VGB POWERTECH 7 (2021) - International Journal for Generation and Storage of Electricity and Heat

VGB PowerTech 7 l 2021
Continuation of table 8 on the next page
rence of SSE and CDF, it can be seen that
the correlation between the two variables
is high, as shown in F i g u r e 1 .
Therefore, if this value is broadly divided
into four types, as shown in Ta b l e 7, it is
possible to classify the possibility of earthquake
occurrence on the site by reoccurrence
period.
In the methodology proposed in this paper,
the probability of SSE occurrence is basically
divided into four major sections, and
we intend to use this as the basis for determining
the equipment groups that need to
be subjected to fragility analysis. In the
case of Region A, since earthquakes are
very likely to occur, it is suggested that the
number of equipment groups that need to
be analyzed for fragility is most; and in the
case of Region D, the equipment target for
fragility analysis is least because of the lowest
probability of earthquakes. To examine
the adequacy of the four distinct values,
the data on the seismic hazard values of
power plants operating in the US [8] are
examined as shown in F i g u r e 2 .
Based on these values, it can be seen that
the 61 power plants comprise 7 % in Region
A, 21 % in Region B, and 26 % in Region C.
Lastly, Region D occupies 46 %. It can be
seen that the criteria are valid for classifying
the overall seismic hazard trend of a
specific site.
Annual Frequency of exceedance (/yr)
3.00E-03
2.50E-03
2.00E-03
1.50E-03
1.00E-03
5.00E-04
0.00E+00
0.05 0.08 0.15 0.19 0.25 0.3 0.4 0.5 0.65 0.8 1
Accelation (g)
Fig. 2. Hazard curve for US nuclear power plant [8].
Tab. 8. Categorized equipment group for general fragility data.
Group Category Equipment HCLPF
I
Electrical Equipment Offsite power 0.09
Structures and Tanks Large flat-bottomed tank 0.15
Electrical Equipment
480 VAC Motor Control Center (MCC) / Switchgear /
Bus (unanchored)
0.17
Electrical Equipment 5 kV+ AC Bus / Switchgear (Unanchored) 0.17
Electrical Equipment
DC Motor Control Center (MCC) / Switchgear / Bus (Unanchored)
0.17
Electrical Equipment Panel (Electric or Instrument) (Unanchored) 0.17
4.2 Determination of equipment group
for fragility analysis
The second step of the SPSA is seismic fragility
analysis. Seismic fragility analysis is
performed by a structural expert, and it is a
step to evaluate the seismic resistance for
the weakest failure mode of each piece of
equipment and to determine the median
acceleration capacity (A m ); with β R and β U
representing the variability. Seismic fragility
analysis requires the greatest consumption
of time and budget among the three
steps, as structural experts with the particular
expertise need to perform the analysis,
as well as review and conduct on-site
verification of many data such as design,
construction, and installation works.
Therefore, the methodology proposed in
this paper is a method that suggests a way
to minimize such analysis. First, through a
survey of sufficient data on the fragility of
general equipment, we examine the characteristics
of the fragility of equipment generally
installed in power plants. A great deal
of research has been conducted on the fragility
of general equipment. Among this research,
according to the SPID report [9],
the fragility of SSCs can be largely classified
into three, and the first inherently rugged
SSCs generally have very high seismic resistance,
so there is no need to include inherently
rugged SSCs in the SPSA model.
Second, SSCs with somewhat high seismic
resistance are reflected in the SPSA model
if the impact on SPSA is significant after reviewing
the magnitude. In the last case,
II
III
Pump & Compressors Diesel-driven pump (non-safety) 0.17
Structures and Tanks Turbine building 0.17
Structures and Tanks Other non-safety buildings 0.17
Piping Buried piping (non-safety pipe) 0.18
Piping Distributed piping system (welded steel pipe) 0.19
Electrical Equipment Cable tray 0.21
Pump & Compressors Motor-driven pump 0.25
Pump & Compressors Turbine-driven pump 0.25
Electrical Equipment 480 VAC Motor Control Center (MCC) / Switchgear /
Bus (Anchored)
0.26
Piping Distributed piping system (cast iron pipe) 0.26
Structures and Tanks Small tank 0.30
HX & HVAC Chiller 0.31
Piping Small LOCA (SLOCA) 0.31
HX & HVAC Air handling unit (AHU) / Room Cooler / Fan 0.33
Electrical Equipment Panel (Electric or Instrument) (Anchored) 0.34
Electrical Equipment Relay Chatter Failure (During Seismic Event) 0.34
Pump & Compressors Large vertical, centrifugal pump (motor-driven, non-safety) 0.34
Electrical Equipment Batteries 0.35
Structures and Tanks Reactor internals and core assembly 0.35
Piping Buried piping (safety pipe) 0.36
Electrical Equipment Transformer (Indoor) 0.37
Structures and Tanks Containment building / drywell 0.38
Electrical Equipment Emergency Diesel Generator (EDG) 0.40
Pump & Compressors Diesel-driven pump (safety) 0.45
HX & HVAC HVAC duct 0.48
Pump & Compressors Reactor coolant pump / Recirculation pump 0.50
Continuation of table 8 on the next page
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