atw 2018-02

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atw Vol. 63 (2018) | Issue 2 ı February

OPERATION AND NEW BUILD 96

In 10 CFR 50 Appendix R, Section

III.G.1 are specified the fire protection

requirements for the emergency

shutdown of nuclear power plants:

1. One train of systems necessary to

achieve and maintain hot shutdown

conditions from either

the control room or emergency

control station(s) is free of fire

damage.

2. Systems necessary to achieve and

maintain cold shutdown from

either the control room or emergency

control station(s) can be

repaired within 72 hours [NRC,

2007].

In 10 CFR 50 Appendix R, Section

III.G.2 are outlined specific isolation

requirements for redundant cables

and safe shutdown systems within the

same fire compartment: “Except as

provided for in paragraph G.3 of this

section, where cables or equipment,

including associated non-safety

circuits that could prevent operation

or cause maloperation due to hot

shorts, open circuits, or shorts to

ground, of redundant trains of systems

necessary to achieve and maintain hot

shutdown conditions are located

within the same fire area outside of

primary containment, one of the

following means of ensuring that

one of the redundant trains is free

of fire damage shall be provided.”

10 CFR 50 Appendix R, Section

III.G.3 specifies the situations in

which fire compartments are required

to have dedicated safe shutdown

capabilities involving modification or

replacement of dedicated cables and/

or circuitry.

Cables, systems and components

should be independent of area, room,

zone if the following conditions are

met:

1. Where the protection of systems

whose function is required for hot

shutdown does not satisfy the

requirement of paragraph G.2 of

this section; or

2. Where redundant trains of systems

required for hot shutdown located

in the same fire area may be subject

to damage from fire suppression

activities or from the rupture or

inadvertent operation of fire

suppression systems.

3. Furthermore, fire detection and a

fixed fire suppression system shall

be installed in the area, room, or

zone.”

Guidance IX of the NRC Information

Notice 84-094 lists the minimum safe

shutdown monitoring parameters

accepted by the NRC [NRC Information

Notice, 1984].

NUREG-1852 presents the feasibility

and reliability criteria [NUREG,

2007] accepted by the NRC in the

event that Operator Manual Actions

(OMAs) are used to perform post-fire

safe shutdown.

The above fire protection regulations

provide the parameters relevant

to safe shutdown capabilities and

fire protection. We compared these

parameters with those of the nuclear

power plant in our case study to

identify problems associated with

safe shutdown capabilities and fire protection.

However, this is an enormous

and complex task. Thus, we developed

an innovative approach to achieve this

using knowledge management in

conjunction with TRIZ.

3 Methodology

This study sought to improve the safe

shutdown performance of nuclear

power plants in the event of fire.

Knowledge management was first

used to identify the factors essential

to safe shutdown. We then sought

to identify the factors that are not

adequately addressed in US nuclear

power regulations. Finally, TRIZ was

used to guide the formulation of

recommendations aimed at overcoming

current regulatory shortcomings.

3.1 Knowledge management

and construction of database

Knowledge management was organized

into the following phases to

define core knowledge and construct a

database for research [Rosner et al.,

1998].

Phase 1: Progress from the macroscopic

system level to the microscopic

equipment level.

Phase 2: Identify wiring associated

with post-fire safe-shutdown.

Phase 3: Conduct post-fire safe-shutdown

circuit analysis [Debowski,

2007].

Phase 4: Establish post-fire hot shutdown

path based on APP.R.

Phase 5: Construct a distribution of

post-fire safe hot shutdowns procedures

throughout the plant.

Phase 6: Establish basic fire prevention

database [National Fire Protection

Association, 2001].

3.2 Application of TRIZ to

improve safe shutdown

system

TRIZ is a highly reliable problemsolving

method, which was developed

by Altshuller et al. in his review of over

300,000 patents between 1946 and

1985 [Altshuller, 1999]. TRIZ is based

on the concept of abstraction, taking

an algorithmic approach to the invention

of new systems and the refinement

of old systems [Mann, 2007].

In this study, we combined

knowledge management and TRIZ

in the development of a novel

method by which to improve safe

shutdown procedures, as follows

(comp. Figure 1):

1. Collect data pertaining to

current conditions and existing

designs.

2. Formulate standards and definitions

based on existing regulations

related to post-fire safe

shutdown.

3.1. Define and clarify issues. If

sufficient data is available, proceed

to Step 4; otherwise, proceed

to Step 3.2.

3.2. Search available data and current

regulations for designs that could

be improved through knowledge

management. Compare results

with the safety conditions stipulated

in current regulations, and

then conduct enhancement

analysis based on the following

knowledge management techniques:

(1) establish operating

standards; (2) identify interdependent

relationships between

existing systems; (3) organize

operational procedures; (4) set

safe shutdown function codes;

(5) establish safe shutdown path

combinations; (6) compare results

with regulation requirements;

(7) identify all devices associated

with post-fire safe shutdown

(8) set operating status parameters;

(9) compare results with

corresponding wire/circuit design

data of original equipment;

(10) identify wires/circuits associated

with post-fire safe shutdown;

(11) conduct wire/circuit failure

analysis; (12) compile results of

wire/circuit analysis in the form

of a database; (13) establish wire/

circuit paths in fire zones. If

level-by-level comparisons show

that the existing system complies

with regulations, then proceed

to Step 6.

4. Search through database of

existing system for instances of

mismatch with regulations. If the

database does not meet safety

requirements, then return to

Step 1. If the database meets

safety requirements, then perform

an assessment of ...

5. Determine whether non-compliant

systems affect safe shutdown

capabilities.

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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