RPV WELDING REPAIRS | OPERATIONS & MAINTENANCE
Working conditions in the work area of reactor lower plenum included being submerged in heavy water at ~ 0.8 bar, at a temperature of some 60°C and located 14 metres below the reactor cover. Access would be provided through four holes of 11 cm diameter each. The two Flux-cored arc welding (FCAW) welding tools
were intended to perform a pair of welds on each of the three remaining supports which were still fixed to the reactor lower fill body plate in their correct positions. The objective here was to improve their fixation to prevent those remaining supports from moving from their positions in the future. The CONUAR scope of supply for the welding tools included: hydraulic, pneumatic and mechanical actuators, welding heads, a column to guide the hydraulic and pneumatic line access, the filler metal and the gas supply, connections to the remote motion control board (both hydraulic and pneumatic) and a remote human machine interface (HMI) control panel to control the welding process. All processes were tested and functionally validated on mock-up facilities in both CONUAR and NA-SA tailor- made facilities. In addition, the procedures, welding test coupons and welders were formally qualified to ensure the intervention would be a success and gaining the relevant approvals from the Argentinian Nuclear Regulatory Authority (ARN). Subsequently, all of the necessary repair welds were performed on site by NA-SA with an exclusive
Left: A failure in a support structure required repairs to be made from within the Atucha II reactor pressure vessel
CONUAR assistance team and controlled by NA-SA remote video-cameras.
The gripping and vacuum handling tools were part of a
set of tools used by NA-SA for extracting the loose support. Led by NA-SA, the detailed plans and subsequent actions to repair the lower plenum support within the reactor pressure vessel allowed Atucha NPP to be returned to service in just 10 months from the out of service date. This is a significant improvement on the six years initially estimated by NA-SA. Furthermore, the necessary tasks were completed at an expenditure one twentieth of that required if the conventional solution had been implemented. ■
NS ENERGY
www.nsenergybusiness.com
The industry’s largest resource for energy content, up-to-the-minute news, projects, developments and research, NS Energy Business is the needs and behaviour of the individual energy professional.
With users in more than 100 countries, supported by daily e-newsletters and extensive social media coverage, NS Energy Business examines the drivers that are transforming the whole of the energy sector, from generation to transmissionand distribution, upstream oil and gas and beyond.
No other resource can offer such extensive insight in a single place. For advertising and editorial enquiries, please contact
Roy Morris, Group Sales Manager T: +44 (0)20 7406 6619 E:
roy.morris@
progressivemediainternational.com
NSEnergyBusiness_HP_HOZ
Advert.indd 1 Half Page (124x178).indd 1
21/11/2023 10:11 27/04/2023 08:25
www.neimagazine.com | September 2024 | 29
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49
