A simplified model of aerosol removal by containment sprays

Technical Report · Tue Jun 01 00:00:00 EDT 1993

DOI:https://doi.org/10.2172/6503368· OSTI ID:6503368

Powers, D A ^[1]; Burson, S B ^[2]

---

1. Sandia National Labs., Albuquerque, NM (United States)
2. Nuclear Regulatory Commission, Washington, DC (United States). Div. of Safety Issue Resolution

Spray systems in nuclear reactor containments are described. The scrubbing of aerosols from containment atmospheres by spray droplets is discussed. Uncertainties are identified in the prediction of spray performance when the sprays are used as a means for decontaminating containment atmospheres. A mechanistic model based on current knowledge of the physical phenomena involved in spray performance is developed. With this model, a quantitative uncertainty analysis of spray performance is conducted using a Monte Carlo method to sample 20 uncertain quantities related to phenomena of spray droplet behavior as well as the initial and boundary conditions expected to be associated with severe reactor accidents. Results of the uncertainty analysis are used to construct simplified expressions for spray decontamination coefficients. Two variables that affect aerosol capture by water droplets are not treated as uncertain; they are (1) [open quote]Q[close quote], spray water flux into the containment, and (2) [open quote]H[close quote], the total fall distance of spray droplets. The choice of values of these variables is left to the user since they are plant and accident specific. Also, they can usually be ascertained with some degree of certainty. The spray decontamination coefficients are found to be sufficiently dependent on the extent of decontamination that the fraction of the initial aerosol remaining in the atmosphere, m[sub f], is explicitly treated in the simplified expressions. The simplified expressions for the spray decontamination coefficient are given. Parametric values for these expressions are found for median, 10 percentile, and 90 percentile values in the uncertainty distribution for the spray decontamination coefficient. Examples are given to illustrate the utility of the simplified expressions to predict spray decontamination of an aerosol-laden atmosphere.

• Research Organization: Nuclear Regulatory Commission, Washington, DC (United States). Div. of Safety Issue Resolution; Sandia National Labs., Albuquerque, NM (United States)
• Sponsoring Organization: NRC; Nuclear Regulatory Commission, Washington, DC (United States)
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 6503368
• Report Number(s): NUREG/CR-5966; SAND--92-2689; ON: TI93015368
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
210100 -- Power Reactors
Nonbreeding
Light-Water Moderated
Boiling Water Cooled
210200 -- Power Reactors
Nonbreeding
Light-Water Moderated
Nonboiling Water Cooled
22 GENERAL STUDIES OF NUCLEAR REACTORS
220900* -- Nuclear Reactor Technology-- Reactor Safety
ACCIDENTS
AEROSOLS
BWR TYPE REACTORS
CALCULATION METHODS
CLEANING
COLLOIDS
CONTAINMENT
CONTAINMENT SPRAY SYSTEMS
CONTAINMENT SYSTEMS
DECONTAMINATION
DISPERSIONS
ENGINEERED SAFETY SYSTEMS
ENRICHED URANIUM REACTORS
LOSS OF COOLANT
MATHEMATICAL MODELS
MONTE CARLO METHOD
POWER REACTORS
PWR TYPE REACTORS
REACTOR ACCIDENTS
REACTORS
SCRUBBING
SOLS
STATISTICAL MODELS
THERMAL REACTORS
WATER COOLED REACTORS
WATER MODERATED REACTORS