Preliminary hydraulic design

After selection of the column internal diameter (the fundamental column specification), the sieve plates must then be designed. This involves a trial and error approach. A preliminary plate design is proposed based upon typical tray configurations, then the hydraulic... 

Tray layout. The preliminary tray and downcomer layout is prepared in the column-sizing phase and refined during the hydraulic design phase. In addition to the parameters previously set, such parameters as hole diameter or the type of valve unit are determined. 

Thermal hydraulic design. The preliminary core thermal hydraulic design reported here needs to be continued using multidimensional methods to establish the heat removal capability and coolant pump sizing for the target power level and for assessing the reactor s performance in anticipated transients. 

The airflow equations presented above are based on the assumption that the soil is a spatially homogeneous porous medium with constant intrinsic permeability. However, in most sites, the vadose zone is heterogeneous. For this reason, design calculations are rarely based on previous hydraulic conductivity measurements. One of the objectives of preliminary field testing is to collect data for the reliable estimation of permeability in the contaminated zone. The field tests include measurements of air flow rates at the extraction well, which are combined with the vacuum monitoring data at several distances to obtain a more accurate estimation of air permeability at the particular site. 

In the recycle flow pressurization system (Figure 27.10), a portion (15-50%) of the clarified effluent from the flotation chamber is recycled, pressurized, and semisaturated with air in the air dissolving tube. The recycled flow is mixed with the unpressurized main influent stream just before admission to the flotation chamber, with the result that the air bubbles come out of aqueous phase in contact with suspended particulate matter at the inlet compartment of the flotation chamber. The system is usually employed in applications where preliminary chemical addition and flocculation are necessary and ahead of flotation. It eliminates the problems with shearing the flocculated particles since only the clarified effluent passes through the pressurizing pump and the friction valve. It should be noted, however, that the increased hydraulic flow on the flotation chamber due to the flow recirculation must be taken into account in the flotation chamber design. 

LMRs with oxide-fueled core Models modified and newly developed mto the code so far mclude models for reactivity feedback effects and pool thermal-hydraulics In order to venfy the logic of the models developed, and to assess the effectiveness of the inherent safety features based upon the negative reactivity feedbacks m achieving the safety design objectives of passive safety, a preliminary analysis of UTOP and ULOF/LOHS performance has been attempted... 

In addition to the deterministic analyses, and the simulations performed with thermal-hydraulic computer codes, a preliminary Level 1 PSA study has been completed in a joint effort by ABB Atom and the Italian oitities ENEA-DISP/ENEL (ENEA-DISP is the state regulator and ENEL is the (former) state utility) The study represents a first comprehensive review of the PIUS plant design, based on ultra-conservative assumptions - the failure fi-equency for the prestressed concrete vessel ended up as somewhat higher than for a steel vessel, and a number of transients were just postulated to yield core damage even though calculations showed that they would not Still, the resulting "core damage" frequency is below 10 ... 

Preliminary safety analyses have been performed on the former design (1,100 MWt) with the thermal-hydraulic transient analysis code RETRAN-2 to understand the basic characteristics of SPWR. Examples of the events analyzed are as follows ... 

SEFIDVASH, F., Status of the small modular fluidized bed light water nuclear reactor concept. Nuclear Engineering and Design, 167 pp. 203-214 (1996), SEFIDVASH, F., A preliminary thermal-hydraulic study of the fluidized bed nuclear reactor concept, Kerntechnik, 60, 1, pp.48-51 (1995). 

Thus, IRIS has adopted the internal CRDMs as reference (traditional CRDMs remaining as backup) because (1) they eliminate the corrosion problem, (2) they are one more implementation of the safety-by-design IRIS philosophy, and (3) current advancements which have occurred in Japan in regard to the electromagnetic concept, while internally to the IRIS project. Polytechnic of Milan has further advanced the hydraulic drive concept. IRIS is currently evaluating candidate concepts for the internal CRDMs to proceed with the preliminary design of the chosen one. 

As shown in the sketch of Fig. 7.1, the fuel salt flows from the bottom to the top of the core cavity (note the absence of in-core solid matter). In preliminary designs developed in relation to calculations, the core of the MSFR is a single compact cylinder (2.25 m high x 2.25 m diameter) where the nuclear reactions occur within the liquid fluoride salt acting as fuel and as coolant. Thermal-hydraulic studies performed in the frame of the EVOL project have shown that a toms-shaped core (see Fig. 7.1) improves thermal flow (Laureau et al., 2013 Rouch et al., 2014 Laureau, 2015c). 

Rouch, H., Geoffroy, O., Rubiolo, P., Laureau, A., Brovchenko, B., Heuer, D., Merle-Lucotte, E., 2014. preliminary thermal-hydraulic core design of the molten salt fast reactor (MSFR). Annals of Nuclear Energy 64, 449—456. 

Examine the use of alternative coolants and concepts such as the Modular High Temperature Gas-Cooled Reactor (MHTGR) and the Advanced Liquid Metal Reactor (ALMR). There was not time in the preliminary design work to study in detail the possibility of use of other coolants. Alternative coolants should be evaluated considering both core neutronics and thermal hydraulics. 

Some manuals present guidelines for the relative void ratio or relative porosity. These values can be used as a guideline in the preliminary design of a hydraulic fill. It should be kept in mind that the relative density is an indirect way of defining the strength (see Section 8.3). The required relative density of non-cohesive soils in hydraulic fills depends on the type of utilisation, which is laid down in the functional requirements. 

For preliminary calculation, PI can be assumed to be equipment relieving pressure at 10% ovetpressure for non-fire case or 21% overpressure at fire case. After PRD inlet and outlet piping are designed, an updated PI and P2 based on hydraulic calculation should be used to recheck the vapor relief is sonic or not... 

In order for the internally insulated hot leg piping concept to have adequately performed hydraulically, thermally, and structurally, appropriate materials would need to have been selected In addition, the chosen materials would need to have met all system requirements and constraints. Final selection of the reactor plant materials would not have occurred for several years due to radiation testing and other long term materials testing however, preliminary material selection would have been required in the near term to support conceptual design and proof of principal testing. Material development efforts would have been required for the outer pipe, insulation, and liner. 

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