Reflooding

ORNL small-break LOCA tests Experimental investigation of heat transfer and reflood analysis was made under conditions similar to those expected in a small-break LOCA. These tests were performed in a large, high-pressure, electrically heated test loop of the ORNL Thermal Hydraulic Test Facility. The analysis utilized a heat transfer model that accounts for forced convection and thermal radiation to steam. The results consist of a high-pressure, high-temperature database of experimental heat transfer coefficients and local fluid conditions. 

Anklam, T. M., 1981b, ORNL Small-Break LOCA Heat Transfer Test Series 1 High Pressure Reflood Analysis, NUREG/CR 2114, ORNL/NUREG/TM-446, Oak Ridge Natl. Lab., Oak Ridge, TN. (4)... 

Kawaji, M., and S. Banerjee, 1987, Application of a Multifield Model to Reflooding of a Hot Vertical Tube, Part I—Model Structure and Interfacial Phenomena, Trans. ASME, J. Heat Transfer 709.204-211. (4)... 

Riedle, K., H. P. Gaul, K. Ruthrof, and J. Sarkar, 1976, Reflood and Spray Cooling Heat Transfer in PWR and BWR Bundles, ASME Paper 76-HT-10, Natl. Heat Transfer Conf., St. Louis, MO, ASME, New York. (4)... 

Dieldrin was then used in a series of 27 quarter-acre plots during the summer of 1953. A third of the plots were treated with dieldrin at the rate of 4 ounces per acre just previous to the first flooding and they were flooded continuously the balance of the season. One half of the untreated plots were drained as larval root feeding approached its peak (July 15) and then reflooded when the soil became dry (July 31). The balance of the untreated plots were continuously flooded. Counts of weevil larvae were taken in each plot twice each week from July 7 to August 14. 

These counts (32) clearly show that the treated plots contained far fewer larvae than either those drained for weevil control or the untreated and continuously flooded plots. The cost of the insecticidal treatment is believed to be less than half as much as draining, drying, and reflooding fields. Counts of mosquito larvae in all plots taken 4 days after the drained plots were reflooded showed less than 1% as many mosquitoes in the undrained plots as in those drained and reflooded. Less water was required for continuous flooding than for draining and reflooding. 

Cordova A.M. Longo K. Freitas S. Gatti L.V. Artaxo P. Procopio A. Silva Dias M.A.F. and Freitas E.D. (2004). Nitrogen oxides measurements in an Amazon site and enhancements associated with a cold front. Atmos. Chem. Phys. Discuss., 4, 2301 -2331. Corstanje R. and Reddy K.R. (2004). Response of Biogeochemical Indicators to a Drawdown and Subsequent Reflood. J. Environ. Qua ., 33, 2357-2366. 

Aldrin from Rice. An important off-take for aldrin is in the treatment of rice seed to protect the seedling against grape colaspis larvae and rice water weevils. The seed is usually sprayed with sufficient volume of an aldrin-hydrocarbon solution to give 2-4 oz. of aldrin per bushel of seed. The seed is either flown onto flooded fields or drilled into dry fields and then flooded. The planting rate, which determines the amount of aldrin applied per acre, will vary with the variety and local cultural practices. The fields are drained and reflooded a few times before harvest, the frequency depending upon the amount of rainfall and degree... 

J. G. Collier, Heat Transfer in the Post Burnout Region and During Quenching and Reflooding, in Handbook of Multiphase Systems, G. Hetsroni ed., chap. 6.5, McGraw-Hill Book Company, New York, 1982. 

Draining and flooding cycles influence N2O emissions (Figure 16.8). Draining the floodwater from salt marsh cores resulted in increased N2O emissions. However, the emission of NjO decreased when the sediment was reflooded. Results demonstrate that the N2O emission from natural wetlands... 

Qui, S. and A. J. McComb. 1994. Effects of oxygen concentration on phosphorus release from reflooded air-dried wetland sediments. Aust. J. Mar. Freshw. Res. 45 1319-1328. 

A typical reflood velocity of the core after uncovering is 5 x 10 m... 

Vapor burst instability occurs due to sudden vaporization of the liquid phase with rapid decrease in mixture density. For example, a very clean and smooth heated surface may require high wall superheat for nucleation. The fluid adjacent to the surface is highly superheated and vapor generation is rapid when nucleation starts. This in turn ejects liquid from the heated channel. Rapid vaporization cools the surface, and cooler liquid keeps the vaporization suppressed until wall temperature reaches required nucleation superheat and the process repeats. Vapor burst instabilities are observed during reflood phase of the reemergence core cooling of reactor. 

The typical ECCS for BWRs is also composed of three subsystems with equipment and flow path redundancy. The first subsystem is a high-pressure spray system that sprays water on the reactor core. For small pipe breaks, the high-pressure spray can maintain the water level in the reactor vessel so that the core remains covered. For larger breaks, this system cools the core by spraying water on the fuel rods. The second subsystem is a low-pressure spray system that delivers a large-volume water spray to the top of the core. The third subsystem is a low-pressure core injection system that provides a large flow of water to the reactor vessel to reflood and cover the core. 

As was discussed above, the release of fission products from the fuel rods which failed during the burst, refill and reflood phases of the loss-of-coolant design basis accident is limited to their gap inventories due to the comparatively low maximum... 

For this experiment, the reactor core had been equipped with a central fuel module containing 100 pre-pressurized fuel rods, the UO2 fuel of which had been enriched to 9.7% and which had been pre-irradiated to a bumup of about 450 MWd/t U. The transient phase started with the reactor scram and was terminated about 30 minutes later when the external temperatiure on the surface of the shroud of the central fuel module reached 1517 K at this time, the highest measured cladding temperature reached 2100 K. When reflooding of the reactor core with emergency coolant was started, a rapid temperature excursion occurred within the central fuel module which was caused by the enhanced metal—water reaction. The transient was followed by a post-transient period of 44 days during which the reactor core was cooled by recirculating coolant and the concentrations of fission products deposited in the primary coolant system as well as their behavior in the blowdown suppression tank were measured. 

Modro, S. M., Carboneau, M. L. The LP-FP-2 severe fuel damage scenario Discussion of the relative influence of the transient and reflood phase in affecting the final condition. Proc. Open Forum The OECD Loft Project Achievements and Significant Results. Madrid, Spain, 1990, p. 388-402... 

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