Session: 17-05-01: Steam Turbine Generators & Auxiliaries

Paper Number: 173182

Nuclear Power Plant Thermal Uprate Studies and Steam Turbine Generator Impacts 

Recent actiivty in the nuclear industry and specifically on existing nuclear power plants have shown renewed acceptance in nuclear energy due to it's carbon free benefits and much needed contribution to base load power generation.  With this renewed acceptance, many nuclear power plants are experiencing a "new lease on life" with carbon free nuclear produced electricity filling the production gap as much of the world transitions from coal, oil, and natural gas produced power.  This includes preserving the existing fleet of nuclear plants which produce about 20% of the electricity in the United States.  Many of the operating nuclear plants have received financial incentives at both the state and federal level to extend their operating licenses, and in some cases, targeting an additional 40 years beyond their original operating licenses. 

An integral part of extending the operating life of existing nuclear plants is maximizing output and extending the life of the equipment.  From a steam turbine-generator perspective, an engineering uprate study is required to determine any impacts of a reactor uprate will have on the steam turbine-generator and auxilary systems.  The areas of thermal uprate study that will be discussed in this presentation are:

1. Uprate Thermal Conditions - steam turbine parameters are provided that will service as thet starting point to create heat balance diagrams.

2. Thermal Evaluations - this is a summary of thermal evaluation results, including swallowing capacity and flow margin assessment for the Uprate cases.  Iincluded are a qualitative description of expected High Pressure turbine modification(s) to achieve proper flow margins and expected  MWe improvement.

3. Mechanical Study - at a single thermal uprate condition, a mechanical evaluation will consist of: 
• Pass/Fail Mechanical Analysis of Blading and Mechanical Components on Main Steam Turbine 
• Evaluation of Steam Turbine Auxiliaries 
• Fatigue/Vibration Analysis of Applicable Steam Turbine Components 
• Steam Turbine-Generator Foundation Review 
• Recommendations for More Details/Additional Studies based on pass/fail evaluations. 
• Final Report and Recommendations 

4. Generator Mechanical and Electrical Study - this feasibility analysis will evaluate the existing generator components at the uprate conditions.  The generator components evaluated are: 

• Stator Winding Thermal and Electrical analysis including bushings, main leads and parallel rings. 
• Determine Stator Core heating and alterations needed to meet rating. 
• Rotor Thermal and Electrical analysis 
• Determine Excitation requirements and alterations needed to make the rating objectives. 
• Auxiliaries analysis to evaluate ventilation and to assess the ability of the coolers to meet the rating objectives. 
• Rotor Torsional analysis at the uprated conditions. 
• Evaluate the generator frame to foundation interface for potential modifications as result of the generator increase MVA capability. 
• Provide Generator parameters at uprate conditions for the plant owner to assess balance of plant components such as isophase, AVR and step-up transformer. 
• Evaluation and recommendations relative to the existing generator current transformers 
• List of critical and highly recommended actions in support of the uprate target conditions.

5. Additional Studies and Support

Recent industry experience will be shared by subject matter experts making this presentation.

Presenting Author: Michael Smiarowski Siemens Energy

Presenting Author Biography: Manager of the Steam Turbine Modernization group of Siemens Energy, Inc. Orlando, Florida
Bachelor’s degree in Mechanical Engineering from Clarkson University (Potsdam, New York, USA)
Master’s Degree in Engineering Management from the Milwaukee School of Engineering (Milwaukee, Wisconsin, USA).

ASME Power Division
Current – Past Chairman Advisor Group
Past Executive Committee Chairman (2017)
Turbine, Generator, and Auxiliaries Committee

Treasurer/Member-at-large for the ASME Central Florida Chapter (2022-present).

Authors:

Michael Smiarowski Siemens Energy