Hazards Analysis, Code Compliance & Procedure Development

Services to identify process safety hazards and facilitate compliance with established standards and codes.

Combustible Dust Testing

Laboratory testing to quantify dust explosion and reactivity hazards

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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

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


Classification of hazardous materials subject to shipping and storage regulations

Safety Data Sheets

Develop critical safety data for inclusion in SDS documents


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


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

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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

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Nuclear Overview

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 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


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

Recent Posts

Evaluation of Max Allowed Temp for RHR Suction Piping System Aligned to ECCS

Posted by The Fauske Team on 05.25.17

By: Jaehyok Lim, Ph. D., Principal Nuclear Engineer, Plant Services, Fauske & Associates, LLC 



A series of calculations have been performed computer.jpgto investigate the thermal hydraulic behavior of the Residual Heat Removal (RHR) suction piping system should a Loss-of-Coolant Accident (LOCA) would occur shortly after transition from the shutdown cooling mode to the standby Emergency Core Cooling System (ECCS) injection mode. This condition can occur during startup and shutdown operations and has the potential of hot fluid being trapped in the Residual Heat Removal (RHR) hot leg suction line for the period of time required for the trapped fluid to cool down to ambient conditions. Depending on the piping configuration, this cooldown could require in excess of 24 hours, leaving a window of time in which the RHR system could be considered vulnerable to behaviors associated with elevated fluid temperatures in this location should the system be needed in response to an accident. These behaviors include the potential for steam intrusion into the RHR pump and to create conditions conducive to condensation induced water hammer on the initiation of Refueling Water Storage Tank (RWST) injection as well as during the switchover to the sump recirculation mode. This issue has been raised in Nuclear Safety Advisory Letter (NSAL), NSAL-93-004 (Ref. [1]) and NSAL-09-8 (Ref. [2]). Therefore, the analysis was intended to address this issue for the Westinghouse three-loop Pressurized Water Reactor (PWR). A RELAP5 model of the RHR system was developed to follow this two-phase, steam-water transient behavior. The RELAP5 results show that the largest concern for the RHR suction piping is the potential to experience steam ingestion into the RHR pump due to flashing of the trapped hot fluid in the hot leg suction line. This calculation has conservatively generated temperature limits for the isolation of the RHR shutdown cooling to ensure no steam ingestion into the pump will occur. As long as the maximum water temperature is less than 232 °F, there will be no steam intrusion. The considerations for a potential water hammer were not of concern. However, results can be changed for other plants with different geometries and conditions.


1. Westinghouse, 1993, RHRS Operation as Part of the ECCS during Plant Startup, NSAL-93-004: Nuclear Safety Advisory Letter.

2. Westinghouse, 2009, Presence of Vapor in Emergency Core Cooling System/Residual Heat Removal System in Modes 3/4 Loss-of-Coolant Accident Conditions, NSAL-09-8: Nuclear Safety Advisory Letter. 


Click here to read the full article. Or, for more information, contact Jaehyok Lim at 877-328-7531, or info@fauske.com, www.fauske.com



 #maximum allowable temperature



Topics: thermal stability, nuclear plant, news


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