BBR engineers were pioneers in the truest sense of the word when it came to developing high capacity tendons for nuclear applications. As early as the 1960s, they tested the first generation of large tendons for nuclear power plants – BBR wire tendons with button heads and BBR strand tendons with wedges. This early BBR testing of tendons involved the construction of a special facility at the tendon assembly plant in Switzerland, in order that large tendons could be tested in conditions which simulated the environment of a reactor vessel. Although in the sixties, at the beginning of this new application, some pressure vessels had been realised with tendons which are today considered quite small, the use of large capacity tendons soon became common practice. Since 1965, prestressing by post–tensioning has become a clearly established technique for pressure confinement in the nuclear power industry. Today, the recognised adaptability and reliability of BBR Prestressing Systems for the post-tensioning of nuclear power plant pressure and containment vessels has made them some of the best known internationally. The BBR team has now completed close to 100 nuclear energy projects in 15 countries.

The BBRVT CONA CMI system has passed all prescribed European Organisation forTechnical Approvals (EOTA) tests with flying colours – and has even withstood more stringent voluntary testing commissioned by the dedicated BBR engineers. From the very beginning, ever since the foundation of the BBR partnership in 1944, many hundreds of tests have been executed in different technical laboratories for the approval of various anchorage types in many countries. However, since 2002, BBR VT CONA CMI bonded post-tensioning anchorage types have been developed and tested extensively in accordance with standards set by EOTA – and have secured European Technical Approval. Static load, resistance to fatigue and load transfer tests were completed successfully according to ETAG guidelines. Although well in excess of the ETAG requirements, the team decided to go above eight million load cycles – already over four times more than required – in one additional voluntary test run. It was amazing that, even under these extremely hard conditions, the tendon endured this gruelling fatigue testing without any strands breaking. It is worthy of note that these tests were carried out as part of the certification of the largest post-tensioning tendon ever to be tested to these guidelines – anywhere in theWorld. In addition, a full scale installation, replacement and grouting test was undertaken for the 6106, similar to the trials carried out on smaller tendons by BBR forefathers.