Transcript Norwegian Water Resources and Energy Directorate

2nd IMPACT WORKSHOP, Mo i Rana, Sept. 2002
Risk analysis
Norwegian practice - new research
by Grethe Holm Midttømme
The Norwegian Water Resources and Energy Directorate (NVE)
Photo: NVE
1 17. jul.
The Norwegian Water Resources and Energy
Directorate (NVE)
2 17. jul.
Norwegian practice
Development of RA for dams in Norway - brief
overview
•1987: First project initiated by NVE and EBL (RA for 2 dams)
•1987-1995: A few projects on RA for dams, spillway gates and penstocks,
among others a project on estimation and comparison of the probability of
failure in large rockfill dams using event trees (Johansen et al. 1997,
Hydropower’97)
•1995 - 2002: Several risk analyses performed, mostly probabilistic event
tree analyses, e.g. RA of the rockfill dam Valldalen (Funnemark et al. 2000,
Q.76, ICOLD congress Beijing)
•Very few analyses include consequence analyses, i.e. assessment of
probability of failure is emphasized
3 17. jul.
G.H.Midttømme - 2nd IMPACT WORKSHOP, Mo i Rana, Sept. 2002
Norwegian practice
Development of RA for dams in Norway - brief
overview (continued)
In general:
•Dam owners seem to use PRA’s mainly as a systematic way of identifying
deficiencies and ranking safety improvements, e.g. as part of a dam safety
reassessment
•PRA methodology usually include: site inspections, hazard identification,
construction of event trees, probability assessment (statistics and
engineering judgment) and evaluation of results
• A method for consequence analysis adapted to Norwegian conditions has
been developed (Funnemark et al. 1998, ICOLD European Symposium on
Dam Safety in Barcelona 1998)
4 17. jul.
G.H.Midttømme - 2nd IMPACT WORKSHOP, Mo i Rana, Sept. 2002
Norwegian practice
Regulations and guidelines
Revision of the first dam safety guidelines (1981) included a working group
on risk analysis and emergency action planning
• 1997: Guidelines on application of RA for dams (NVE)
• 1999: Guidelines on the use of PHA for emergency planning (EBL)
• 2001: New regulations on dam safety (§2.8 - NVE may demand risk
analyses conducted by the responsible dam owner)
• 2001: Practical guidelines describing how to perform event tree and fault
tree analyses (EBL)
5 17. jul.
G.H.Midttømme - 2nd IMPACT WORKSHOP, Mo i Rana, Sept. 2002
Norwegian practice
Regulations and guidelines (continued)
There are plans for developing new guidelines on application of RA (NVE) ->
focus will probably be on qualitative methods and analyses for EAP
Planned ICOLD-bulletin on Risk Assessment in Dam Safety Management and
ongoing projects related to risk analysis will be looked at
6 17. jul.
G.H.Midttømme - 2nd IMPACT WORKSHOP, Mo i Rana, Sept. 2002
New research
Recent dr.ing. studies at the Norwegian
University of Science and Technology (NTNU),
Trondheim
Hilde Marie Kjellesvig: Dam Safety - The Passage of Floods that Exceed
the Design Flood, Thesis published July 2002
Parts of the research work has been done in close cooperation with the
project ”Stability and Breaching of Embankment Dams”
Grethe Holm Midttømme: Flood Handling and Emergency Action Planning
for Dams, June 2002
7 17. jul.
G.H.Midttømme - 2nd IMPACT WORKSHOP, Mo i Rana, Sept. 2002