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Mechanical Stress Improvement Process
Dr. O'Donnell and Dr. Porowski were co-inventors of the Mechanical Stress Improvement Process (MSIP). In considering the stress corrosion cracking problem in the heat affected zone of field welds in BWR primary pumping, they developed a reliable mechanical stress improvement process which applies compressive stresses and is easy to control and verify. MSIP was developed with supporting finite element analysis and tests which show that it provides compressive stress fields in both the axial and circumferential directions at the inner surface of weldments. The Process was developed for pipe-to-pipe, pipe-to-discontinuity (such as valve body) and pipe-to-vessel nozzle configurations. MSIP has been performed at 40 nuclear power plants worldwide:


Utility Plant Year Pipe & Fittings Nozzles & SE's Total Notes
CeCo Dresden 3 1986 50 2 52  
CeCo LaSalle 2 1987 25 29 54  
CeCo Quad Cities 1 1987 36 2 38  
CP&L Brunswick 2 1988 0 15 15 1
CeCo Quad Cities 2 1988 43 4 47  
Nuclenor Santa Maria de Garona 1988 24 0 24  
OKG Aktiebolag Oskarshamn 1988 1 0 1 1
CP&L Brunswick 1 1988 0 10 10  
CeCo LaSalle 1 1988 15 15 30  
CeCo LaSalle 2 1988 8 0 8  
CeCo Dresden 2 1988 82 22 104  
PeCo Limerick 2 1989 2 16 18  
Northeast Millstone 1 1989 0 22 22  
Detroit Edison Fermi 2 1989 6 21 27  
CeCo Quad Cities 1 1989 28 12 40  
CP&L Brunswick 2 1989/1990 16 20 36 2
CeCo Quad Cities 2 1990 30 14 44 2
Teollisouden Voima Oy TVO 1990 5 0 5  
Niagara Mohawk Nine Mile Pt 2 1990 0 1 1  
Taiwan Power Kuosheng 2 1990 2 0 2 1
CP&L Brunswick 1 1990/1991 10 24 34 2
Northeast Millstone 1 1991 34 9 43  
Iberdrola Cofrentes 1991 0 42 42  
Boston Edison Pilgrim 1 1991 16 0 16 2
PeCo Peachbottom 3 1991 10 0 10  
PeCo Limerick 1 1992 0 7 7  
Cleveland Elec. Perry 1 1992 0 27 27 1
TVA Browns Ferry 3 1992 71 29 100 2
GPU Oyster Creek 1992 70 0 70 2
Georgia Power Hatch 1 1993 18 11 29  
TVA Browns Ferry 2 1993 12 0 12 2
PP&L Susquehanna 2 1993 8 6 14  
PeCo Limerick 1 1994 4 14 18  
Georgia Power Hatch 2 1994 0 18 18  
PP&L Susquehanna 2 1994 7 5 12  
GSU River Bend 1994 0 28 28  
WPPS WNP-2 1994 6 38 44  
GPU Oyster Creek 1994 39 16 55  
      678 479 1157  

(1) Some weldments with pre-existing cracks
(2) Weldments for replacement piping made of SCC immune materials



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