atw 2018-02

atw Vol. 63 (2018) | Issue 2 ı February
6. If the current safe shutdown
capabilities meet or surpass those
stipulated in the regulations, then
proceed to Step 8. If the current
safe shutdown capabilities do
not meet those stipulated in the
regulations, then proceed to
Step 7.
7. Use TRIZ to search for improvement
methods, while taking into
account construction costs and
probable benefits.
8. If the current status of the nuclear
power plant complies with the
basic safety conditions stipulated
in the regulations, then it is
assumed that the plant possesses
satisfactory safe shutdown capability.
4 Empirical results
4.1 Application of knowledge
management
We selected a nuclear power plant for
use as a case study. Fire compartments
were drawn up according to the floor
plan and final safety analysis report
(FSAR) (Table 1). Most nuclear power
plants include the following: containment
or drywell building, reactor
(auxiliary) building, turbine building,
intake structure (screenhouse), fuel
building, diesel generator building. In
principle, if an area is enclosed by
fire-shielding concrete walls, then
smaller fire zones can be drawn up
within the larger fire zone in order to
differentiate between similar paths. In
this case, the original fire compartment
C101 includes numerous rooms.
ESF 4.16KV SWGR ROOM A was designated
fire compartment 5 in order to
re-partition the space according to
their function.
Phase 1: Progress from the macroscopic
system level to the microscopic
equipment level.
Step 1: Define the scope of the
post-fire safe shutdown capacity.
Shutdown objectives include the
following: 1. reactivity control;
2. reactor coolant makeup; 3. reactor
heat removal; 4. process monitoring;
5. supporting functions; 6. achieve hot
Unit
FL
No.
FL
Code
Factory
building
| | Tab. 1.
Examples of partitioning fire compartment in nuclear power plant.
| | Fig. 1.
Application of knowledge management and TRIZ to improve post-fire safe shutdown performance.
standby status and maintain systems
required to (i) prevent fire damage,
(ii) enable the power unit to last
through hot standby status for over
72 hours, and (iii) receive power
from emergency power system;
7. achieve cold shutdown status
and maintain systems required to
prevent fire damage. The above
objectives do not cover the following:
(1) seismic category I criteria,
(2) single failure criteria, or (3) other
plant accidents.
Step 2: Define the core knowledge
parameters of post-fire safe shutdown
capacity.
1) Establish map of interdependence
among systems employed in
post-fire safe shutdown. 2) Define
operating procedures of post-fire safe
shutdown systems and construct
operational flowchart. 3) Define
parameters of post-fire safe shutdown
functions and construct function code
list. 4) Identify function code combinations
required for post-fire safe
shutdown path and construct path
combination table.
Step 3: Refer to existing regulations
NEI-0001 and RG1.189 of
US–NRC to confirm that the post-fire
safe shutdown and wire/circuit
analysis methods are acceptable.
First step: Determine Regulatory
Requirements
Space
FL Name
1 1 C101 CTRL 80' ESSENTIAL CHILLER ROOM A
1 2 C101 CTRL 80' ESF 4.16KV SWGR ROOM A
1 3 C101 CTRL 80' ESF SWGR ROOM A
1 4 C102 CTRL 80' ESSENTIAL CHILLER ROOM B
1 5 C102 CTRL 80' ESF 4.16KV SWGR ROOM B
The primary regulations include
10 CFR 50 Appendix A, General Criterion
3, and 10 CFR 50 Appendix R.
Second step: Determine SSD
Functions, Systems, and Path
This is meant to ensure that any
single fire within any fire area in the
nuclear power plant does not lead to
incidents such as furnace core meltdown,
loss of reactor cooling water, or
damage to the primary containment
structure. To achieve this objective,
the safe shutdown functions of the
reactor must first be confirmed and
the existing system equipment and
pipelines in the plant analyzed and
combined to form a safe shutdown
path as well as achieve and maintain
the safe shutdown status of the power
unit.
Third step: Select Equipment
Required for Post-Fire Safe shutdown
This equipment is used for post-fire
safe shutdown or to serve as a backup
in the event of fire-induced malfunctions.
Fourth step: Select Wires/Circuits
for Post-Fire Safe shutdown
These wires/circuits are used for
post-fire safe shutdown or to serve as a
backup in the event of fire-induced
malfunctions
Below are the basic assumptions
used in the analysis of post-fire safe
shutdown capacity:
1. Only one fire occurs in the plant at
any one time.
2. In the event of loss of external
power due to fire, systems can
provide backup power for at least
72 hours.
3. The only equipment or system
malfunctions are associated
directly with the fire.
4. After the safe shutdown of the
power unit, there are no additional
accidents due to plant design
OPERATION AND NEW BUILD 97
Operation and New Build
The Application of Knowledge Management and TRIZ for solving the Safe Shutdown Capability in Case of Fire Alarms in Nuclear Power Plants ı Chia-Nan Wang, Hsin-Po Chen, Ming-Hsien Hsueh and Fong-Li Chin