In the financial world, portfolio selection is used to give a balanced collection of assets that provides investors with an appropriate balance of security and opportunity. Similarly, in the energy and environmental sectors there is often a need to select an optimum set of activities that together satisfy a range of requirements, rather than trying to achieve them with a single option.
Portfolio selection is useful at all levels of decision making. At a national or organisational level, it can be used to help select the most appropriate mix of policy options to meet strategic goals. At a programme level, it can help to decide the optimum mix of projects that meet agreed policies in the most efficient manner in the face of uncertain externalities. At a project level, it can be a useful automated tool for picking a set of tasks that are consistent with a range of complex constraints. For example, Quintessa has applied portfolio analysis:
- to provide a powerful method for optimising an environmental monitoring programme;
- to identify a suite of measurements in soil, water and environmental materials at a variety of locations that best characterise a nuclear site’s discharges;
- to identify a preferred restoration strategy for an entire nuclear site which also considers the 'portfolio' of individual facilities that are present, and their individual characteristics and constraints; and
- to provide support to Sellafield’s Plutonium Contaminated Material (PCM) BPEO programme.
Quintessa supports clients in developing a balanced portfolio of options using structured approaches ranging from qualitative decision analysis (underpinned by quantitative evidence) to highly quantitative decision-support techniques embedded in custom software packages.
An example of a qualitative approach is the facilitation of decision meetings to select an optimal set of radioactive waste treatment options meeting a variety of technical, environmental and financial constraints. For example, legacy wastes may involve a wide range of forms, inventories and uncertainties that might not be resolvable at the start of a decommissioning and/or waste treatment programme. A selection of techniques will need to be available to deal with the uncertainties involved. We have supported a range of portfolio selection options studies that are based upon maximising confidence in the ability of a portfolio of techniques to deal with uncertainty in waste forms and treatment.
At the quantitative end of the spectrum, Quintessa has developed a custom software package, CHANSELA (Channel Selection Assistant), which takes account of a wide range of factors to support decisions on which selection of channels of a nuclear reactor should be inspected to support continued safe operation. This software employs some novel concepts including a genetic algorithm for optimising channel selections and flexible methods for providing queries to the software.