African Fusion

SAIW executive director Sean Blake shares experiences of his visit to France, where he toured the Chalon Saint-Marcel manufacturing plant of Areva Heavy Equipment before visiting Alstom Transport in Le Creusot.

Following a visit by a French delegation to the SAIW facility in February 2016, an invitation was extended by the Areva to visit its Heavy Equipment Manufacturing facility in St Marcel – Chalon, France. This facility was opened in 1976 and some of the components for the Koeberg Nuclear Power station were built in that facility. The facility primarily manufactures the steam generators for Areva’s 3rd generation EPR nuclear power plant.

Areva St MarcelThe Chalon Saint-Marcel manufacturing plant of Areva Heavy Equipment in France.

Some of the components for the Koeberg steam generator replacement project may also be manufactured in the facility with the balance planned for manufacture in an Areva manufacturing facility in China. I took the opportunity to visit this facility in conjunction with IIW meetings scheduled for May 25 and 26 in Gent, Belgium for the IIW Inspector working group.

During discussions with Areva personnel, they suggested that I could also visit the Alstom Transport site in Le Creusot, which is a short drive away from Chalon. The Alstom Transport facility is in the process of building bogies for PRASA and is the technology partner for Gibela, which is currently establishing a manufacturing facility in Dunnotar, Nigel for the local manufacture of passenger rail vehicles.

AREVA Heavy Equipment’s manufacturing facility

The fabrication facility is composed of four bays, an ancillary bay for support activities including welder training, a light bay with capacity for up to 50 t, a medium bay for up to 350 tons; and heavy bay for fabrications of up to 1 000 tons. The facility employs 364 operators of which 62 are boilermakers, 80 are welders, with 348 technicians and 205 managers and engineers. Due to the nature and quality requirements of the product manufactured at this facility, there is a high ratio of engineers and technicians to operators. Quality control and engineering are key factors in this operation with a ratio of one manufacturing hour for each engineering hour.

Manufacturing methods have been studied and developed specifically for the Areva activities and have been developed over a period if more than 30 years. The drilling and broaching process is a key example of this, where tubes sheets of up to 600 mm thick are drilled and broached to an accuracy of 0.01 mm. A matching sample is kept of every tube sheet bored as a quality control requirement.

Owing to Koeberg being built by Framatome (a predecessor of Areva), a close working relationship is maintained between Eskom and the French power consortium of Areva and EDF.

All assembly operations are conducted in clean rooms. Unfortunately, due to the cleanliness requirements and rules of the facility, I was not able to enter the assembly area, however, I could view the operation from the outside through a glass window. The assembly is carefully controlled with each item being identified and weighed with multiple checks to ensure proper assembly.

Within the facility, there is a welding technology department, which is working on a number of new welding developments including developing welding processes for the ITER Tokamak nuclear fusion project. They are also working on powder metallurgy solutions using Hot Isostatic Pressing (HIP) technologies as well as the joining of a stainless steel/copper and beryllium composite for water cooling for this project. The development group is also working on GMAW welding techniques as well as the automatic feed of filler material for GTAW welding in order to improve productivity and automation.

Within the facility they have a welder training and testing facility, which is manned with training instructors and welding management. For a welder to work on the nuclear components, a minimum of 10 years training and experience is required.

Interestingly, Areva is using electroslag welding as a weld build-up and cladding technique. The process is preferred for some applications due to the low dilution achieved. Within the facility they are also using robotic GMAW welding as a cladding process. Polysoude’s TIGer (TIG with and electric resistance/hot wire feed wire) is utilised in order to improve productivity.

The facility has a second welder training facility that is remote from the manufacturing facility. Within this facility there are two welding bays with simulated environments where welders are trained and tested in a temperature and humidity controlled working environment with jigs for restricted access. Much of this second welder training facility was dedicated to the use of automated welding techniques with training and development of narrow-gap orbital TIG. All the welding equipment was supplied by Liburdi.

AREVA –NETEC

I also visited Areva’s non-destructive examination technical centre (NETEC) during my visit, which provides NDT services to industry, Eskom being a notable customer. The centre employs 330 people with 85 personnel in research and development, along with 155 NDT agents who are all certified by COFREND, the French NDT personnel certification body.

NETEC has developed the MIS manipulator, which is inserted into the reactor pressure vessel with a number of inspection tools for automated in-service inspection of the reactor vessel. Inspections are undertaken in accordance to the requirements of RSE-M and ASME codes, which define the necessary in-service inspection operations.

The developments that NETEC are working on are the replacement of RT with UT and the replacement of PT with PTC (photo thermal camera) testing. This technology may replace MT, PT and even ECT (eddy current testing) in some cases. The organisation is continually working on different probe designs in order to meet specific in-service conditions. An example of probe designs being worked on is new single or arrayed eddy current probes, eddy-current probes for inspection of heat exchanger tube bundles being one of the key competencies of the organisation.

An exciting development that NETEC is currently working on is thermography and they see many opportunities for this technology. The technology can be used to accurately locate indications by using thermal imaging using a camera 10 cm to 2.0 m away from the component being examined – and the component can be at temperatures of up to 300°C.

The technique enables inspections to be done more quickly, since the component does not need to be cooled down to room temperature for inspection as is required for conventional inspection techniques. Complex shapes can be inspected with better resolution than conventional techniques. Thermography can also be used as an alternative to MT testing, as has been demonstrated by the successful use of this technology for the inspection HVOF coated Pelton wheels. Thermography technology relies on a laser heating the surface of the component under investigation. Any cracks will prevent heat conduction, allowing the crack to be detected by the thermal camera. Examples seen show that the resolution was far superior to that obtained via penetrant testing (PT), which was traditionally used.

Alstom Transport – Le Creusot

The director of the International Institute of Nuclear Energy, Yves Fanjas, and I visited the Alstom Transport manufacturing facility together. We were hosted by Sebastion Ciron and Francoiss Vachon who are the responsible welding co-ordinators for the manufacturing facility.

Sean Blake France Alstom Bogie fabrication Le CreusotThe bogie assembly line at Alstom Transport’s EN 15085 CL1-certified Le Creusot site in France. Photo courtesy of Alstom Transport

The facility has been certified compliant to EN 15085 by GSI-SLV who is the leading organisation for certification to this railway manufacturing standard. The facility employs 670 permanent employees, 38% are operators and 32% engineers – once again a high ratio of operators to engineers. Currently, the organisation has approximately 100 projects in development and an order book spanning three years of activity. 1 500 Railway bogies are manufactured each year as well as 15 000 dampers, which are the facility’s primary products. The facility is also the design authority for all projects.

This facility is working closely with Gibela on the PRASA project and while I was visiting, one line was dedicated to manufacturing the initial bogies for the PRASA project. The primary competencies of the facility are welding and machining.

 bogies are fabricated at this facility from 6.0 to 25 mm boilerplate (Grade P355 NL and P275 NL). Welding operations are extensively conducted by robots due to the lack of welding skills in most areas as well as to improve working conditions in the workshop. Wheels and axles are purchased from external forging facilities located in France, Italy and China and gearboxes, brakes and suspension components are also sourced from third party suppliers.

Incoming plate material is prepared by shot peening before being cut using plasma machines. The weld preparation follows, the plate is champhered with no cutting lubricant being used, due to possible contamination leading to welding problems. The facility applies a flatness specification of 1.0 mm/m to its plate material.

All components are assembled in jigs and all jigs are manipulated such that welding can be done in the flat position. There is a strong focus on fatigue improvement techniques throughout the operation. Root runs are done manually as a human welder can perform a better quality weld than a robot, taking into account variations of fit-up. All butt welds have run-on and run-off tabs, which are removed from the final assembly. All start-stops are ground to remove any defects in this portion of the weld and TIG dressing is performed extensively as a fatigue improvement technique on the assembly.

After fabrication, the bogie is stress relieved in a heat treatment furnace. Welds around corners are also done manually as it has also been found that quality is better where there are possible dimensional variations, which cause problems for robots even when seam tracking technologies are used.

Quality control is a key feature of the operation with all components being identified. There is complete traceability of the manufacturing process, with each operation recorded including welder identification, which is also stamped onto the frame.

All structural welds are inspected using ultrasonics (UT) and Alstom is working on utilising phased array technologies, however, this is limited due to the lack of standards in this area.

 

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