Margin Management for Nuclear Power Plants


What is the purpose of Margin Management (MM)?

Margin Management is a subset of Configuration Management and provides a methodology for preserving the safety margins of a nuclear power plant by identifying, recording, and analyzing certain measured values, called Design Parameters, associated with structures, systems, and components that make up the plant.

Why is Margin Management needed?

Margin Management accounts for variables that change over time in order to maintain the configuration of a nuclear power plant. These include normal wear and tear, operational changes in setpoints and operating ranges, design changes, and compromise of design assumptions. Margin Management provides a mechanism for managing the large amounts of data and variables associated with maintaining the design and licensing configuration of a nuclear power plant.

What does Margin Management do?

Through tracking and trending of changes in operating points of these Design Parameters, Margin Management ensures that the plant is operated as designed and licensed and that the plant operator can anticipate and manage the operation and maintenance of the plant to preserve the approved facility configuration.

What is the current state of Margin Management in the US?

Currently, there is a great degree of variance in the understanding and implementation of Margin Management in the United States. Most plants adopt a process of identifying issues using screening criteria, and then track changes in margin subjectively based on management understanding of the variables influence on the parameter of concern.

Why is the current state of MM the way it is in the US?

Margin Management evolved in the US to address concerns that safety margins were eroding over time due to wear and tear, and compromise of design assumptions. Since there is no effective and complete Configuration Management process at any US plant, tracking design assumptions, licensing commitments, and the associated margins is near impossible. Margin Management evolved as a subset of Configuration Management to provide some means of evaluating reductions in safety margin.

What is Interlogic, Inc. delivering with the MM project?

The Interlogic Margin Management Project essentially requires the delivery of six procedures defining the Margin Management process, a Margin Management Information System, and training necessary to use and adapt the Margin Management process to a client’s situation.

What do the procedures do?

The procedures provide guidance for:
• Roles and Responsibilities
• Function of the Margin Management Review Committee
• Identifying parameters to be included in the Margin Management Program
• Using the Margin Management Information System (MMIS) for data storage
• Identifying and evaluating low margin parameters
• Generating a periodic Margin Management Health report.

What does the MMIS do?

The Margin Management Information System is a digital repository for storing, maintaining, and evaluating Margin Management data.

MMIS has the potential to be expanded to automatically evaluate and identify low margin parameters, and automatically generate the Margin Management Health report.

Why is MMIS needed?

Tracking the number of parameters necessary for effective margin management is impossibly difficult without sophisticated data management tools. The analysis and evaluation of this data is an even greater hurdle in the absence of the MMIS. Without the MMIS there would be no confidence that Margin Management issues are being addressed effectively.

What is involved in the training?

Attendees at the training will learn: the fundamentals of margin management, the relationship of margin management to configuration management, the margin management process, use of procedures, and data entry and maintenance using the MMIS.

Why is the training needed?

Effective margin management is not a standard practice at any nuclear power production plant today. It is a complex issue with significant consequences of failure. A thorough understanding of margin management is a prerequisite of anyone involved in the Margin Management project.

What is the value of Margin Management?

The most visible benefit of margin management is increased confidence in nuclear safety. Effective margin management ensures that the plant is operated as designed and licensed and that the plant operator can anticipate and manage the operation and maintenance of the plant to preserve the approved facility configuration. These combine to provide fewer challenges by the regulatory authority, and increased confidence on the part of public and governmental authorities that the plant is being operated safely.

How does MM integrate with Configuration Management?

Margin Management is a subset of effective Configuration Management. Margin Management deals specifically with Design Parameters, and the margins to design and licensing commitments, which are just a fraction of the issues managed in configuration management.

How does the MMIS integrate with the proposed CMS?

The Margin Management Information System is designed such that data can be exported efficiently and imported directly into the proposed Configuration Management System with no additional modification or adjustment required.

For additional information on this topic, please contact Interlogic: