Industry effects have been largely successful in managing degradation of steam generator tubes due to wastage, pitting, and denting, but fretting, SCC and intergranular attack have proved more difficult to manage. Although steam generator replacements are proceeding there is substantial industry interest in operating with degraded steam generators, and significant numbers of plants will continue to do so. In most cases degradation of steam generator tubing by stress corrosion cracking is still managed by plug or repair on detection, because current NDE techniques for characterization of flaws are not accurate enough to permit continued operation. This paper reviews some of the historical background that underlies current steam generator degradation management strategies and outlines some of the additional research that must be done to provide more effective management of degradation in current generators and provide greater assurance of satisfactory performance in replacement steam generators.

The purpose of this analysis is to provide rational judgment for the most pernicious impact angle of dropping. A numerical simulation method, finite element analysis, is adopted for this study. The general-purpose finite element analysis code, ABAQUS(R) [HKS, 1998], facilitates the numerical computation. The geometrical finite element modeling is developed with the software PATRAN(R) [MSC, 1999]. The finite element code ABAQUS(R)has been verified according to the QA plans.

A high harmonic fast wave (HHFW) antenna array, designed to provide up to 6 MW of power at 30 MHz for heating and current drive applications, has been operated on the NSTX experiment at Princeton Plasma Physics Laboratory (PPPL). The full array consists of twelve evenly spaced, identical current strap modules connected in pairs. Each pair is connected as a half-wave resonant loop and is intended to be driven by one transmitter, allowing rapid phase shift between transmitters. A decoupling network compensates for the mutual inductive coupling between adjacent current straps, effectively isolating the six transmitters from one another. Initial rf operation between November 1999 and January 2000 used eight straps to form four loops, which were driven by two transmitters. Two adjacent loops were connected with a {lambda}/2 coax section to be driven out of phase by a single transmitter. Up to 2 MW of power was delivered during this stage of operation; inter-loop phasings of 0-{pi}-{pi}-0 and 0-{pi}-0-{pi} were investigated. Models of the power distribution system indicate the nominal plasma loading was about 5{Omega}/m, close to the design value of 6{Omega}/m. The HHFW system has now been reconfigured for 12-strap, 6-transmitter operation with decouplers; low power vacuum and …