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.

Published December 18, 2018

Safe Packaging of Chemically Reactive Radioactive Waste

James P. Burelbach, PhD, Fauske & Associates


Fauske-&-Associates,-LLC-Test-Cell-1In the chemical process industry bench-scale thermal hazard testing is an effective approach to quickly collect critical safety data for process scale-up and management of change.

These accepted test methods are directly relevant to the packaging, transport, and storage of radioactive waste that is or can become chemically reactive.

For chemically reactive waste streams it is vital to identify safe temperature and pressure conditions and to quantify adiabatic heat and gas generation rates in order prevent or accommodate thermal instability within the waste package or storage facility.


High level waste streams can include organic-bearing sludge and salt cake waste. Organic complexants like sodium acetate along with oxidizers like sodium nitrate present the potential for spontaneous runaway chemical reactions (thermal instability).

The data below are for 20.5% sodium acetate (6% Total Organic Carbon, or TOC) in a simulant oxidizer mixture heated at 1 °C/min. These data show significant exothermic activity at 200 °C with “ignition” at 300 °C.

chemical reactive waste   runaway chemical reactions

Ammonium nitrate is another common oxidizer that has been involved in large scale industrial disasters and is potentially explosive when mixed with organic fuel.  The data below illustrate the effect of a small amount of organic contamination (polyethylene scrap).

large scale industrial disaster


VSP2™ (Vent Sizing Package 2)

  • Up to 100 ml sample size
  • Stainless, Hastelloy, or glass-lined test cells
  • Pressure balancing
  • Closed cell testing gives direct vapor pressure
  • Strong mixing suitable for two-phase or slurries
  • Scale suitable for contamination studies
  • Scale suitable for in-test dosing or sampling
  • Test setup takes about 2 hrs


  • Test solids or liquids (magnetic stirring)
  • Light-weight test cell à low thermal inertia
  • Test cell heat capacity << sample heat capacity
  • “Phi-factor” ϕ close to unity ~ 1.05 to 1.1
Phi Factor testing
  • Evolved heat is not lost to the container (or the environment) but increases the sample temperature


  • Data are directly scalable
  • Measure adiabatic temperature rise (ATR)
  • Measure temperature rise rate dT/dt = f(T)scalable tempurature data
  • Measure pressure rise rate dP/dt = f(T)
  • Infer molar gas generation rate
  • Kinetic modeling


  • Emergency vent sizing (pressure relief)
  • Safe storage temperature
  • Safe package/container size
  • Time to maximum rate (TMR)
  • Temperature of no return (TNR)
  • Self-accelerating decomposition temperature (SADT)

ARSST™ (Advanced Reactive System Screening Tool)advanced reactive system screening tool

  • Up to 10 ml sample size
  • Scale suitable for thermal screening (identify energetic reactions)
  • Normally open cell testing
  • Scale suitable for large rates of gas generation (decomposition)
  • Scale suitable for operation in a glove box or hot cell
  • Test setup takes about 20 min



Tri-n-butyl phosphate (TBP) saturated with concentrated nitric acid (HNO3) can form two-layer organic/aqueous morphology in  solvent extraction system evaporators and tanks.  The organic phase reacts exothermically and under certain conditions this can lead to a thermal runaway

(e.g. Tomsk-7 reprocessing plant explosion in Russia, 1993).

Red Oil Experiment Red Oil Temperature Red Oil Self Heat Rate Red Oil Self Heat Rate experiment



  • Organic contamination in an oxidizer such as sodium nitrate or ammonium nitrate can lead to an Arrhenius runaway reaction followed by a wave-like “propagating reaction”
  • Thermal hazard testing can identify the minimum TOC required for a reaction to propagate, and the observed kinetics provide a technical basis for safe packaging and storage


Two separate exotherms were observed

  • The 1st exotherm at 80 °C is mild (< 1 °C/min)Test cell heat rates
  • Tempering (under atmospheric pressure) occurs at about 100 °C due to evaporation of dissolved water
  • The 2nd exotherm (two peaks) is stronger (< 10 °C/min)
  • Peak rates are reduced for lower HNO3 concentrations or in the presence of decomposition products (e.g. butyl nitrate) but the activation energy (inferred from the dT/dt slope) is unchanged
  • In a “closed cell” configuration (e.g. if the process vessel vent is closed or plugged) tempering does not occur and pressure builds
  • Closed cell self-heat rates increase exponentially to 1000 °C/min
  • The Tomsk-7 accident can be explained by a combination of weak tempering and insufficient venting capacity

Containment Vessels


Burelbach & Theis (2005). “Thermal Hazards Evaluation using the ARSST,” 3rd Intl. Symposium On Runaway Reactions, Pressure Relief Design, and Effluent Handling, Cincinnati.

Epstein, M., et al. (2008). “Thermal Stability and Safe Venting of the Tri-n-Butyl Phosphate-Nitric Acid-Water (‘Red Oil’) System—II: Experimental Data on Reaction Self-Heat Rates and Gas Production and their Correlation,” Vol. 163, Nuclear Technology, Aug. Ibid, “III: Predictions of Thermal Stability Boundaries and Required Vent Size.”

 Subscribe to Blog

Sign up for our newsletter to Get all the latest information

Share this article

Find more resources articles