ETL 1110-2-550
30 May 97
reduction of the costs from unplanned outages,
(1) The paper, "Engineering Risk Assessment
reduction of future O&M costs, and various
for Hydro Facilities" (Laurence 1991), describes a
combinations of these. The model provides a
risk assessment which evaluates the risk in terms of
probabilistic treatment of the hazard function
dollars to hydroelectric facilities due to earthquake,
(likelihood of unsatisfactory performance) and loss
tsunami, flood, wind, and other natural perils. The
function (likelihood of costs accruing for the
methodology included initially evaluating facility
various feature losses considered) that are based on
design criteria to determine how well various
use of historical data. The estimated costs from the
systems and structures would hold up to the
loss function incorporate the amount of excess
catastrophe. Next, varying degrees of catastrophe
capacity that may exist within the facility or system.
severity were established and probabilities of each
Monte Carlo simulation techniques are used to
catastrophe were estimated using historical/
calculate the distribution of the life-cycle costs for
meteorological data. Damages (in dollars) for each
the facility considering the maintenance, repair, and
catastrophe were estimated based on the design
operation cost categories as well as investment
criteria of the structures/systems and the codes to
costs for all alternative rehabilitation strategies
which the structures/systems were built. Finally,
evaluated.
the risk (in dollars) was calculated based on the
probability of the catastrophe occurring and the
(5) This paper (Moser et al. 1995) describes
damage consequences.
the underlying concept of an economic risk analysis
prescribed for the major rehabilitation program and
(2) The paper, "Risk Analysis Applications for
the development of a computer program by the
Dam Safety" (Moser 1991), presents the principles
Institute for Water Resources for use in conducting
and issues of risk analysis as they have evolved in
the economic analysis of rehabilitation proposals.
the evaluation of dam safety improvements. The
The paper describes the economic framework used
paper also reviews some results of the Corps' Dam
in the computer program for performing these
Safety Research program in applying risk analysis
analyses as well as the approach for incorporating
and risk-based methods to dam safety evaluations.
probabilistic risk-based analysis into the computer
This paper describes several risk-based methods
program through Monte Carlo simulation using
that have been used to evaluate the effects on risk of
historical data. The paper also addresses the figure
widening spillways and raising dams in an effort to
of merit incorporated into the computer program for
minimize the effects of floods. These discussions
assessing the rehabilitation alternatives and making
include both economic costs as well as human life
rehabilitation decisions. The user interface for this
considerations.
program is presented with an example application.
This paper addresses implementation of risk,
(3) The paper, "Evaluation of Rehabilitation
reliability, and economic considerations that are
Alternatives for Small Hydropower Plants"
mandated for evaluations of rehabilitation options
(Prakash and Sherlock 1991), describes methods for
under the major rehabilitation program. The
comparative evaluation of alternative rehabilitation
methodology described is technically
measures for aging small-scale hydroelectric power
comprehensive and should be considered the
plants. The evaluation criteria include both dollar-
standard for economic analyses.
denominated and nondollar denominated impacts
associated with different rehabilitation options. The
b. The Proceedings of the International
comparative evaluation is performed using a
Conference on Hydropower, Denver, Colorado, July
combination of the delphi and fuzzy-set approaches.
1991, Volume 2, includes a few papers that
In the delphi approach, a panel of experts determine
describe various aspects or risk analysis uses in the
the factors for comparative evaluation of
hydroelectric power industry and cases of
rehabilitation alternatives, and assign weights to
rehabilitation program implementation to various
each factor. Next, the experts score each
stations.
alternative. The evaluation factors form the
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