Combustible Dust Testing

Laboratory testing to quantify dust explosion & reactivity hazards

Flammable Gas & Vapor Testing

Laboratory testing to quantify explosion hazards for vapor and gas mixtures

Chemical Reactivity Testing

Laboratory testing to quantify reactive chemical hazards, including the possibility of material incompatibility, instability, and runaway chemical reactions

DIERS Methodology

Design emergency pressure relief systems to mitigate the consequences of unwanted chemical reactivity and account for two-phase flow using the right tools and methods

Deflagrations (Dust/Vapor/Gas)

Properly size pressure relief vents to protect your processes from dust, vapor, and gas explosions

Effluent Handling

Pressure relief sizing is just the first step and it is critical to safety handle the effluent discharge from an overpressure event

Thermal Stability

Safe storage or processing requires an understanding of the possible hazards associated with sensitivity to variations in temperature

UN-DOT

Classification of hazardous materials subject to shipping and storage regulations

Safety Data Sheets

Develop critical safety data for inclusion in SDS documents

Biological

Model transport of airborne virus aerosols to guide safe operations and ventilation upgrades

Radioactive

Model transport of contamination for source term and leak path factor analysis

Fire Analysis

Model transport of heat and smoke for fire analysis

Flammable or Toxic Gas

transport of flammable or toxic gas during a process upset

OSS consulting, adiabatic & reaction calorimetry and consulting

Onsite safety studies can help identify explosibility and chemical reaction hazards so that appropriate testing, simulations, or calculations are identified to support safe scale up

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Engineering and testing to support safe plant operations and develop solutions to problems in heat transfer, fluid flow, electric power systems

Battery Safety

Testing to support safe design of batteries and electrical power backup facilities particularly to satisfy UL9540a ed.4

Hydrogen Safety

Testing and consulting on the explosion risks associated with devices and processes which use or produce hydrogen

Spent Fuel

Safety analysis for packaging, transport, and storage of spent nuclear fuel

Decommissioning, Decontamination and Remediation (DD&R)

Safety analysis to underpin decommissioning process at facilities which have produced or used radioactive nuclear materials

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Our Nuclear Services Group is recognized for comprehensive evaluations to help commercial nuclear power plants operate efficiently and stay compliant.

Severe Accident Analysis and Risk Assessment

Expert analysis of possible risk and consequences from nuclear plant accidents

Thermal Hydraulics

Testing and analysis to ensure that critical equipment will operate under adverse environmental conditions

Environmental Qualification (EQ) and Equipment Survivability (ES)

Testing and analysis to ensure that critical equipment will operate under adverse environmental conditions

Laboratory Testing & Software Capabilities

Testing and modeling services to support resolution of emergent safety issues at a power plant

Adiabatic safety calorimeters (ARSST and VSP2)

Low thermal inertial adiabatic calorimeters specially designed to provide directly scalable data that are critical to safe process design

Other Lab Equipment (DSC/ARC supplies, CPA, C80, Super Stirrer)

Products and equipment for the process safety or process development laboratory

FERST

Software for emergency relief system design to ensure safe processing of reactive chemicals, including consideration of two-phase flow and runaway chemical reactions

FATE

Facility modeling software mechanistically tracks transport of heat, gasses, vapors, and aerosols for safety analysis of multi-room facilities

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Recent Posts

Severe Accident (Level II) Uncertainty Analysis

Posted by The Fauske Team on 07.21.15

Robert W. Reeves, Director, MAAP4 Maintenance, Fauske & Associates, LLC

The study of severe nuclear accidents and the various phenomena (steam explosions, in-vessel retention of the core debris, molten core concrete interactions, hydrogen combustion, etc…) associated with them are far from exact science.  The use “uncertainty analyses” is the process of quantifying the range of possible results from a complex analysis.  This process consists of performing numerous numerical analyses and investigating the impact of varying various inputs over a range of uncertainties to determine a “band” of results.  Uncertainty analysis can be used to reduce the conservatism in an analysis and provide a more realistic calculation.  In addition, many nuclear regulators are now requiring that uncertainty analyses be performed and presented.

The process of performing an uncertainty analysis involves a review of experimental evidence and literature to determine the uncertainty parameters and ranges of uncertain inputs for these parameters. The determination of the uncertain parameters is then followed by a stochastic analysis to propagate the uncertainties through an analytical model in order to calculate the range of outputs. The plot below illustrates an example of the impact of cavity ablation (erosion of the concrete material in the reactor cavity beneath the reactor vessel) depth on the time delay to submerge the core debris in a pool of water.

Molten_Core_-_Concrete_Interaction

Fauske and Associates, LLC (FAI) has a long history of performing uncertainty analysis for phenomena involved in severe nuclear accidents including Hydrogen Combustion, Molten Core-Concrete Interaction, Source Term Calculation, and In-Vessel Retention.  

FAI was the principal author of the original Severe Accident Management (SAM) Technical Basis Report (TBR) (FAI/91-19 Volumes 1 and 2 also known as EPRI TR-101869).  This report provided the technical bases upon which the PWR Owners Groups at the time (Westinghouse (WOG), Combustion Engineering (CEOG), and Babcock & Wilcox (B&WOG)) developed generic severe accident management guidance (SAMG) support material, which served as a framework for each utility’s plant-specific SAMG program.

In the aftermath of the Fukushima accident, EPRI commissioned an update to the original TBR, and FAI again was a principal author in this update.  In addition to the immediate insights from the Fukushima accident, the TBR update also incorporates a significant amount of research and experimental information that post-dated the original TBR and therefore was absent from the technical basis.

For more information, please contact Bob Reeves at reeves.fauske.com or 630-887-5220, www.fauske.com

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Topics: severe accident

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