scholarly journals Staffing decision processes and issues: Case studies of seven US Nuclear Power Plants

1994 ◽  
Author(s):  
B. Melber ◽  
A. Roussel ◽  
K. Baker ◽  
N. Durbin ◽  
P. Hunt ◽  
...  
Keyword(s):  
Case Studies ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Decision Processes

Qualification of Motor Actuated Valve Assemblies for Safety Related Nuclear Applications: Lessons Learned

2018 ◽  
Author(s):  
Ronald Farrell ◽  
L. Ike Ezekoye
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Decision Processes ◽  
Lessons Learned ◽  
Mechanical Equipment ◽  
Missed Opportunities ◽  
Ieee Standards ◽  
Electrical Components ◽  
Nuclear Applications

Safety related valves in nuclear power plants are required to be qualified in accordance with the ASME QME-1 standard. This standard describes the requirements and the processes for qualifying active mechanical equipment that are used in nuclear power plants. It does not cover the qualification of electrical components that are addressed using IEEE standards; however, QME-1 recognizes that both mechanical and electrical components must be qualified when they are interfaced as an assembly. Qualifying both mechanical and electrical valve assemblies can be challenging. Considerable amount of judgment is used when developing the plan to qualify any valve with an electric motor actuator. If the wrong steps are taken in planning the tests, the results from the tests may not be useful thus triggering the need to perform additional tests to comply with QME-1 requirements. This paper presents lessons learned in the process of qualifying valve assemblies to meet QME-1 requirements. The lessons include the decision processes associated with planning and executing valve testing, analysis of the valve assemblies for natural frequency determination, and missed opportunities to capture relevant test data during the tests. Finally, the paper will discuss challenges associated with justifying the tests and extending the results of the tests to cover untested valve assemblies.

scholarly journals State-of-the-Art Water Treatment in Czech Power Sector: Industry-Proven Case Studies Showing Economic and Technical Benefits of Membrane and Other Novel Technologies for Each Particular Water Cycle

Membranes ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 98
Author(s):  
Jaromír Marek
Keyword(s):  
Water Treatment ◽  
Case Studies ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Water Cycle ◽  
Liquid Waste ◽  
Novel Technologies ◽  
Turbine Condensate ◽  
Common Cycles

The article first summarizes case studies on the three basic types of treated water used in power plants and heating stations. Its main focus is Czechia as the representative of Eastern European countries. Water as the working medium in the power industry presents the three most common cycles—the first is make-up water for boilers, the second is cooling water and the third is represented by a specific type of water (e.g., liquid waste mixtures, primary and secondary circuits in nuclear power plants, turbine condensate, etc.). The water treatment technologies can be summarized into four main groups—(1) filtration (coagulation) and dosing chemicals, (2) ion exchange technology, (3) membrane processes and (4) a combination of the last two. The article shows the ideal industry-proven technology for each water cycle. Case studies revealed the economic, technical and environmental advantages/disadvantages of each technology. The percentage of technologies operated in energetics in Eastern Europe is briefly described. Although the work is conceived as an overview of water treatment in real operation, its novelty lies in a technological model of the treatment of turbine condensate, recycling of the cooling tower blowdown plus other liquid waste mixtures, and the rejection of colloidal substances from the secondary circuit in nuclear power plants. This is followed by an evaluation of the potential novel technologies and novel materials.

Semiconductor Wear Out at Nuclear Power Plants

2000 ◽  
Author(s):  
James B. Riddle
Keyword(s):  
Failure Analysis ◽  
Case Studies ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Light Output ◽  
Analysis Techniques ◽  
Root Cause ◽  
Corrective Actions ◽  
Control Circuits

Abstract This paper will examine semiconductor wear out at San Onofre Nuclear Generation Station (SONGS). The topics will include case studies, failure mechanisms, diagnostic techniques, failure analysis techniques and root cause corrective actions. Nuclear power plants are unique in that instrumentation and control circuits are continuously energized, are periodically tested, and have been in operation for greater than 25 years. Root cause evaluations at SONGS have identified numerous semiconductor failures due to wear out. Case studies include light output deterioration in opto-isolators, junction alloying failures of transistors and integrated circuits and parametric shifts in operational amplifiers. In most cases the devices do not fail catastrophically but degraded to the point of circuit level functional failure. Failure analysis techniques include circuit analysis, board level troubleshooting to identify the degraded components. Intermittent failures require power cycling, thermal cycling, and long term monitoring to identify the responsible components. Corrective actions for semiconductor wear out at SONGS include enhanced monitoring and proactive change out of identified part types.

scholarly journals Fire Safety in Nuclear Power Plants: A Risk-Informed and Performance-Based Approach

1999 ◽  
Author(s):  
Mohamed A. Azarm ◽  
Richard J. Travis
Keyword(s):  
Case Studies ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Fire Risk ◽  
Policy And Practice ◽  
Fire Risk Analysis ◽  
Regulatory Decision ◽  
Near Term ◽  
And Performance

Abstract The consideration of risk in regulatory decision-making has long been a part of NRC’s policy and practice. Initially, these considerations were qualitative and were based on risk insights. The early regulations relied on good practices, past insights, and accepted standards. As a result, most NRC regulations were prescriptive and were applied uniformly to all areas within the regulatory scope. Risk technology is changing regulations by prioritizing the areas within regulatory scope based on risk, thereby focusing on the risk-important areas. Performance technology, on the other hand, is changing the regulations by allowing requirements to be adjusted based on the specific performance expected and manifested, rather than a prior prescriptive requirement. Consistent with the objectives of risk-informed and performance-based regulatory requirements, BNL evaluated the feasibility of applying risk- and performance-technologies to modifying NRC’s current regulations on fire protection for nuclear power plants.(1) This feasibility study entailed several case studies (trial applications). This paper describes the results of two of them. Besides the case studies, the paper discusses an overall evaluation of methodologies for fire-risk analysis to support the risk-informed regulation. It identifies some current shortcomings and proposes some near-term solutions.

scholarly journals Methodology for Establishing Segmentation Strategy for Large Metal Components from Nuclear Power Plants with Consideration of Packaging into Containers

2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Jae Min Lee ◽  
Jae Hak Cheong ◽  
Jooho Whang
Keyword(s):  
Case Studies ◽  
3D Modeling ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Sensitivity Analyses ◽  
Optimal Dimension ◽  
New Approach ◽  
Segmentation Strategy ◽  
Ellipsoidal Shape

A methodology for segmenting large metal components from nuclear power plants has been developed with a view to minimizing the number of containers to emplace segmented pieces. Spherocylinder-type and rectangular prism-type objects are modeled in shapes, and equations to calculate heights, widths, lengths, or angles for segmentation and the number of pieces are derived using geometric theorems, with a hypothetical ‘virtual rectangle’ being introduced for simplification. Applicability of the new methodology is verified through case studies assuming that each segmented piece is packaged into a 200 L container, and a procedure for adjusting potential overestimation of the segmented pieces due to the virtual rectangle is proposed. The new approach results in fewer segmented pieces but more containers than an existing segmentation study using 3D modeling. It is demonstrated that the number of containers can be further reduced, however, if the generalized methodology is followed by 3D modeling. In addition, it is confirmed that the generalized approach is also applicable to a nonstandard shapes such as ellipsoidal shape but only under limited conditions. Sensitivity analyses are conducted by changing dimensions of the objects and container, which brings about an optimal dimension of container as well. The generalized approach would be utilized either alone in decommissioning planning to estimate waste from segmentation of large metal components or combined with 3D modeling to optimize segmentation operation.

Work structure in nuclear power plants

1983 ◽  
Author(s):  
Marjorie B. Bauman ◽  
Richard F. Pain ◽  
Harold P. Van Cott ◽  
Margery K. Davidson
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Work Structure
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