Modelling and simulating the replacement of the reactor coolant pump (RCP) motor at Waterford 3 revealed a maintenance structure – not shown on plans – that would hinder RCP motor movement. By catching this early, Entergy estimates it will reduce outage time by 1-2 days, with savings estimated to be up to $1 million per day. This is one example of how the US utility has been tying the use of laser scanning technology with 3D technology as part of the plant lifecycle management (PLM) programme at Waterford 3.
Computer drawings based on detailed site measurements enabled waterford 3 staff to plan a vessle movement step-by-step
Entergy first used 3D PLM technology during a fire protection project at Waterford 3, in 2007. The project involved the replacement of panels to meet the latest fire codes. John Mahoney, innovations leader for Entergy’s nuclear operations, says that Entergy chose to use the software due to the tight quarters and the logistics of getting the replacement panels in and out.
The laser scanning services for the project were provided by Areva Metrology Services. Digital 3D models were created using CATIA and the project work was simulated using DELMIA, both from Dassault Systèmes. BCP Engineers & Consultants served as the prime contractor for the project.
“It used to be that people would come into a room and take some Lego or Playmobil [toys], which are very primitive ways of trying to understand the project, and are not precise,” says Rolf Gibbels, global energy industry leader at Dassault. “Now we can bring in outside companies; rigging companies and large EPCs were involved to perform some of these tasks and plan it out precisely. The planning aspect happens at the same time as a training element; they are not just determining how to go about it; they need to understand once they are on site exactly how they are going to perform it.” He adds that the process takes about six weeks to turn a laser scan and 2D plans into a first 3D environment, and another three months for a final simulation.
Following the success of a fire protection project, Entergy decided to expand its use of 3D modelling tools to support long-range planning of projects, including steam generator replacement, scheduled for 2012; the RCP motor replacement, due to be carried out in this month’s outage; and in-core instrumentation thimble replacement.
Mahoney says that the way most utilities are using simulation technology is for large projects, or projects that haven’t been done before.
Mahoney told NEI about how computer simulation technology helped to detect two structures that would have interfered with the RCP motor lift.
“A maintenance structure, built after the plant was designed…was installed above the reactor coolant pump. The structure is not shown on the drawings that people would pull to do maintenance, so nobody knew it was there. If it wasn’t for laser scanning and 3D modelling, we wouldn’t have detected the structure until the motor was lifted above the pump.”
Once the structure was detected the maintenance team would have had to make sure the 57- ton pump was in a safe position, either by reinstalling it or safely suspending it, before planning what action to take. The problem could have added two days to the outage.
Now, knowing that the maintenance structure is an obstruction, Entergy can plan to remove it and re-rig the motor.
The upcoming Waterford 3 steam generator replacement project is also being planned using similar modelling tools by SGT (a partnership between URS and Areva). Waterford 3 aims to cut project duration by up to 20% with this 3D PLM technology.
“The software helped us to identify clearance issues. We used to cut steam generators apart inside the containment, but 3D modelling revealed that there was enough clearance to remove them whole,” Mahoney said. This, he says, will lead to savings of 13–15 days on the critical path or $13-$15 million.
However the technique is not yet widely used in the nuclear industry, mainly due to the expense.
“Each plant requires a unique scanning and to implement that in a larger plant it takes a lot of work.” Also, once modifications are made, that area of the plant needs to be scanned again.
However, Mahoney feels that the technology will be implemented more widely in future as new plants will have generic models available, and CAD software becomes more popular. In the future, Entergy hopes to link the project schedule activities to the current Waterford 3 model, to help optimise outage schedules.
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