Office of Nuclear Reactor Regulation Division of Systems Safety and AnalysisPlant Systems BranchFire Protection Engineering and Special Projects Section

1

CHAPTER 15. ESTIMATING PRESSURE INCREASE AND EXPLOSIVE ENERGYRELEASE ASSOCIATED WITH EXPLOSIONS Version 1805.0The following calculations estimate the pressure and energy due to an explosion in a confined space.Parameters in YELLOW CELLS are Entered by the User.Parameters in GREEN CELLS are Automatically Selected from the DROP DOWN MENU for the Fuel Selected.All subsequent output values are calculated by the spreadsheet and based on values specified in the inputparameters. This spreadsheet is protected and secure to avoid errors due to a wrong entry in a cells(s).The chapter in the NUREG should be read before an analysis is made.

INPUT PARAMETERSEXPLOSIVE FUEL INFORMATION

1 percent for unconfined mass release and 100percent for confined vapor release energyparticipating in blast wave generation

THERMAL PROPERTIES FOR FUELS FLAMMABILITY DATA FOR FUELS

FuelAdiabatic Flame Temperature

Acetylene 4779

Carbon Monoxide 4329Ethane 2244Ethylene 4152Hydrogen 4085Methane 2143n-Butane 2442n-Heptane 2586n-Pentane 2356n-Octane 2478Propane 2338Propylene 4050User Specified Vlaue Enter Value

Adiabatic Flame Temperature of the Fuel ((Tad)

Heat of Combustion of the Fuel (DHc)Yield (a), i.e., the fraction of available combustion

Mass of Flammable Vapor Release (mF)

Ambient Air Temperature (Ta)

Initial Atmospheric Pressure (Pa)

Tad (°F)

Reference: SFPE Handbook of Fire Protection Engineering, 2nd Edition, 1995, Page 1-86.

Office of Nuclear Reactor Regulation Division of Systems Safety and AnalysisPlant Systems BranchFire Protection Engineering and Special Projects Section

2

METHOD OF ZALOSH

Pressure Rise from an Confined Explosion

Where

528.57 kPa

Blast Wave Energy Calculation

Where E = blast wave energy (kJ) [E is the Trinitrotoluene (TNT) equivalent energy]

E = 1011490.91 kJ

TNT Mass Equivalent Calculation

Where

E = explosive energy release (kJ)

224.78 kg

The above calculations are based on principles developed in the SFPE Handbook of Fire Protection

Calculations are based on certain assumptions and have inherent limitations. The results of such

calculations may or may not have reasonable predictive capabilities for a given situation, and should

only be interpreted by an informed user.

Although each calculation in the spreadsheet has been verified with the results of hand calculation,

there is no absolute guarantee of the accuracy of these calculations.

Any questions, comments, concerns, and suggestions, or to report an error(s) in the spreadsheet,

please send an email to nxi@nrc.gov or mxs3@nrc.gov.

Reference: SFPE Handbook of Fire Protection Engineering, 2nd Edition, 1995, Page 3-312.

(Pmax)/Pa = (Tad/Ta)

Pmax = maximum pressure developed at completion of combustion (kPa)

Pa = initial atmospheric pressure (kPa)

Tad = adiabatic flame temperature (K)

Ta = ambient temperature (K)

Pmax = (Tad/Ta) Pa

Pmax =

E = a DHc mF

a = yield (a is the fraction of available combustion energy participating in blast wave generation)

DHc = heat of combustion (kJ/kg)

mF = mass of flammable vapor release (kg)

WTNT = E/4500

WTNT = weight of TNT (kg)

WTNT =

Engineering, 2nd Edition, 1995.

NOTE

Office of Nuclear Reactor Regulation Division of Systems Safety and AnalysisPlant Systems BranchFire Protection Engineering and Special Projects Section

3

Prepared by: Date

Checked by: Date

Additional Information

Revision Log Description of Revision

1805.0 Original issue with final text.

Office of Nuclear Reactor Regulation Division of Systems Safety and AnalysisPlant Systems BranchFire Protection Engineering and Special Projects Section

4

CHAPTER 15. ESTIMATING PRESSURE INCREASE AND EXPLOSIVE ENERGY

The following calculations estimate the pressure and energy due to an explosion in a confined space.

Parameters in GREEN CELLS are Automatically Selected from the DROP DOWN MENU for the Fuel Selected.All subsequent output values are calculated by the spreadsheet and based on values specified in the inputparameters. This spreadsheet is protected and secure to avoid errors due to a wrong entry in a cells(s).

2338 °F 1281.11 °C

1554.11 K

46360 kJ/kg

100.00 % 1

48.00 lb 21.82 kg

77.00 °F 25.00 °C

298.00 K

14.70 psi 101.35 kPa

Calculate

Heat of Combustion Select Fuel Type

48,220

10,10047,49047,170130,80050,03045,72044,56044,98044,44046,36045,790Enter Value

DHc (kJ/kg)

Scroll to desired fuel type then

Click on selection

Office of Nuclear Reactor Regulation Division of Systems Safety and AnalysisPlant Systems BranchFire Protection Engineering and Special Projects Section

5

76.66 psi

E = blast wave energy (kJ) [E is the Trinitrotoluene (TNT) equivalent energy]

957983.04 Btu

495.55 lb

The above calculations are based on principles developed in the SFPE Handbook of Fire Protection

Calculations are based on certain assumptions and have inherent limitations. The results of such

calculations may or may not have reasonable predictive capabilities for a given situation, and should

Although each calculation in the spreadsheet has been verified with the results of hand calculation,

Any questions, comments, concerns, and suggestions, or to report an error(s) in the spreadsheet,

= maximum pressure developed at completion of combustion (kPa)

is the fraction of available combustion energy participating in blast wave generation)

Answer

Answer

Answer

Office of Nuclear Reactor Regulation Division of Systems Safety and AnalysisPlant Systems BranchFire Protection Engineering and Special Projects Section

6

Organization

Organization

Date

January 2004