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Energy Solutions

WITNESS simulation helps EnergySolutions, a leading nuclear services company, demonstrate best practice and secure multi-billion dollar contracts.


EnergySolutions provides a full range of services for the decommissioning and remediation of nuclear sites and facilities, management of used nuclear fuel (UNF), the transportation of nuclear material and the environmental cleanup of nuclear legacy sites such as the uranium mill tailings site in Moab, Utah. It owns and operates several state-of-the-art facilities including a metal melt facility in Tennessee and a low-level waste disposal facility in Utah.

Its projects are diverse and recent work has provided solutions for existing second generation nuclear facilities such as the Advanced Mixed Waste Treatment Plant in Idaho and the Uranium 233 Downblending Facility in Oakridge Tennessee, and a project with Hanford Site to manage and close World War II era underground tanks containing liquid high level nuclear waste in a safe manner.

Stepping up to the Challenge

EnergySolutions faces a number of challenges in the competitive marketplace for nuclear services. In winning bids for a diverse mix of large scale contracts, it must demonstrate that its proposed approaches for the processing of nuclear waste are appropriate, its capabilities proven, and reliability and accuracy are assured. It must also prove without doubt that it can meet specified deadlines and comply with ever-changing legislation and be transparent at all times.

In May 2007, the US Department of Energy (DOE) provided financial assistance to successful industry applicants to produce conceptual designs for UNF recycling facilities and advanced fast reactors in the United States. EnergySolutions led one of four teams awarded funding.

Finding a Solution

EnergySolutions has used simulation modeling over the last 15 years to accurately predict throughput and performance of multiple new and existing nuclear facilities. In developing its conceptual designs, EnergySolutions used WITNESS from Lanner to help develop a facility design based on mature, commercially deployed nuclear fuel recycling technology and operational facilities.

Using WITNESS, EnergySolutions performed a Conceptual Design Study for the proposed Nuclear Fuel Recycling Centre. The design encompassed the receipt and temporary storage of UNF from pressurised water (PWR) and boiling water (BWR) reactors. Head End fuel shear and dissolution functions were included, as well as downstream primary separations, purification and finishing functions, all downstream waste management facilities and supporting balance of facility plants.

Modeling provides an invaluable insight into how existing or new processes operate, taking into account all the constraints involved in the day to day operations of a nuclear facility. Through using WITNESS’ modeling capabilities, Energy Solutions was able to predict facility throughput and identify key process bottlenecks within complex nuclear operational units.

By modeling the facility, EnergySolutions identified that the production target of 1,500 metric tonnes of uranium (MTU) per year could not be achieved with the existing baseline design. Therefore, several process improvements would need to be implemented in order to optimize throughput and performance.

The Plant model was developed entirely using the WITNESS software. The model was underpinned by various conceptual design media including process descriptions, process flow diagrams, mechanical handling diagrams and mass balance calculations. The model also incorporates key operational experience from the reference Sellafield Thermal Oxide Reprocessing Plant (THORP) in the UK.

For this project, EnergySolutions also used the 3D modelling capabilities in WITNESS in order to demonstrate the process planning in a format which is easy to understand.


Through using WITNESS, EnergySolutions’ was able to identify the design improvements required to meet the annual production target of 1,500 MTUs per year. In summary, these design improvements include:

  • Doubling the capacity of the fuel removal machine, fuel elevator and shear machine such that 2 BWR assemblies can be processed at the same time.
  • Reducing the dissolver vessel heat up times by 10%
  • Allowing the Container Process Crane to substitute for the Dissolver Basket Process Crane operations during an outage and vice versa
  • Providing an additional maintenance area in the cave to improve Dissolver Basket Handling Cave repair times
  • Increasing the reliability of the Dissolver Control System, Hulls Monitor, Tipping Machine, Fuel Removal Machine and Rack Transfer Machines

When each of the proposed improvements is implemented, facility throughput can be increased by as much as 86%.

These improvements, together with the lessons learned from previous plant operations at the Thermal Oxide Reprocessing Plant (THORP) in the UK, have been incorporated into the facility design to ensure the annual target throughput of 1,500 MTU can be achieved.

WITNESS modeling was key to EnergySolutions, giving the client confidence in the conceptual design as it enabled process design and improvements to be clearly mapped out, outcomes assured and the design to be spelled out in detail.

Joanne Berry, Principal Analyst at EnergySolutions comments:

“It's never too early in a project to develop simulation models and the effort required and return on investment should not be underestimated. Early model development identifies restrictions to facility throughput and operability at a time when the issues are easily resolved and the cost impact is less. WITNESS helps EnergySolutions to identify whether briefs and deadlines can be met at the outset of a project and where improvements to process design can be made to make the process faster and safer.” 

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EnergySolutions is an international nuclear services company with operations across the world. With over 5,500 employees, EnergySolutions is a world leader in the safe recycling, processing and disposal of nuclear material. EnergySolutions provides integrated services and solutions to the nuclear industry, the United States Government, the Government of the United Kingdom, hospitals and research facilities.

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