Retrofitting of attachments of the RA-piping system for fluid dynamic load cases after uprating

Assignment of tasks

Within the scope of a submitted uprating the RA-system has to be proven for the load cases:

  • Turbine trip at 100% power (TUSA100 – level B)
  • Turbine trip at partial load operation of a leg respectively (TUSA300 – level B)
  • Opening of the discharge-lock valve S004 (AAV – level B)
  • 0,1F-crack (level D)
  • 2F-fracture (level D)

and an optimization and retrofitting of the attachments has to be carried out.


Due to the huge loads from the fluid dynamic load cases it wasn't able to prove the attachments – especially the power house fixed point (MH-FP) – and the structure of a building in traditional way. Extensive redevelopment measures up to the reinforcing of the structure of a building (fundaments, floors) would have been the consequence.

By the following measures the attachments and the structural attachments were reduced:

  •     Valve optimization in load case AAV,
  •     Integration of single attachments (e.g. MH-FP) in the piping calculation model,
  •     Transient analysis of the fluid loads and
  •     Choice of a weaker attachment concept
RA support optimization

Results of the optimization

Elimination of attachments

  • RAx2-H0003 FL (AK–floor)
  • RAx0-H0007/H0008 VD (access MH)
  • RAx0-H0012.2/H0013.2 SB (across before steam filter)
  • RA10 ZU-U-06/01864 F, RA10 ZU-U-06/01865 F, RA40 ZU-U-06/01866 F (heat pipe)
  • RA30/40-H0055 SB (heat pipe)
  • RA10/20-H0060 SB (discharge pipe)
  • RAx0 S006/S007: valve yoke attachments (SB, F)

Reconstruction of attachments

  • RAx0-H0008/H0009 FP -> H + weak axial stop (MH-FP)
  • RA50-H0008 FP -> 3/6 FP (bypass station)
  • RA30/40-H0056 FS/Ax -> S/Ax (heat pipe)
  • RAx0-H0057/H0058 FL -> F (heat pipe)
  • RA10/30/40-H0004 FH -> pressure-resistant insulation in wall pipe (AK-blanket)

New construction of attachments

  • in area of the MH-FP: pipe coupling
  • RA50 bypass collector: SB
  • RAx0-H0007/H0008: horizontal guide (MH access)
  • RA20: FL underneath AK


 Software  Hardware

 Fluid dynamic calculations 11

 Structural dynamic calculations 4

 Single proofs 2

 attachments altogether 189

 removal 35

 reconstruction 73

 New construction 2