atw 2018-02

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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

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