Vessel nozzles

The disc must be installed within 8 pipe diameters of the vessel nozzle. 

Velocities of both phases should be about the same through the unit. By adjusting mechanical internals, a ratio of < 2 1 is suggested (internals do not need to be equal) [32]. Velocities for entrance and exit at the vessel nozzle should be low, in the range of 0.5 to 1.5 ft/sec. The... 

The vessel nozzle diameter (inside) or net free area for relief of vapors through a rupture disk for the usual process applications is calculated in the same manner as for a safety relief valve, except that the nozzle coefficient is 0.62 for vapors and liquids. Most applications in this category are derived from predictable situations where the flow rates, pressures and temperatures can be established with a reasonable degree of certainty. 

In-line instruments or sensors are necessary components for automated processes. For ease of cleaning, sensors should be chosen that directly mount onto vessel nozzles or piping tees with minimum dead leg distances. Also, the instru-... 

Frequently, SRV sizes are determined by merely matching the size of an existing available vessel nozzle or the size of an existing pipeline connection. This operating method is extremely dangerous and does not comply with the codes. 

Finally, estimate the pressure drop across the bed to conqtlete the design of the reactor system. To promote uniform flow distribution across the bed, Tram-bouze et al. [8] recommend a pressure drop per unit length of bed of at least 2500 Pa/m (0.11 psi/ft). To the pressure drop across the bed, add an additional pressure drop equivalent to about 3 ft (0.914 m) of bed height [21] to accormt for pressure losses caused by the vessel nozzles, distributor (balls or other devices), and bed supports, if needed. 

Figure 7-82. Horizontal vessel nozzles, when used for safety valve mounting, can be connected this way.

The morphology of the resulting solid material depends both on the material structure (crystalline or amorphous, composite or pure, etc.) and on the RESS parameters (temperature, pressure drop, distance of impact of the jet against the surface, dimensions of the atomization vessel, nozzle geometry, etc.)[ l It is to be noticed that the initial investigations consisted of pure substrate atomization in order to obtain very line particles (typically of 0.5-20 m diameter) with narrow diameter distribution however, the most recent publications are related to mixture processing in order to obtain microcapsules or microspheres of an active ingredient inside a carrier. 

The bottom head of the reactor pressure vessel is manually examined from the outside surface, therefore, an access tunnel is provided to allow personnel into the area below the bottom head. Insulation is provided by removable panels over the bottom head weld seams. For interim inspections of the vessel nozzle-to-shell welds and inner radii of the outlet nozzles are accessible from inside the pressure vessel without removal of the vessel internals by using remote automated equipment. Remote inspection devices to be used in periodic ISI will be used for Preservice Baseline Inspection Program to demonstrate feasibility. 

The arrangement of the circulation circuit inside the reactor vessel eliminates large diameter recirculation pipelines and hence the accidents with large and medium primary coolant leaks. All pipelines are connected to the reactor in its upper part and the vessel nozzles are provided with flow restrictors of equivalent diameter (ED), 50 mm in the steam-gas region and ED 32 mm in the water volume. 

A break in a large reactor coolant pipe could cause several rapidly occurring internal and external transient loads to act upon the reactor vessel. In the event of a postulated LOCA at the vessel nozzle, asymmetric LOCA loading could result from forces induced on the reactor internals by transient differential pressures across the core barrel and by forces on the vessel due to transient differential pressures in the reactor cavity. Differential pressures, although of short duration, could place significant loads on the reactor vessel supports, thereby affecting their integrity. 

The reactor vessel design is based on proven historic SFR technology. The most important new feature of the PRISM reactor vessel and internals is that the reactor vessel has no penetrations (below the reactor closure head). This reactor vessel nozzle configuration precludes any large pipe ruptures at or below the elevation of the core. It is a key factor of the PRISM safety systems to keep the core completely and continuously flooded for the entire spectrum of design basis events/accidents. The reactor vessel is filled with liquid sodium and a helium cover gas. 

Fluxes and reaction rates were calculated in the channel pots, the boron shield, the pressure vessel, the pressure vessel nozzles, the concrete roof liner, the roof sleeve, the standpipe divided into several axial regions, the refuelling penetration muff shield and the concrete roof divided into several axial regions. In all, fluxes and reaction rates were calculated in 75 components. 

Safe ends" (short transition pieces between vessel nozzles and the piping) that have been highly sensitized by fiimace heat treatment while attached to vessels during fabrication were very early (late 1960 s) found to be susceptible to IGSCC. Because of this, the US AEC took the position in 1969 that furnace-sensitized safe ends should not be used on new applications. Most of die fiimace-sensitized safe ends in older plants have been removed or clad with a protective material, and there are only a few BWRs that still have furnace-sensitized safe ends in use. Most of these, however, are in smaller diameter lines. 

To determine the amount of leg needed to sati the vessel nozzle allowables, the designer must first know the allowable vessel nozzle loads. Once the designer knows the allowable loads, he or she can enter a nomograph and determine the amount of leg needed to satisfy the loads. 

Vessel equipment nozzle allowable loads The maximum allowable load on a nozzle of a vessel is expressed in stress. Earlier, we e q)ressed the rotating equipment allowables in pounds. However, for this section it is useful to express vessel nozzle allots ble in pounds per square inch or stress. 

Given these numbers and the known allowable of 14,000 psi for vessel nozzles, we can now enter the nomograph shown in Exhibit 16-19 and determine if the available absorbing legs we summed earlier is sufficient... 

The last step is to determine the vertical expansion and its impaa on the vessel nozzles. 

The riser connects the jet pump to the RPV recirculation inlet nozzle and provides the flow path, which directs the high-pressure driven flow upward from the vessel nozzle and divides the flow equally between the two jet pumps connected to each riser. The riser includes an elbow at the inlet, a vertical section of pipe with a restraint bracket attached near the midsection, two riser support braces and a transition casting. 

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