Westinghouse Electric Company, United States

Cutting Construction Costs: Eliminating Months from Nuclear Plant's Schedule

Linking the 3D model to the schedule saves time and money before construction even begins

electricNuclear power is safe, clean and vital to a balanced energy supply to meet the world's growing need for electricity. The improved performance, reliability, and efficiency of present-day nuclear power plants have sparked new interest in plant construction. However, the industry must take a greater role in lowering new power plant construction costs.

Enter the AP600, a 600-megawatt advanced pressurized light-water reactor plant developed jointly by Westinghouse, its subcontractors and contributors, the U.S. Department of Energy and the Electric Power Research Institute (EPRI).

The AP600 project focuses on reducing two of the top contributors to power plant construction cost: financing during construction and onsite skilled craft labor. By using modular construction methods, Westinghouse and its project partners found that the AP600 - and its larger successor, the AP1000 - can be built in 36 months, from the first concrete pour to fuel loading. This is one-fourth to one-half the construction time of the most recent nuclear plants in the United States.

To ensure the 36-month timeframe could be met, EPRI suggested that Westinghouse investigate the "4D" concept, which involves visually linking specific parts of the 3D plant model to its related installation activities. Intergraph provided the core plant modeling software for the virtual construction project: PDS®, SmartPlant® Review and FrameWorks® Plus.

The AP600 project team not only verified the schedule through visualization, but it found another three to five months could be eliminated through logic and design changes alone. This has a significant positive impact on financing costs.

"Building a nuclear plant is extremely capital intensive," says Ed Cummins, Westinghouse's director of passive plant development. "Cutting down construction time greatly reduces investment costs. Not tying up roughly $1 billion for an extra four months adds up to significant improvements in power plant construction cost. The plant also can begin operating and generating income sooner, contributing to the economic benefits."

Shortening the construction cycle

One of the more dramatic schedule opportunities that was found during the electric plant engineering involved reinforcing bars, commonly known as rebar. During a visualization exercise involving the AP600 critical path, something hidden in 300 sheets of written activity reports became obvious. For virtually weeks, nothing was happening on the nuclear island. When activity finally continued, it was clear that the delay was tied to some rebar, which had to be placed after the containment vessel head was installed.

Alternatives were quickly researched. Westinghouse found that the rebar could be included in the containment vessel head before placing the structure in the plant. This could be done in the yard with no negative impacts. The crane could still lift the structure, and the design remained robust.

The change was made in the model and it immediately shortened activities by a full month. This not only addressed the first objective of reducing the nuclear plant construction cycle, but it also demonstrated the value of visualization.

Considering that indirect power plant construction costs - leases, taxes, insurance, interest and the like - for this project will be about $70,000 per day, this one change will save about $2 million. This is an incredible return on the visualization effort. The power plant design software paid for itself right then.

© Copyright 2012 Intergraph Corporation - Printed from www.intergraph.com on 10/24/2016 1:54:24 AM