation utilities may be keen to upgrade the reactor output and /or to ask their regulatory bodies for longer term operation. Under the research financed in the Euratom part of the Research Directorate (RTD) of the European Commission several projects explicitly address the safe long term operation of nuclear power plants (NULIFE, LONGLIFE) and the topics proposed in the 2010 call explicitly address issues concerning component ageing, in particular non metallic components, i.e. instrumentation and cables (I&C) and concrete ageing. This paper presents an overview of the plans for long term operation (LTO) of nuclear power plants in the EU. Special emphasis is given on research activities on component ageing management and long term operation issues related to safety.

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