Combustible Dust Testing

Laboratory testing to quantify dust explosion and reactivity hazards

Safety Data Sheets

Develop critical safety data for inclusion in SDS documents

Gas and Vapor

Laboratory testing to quantify explosion hazards for vapor and gas mixtures

Classification of hazardous materials subject to shipping and storage regulations
Testing and consulting on the explosion risks associated with devices and processes which use or produce hydrogen
Safety Data Sheets

Develop critical safety data for inclusion in SDS documents

Thermal Stability

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

Adiabatic Calorimetry
Data demonstrate the consequences of process upsets, such as failed equipment or improper procedures, and guide mitigation strategies including Emergency Relief System (ERS) design
Reaction Calorimetry
Data yield heat and gas removal requirements to control the desired process chemistry
Battery Safety

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

Safety Data Sheets

Develop critical safety data for inclusion in SDS documents

Cable Testing
Evaluate electrical cables to demonstrate reliability and identify defects or degradation
Equipment Qualification (EQ)
Testing and analysis to ensure that critical equipment will operate under adverse environmental conditions
Water Hammer
Analysis and testing to identify and prevent unwanted hydraulic pressure transients in process piping
Acoustic Vibration
Identify and eliminate potential sources of unwanted vibration in piping and structural systems
Gas & Air Intrusion
Analysis and testing to identify and prevent intrusion of gas or air in piping systems
ISO/IEC 17025:2017

Fauske & Associates fulfills the requirements of ISO/IEC 17025:2017 in the field of Testing

ISO 9001:2015
Fauske & Associates fulfills the requirements of ISO 9001:2015
Dust Hazards Analysis
Evaluate your process to identify combustible dust hazards and perform dust explosion testing
On-Site Risk Management
On-site safety studies can help identify explosibility and chemical reaction hazards so that appropriate testing, simulations, or calculations are identified to support safe scale up
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 safely handle the effluent discharge from an overpressure event

FATE™ & Facility Modeling

FATE (Facility Flow, Aerosol, Thermal, and Explosion) is a flexible, fast-running code developed and maintained by Fauske and Associates under an ASME NQA-1 compliant QA program.

Mechanical, Piping, and Electrical
Engineering and testing to support safe plant operations and develop solutions to problems in heat transfer, fluid, flow, and electric power systems
Hydrogen Safety
Testing and consulting on the explosion risks associated with devices and processes which use or produce hydrogen
Thermal Hydraulics
Testing and analysis to ensure that critical equipment will operate under adverse environmental conditions
Nuclear Safety
Our Nuclear Services Group is recognized for comprehensive evaluations to help commercial nuclear power plants operate efficiently and stay compliant
Radioactive Waste
Safety analysis to underpin decomissioning process at facilities which have produced or used radioactive nuclear materials
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 and Parts for the DSC/ARC/ARSST/VSP2 Calorimeters

Products and equipment for the process safety or process development laboratory


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


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


Our highly experienced team keeps you up-to-date on the latest process safety developments.

Process Safety Newsletter

Stay informed with our quarterly Process Safety Newsletters sharing topical articles and practical advice.


With over 40 years of industry expertise, we have a wealth of process safety knowledge to share.

MAAP - Modular Accident Analysis Program

Expert MAAP Analysis

The Modular Accident Analysis Program (MAAP) - an Electric Power Research Institute (EPRI) owned and licensed computer software - is a fast-running computer code that simulates the response of light water and heavy water moderated nuclear power plants for both current and Advanced Light Water Reactor (ALWR) designs. It can simulate Loss-Of-Coolant Accident (LOCA) and non-LOCA transients for Probabilistic Risk Analysis (PRA) applications as well as severe accident sequences, including actions taken as part of the Severe Accident Management Guidelines (SAMGs). There are several parallel versions of MAAP for BWRs, PWRs, CANDU designs, FUGEN design and the Russian VVER PWR design.

The original MAAP code was developed in the 1990’s by Fauske & Associates, LLC (FAI) as part of the Industry Degraded Core Rulemaking (IDCOR) program. FAI continues to support the code owner EPRI and their MAAP customers for software updates, maintenance, and training, drawing on decades of experience in modeling severe accidents at nuclear power plants. FAI also has extensive experience in implementing MAAP into nuclear training simulators.

Modular Accident Response System (MARS™) and ADEES

The Modular Accident Response System (MARS™) was developed by FAI as a software suite that monitors and predicts potential future states of a nuclear power plant under abnormal and accident conditions. MARS™ can be used to:

  • Demonstrate the effectiveness of procedures
    Support accident management
  • Train on reactor response to accident conditions
    Generate emergency planning scenarios
  • Predict the potential time of core damage during an accident

In recent years FAI has developed updated software called ADEES which effectively replaces the MARS software.




Following the accident at Three Mile Island Unit 2, the nuclear power industry developed the MAAP (EPRI owned and licensed computer software) computer code as part of the industry degraded core rulemaking (IDCOR) program. Its objective was to provide a useful tool for analyzing the consequences of a wide range of postulated plant transients and severe accidents for current plant designs and Advanced Light Water Reactors (ALWRs). The code can predict the progression of accident scenarios to a safe, stable, coolable state within the core or it can predict the occurrence of vessel failure and model the containment performance with successful debris cooling or pressurization of containment to a pre-defined failure condition. MAAP5 is the latest version of the suite of MAAP computer codes designed specifically to perform accident and severe analyses for numerous nuclear plant designs.


Since the events at Fukushima, there has been an increased interest to expand current simulator capability to address severe accidents. The Modular Accident Analysis Program (MAAP), an Electric Power Research Institute (EPRI) owned and licensed computer software, was developed to simulate and study severe accidents. MAAP is an integral code simulating both containment and primary system during severe accidents. FAI has been under contract to improve MAAP models related to BWR primary system, lower plenum, instrument tubes, molten core concrete interaction and others in order to better follow the severe accident at Fukushima.

Simulators can be expanded to cover severe accidents by implementing the MAAP code into the existing simulator. This implementation using MAAP4 was done for Krsko in Slovenia and Ulchin in Korea. MAAP5 was implemented for Daya Bay in China and Kori in Korea.

MAAP5 PWR code can be a good thermal hydraulic engine for PC based simulator for severe accident training.

The MAAP5 PWR code is the latest generation of MAAP and it implements new models to calculate forced and natural circulation inside a reactor coolant system (RCS) with more detailed nodalization, point kinetic and 1-D neutronics models, features to address details of new advanced reactor designs such as AP1000 and EPR, and improved containment models.

Improvements were also made to include a steam header model with detailed steam dump logic so that the code can calculate initial RCS and steam generator responses after a reactor scram. In addition, MAAP5 has improved models for shutdown states such as modeling nozzle dams in the RCS loops, mid-loop operation, and reactor head open with the vessel submerged under the refueling water pool.

MAAP5 code can also calculate the ANS-3-5 transients required for simulators. These transients include a manual reactor trip, simultaneous trips of feed water pumps, simultaneous closure of all MSIVs, trip of any single reactor coolant pump (RCP), loss of coolant accidents, main steam line break, maximum power ramp, and maximum design load rejection.


The MAAP5 code enhancements build on the substantial MAAP4 code enhancements to assess the approach to, and progression of, severe MAAP Services and PWR RCS Coolant Loop Viewaccidents in BWRs and PWRs operated in the western hemisphere and extends these to the plant specific features that are presently represented in the state-of-the-art models for Probabilistic Risk/Safety Assessments (PRAs/PSAs), Severe Accident Management Guidelines (SAMGs), Emergency Operating Procedures (EOPs) and full scope control room simulators.

The substantial enhancements in the current MAAP5 code are summarized below:

  • Natural circulation flows in the core, the hot leg and steam generators, before and after the core is uncovered
  • Improved computation to handle a greater range of transients with one-dimensional and point kinetics neutronics models
  • Increased capability for Steam Generator Tube Ruptures (SGTRs), Main Steam Line Breaks (MSLBs), Loss-Of-Coolant Accidents (LOCAs) analyses which require better steam generator models
  • Improved models for the lower plenum debris pool response including detailed metal layer to wall heat transfer and heavy metal layer formation in the bottom of the lower plenum. It also has a detailed ex-vessel heat transfer model (nucleate boiling and critical heat flux as a function of azimuthal angle) for in-vessel retention evaluations
  • A spent fuel pool model capable of modeling severe accidents in a spent fuel pool. The model is capable of calculating fuel uncovery, spent fuel heat up and degradation, Zr oxidation, hydrogen combustion events, Zr fires due to Zr + air interactions, etc.
  • The PWR Reactor Coolant System (RCS) models have continued to advance as the requirements for MAAP have evolved.

The focus of the MAAP5 RCS model is to provide a fast-running, best-estimate representation of plant response to all types of plant accident conditions. The goal is to consistently describe the physical processes associated with the integral system response to plant upset conditions, especially those that can progress to severe accident conditions. MAAP5 models are not intended to replace other software codes that deal with large break guillotine ruptures, which require analysis of the rapid flow reversal within the core, however, it is intended to provide a best estimate description of the core, reactor coolant system, steam generators and containment needed for engineering assessments, including best estimate evaluations of operator procedures and success criteria for PSAs.

Of particular note in MAAP5 is the ability of the primary system model to accommodate independent coolant loop response for PWR designs which can have 1, 2, 3 or 4 steam generator loops. MAAP5 models the responses of each steam generator (including the number of tubes that are plugged in each generator) depending on the feedwater flows to the generators and their individual steaming rates. This multiple generator representation can assess the mid-loop operation status for steam generator repair scenarios.

MAAP5 contains both a point-kinetics and a one-dimensional core neutronics model. As part of this, MAAP5 models the boron distribution within the RCS. This capability is combined with natural circulation flows due to density differences between 1) the core and the downcomer, and 2) the hot leg and cold leg side of the steam generator tubes. This provides an integral representation of the RCS and core response when natural circulation flows are important, such as for Anticipated Transient Without Scram (ATWS) conditions.

The MAAP5 containment model builds on the MAAP4 Generalized Containment Model. It extends the capabilities into several new applications, including Design Basis Accident (DBA). This model has been extensively benchmarked with containment experiments with the full scale tests from HDR (PWR) and Marviken (BWR) being some of the most important. Not only do these tests represent the containment response to DBA conditions, but the HDR tests also demonstrate the conditions that would 1) cause hydrogen stratification and 2) the conditions that would result in global mixing to eliminate stratification.

The MAAP5 containment model has been enhanced so that it can be used for Design Basis Accident (DBA) analyses. This model will support either a single node or multi-node analysis. It can also be used to assess the margin in the DBA calculation that results from assuming no contribution from forced convection as a result of the pipe break. The model also addresses the thermal resistance due to paint layers on the walls. The containment model includes all the fission product isotopes needed to perform Alternate Source Term (AST) evaluations which are coupled with MAAP5 such that the in-plant and ex-plant doses and dose rates can be calculated in a single run. It also contains models for the aerosol transport and deposition mechanisms to assess the retention capabilities.

The containment model also includes hydrogen burn models to assess the extent of localized burning (for those conditions where the containment atmosphere is not inerted) that could occur in the containment for severe accidents. Thus MAAP5 can be used to evaluate the equipment survivability envelope for such conditions.

Additionally, the containment model now has the capability to model all aspects of an accident where the integrity of the spent fuel pool can be challenged. The MAAP5 code can calculate the time to boil away the pool water inventory, model the heatup and relocation of the spent fuel, the potential for the release of hydrogen from the spent fuel cladding due to Zr oxidation (due to steam and air) and the potential for any type of hydrogen combustion event in the spent fuel pool room/enclosure.


The MAAP5 software package provides engineers with a tool to rapidly evaluate the progression of accidents in terms of the reactor core (is the MAAP Services and MAAP5 Primary System Nodalization Schemefuel damaged or not?), the containment (is containment integrity being challenged?) and radiological consequences (do the dose rates inside the plant or in the population areas present concerns in terms of taking precautionary measures such as shelter or evacuation?).

MAAP5 also can model the progression of an accident in a plants’ spent fuel pool. The MAAP5 code can calculate the time to boil away the pool water inventory, model the heatup and relocation of the spent fuel, the potential for the release of hydrogen from the spent fuel cladding due to Zr oxidation (due to steam and air) and the potential for any type of hydrogen combustion event in the spent fuel pool room/enclosure. Due to the rapid computation speeds and its capability to model all types of reactor transients, Loss-Of-Coolant Accidents and loss of AC/DC power events (SBOs), MAAP5 is a powerful code that can be used in the development of a plant’s accident management strategies.


Originally developed by Fauske & Associates, LLC (FAI) as part of the Industry Degraded Core Rulemaking (IDCOR) program, FAI has developed and maintained the code under the sponsorship of the Electric Power Research Institute (EPRI) and the MAAP Users Group (MUG).

MAAP5, and its predecessor MAAP4, have been used solely by the nuclear industry throughout the world for more than two decades as an engineering tool for severe accident analysis and associated severe accident phenomena, including hydrogen generation and combustion, direct-containment heating, rapid pressurization due to steaming, core concrete interactions, fission product releases, transport and deposition etc. The MAAP code is also used extensively in the PRA/PSA arena as well for success criteria evaluations, human reliability analyses (HRA) and Level II source term evaluations etc.

Interested in learning more about MAAP?

MAAP and Related Resources

Application of Uncertainty Analysis with the MAAP4 Code
Best-Estimate Facility Source Term Analysis
Dynamic Benchmarking of Simulation Codes
External Cooling of a Reactor Vessel Under Severe Accident Conditions
Fire Hazard Analysis
Formulation and Use of Uncertainty and Sensitivity Analysis
How to Use Expert Judgement to Assess Uncertainties
Isolation Valve Closure Following a High Energy Line Break
MAAP4 Uncertainty and Sensitivity Analysis
Modeling Gas Stratification in Small Break Loca Containment Analyses Part 2
Potential for Hydrogen Combustion in a Hight Level Waste Storage Tank
Thermal Impact of Line Break on Equipment