Fire growth

The surface burning characteristics (flame spread index and smoke developed index) for wood and wood products as measured by American Society for Testing and Materials (44) can be reduced with fire retardant treatments, either chemical impregnation or coatings (48). Fire retardant treatments also reduce the heat release rate of a burning piece of wood (49,50). The heat release rates (51) of the burning materials are an important factor in fire growth. 

Assess the effects of initiating fires and subsequent fire growth on the initiating events, such as LOCAs and transients. 

The plant internal PSA can be used to identify critical equipment that could be damaged by fire. This form of screening was employed in the fire-risk portions of ZIP. At each location considered, the loss of all the equipment in the zone is postulated regardless of the size or position of the fire in the zone. If this does not show the occurrence of an initiating event (LOCA or transient) or if the safety functions are not damage to required for safe shutdown, the location is eliminated from consideration. If the location is found to be critical, it is considered furilier lot-detailed fire growth and fire suppression analyses. 

The large size of nuclear power plant enclosures and the relatively small amounts of readily ignitable fuel in those enclosures make flash combustion unlikely therefore, the concentration is on the fire growth phase. 

Fire growth and suppression are treated separately as independent processes. 

FIRAC is a computer code designed to estimate radioactive and chemical source-terms as.sociaied with a fire and predict fire-induced flows and thermal and material transport within facilities, especially transport through a ventilation system. It includes a fire compartment module based on the FIRIN computer code, which calculates fuel mass loss rates and energy generation rates within the fire compartment. A second fire module, FIRAC2, based on the CFAST computer code, is in the code to model fire growth and smoke transport in multicompartment stmetures. 

FIRE SIMULATOR predicts the effects of fire growth in a 1-room, 2-vent compartment with sprinkler and detector. It predicts temperature and smoke properties (Oj/CO/COj concentrations and optical densities), heat transfer through room walls and ceilings, sprinkler/heat and smoke detector activation time, heating history of sprinkler/heat detector links, smoke detector response, sprinkler activation, ceiling jet temperature and velocity history (at specified radius from the flre i, sprinkler suppression rate of fire, time to flashover, post-flashover burning rates and duration, doors and windows which open and close, forced ventilation, post-flashover ventilation-limited combustion, lower flammability limit, smoke emissivity, and generation rates of CO/CO, pro iri i post-flashover. 

Tones, W. W. and R. D, Peacock, 1994 Refinement and Experimental Verification of a Model for Fire Growth and Smoke Transport, 2nd lAFSS Meeting. 

Nicolette,V. et al., 1989, Observations Concerning the COMPBRN IB Fire Growth, ANS/ENS Conference on PRA, Pittsburgh, PA, April 12,and SAND 88-2160. 

Peacock, R D., et al., 1993a, CFAST, The Consolidated Model of Fire Growth and Smoke Transport , NIST Technical Note 1299, NIST. 

In a joint research project in Sweden under the main title "Fire hazard - Fire growth in compartments in the early stage of development (pre-flashover)" (1, 2) a number of different factors have been studied. In the process of developing a full-scale fire test method - "room-corner" configuration - for surface lining materials, Nordtest NT-FIRE 025, the emission of smoke and gas was studied. That study covers data from thirteen different single and... 

Probably the best way of assessing fire hazard is by calculations via mathematical fire growth and transport models, such as HAZARD I [58], FAST [59], HARVARD [60] or OSU [61]. These models predict times to reach untenable situations. They are often combined with fire escape models and will, then, yield times to escape. 

The flame extinguishment data for Halon 1301 measured in this study suggest that for extended ignition zone covering large surface areas, maintenance of a concentration in excess of A by volume would be sufficient for the control of fire growth and extinguishment for the MTL samples. 

This report presents experimental and theoretical results from a study within the project "Fire Hazard - Fire Growth in Compartments in the Early Stage of Development (Prefiashover)". The project is carried out jointly by the department of Fire Safety Engineering at Lund University and the Division of Fire Technology at the Swedish National Testing Institute. An outline of the research program is... 

Room fire growth on combustible linings has been a problem of concern to the legislators and authorities since the advent of building fire safety regulations. Work in this area has included... 

Magnusson, S.E., Sundstrom, B., "Combustable Linings and Room Fire Growth - A First Analysis", Report LUTVDG/(TVBB 3030), Department of Fire Safety Engineering, Lund University, Lund 1985. 

It would be useful to pause for a moment in our discussion of solids to put into perspective the heat fluxes encountered under fire conditions. It is these heat fluxes that promote ignition, flame spread and burning rate - the three components of fire growth. 

Convective heating in fire conditions is principally under natural convection conditions where for turbulent flow, a heat transfer coefficient of about 10 W/m2 K is typical. Therefore, under typical turbulent average flame temperatures of 800 °C, we expect convective heat fluxes of about 8 kW/m2. Consequently, under turbulent conditions, radiative heat transfer becomes more important to fire growth. This is one reason why fire growth is not easy to predict. 

Heat flux is an important variable in fire growth and its determination is necessary for many problems. In general, it depends on scale (laminar or turbulent, beam length ), material (soot, combustion products) and flow features (geometric, natural or forced). We... 

An interesting correlation of the rate of fire growth measured by flame volume was given by Labes [24] and Waterman [25]. They show that after room flashover in a room of volume Vo, the Are volume (Vf) grows as... 

Figure 8.24 Correlation of volumetric fire growth for a dwelling with similar compartment characteristics [24]...

Gas Temperature Approximate Scale EC) Figure 11.22 Surface spread fire growth... 

The Semenov criticality diagrams for fire growth are useful to understand the complex interactions of the fire growth mechanisms with the enclosure effects. These diagrams can be used qualitatively, but might also be the bases of simple quantitative graphical solutions. 

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