Fire Safety in Nuclear Power Plants and Modeling Fire in a Generic EDG Room by COMPBRN III M. B. Öztemiz, Ş. Ergün Hacettepe University Nuclear Engineering.

Fire Safety in Nuclear Power Plants Fire Safety in Nuclear Power Plants and Modeling Fire in a Generic EDG and Modeling Fire in a Generic EDG

Room by COMPBRN IIIRoom by COMPBRN IIIM. B. Öztemiz, Ş. ErgünM. B. Öztemiz, Ş. Ergün

Hacettepe University Nuclear Engineering Hacettepe University Nuclear Engineering DepartmentDepartment

BgNS Conference 2013BgNS Conference 2013

OutlineOutline

IntroductionIntroduction COMPBRN ModelingCOMPBRN Modeling SimulationsSimulations ResultsResults ConclusionsConclusions

IntroductionIntroduction

Operational experiences and fire Operational experiences and fire safety assessments showed that safety assessments showed that fires and explosions have fires and explosions have substantial effects on NPP safetysubstantial effects on NPP safety– Diesel generators and batteries (which Diesel generators and batteries (which

are primarily critical to maintain are primarily critical to maintain electricity to pumps) have to be well electricity to pumps) have to be well protected from the effects of fires and protected from the effects of fires and explosions.explosions.

IntroductionIntroduction

Fukushima DaiichiFukushima Daiichi accident showed us accident showed us that no matter how well an NPP is that no matter how well an NPP is protected against internal and external protected against internal and external events, events, failurefailure of diesel generators ends of diesel generators ends up with a severe nuclear accident. up with a severe nuclear accident. – TThese systems can be mentioned as hese systems can be mentioned as

shoulder to shoulder systems, which shoulder to shoulder systems, which cannot perform their primary tasks when cannot perform their primary tasks when they operate alone. they operate alone.

IntroductionIntroduction

History of the nuclear power plant History of the nuclear power plant fires shows that most of the fires fires shows that most of the fires are cable related.are cable related.– San Onofre, Brown’s Ferry, San Onofre, Brown’s Ferry,

Greifswald, Beloyarsk, Zaporoshye, Greifswald, Beloyarsk, Zaporoshye, Kalinin, Ignalina, Waterford fires.Kalinin, Ignalina, Waterford fires.

COMPBRN ModelingCOMPBRN Modeling

COMPBRN uses Hot Gas Layer ModelCOMPBRN uses Hot Gas Layer Model

COMPBRN ModelingCOMPBRN Modeling

For the analysis, the validity of using COMPBRN III for cable fires was investigated (an experiment performed as part of International Collaborative Fire Modeling Project was modeled and simulated)

Hot Gas Layer Temperature Prediction by COMPBRN III

COMPBRN ModelingCOMPBRN Modeling

Once the validation calculations showed that Once the validation calculations showed that conservative calculations can be performed with the conservative calculations can be performed with the code a typical diesel generator building was modeled code a typical diesel generator building was modeled and to simulate the fire three scenarios were carried out and to simulate the fire three scenarios were carried out in a diesel generator. Fire was assumed to break out in in a diesel generator. Fire was assumed to break out in the burned air cleaning room, A3the burned air cleaning room, A3

COMPBRN ModelingCOMPBRN Modeling

Set up for Scenario 1. Set up for Scenario 2.

Set up for Scenario 3.

ResultsResults

After 157 minutes of fire

start

Scenario 1 Scenario 2 Scenario 3

Target cable set surface

temperature (K)

329 329 354

Wall surface temperature (K)

311 335 335

Heat Flux measured on the target cable set surface (W/m2)

336 340 1790

ConclusionsConclusions

Cables should be routed on different Cables should be routed on different paths and separated physically in paths and separated physically in order to maintain diversity.order to maintain diversity.

Cables having same tasks should be Cables having same tasks should be used in different places of different used in different places of different systems in order to maintain systems in order to maintain redundancy.redundancy.

ConclusionsConclusions

Beyond the all analyses conducted or will be Beyond the all analyses conducted or will be conducted, serious importance should be given conducted, serious importance should be given into human factor. Even if all analyses are made into human factor. Even if all analyses are made clearly perfect, in the past or in the future, often clearly perfect, in the past or in the future, often ignored human factor can be trouble and reason ignored human factor can be trouble and reason for fires to breakout. for fires to breakout.

Each fire broke out and lessons learned from Each fire broke out and lessons learned from fires should be assessed in a cause and effect fires should be assessed in a cause and effect relationship, documentation should be relationship, documentation should be maintained and utilities, designers and regulators maintained and utilities, designers and regulators should analyze these parameters well.should analyze these parameters well.