1. Nuclear Power Plant Life Management
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The Challenges
The first three sections of this write-up are
quoted from the IAEA June 2006 "Nuclear
Power Plant Life Management Processes".
"The design life of a nuclear power plant
(NPP) does not necessarily equate with the
physical or technological end-of-life (EOL) in
terms of its ability to fulfill safety and
electricity production requirements.
Operating equipment, generically called
critical systems, structures and components
(CSSCs) in a NPP is subjected to a variety of
chemical, mechanical and physical conditions
during operation. Such stressors lead to
changes with time in the CSSC material
properties, which are caused and driven by
the effects of corrosion, varying loads, flow
conditions, temperature and neutron
irradiation."
Life Extension Strategies
"Even allowing for significant ageing effects
in CSSCs, it is quite feasible that many NPPs
will be able to operate for times in excess of
their nominal design lives, provided
appropriate and proven ageing management
measures are implemented in a timely
manner. This aspect has been recognized by
operators and regulators alike, as seen in the
number of license renewal applications and
approvals, respectively, in the USA, and,
elsewhere, by extending licensing procedures,
primarily based on periodic evaluation of
safety, i.e. periodic safety reviews (PSR)."
Critical Systems Structures and
Components (CSSCs)
"Key attributes of an effective plant life
management program include a focus on
important CSSCs (see Figure 1) which are
susceptible to ageing degradation, a balance
of proactive and reactive ageing management
programs, and a team approach that ensures
the coordination of and communication
between all relevant NPP and external
programs."
Figure 1. Pyramid of Plant Life Management CSSCs – IAEA June 2006 report on Nuclear Power
Plant Life Management Processes.

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"Continued plant operation, including
operation beyond design life (usually called
long term operation), depends, among other
things, on the physical condition of the
plant."
It comes down to assessing a number of life
extending strategies for CSSCs such as Fuel
Channels, Pressure Vessels, Feeders, and
Steam Generators. Each of these strategies
carries accompanying risks of success.
Multi-Unit Stations
Some station operators also deal with
implementing these strategies over multiple
reactor units which have different ageing
rates and mechanisms. Risk informed
scenario analysis is required to fully evaluate
the possible impacts of implementing the
various strategies across multiple CSSCs,
units and stations.
Commercial Considerations
Market pricing structures, electricity demand
and operational cost uncertainties
significantly impact operation, maintenance
and outage strategies. These commercial
considerations are subject to environmental
issues and the expanding demand for
alternate energy sources. Commercial
uncertainties contribute to the large number
of complex scenarios to be assessed. In
addition, the information, both technical and
commercial is dynamic and uncertain.
Figure 2, published in the Chockie Group
International Oct 2006 Ageing Management
and Life Extension in US Nuclear Power
Industry report, also recommends a scenario
approach to Life Cycle Management (LCM).
Here is a quote from their report.
"All potential LCM enhancements should be
identified, such that a concise list of new or
Figure 2. Life Cycle Management Flowchart - Technical and Economic Evaluation

3. Nuclear Power Plant Life Management
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modified maintenance activities can be
compiled, along with their costs and timing of
implementation. Each goal can be met by
a number of different options, called
Alternatives in the LCM process."
Scenario Charting Support
Scenario Charting Process
Enablement
The above described challenges can be
effectively approached with a software
enabled scenario analysis process that
supports the LCM assessment steps shown in
Figure 2. Each scenario model consists of
alternate actions and mitigation plans that are
integrated with a unit base plan. Scenario
Charting software calculates and reports the
predicted impacts on unit maintenance and
refurbishment outage schedules and costs,
operational earnings and long term net profits
for each scenario.
Scenario Charting Process
VisiSuite LLC has developed the Scenario
Charting process to support the Nuclear
Power Industries efforts to more effectively
manage plant life sustainability and
implement effective CSSC life extension
strategies. Scenario Charting with our
VisiSuite software application enables and
enhances a highly successful visual planning
process. VisiSuite provides a seamlessly
integrated visual system for strategic, tactical,
scenario planning, scheduling, estimating and
analysis.
Visually Structured Planning
Process
The Visually Structured Planning process
shown in Figure 3 is a consistently successful
work group planning technique that utilizes
clear meaningful pictures to focus program
planning. Its effectiveness is directly
dependent on the quality of the pictures and
Figure 3. Visually Structured Planning Process – Planning pictures are as important to planning as
design diagrams are to system development.

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facilitation techniques employed. Clear,
professional-quality visuals help a team cut
through the complexity of ideas being
presented, negotiate agreement and remain on
the same page during program execution.
Supporting Life Cycle
Management
Predictive Life Cycle Analysis
At the heart of the Scenario Charting process
is a data repository containing a unit base
plan as well as additional or alternate actions,
designed to address uncertainties and mitigate
risks. These Scenario Charting elements are
configured into a set of scenarios that
implement various life extension strategies
and provide critical contingency plans as
shown in Figure 4.
Notional Power Plant Life Cycle
Model
The remaining figures in this write-up are
snapshots from a notional "CANDU"
Scenario Charting program that helps
describes the predictive modeling, process,
analysis and capabilities of Scenario
Charting.
The Base Plan
This notional Canadian station unit plan
covers a six year period. For demonstration
purposes, the plan shows 329 day operational
periods followed by 36 day maintenance
outages each year. This hypothetical unit is
near the end of its normal operational life.
Therefore the last two years include a major
refurbishment followed by one operational
period. (A real plan base plan should exceed
its design lifetime.)
Figure 4. Scenario Charting Process – Scenario Charting actions are configured into a set of
scenario - schedule/cost/profit projections.

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Drivers
The process of planning scenarios begins
with the identification of environmental and
technological "drivers" from which various
life extension strategies, risks and
commercial uncertainties are derived.
Drivers are critical factors that influence
whether or not the key objectives will be
achieved.
Multiple Complex Scenarios
The base plan represents normal unit
operation and maintenance outages that
historically have proven to be effective. It
represents the current situation that will serve
as the common departure point of each of the
scenarios. Environmental uncertainties and
potentially effective life extension strategies
are then defined as scenarios. Additional
actions, alternative actions, and contingency
plans can be considered in the development
of the scenarios.
Additional and Alternate Actions
Additional or alternate actions to be
implemented in conjunction with the base
plan are specified for the defined scenarios.
Additional actions (such as preventive
mitigation activities) will be added to the base
plan when a corresponding scenario is
activated.
Alternate actions may be necessary instead
of, or in addition to, additional actions.
Alternate actions will replace corresponding
base plan efforts when a scenario is activated.
(These actions are the gray bars shown in
Figure 5.)
Contingency Plans
High risk life extending actions may require
contingency actions that will be required
should the life extension strategy fail.
Contingency plans are modeled as separate
Figure 5. Scenario Charting Process – A visually constructed plan integrates the actions of various
scenarios with a unit's base plan to provide schedule/cost/profit projections.

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scenarios from the scenarios whose failure
may necessitate their activation.
Critical Dependencies Integrate
Actions
VisiSuite charts focus on the critical
dependencies between base plan actions and
scenario actions. The top-down Visually
Structured Planning process ensures that
these integrating elements are correctly
identified and agreed to during construction
of the plant’s scenario models. Figure 5 also
shows how the CANDU notional model
incorporates these key inter-action
dependencies that determine the start and
finish dates for the planned maintenance or
refurbishment outages. As the various
scenarios are activated these essential
linkages forecast the corresponding outage
schedules, costs, earnings and profits.
Analyze each Scenario's
Schedule, Cost and Net Earnings
A simple to operate VisiSuite dialog allows
the user to activate a different scenario (or the
base plan) by simply selecting it from a pull-
down and clicking the "Change Scenario"
button shown in Figure 6.
In seconds, VisiSuite collects, integrates and
analyzes the appropriate actions, then updates
the charts (target and schedule dates) and
provides the "Scenario Summary" that is also
Figure 6. Scenario Charting Process – Activate scenarios using this dialog. A new integrated program
plan/schedule is created, the chart dates are updated and results displayed

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shown in Figure 6. All scenario values are
maintained in the VisiSuite database, so that
an up-to-date Scenario Register spreadsheet
can be generated by clicking a command
button on the bottom of the dialog.
Rapid What-if Scenario
Modifications
Using the Find Adjust function, scenario
charting with VisiSuite allows rapid
adjustment to scenarios to answer "what-if"
questions.
Figure 7 illustrates this process. First it
presents each of the scenarios actions and
allows you to enter a "Desired Duration" or
"Desired Finish" date before clicking the
"Update this Work Effort" command button.
You can make several adjustments before
deciding whether you wish to make the
adjusted scenario permanent or discard it and
re-activate the original version.
Dynamic Commercial and
Technical Environment
The Scenario Charting process is easily
extendable and dynamic. Scenario models
can be modified or extended quickly. The
Visually Structured Planning charts can then
be reviewed with your team to ensure the
intended extensions and revisions have been
properly incorporated.
Figure 7. Scenario Charting Process – Use this dialog to modify scenarios. A new integrated
program plan/schedule is created, the chart dates are updated and results displayed

8. Nuclear Power Plant Life Management
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Risk Management
Analyzing CSSC life extending strategies
requires assessing the accompanying risks of
success. These are "speculative risks" that
provide the potential for gain as well as loss.
Traditional risk management addresses
"hazard type" risks which only provide the
potential for loss. This tactical bottom-up
type of risk management, works best in
environments with low uncertainty.
The newer strategic methods for managing
speculative risks, in uncertain environments,
analyze "mission risks" top-down using a
systemic focus. The Software Engineering
Institute (SEI) calls their approach Mission
Oriented Success Analysis and Improvement
Criteria (Mosaic).
VisiSuite comprehensively supports both
tactical and strategic risk analysis methods.
Because the Nuclear Power Plant Life
Management environment contains
speculative risks and uncertainties. It can
derive considerable value from a top-down
strategic methodology.
Scenario Planning begins with identifying
Scenario Drivers for meeting the specific
objectives of life extension strategies (called
Mission Objective Drivers). These are also
the Mission Risk Drivers that assess a
program's potential for success or failure as
shown in Figure 8.
By assigning probability-of-success and
impact values to each Mission Objective
Driver, the team is simultaneously identifying
the Mission Risk Exposures. (Each driver
becomes a separate category of risk.)
Figure 8. Life Extension Risk Profile – The VisiSuite “Mission Risk Profile – Driver Framework View”
presents Risk Exposure values in relation to a Risk Driver framework.

9. Nuclear Power Plant Life Management
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Figure 9 shows the “Mission Driver Profile"
graph provided by VisiSuite. This graphic
displays the same set of Mission Drivers
along with their respective probability-of-
success and impact values.
Extendable Risk Management
The above described scenario and risk driver
profiles are excellent presentations for
executives and stakeholders. There is very
little extra effort required to implement this
level of Mission Oriented Success Analysis
and Improvement along with Scenario
Charting.
VisiSuite also provides the following
program risk management capabilities:
 Program scheduling with risks and
uncertainties
 Risk register threats opportunities and
status
 Risk probability vs. impact Matrix
 Risk mitigation decision events
 Risk mitigation costs
 Scheduled risk mitigation tasks
showing risk level changes at decision
events
 Enterprise risk breakdown structures
 Program and enterprise risk registers
 Enterprise risk driver structures
 Risk multiplier tools that quickly
adjust mitigation durations and costs.
 Risk cost and schedule variances for
the base plan and each configured
scenario.
Therefore, extensive tactical or strategic risk
management can be incorporated into your
software enabled Nuclear Power Plant Life
Management process.
In addition, the new "Event Chain
Methodology" can be implemented by using
scenarios as contingency actions that can be
triggered anywhere along a chain of risk
decision events. Event chain methodology is
an uncertainty modeling and program
analysis technique that focuses on identifying
and managing events and event chains in
order to easily model uncertainties and
mitigate the impact of risks. VisiSuite
supports Event Chain Methodology.
Figure 9. Driver Profile – The VisiSuite “Mission Driver Profile” supports the Mission Oriented Success
Analysis and Improvement Criteria (Mosaic) methodology.