ETL 1110-2-550
30 May 97
increase the probability of failure and the baseline
equipment can then be estimated by approximating
frequency curve is adjusted. It is important to note
the distribution of factor of safety as log-normal.
that the methodology to be used in applying CI's to
Mlaker (1993) and Mlaker and Bryant (1994)
the reliability analysis is continuing to be devel-
present technical details of this approach, along
oped. Current guidance should be sought by
with an example. Their work is summarized in
contacting HDC.
Appendix F.
8. Risk Analysis Using Capacity and
9. Recommendations
Demand
It is recommended that the procedures contained
herein be used as guidance toward assessing the
This method of determining the dependability of
reliability of hydropower equipment. This ETL
equipment uses a statistical approach toward
should be utilized in a team effort involving
determining both the demands placed on the
Operations, Engineering, Planning, Project
equipment and its ability to handle those demands.
Management, and the HDC to contribute to the
This method is an adaptation of the structural
evaluation of rehabilitation or upgrade alternatives.
reliability assessment methods described in
ETL 1110-2-532. In this procedure, limiting states
of hydropower equipment performance are written
10. Additional Information
as a factor of safety equal to the quotient of the
capacity and demand. The variables describing this
Much of the work that is covered by this ETL is still
capacity and demand are considered random, and
under development. The latest information can be
estimates of means and standard deviations are
obtained from the HDC in Portland, OR, telephone
made based upon experience. Estimates of the
(503) 808-4225. Also, worldwide web sites con-
mean and standard deviation of the factor of safety
taining information relating to the hydroelectric
are then made using a Taylor Series Finite
power industry are listed in Appendix G.
Difference procedure. The reliability index of the
FOR THE COMMANDER:
7 Appendices
STEVEN L. STOCKTON, P.E.
APP A - References
Chief, Engineering Division
APP B - Reliability Study Process
Directorate of Civil Works
APP C - Example Problem Description
APP D - Hydroelectric Power Benefits Calculations
APP E - Economic Models
APP F - Review of Recent Research in Hydropower
Reliability Analysis
APP G - Worldwide Web Sites
7
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