siemens - Public Service Commission

SUSQUEHANNA STEAM ELECTRIC STATION
TURBINE RETROFIT/GENERATION UPRATE:
DECISION FACTORS FOR LONG TERM RELIABILITY
AND IMPROVED PERFORMANCE
Co-Authors
John A. Bartos, PPL Susquehanna, LLC
Michael S. Corski, PPL Susquehanna, LLC
Lawrence E. Olah, PPL Susquehanna, LLC
Michael IK Smiarowski, Siemens Westinghouse Power Corporation
INTRODUCTION/ABSTRACT
Nuclear power is a cost-effective source of electric power. According to Robert Smock, editor
of Power Engineering Magazine, “with almost 400,000 MW of new capacity needed to meet
demand growth over the next 20 years, nuclear power must contribute to this need and it is
evident that electrical utilities must increase capital investment in electrical facilities.”’ Nuclear
Plant operators are relicensing and retrofitting the plants to achieve maximum output and useful
life from the plants. PPL’s Susquehanna Steam Electric Station (SSES) Units 1 and 2, a Boiling
Water Reactor Plant in Benvick, PA, with a 1100 MWe nominal rating per unit, is such a plant
looking to operate at peak efficiency and reliability for its operating life.
The Susquehanna Station was faced with long term maintenance issues on its original disc type
OEM low-pressure (LP) turbines (circa 1982). The original LP rotors suffered from stress
corrosion cracking (SCC) in the disc/keyway and blade attachment areas, which is a common
design issue on certain rotor designs. Even though all six of the original disc type Unit #1 and #2
LP rotors were replaced with the current monoblock design in 1986 and 1988 respectively, there
were still concerns that these monoblock LP rotors would develop SCC in the blade attachment
areas. In addition, another significant long-term maintenance issue was LP casing erosion on the
current operating LP turbines, which PPL also wanted to address.
A team was formed to investigate the long-term options for the Susquehanna plant to both
increase performance and reduce long term maintenance on the turbines. In November 1999,
PPL issued requests for bids to replace the six (6) low-pressure turbines with an option to replace
the two (2) high-pressure turbines. Upgraded erosion resistant materials options were also part
of PPL’s request for the LP construction.
Although many factors are considered when developing an effective contract, the keyhnique
factors PPL used in the selection process of the turbine retrofit were:
1
Smock, Kobert, W , Power Engineermg, July 2001 (Vol 105, no 7), p 3