SI Chemistry has developed computer hydraulic models to analyze a variety of systems important to nuclear power plant performance. These models have been used to evaluate the causes of system performance issues, to assess changes for performance improvement, and to assess the impacts of flow and temperature increases that occur from plant changes, such as extended power uprates. Examples of steady state and non-steady state models are:

Piping Network Analysis

Hydraulic models are often based on a 3-D CAD model of the piping system. Examples include: condensate deep bed demineralizer systems, condensate filtration systems, condensate filter demineralizer systems, and reactor water cleanup systems.

Top Tubesheet Filter Backwash

Unsteady-state model to evaluate the effectiveness of current configurations and settings and effects of design and operating changes.

System Performance Evaluation 03 Shell Tube

Bottom Tubesheet Filter Backwash

Steady-state and unsteady-state (i.e., air surge) backwash models.

Flow Distribution

In collaboration with Organo Corporation, flow distribution within a bottom tubesheet filter vessel is modeled by CFD (computational fluid dynamics) for the purpose of design in components for internal flow distribution improvements. This allows the IFD (integrated flow distributor) design to be customized to the geometry and flow range of each vessel. The radial flux distribution along the length of filter elements is modeled using a finite element approach. The combination of CAD and hydraulic modeling is used to improve the flow distribution within deep bed demineralizer vessels.

System Performance Evaluation 02


Plant systems evaluated for performance improvement often include shell and tube heat exchangers. As part of the overall system evaluation, operational impacts are evaluated on heat exchanger performance (hydraulic, thermal, etc.). Using both proprietary and commercial software, we have the capability to perform the necessary evaluations.

Thermal Analysis

Utilizing the heat exchanger's specification sheet, the exchanger system is modeled until the available/required thermal capacity is determined via correlation with current operating conditions. One of the following solution methods may be used to converge on results:

  • LMTD (Log Mean Temperature Difference)
  • Effectiveness - NTU (Number Transfer Units)


We have performed numerous evaluations of existing liquid radioactive waste processing systems for BWRs and PWRs. Services involve the following processes:

  • Filtration: Filter demineralizers, non-precoat filters
  • Filter Media Selection and Optimization
  • Body Feed Optimization
  • Deep Bed Demineralization: Resin/media selection
  • Evaporation
  • Liquid Processing for Recycle or Discharge
  • Membrane Systems

With the advent of high-efficiency iron removal processes in BWRs, we developed a comprehensive program for the application of polyelectrolytes to improve processing of backwash and cleaning liquids in the radwaste plant.

This successful process has resulted in significant cost, labor and dose savings.

Flow-Induced Vibration

TEMA (Tubular Exchanger Manufacturers Association) software is employed to determine if potential flow-induced vibration issues may be present at specific operating conditions. A positive result may require further analysis.

Chemistry Assessments Conceptual Design



For over three decades, we have been engaged in makeup water treatment for nuclear power and industrial applications. Our engineers have strong backgrounds in the research and development, design, startup, troubleshooting and evaluation of a wide variety of systems and materials used in the purification of water and other aqueous solutions. Applicable makeup water technologies in which our engineers have direct experience and detailed knowledge include:

  • Water Chemistry
  • Ion Exchange
  • Filtration
  • Coagulation
  • Adsorption
  • Membranes Processes
  • Chemical Cleaning & Sterilization
  • Chemical Treatment