Fast Help for Neckar 2

During a routine reactor coolant pipe inspection at the German PWR unit Neckar 2 during this year's refueling outage, an unexpected discovery was made. A loose thermal sleeve inside a safety injection nozzle in the cold leg of one of the four reactor coolant loops was found using Framatome ANP's SUSI underwater inspection vehicle. A robotic inspection vehicle deployed through the safety injection line up to the loop confirmed the damage. The plant operator subsequently contracted Framatome ANP to repair the sleeve as quickly as possible.

The company immediately put together a team of experts (component designers, material specialists, manipulator experts as well as inspection and repair specialists) and worked out suitable retrieval and repair procedures along with a new inspection concept for the other three loops. All of these were evaluated in less than a day in discussions with the plant operator. The licensing authorities insisted that, as far as possible, as-built conditions be restored. At the same time, efforts got underway - with the support of Framatome ANP's material specialists - to determine the cause of the damage. In just one week - working around the clock - all of the repair and inspection equipment had been built and field personnel trained on mock-ups.

The entire scope of work was completed on schedule in just three weeks. Neckar 2's management praised the work carried out by the Framatome ANP/intelligeNDT team in repairing the thermal sleeve. Wilfried Gehrig, Neckar 2's project manager, found that the excellent cooperation between Framatome ANP's service personnel and their project team played a particularly important role in this success.

Steam Generators Chemically Cleaned at Neckar 1

Benefits of chemical cleaning: higher steam pressure, lower coolant temperature and higher plant output

During this year's annual refueling outage at the German unit Neckar 1, Framatome ANP chemically cleaned all three steam generators, one after the other, on their secondary sides. The entire cleaning campaign had an impact of less than six days on the critical path of the outage. The objective of the chemical cleaning was to remove all hard deposits from the tubesheets as well as all deposits from the outside surfaces of the tubes to extend steam generator service life and to assure long-term component integrity. After cleaning was complete, it was possible - in response to a requirement imposed by the Authorized Inspection Agency - to retrieve a number of foreign objects from inside the steam generators that were embedded in the hard tubesheet deposits and that represented a risk of fretting damage to the tubes.

The customer chose Framatome ANP's High-Temperature Chemical Cleaning (HTCC) process, the most widely used chemical cleaning process in the world, for this project. The high degree of cleanliness achieved with this process was verified through a visual inspection performed after all cleaning steps were completed. Chemical cleaning also resulted in a significant improvement in steam generator heat transfer. After cleaning, steam pressure at Neckar 1 was approximately 1.5 bar higher, yielding a 0.9% increase in plant electric output at the same reactor thermal output as before. This was accompanied by a drop in primary-side temperature of around 0.5°C (.9°F) which will reduce the thermal loads on the fuel assemblies. The steam generator cleaning campaign at Neckar 1 is expected to increase power production and therefore revenue, as well as reduce fuel consumption.