Modeling and Simulation of Subcooled Coolant Loss Through Circumferential Pipe Leakage

The present work demonstrates the leak flow behavior of subcooled water at high pressure and high temperature through a narrow slit analogous to a pipe crack. The modeling and simulations are based on the loss of coolant accident in the primary loop piping of pressurized water-cooled reactors where a subcooled liquid is subjected to a rapid depressurization. Prediction of critical leak flow pattern is crucial in the design methodology of costly high energy pipelines in the perspective of leak before break consideration. Computational techniques have been used to replace costly experiments required for simulating leak flow conditions. For a variety of entry and exit conditions, the interphase mass transfer was studied with a change of boundary conditions. Presence of thermodynamic nonequilibrium has been detected on several occasions due to high transit velocities. A comparison with experimental findings indicates the validity of the flashing model for safety analysis of similar high energy thermal systems.

Active Fluidic Turn-Down Rectifier

Paper discusses a device belonging into an interesting and yet little-known family of no-moving-part active fluidic rectifiers. The generated steady component of flow and pressure are driven by input alternating flow from an external source. The absence of moving components results in the unique capability of unlimited life and reliability, especially useful for safety devices. In the experiment, the rectifier generated a pressure keeping dangerous liquid in the active zone. When the driving oscillation stops (like, e.g., due to coolant loss), the liquid leaves the zone under gravity, stopping the performed reaction. This safety facility is simple, inexpensive, and extremely reliable.

A Numerical Study of Liquid Carryover Based on the VOF Model

Liquid carryover is an important phenomenon during the small break loss of coolant accidents (LOCA). The coolant loss rate due to liquid entrained decides the decreasing height of water level and the ability that the core can be cooled. It is especially important in nuclear heating reactor as it is integral arranged without safety injection system. Therefore, the initial water volume in the reactor vessel and coolant loss rate determines whether the core could be submerged. Numerous experiments have been conducted to investigate the phenomenon of liquid carryover in the pool system. Fruitful outcomes have been proposed involving mechanism of entrained liquid produced as well as semi-empirical formula for engineering purposes. However, the semi-empirical correlations on entrainment are highly data-depended and are less applicable under different experiment settings. This paper presents a numerical method based on the VOF to study the liquid carryover in the pool system. The numerical results are analyzed with mesh independence analysis and compared with previous experiments. Several types of liquid carryover are found in the simulation. The exit effect on liquid loss rate is specifically studied including the setting of exit as well as the range that exit effect dominates.

Design Study of Small Pb-Bi Cooled Non-Refueling Nuclear Power Reactors (SPINNORs)

Small Pb-Bi Cooled Non-refueling Nuclear Power Reactors(SPINNORs) are small lead-bismuth cooled nuclear power reactors with fast neutron spectrum that could be operated for 20 years without on-site refuelling. In this study the results of neutronic design for 62.5-250MWt NPPs are discussed. The reactor cores are designed to have near zero (less then one effective delayed neutron fraction) burn-up reactivity swing during the burn-up period to avoid a possibility of super-prompt critical accident. The basic concept is that the reactor core is adjusted so that its internal conversion ratio is nearly one. During the reactor operation fissile material accumulates in this central region, which helps to compensate fissile material loss in the peripheral core region and also contributes to negative coolant loss reactivity effect. In general higher fuel volume fraction is needed for smaller core.

(P1-72) Advanced Surgical Cooling Garment to Combat Heat Stress in CBW Ppe and Hot Surgical Environments

IntroductionHeat stress is an occupational hazard for all personnel requiring Personal Protective Equipment (PPE). Even “breathable PPE” increases measurable heat stress in active troops and surgical personnel. A novel negative-pressure, semipermeable surgical cooling vests for use in the operating theater was jointly developed by Mountain Laurel Biomedical, Hamilton Sundstrand, and Hartford Hospital.Materials and MethodsSurgical personnel alternated between wearing cooling garment vs no cooling under their surgical gowns (PPE) during surgical procedures lasting up to several hours. Tympanic temperatures were monitored for safety. A questionnaire was completed after the conclusion of surgery to assess perception of comfort. Trials began at ∼18 deg C, but ambient temperature was increased to 24 deg C (40–50% RH) for the third series of trials. Results: The study was terminated prematurely. After wearing the cooling vest, surgeons refused to complete additional control trials due to the heat. They demanded to use the cooling device for all surgery, even outside the protocol! Vest wearers remained dry and reported a statistically significant (p < 0.0001) greater level of comfort compared to control subjects. The weight, fit, and mobility restriction of the vest was not clinically significant.ConclusionActive cooling and drying using a negative pressure cooling vest improves subjective thermal comfort with minimal perceived impact on mobility during surgical procedures. This technology may have utility in other fields that utilize PPE. The Chemical Biological Warfare (CBW) ensemble, in particular, is a promising candidate. Heat stress from PPE ensemble even if “breathable” -Cooling at ∼100 watts with 18 deg C water -Semipermeable membrane allows condensation removal. Wearer stays cool and dry. -Negative pressure prevents coolant loss if punctured -Minimal perceived restriction of shoulder, neck, and waist range of motion - Light weight ∼1.5 lbs. (0.68 kg) - Quick disconnects allow options for cooling source.