Project Sherlock: dissecting an old steam generator to better understand how it ages

Perhaps you've already heard of the Sherlock project, but aren't quite sure what it's all about? To put it simply, EDF asked its partners (including Onet Technologies) to extract very precise samples from an old steam generator at Cruas for laboratory analysis.

The ultimate aim is to gain a better understanding of how these exchangers age, and thus to reduce the need for costly maintenance campaigns.

As a reminder, a steam generator measuring 22 meters in height and weighing 465 tons is made up of numerous components, bundles, plates, etc., all of which make it difficult to access the samples required by EDF.

To this end, since 2018, a dozen Onet Technologies engineers and technicians have been developing several special machines and preparing for interventions on this unique worksite.

A milestone reached

The "corer" is the most imposing of these machines, and required 1? years of development work to be able to take complex samples from the steam generator.

The machine has a wingspan of 4 metres and a weight of around 10 tonnes. It can drill holes with a diameter larger than a basketball, and in steel thicknesses exceeding 50 centimetres.

The development team encountered two main technical challenges during the fine-tuning phase: firstly, the discontinuous nature of the material to be machined, which applies cyclic shocks to the cutting tool inserts, which are traditionally very hard and fragile; secondly, EDF's need not to pollute the samples, which meant not using any lubricating fluid for cutting - a first for this type of machining!

The corer will enable Onet Technologies' operational teams (DISR) to carry out 27 cores over a three-month campaign at the end of 2023.