scholarly journals Oak Ridge National Laboratory Support of Non-light Water Reactor Technologies: Capabilities Assessment for NRC Near-term Implementation Action Plans for Non-light Water Reactors

2017 ◽  
Author(s):  
Randy Belles ◽  
Prashant K. Jain ◽  
Jeffrey J. Powers
Keyword(s):  
National Laboratory ◽  
Light Water Reactor ◽  
Action Plans ◽  
Light Water Reactors ◽  
Light Water ◽  
Water Reactor ◽  
Oak Ridge ◽  
Oak Ridge National Laboratory ◽  
Water Reactors ◽  
Near Term

Synthesis of I-131 labelled iodine species relevant during severe nuclear accidents in light water reactors

2013 ◽  
Vol 101 (10) ◽  
pp. 675-680 ◽  
Author(s):  
S. Tietze ◽  
M. R. St. J. Foreman ◽  
C. Ekberg
Keyword(s):  
Light Water Reactor ◽  
Nuclear Accidents ◽  
Light Water Reactors ◽  
Light Water ◽  
Water Reactor ◽  
Iodine Species ◽  
Water Reactors ◽  
Paint Films ◽  
Elemental Iodine ◽  
Severe Nuclear Accident

Summary Methods for the small scale synthesis of I-131 labelled iodine species relevant to severe nuclear accidents in light water reactors have been developed. The introduced methods allow the synthesis of impurity free, volatile, inorganic elemental iodine and volatile, organic iodides such as methyl- and ethyl iodide, as well as butyl iodide, chloroiodomethane, allyl iodide and benzyl iodide with ease. The radioactive iodine containing products are sufficiently stable to allow their storage for later use. Due to their volatility the liquid species can be easily converted into gaseous species and thus can be used in research in liquid and gaseous phase. The primary motivation for the development of these synthesis methods is to study the behaviour of volatile iodine species under the conditions of a severe nuclear accident in a light water reactor. Thus, the chemicals involved in the synthesis are chosen in a way to not generate impurities (chlorine and organic solvents) in the products which interfere with competing reactions relevant during a severe nuclear accident. Teknopox Aqua VA epoxy paint, which is used in Swedish light water reactor containments, and its reactions with the produced iodine species are described. The synthesised iodine species undergo chemisorption on paint films. Different to elemental iodine, the organic iodides are non-reactive with copper surfaces. The sorbed iodine species are partly re-released mainly in form of organic iodides and not as elemental iodine when the exposed paint films are heat treated. The partitioning and hydrolysis behaviour of gaseous methyl- and ethyl iodide between containment gas phase and water pools is found to be similar. The methods have been designed to minimise the use of harmful materials and the production of radioactive waste.

Auxiliary Beam Stress Improved Laser Welding for Repair of Irradiated Light Water Reactor Components

2019 ◽  
Author(s):  
Jian Chen ◽  
Jonathan Tatman ◽  
Zhili Feng ◽  
Roger Miller ◽  
Wei Tang ◽  
...  
Keyword(s):  
Laser Welding ◽  
Nuclear Power ◽  
Nuclear Reactor ◽  
National Laboratory ◽  
Department Of Energy ◽  
Light Water Reactor ◽  
Development Effort ◽  
Light Water ◽  
Water Reactor ◽  
Oak Ridge

Abstract The welding task focuses on development of advanced welding technologies for repair and maintenance of nuclear reactor structural components to safely and cost-effectively extend the service life of nuclear power reactors. This paper presents an integrated research and development effort by the Department of Energy Light Water Reactor Sustainability Program through the Oak Ridge National Laboratory (ORNL) and Electric Power Research Institute (EPRI) to develop a patent-pending technology, Auxiliary Beam Stress Improved Laser Welding Technique, that proactively manages the stresses during laser repair welding of highly irradiated reactor internals without helium induced cracking (HeIC). Finite element numerical simulations and in-situ temperature and strain experimental validation have been utilized to identify candidate welding conditions to achieve significant stress compression near the weld pool during cooling. Preliminary welding experiments were performed on irradiated stainless-steel plates (Type 304L). Post-weld characterization reveals that no macroscopic HeIC was observed.

Defense-in-Depth Approach for Use in a Risk-Informed, Technology-Neutral Design and Licensing Framework for New Nuclear Plants

2009 ◽  
Author(s):  
Jim Chapman ◽  
Stephen M. Hess
Keyword(s):  
Integrated Approach ◽  
Regulatory Framework ◽  
Light Water Reactor ◽  
Light Water ◽  
Water Reactor ◽  
Safety Standards ◽  
Reactor Technology ◽  
Nuclear Plants ◽  
Defense In Depth ◽  
Water Reactors

The regulatory framework for the current generation of operating plants and advanced light water reactors (ALWRs) planned for near term construction has evolved over several decades to permit effective regulation of the light water reactor designs. To address other reactor types, development of a framework that possesses the attributes of being technology neutral, risk-informed and performance-based with corresponding processes (regulations and guidance) is ongoing by several U.S. and international organizations. A key design and operating principle which is applied to existing plants and will continue to be applied to future plants is defense-in-depth. The advent of advanced reactor designs, some of which are not based on light water reactor technology, provides incentive for changes in the regulatory framework in several areas, including defense-in-depth practices. To support development of an integrated framework, the Electric Power Research Institute (EPRI) conducted research to identify and assess specific elements of possible technology neutral, risk-informed, performance based frameworks that had been proposed by others. The intent was to develop a preliminary framework based on the results of this review and evaluation and to provide recommendations in areas where additional development and testing would appear to be most beneficial. “Technical Elements of a Risk-Informed, Technology-Neutral Design and Licensing Framework for New Nuclear Plants”, EPRI Report 1016150 documents this research (Reference [1]). For defense-in-depth (D-in-D) existing viewpoints from various sources were compared and an alternative integrated approach which addresses key issues was developed. These alternative views are contained in publications such as NUREG-1860 [2], Regulatory Guide 1.174 [6], IAEA Safety Standards Series No. NS-R-1 [3], IAEA 75-INSAG-3 Revision 1 [4], INSAG-12 [4], and IAEA INSAG-10 [5]. The results of this research support the ongoing efforts to develop standards and guidance for advanced plants with safety characteristics which differ from existing and advanced LWRs.

FeCrAl Alloys for Accident Tolerant Fuel Cladding in Light Water Reactors

2016 ◽  
Author(s):  
Raul B. Rebak ◽  
Kurt A. Terrani ◽  
Russ M. Fawcett
Keyword(s):  
Fuel Assembly ◽  
Department Of Energy ◽  
Normal Operation ◽  
Fuel System ◽  
Light Water Reactors ◽  
Light Water ◽  
Oak Ridge ◽  
Operation Conditions ◽  
Fecral Alloys ◽  
Water Reactors

The goal of the U.S. Department of Energy (DOE) Accident Tolerant Fuel Program (ATF) for light water reactors (LWR) is to identify alternative fuel system technologies to further enhance the safety of commercial nuclear power plants. An ATF fuel system would endure loss of cooling in the reactor for a considerably longer period of time than the current systems. The General Electric (GE) and Oak Ridge National Laboratory (ORNL) ATF design concept utilizes an iron-chromium-aluminum (FeCrAl) alloy material as fuel rod cladding in combination with uranium dioxide (UO2) fuel pellets currently in use, resulting in a fuel assembly that leverages the performance of existing/current LWR fuel assembly designs and infrastructure with improved accident tolerance. Significant testing was performed in the last three years to characterize FeCrAl alloys for cladding applications, both under normal operation conditions of the reactor and under accident conditions. This article is a state of the art description of the concept.

scholarly journals High-resolution neutron time-of-flight measurements for light water at the Spallation Neutron Source (SNS), Oak Ridge National Laboratory

2020 ◽  
Vol 239 ◽  
pp. 14005
Author(s):  
Luiz Leal ◽  
Vaibhav Jaiswal ◽  
Alexander I. Kolesnikov
Keyword(s):  
Experimental Data ◽  
Neutron Source ◽  
National Laboratory ◽  
Operating Conditions ◽  
Spallation Neutron Source ◽  
Light Water ◽  
Oak Ridge ◽  
Oak Ridge National Laboratory ◽  
Thermal Scattering ◽  
Reactor Operating

Series of light water inelastic neutron scattering experiments have been made at the Oak Ridge National Laboratory (ORNL), Spallation Neutron Source (SNS) covering temperatures ranging from 295 K to 600 K and pressures of 1 bar and 150 bar. The temperatures and pressures ranges correspond to that of pressurized light water reactors. The inelastic scattering measurements will help the development of light water thermal scattering kernels, also known as S (α,β) thermal scattering law (TSL), in a consistent fashion given the amount and the quality of the measured data. Light water thermal scattering evaluations available in existing nuclear data libraries have certain limitations and pitfalls. This paper introduces the state of the art of the light water thermal scattering cross-section data not only for room temperature but as well as for reactor operating temperatures, i.e. 550 - 600 K. During the past few years there has been a renewed interest in re-investigating the existing TSL models and utilize the recent experimental data or perform molecular dynamics simulations. It should be pointed out that no single TSL evaluation is based entirely on experimental data and one has to rely on TSL models or a combination of both. New TOF measurement of light water at the SNS, with a detailed description of the experimental setup, measurement conditions, and the associated foreseen results is presented in this paper. The analysis of the experimental data would help in validating the existing approach based on old experimental data or based on molecular dynamic simulations using classical water models, knowledge of which is very important to generate TSL libraries at reactor operating conditions.

The Study on Homogeneous Parameters of Light Water Reactor by the Nodal Diffusion Method

2014 ◽  
Vol 666 ◽  
pp. 144-148
Author(s):  
Zhi Bin Liu ◽  
Jin Ma ◽  
Bing Shu Wang ◽  
Xin Hui Duan
Keyword(s):  
Diffusion Equation ◽  
Homogenization Method ◽  
Light Water Reactor ◽  
Diffusion Method ◽  
Coarse Mesh ◽  
Light Water ◽  
Water Reactor ◽  
Spatial Coupling ◽  
Water Reactors ◽  
Nodal Diffusion

Recent progress in the development of coarse-mesh nodal methods for the numerical solution of the neutron diffusion and transport equations is reviewed. Compared with earlier nodal simulators, more recent nodal diffusion methods are characterized by the systematic derivation of spatial coupling relationships which are entirely consistent with the multi-group diffusion equation. These relationships most often are derived by developing approximations to the one-dimensional equations obtained by integrating the multidimensional diffusion equation over directions transverse to each coordinate axis. The objective of this research is to develop accurate and efficient spatial homogenization method for coarse mesh analysis of light water reactors. More sophisticated methods for computing approximate equivalence parameters are also introduced and make use of nonlinear iterations between homogenized reactor calculations and local fixed-source calculations to compute equivalence parameters. This special feature induces the need for the study on homogeneous parameters of light water reactor which takes phenomena of different scale and their interaction into account by means of the nodal diffusion method.

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