Aerosol pressure vessel

Addition funnel pressure reactor, 201 Adjustable pressure relief valve, 200 Aerial oxidation, 64 Aerobic product transfer, 193 Aerosol pressure vessel, 198 Air-sensitive materials decomposition, 147 HPLC analysis, 24 recovering, 193 synthesis and handling, 34 Alkyne electron density, 287 Alkyne ligand, 282 Alkyne it donor orbitals, 287 Alkyne levels, 285 Ambient pressure flow cell, 238-244 Ammonia synthesis, 182 Anaerobic column chromatography, 17-18/ Anaerobic transfer, 144 Anionic polymerization, 182 Apparatus design philosophy, 117 Arc lamp... 

Certain types of equipment are specifically excluded from the scope of the directive. It is self-evident that equipment which is already regulated at Union level with respect to the pressure risk by other directives had to be excluded. That is the case with simple pressure vessels, transportable pressure equipment, aerosols and motor vehicles. Other equipment, such as carbonated drink containers or radiators and piping for hot water systems are excluded from the scope because of the limited risk involved. Also excluded are products which are subject to a minor pressure risk which are covered by the directives on machinery, lifts, low voltage, medical devices, gas appliances and on explosive atmospheres. A further and last group of exclusions refers to equipment which presents a significant pressure risk, but for which neither the free circulation aspect nor the safety aspect necessitated their inclusion. 

HGSystem offers the most rigorous treatments of HF source-term and dispersion analysis a ailable for a public domain code. It provides modeling capabilities to other chemical species with complex thermodynamic behavior. It treats aerosols and multi-component mixtures, spillage of a liquid non-reactive compound from a pressurized vessel, efficient simulations of time-dependent... 

Isolation of Processes To minimize cross-contamination and microbiological contamination, the manufacturer may develop special procedures for the isolation of processes. The level of facilities isolation depends on the types of products to be manufactured. For instance, steroids and sulfas require more isolation than over-the-counter (OTC) oral products [6], To minimize exposure of personnel to drug aerosols and loss of product, a sealed pressure vessel must be used to compound aerosol suspensions and emulsions [21], An example of cross-contamination with steroids was the controversial case of a topical drug manufactured for the treatment of skin diseases. Fligh-performance liquid chromatography/ultraviolet and mass spectrometry (FIPLC/UV, FIPLC/MS) techniques were used by the FDA for the detection of clobetasol propionate, a class 1 superpotent steroid, as an undeclared steroid in zinc pyrithione formulations. The product was forbidden and a warning was widely published [22],... 

Physical phenomena specific to severe accidents (attack of the container bottom, direct containment heating, steam explosions, production and behaviour of hydrogen, behaviour of the fission products in the form of aerosols or of gases and vapours, loading of the reactor vessel by the molten core and its coolability, coolability of the molten core outside the pressure vessel, etc.). 

There are many kinds of pressurized containers in processes and consumer products. They range from aerosol cans to inflated tires, water heaters, tanks, or compressed gas cylinders. Industry also uses many kinds of pressurized vessels. An example is vehicle air bags. In explosions, even buildings and pipes can be pressurized containers. When pressurized to test for leaks and other faults, pipes, pipelines and some process equipment become pressurized containers. 

In the event of a transient, there is no direct contact between the reactor pressure vessel and the containment, so that the steam-gas flow escaping from the reactor pressure vessel, as well as the volatile fission products and the aerosols carried by it, are transported through the relief line to the pressure suppression pool. When it passes through the water volume of this pool, the overwhelming fraction of the aerosols is retained (as well as iodide), while a small fraction of elemental iodine can potentially escape from the water phase due to its volatility... 

Table 7.3. Chemical forms of aerosols in the reactor pressure vessel prior to failure (Wichner and Spence, 1985 Copyright 1985 by the American Nuclear Society, La Grange Park, Illinois)...

Virtually all the substances which are volatilized from the core structural materials have low vapor pressures and, therefore, will condense immediately after having left the high-temperature region to form aerosols. The chemical nature of the aerosols depends on the redox conditions in the gas flow escaping from the reactor pressure vessel, i. e. on the H2 H2O molar ratio which in most of the accident sequences will increase from about 0.1 at the moment of cladding failure to about 0.8 at the time of failure of the reactor pressure vessel. In particular accident se-... 

When source terms for a complete core melt accident (in which the melt progress could not be stopped within the reactor pressure vessel) have to be calculated, the aerosol production during the core - concrete interaction phase also has to be taken into consideration. In the Reactor Safety Study (US NRC, 1975), an empiric approach was used with respect to the fission product release during this phase, in recognition of the fact that during this stage the environment is chemically oxidizing and that a metallic iron phase is present. From this approach, it was concluded that the remainder of the volatile fission products still present in the molten corium... 

The transport and the deposition of the condensation aerosols in the reactor coolant system depend on a number of parameters such as heat and mass transfer, chemical reactions and aerosol kinetics. With respect to their transport behavior, all the substances volatilized from the reactor core do not directly enter the primary circuit. First, they have to pass through the upper plenum of the reactor pressure vessel their residence time here depends on the specific accident sequence. The masses deposited here on the walls and structures will differ and, consequently, the fraction which, after having passed through the upper plenum, enters the actual primary circuit will depend on the details of the accident. 

Some of the iodine species (e. g. Csl) will condense on surfaces or will form aerosols in the reactor pressure vessel or during their residence time in the pipes and components of the primary system they can be transported together with the primary aerosols or deposited within the primary system, but in each case they may undergo further chemical reactions potentially leading to other, more volatile products. Other species such as elemental iodine h are transported in gaseous form inside the primary circuit after having reached the containment free volume, they may enter into a partition equilibrium between sump water and containment atmosphere. For this reason, it is of considerable interest to know the chemical forms of fission product iodine that can be generated within the primary circuit. 

In severe accidents in PWR s, the availability of boric acid vapor and aerosols for reactions with CsOH and Csl depends on the particular accident sequence (see Section 7.3.2.3.I.). These reactions are of greater signiflcance in the high-pressure accident sequence, since in this case the boric acid inventory of the primary coolant and the emergency coolant solutions becomes concentrated in the residual water volume inside the reactor pressure vessel because of the considerable volatility of boric acid at a pressure of 16 MPa, this compound will be partly volatilized with the steam. In contrast, in low-pressure accident sequences most of the primary coolant boric acid inventory will be ejected during blowdown and, thus, not be... 

The largest fraction of radionuclides by far enters the containment attached to aerosol particles which are carried by the steam flow. As was shown in Table 7.3., according to thermodynamic calculations oxides and metals are the predominant species of the refractory aerosols generated in the reactor pressure vessel, and one has to assume that at the lower temperatures prevaihng in the containment no significant changes in the chemical nature of these primary aerosols will occur. The primary aerosol particles will be coated by layers of more volatile substances such as CsOH and Csl which are deposited in regions of lower temperatures in the primary system other fission product species may also be attached to the aerosol surfaces by condensation, chemical reactions and, probably to a lesser extent, by physi- and chemisorption. 

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