atw 2018-02

inforum

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

The Application of Knowledge

Management and TRIZ for solving the

Safe Shutdown Capability in Case of Fire

Alarms in Nuclear Power Plants

Chia-Nan Wang, Hsin-Po Chen, Ming-Hsien Hsueh and Fong-Li Chin

1 Introduction The 2011 the Fukushima nuclear disaster in Japan was caused by a failure in the safe shutdown

system. The severing of power systems incapacitated several of the shutdown devices, thereby hindering the removal of

excess heat from the reactor. Under these conditions, zirconium on the protective cover of the fuel rods reacted with the

cooling water to produce hydrogen gas. The resulting explosion fractured the containment building, thereby allowing

the escape of radioactive materials into the surrounding environment.

Nuclear power plants designed in

the U.S. must conform to regulations

outlined by the Nuclear Regulatory

Commission (NRC). The safe shutdown

capabilities of a facility are

documented in the Final Safety

Analysis Report (FSAR), which must

be submitted to authorities prior to

the licensing of operations. Facility

upgrades are also subject to approval.

Operating specifications include

shut-down procedures to be implemented

in the event of an earthquake

or other environmental disaster. In

1979, the NRC proposed a number of

fire safety measures [10CFR50 App.R];

however, the complexity of nuclear

facilities has greatly hindered implementation

and enforcement. Nuclear

power plants are required to have two

independent safe shutdown systems,

either of which must be able to

manage plant operations during the

transition from operating phase to

cold shutdown. The simultaneous

failure of both of systems would lead

to a catastrophic collapse of the entire

system. This study sought to sought to

improve the safe shutdown performance

of nuclear power plants in the

event of fire. We compiled a wide

range of data pertaining to post-fire

safe shutdown of nuclear power

plants, while dealing with each system

and its components as discrete units.

Our main objectives were as follows:

1. To compile a knowledge base

of issues related to hazards in

nuclear power plants: The

knowledge base defines the safe

shutdown system used in each fire

zone, describes the components

used in each system, and organizes

the shutdown processes in the

form of a flowchart.

2. To assess the components of the

safe shutdown systems using the

Teoriya Resheniya Izobreatatelskih

Zadatch (TRIZ) method:

We defined the attributes and

parameters of various problems

associated with safe shutdown

equipment and developed models

for each individual problem using

TRIZ to identify feasible means of

improvement.

3. Improve the safety regulations

of nuclear power plants based

on case studies and a literature

review: We formulated a novel

approach to the analysis of case

studies with the aim of facilitating

the identification of omissions

and flaws in current evaluation

standards.

2 Literature review

Prior to 1974, there were only two

clauses in the national fire regulations

(U.S.): 10CFR50 Appendix A (fire

protection) General Design Criteria

(GDC) and R.G 1.70.4. In November

1975, after the fire at Browns Ferry

Nuclear Power Plant, the NRC

published the Standard Review Plan

9.5-1. In May 1976, the BTP APCSB

9.5-1App.A (Nuclear Power Plant

Fire Guidelines) came into effect for

nuclear power plants seeking to obtain

building permits after July 1 [NRC,

1976], 1976. In August 1977, the NRC

published the Generic Letter 77-02

[USNRC, 1977], addressing issues

pertaining to administration, the

regulation of organizations, firefighting

procedures, and quality

control measures. In 1980, the NRC

drew up 10CFR50 Appendix R (fire

protection program), detailing the

requirements of all nuclear power

plants that went into operation prior

to January 1st 1979. In February 1981,

the NRC announced 10CFR50.48

(fire protection) as the standing

regulations for nuclear power plant

fire safety [Information Notice, 1984].

Compliance with 10 CFR 50 App. R

was not mandatory for all nuclear

power plants operating before

January 1, 1979 (pre-1979 plants);

however, they had to follow the

basic design requirements. In contrast,

nuclear power plants operating

since January 1, 1979 (post-1979

plants) have had to comply with BTP

CMEB 9.5-1, Revision 2 [CRF, 1979]

In the case study of this paper, an

operating license was obtained for

reactor 1 on July 27, 1984. It should

therefore have been subject to BTP

CMEB 9.5-1 Rev.2 [July 1981]; however,

Section 9.5.1 of the FSAR from

the later Maanshan Nuclear Power

Plant refers to Appendix A to APCB

9.5-1 [NRC Branch Technical Position,

1981]. As a result, both were used

as references. Taiwan uses the fire

regulations of 10 CFR 50 Appendix R

as the basis for fire inspections;

however, these regulations are somewhat

rudimentary [TPC, 1999].

In U.S. federal regulations 10

CFR 50 Appendix A, General Design

Criterion 3 specifies the basic fire

protection requirements for nuclear

power plants [CFR, 2012]. For

example, the design of the fire protection

system must ensure that even in

the event of damage of improper use,

the safety performance would not be

impaired. Fire protection policy based

on defense-in-depth is used to protect

the shutdown system as follows:

1) preventing the occurrence of fires,

2) ensuring the rapid detection, control,

and extinguishing of fires that

do occur, and

3) ensuring the normal operation

of the safe shutdown system if a

fire cannot be extinguished [NCR,

1975].

95

OPERATION AND NEW BUILD

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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