Core spray system

These plants generally have separate shutdown cooling and containment spray systems and a multi-loop core spray system. With the exception of Big Rock Point, which is housed in a large dry containment, these plants use an i,solation condenser... 

These plants are designed with two independent high-pressure injection systems, namely reactor cooling sure coolant injection (HPCl). The associated pumps are each potiered fay turbine. also have a multi-loop core spray system and a multi-mode residual heat re sy.stem that can be aligned for low-pressure coolant injection, shutdown cooling, suppre.ssion pc containment spray functions. 

These i high-pressure core spray (HPCS) system that replaced the HPCI system. The const e motor-driven pump train powered by its own electrical division complete with J diesel fhese plants also have a single train low-pressure core spray system, as well as a RHR system similar to the system design in the BWR. 3/4 group. 

Number of core spray system pumps - this characteristic applies only to BWRs. For other reactors, data providers should enter "N/A". 

Core Spray System Combined with the Emergency core cooling systems ... 

Core Spray System - Feed and bleed Deleted (unnecessary information)... 

In Siemens/KWU-plants (except Wiirgassen), the core spray system may exist but is not necessary, as they are not equipped with external recirculation lines. Due to this, no large leaks or breaks can occur below the core level. Maximum leak sizes to be postulated in the lower part of the RPV can be controlled in these plants by the emergency core cooling system. 

The BWRVIP flaw evaluation guidelines recommend loading combinations for plants that do not have such information in plant documentation. Methodology is provided to take stresses from finite element analyses of the core spray system under these loading combinations and to perform limit load flaw evaluation at each weld. 

Equally important are the administrative requirements for the inventory control. Those include a requirement for the availability of the safety injection (usually low pressure) and accumulators or the core spray systems for BWRs. Many plants have found that the maintenance on those systems could be successfully implemented during the period of low risk (i.e. core unloaded). Administrative requirements would be imposed for selected systems to be available when the risk is higher. 

Coolant Inventory Control and Core Heat Removal High Pressure Coolant Injection System Reactor Core Isolation Cooling System Low Pressure Coolant Injection System Low Pressure Core Spray System Control Rod Drive Cooling System Condensate System High Pressure Service Water System... 

Several other systems are available to control room operators to keep the reactor cool during an emergency. These include the High Pressure Core Spray System, Low Pressure Core Spray System, Residual Heat Removal System, Low Pressure Coolant Injection, and Suppression Pool Cooling. All of these systems require both AC and DC power, plus a sufficient flow of coolant water connected to the ultimate heat sink. At Fukushima this ultimate heat sink was the Pacific Ocean (US Nuclear Regulatory Commission, n.d.a). 

Specimen Location Emergency service water system piping to reactor core spray... 

A system event tree provides this display and uses the Tech Spec ciiicna (n specify the func tion. Figure 3.4.5-4 shows a system event tree developed from the function event tree presented as Figure 3.4.5-2, It should be noted that the functions RS, COl, C02 and ECR are accomplished by systems and are thus unchanged ongoing from a function to system event tree. ECI is quiic complex and may be performed by various system combinations such as 2 or 1 core spray (CS) loops, or various combinations of low pressure in jection (LPCI),... 

Top spray systems During top-spray cooling of an overheated core, the wall temperature is usually higher than the Leidenfrost temperature, which causes water to be sputtered away from the wall by violent vapor formation and then pushed upward by the chimney effect of the steam flow generated at lower elevations (as shown in Fig. 4.25). A spray-cooling heat transfer test with BWR bundles was reported by Riedle et al. (1976). They found the dryout heat flux to be a function of spray rate and system pressure. The collapsed level required to keep the bundle at saturation for various pressures compared reasonably well with that in the literature (Duncan and Leonard, 1971 Ogasawara et al., 1973). 

Core Sampling. After the automatic spray system had been turned off, there was a period with no treatment of the hull. After about 3 years, however, in order to protect the deteriorated surface layer of the wood, an ultimate treatment with PEG 4000 was done. 

The main techniques of encapsulation of probiotic cells are based on spray drying, emulsification, and extrusion, which lead to matrix-type systems, as well as co-extrusion, and fluid-bed coating, which instead lead to core-shell systems. In both cases, the typical size of the encapsulation system is comprised between 1 and 5 pm in diameter, being dictated by the size of the microbial cells to be encapsulated. ... 

S. P. Kutty, M. Narasimhan, K. Narayanaswamy, Design and prediction of discharge rate, cone angle and air core diameter of swirl chamber atomizers, in Proceedings of the First International Conference on Liquid Atomization and Spray Systems, Tokyo, p. 93 (1978). 

As far as possible effects of operator actions are concerned, if electric power is recovered before the core is uncovered, cooling is re-established and the accident is terminated without damage, or with only modest damage, to the core. The operator has also to open the PORV in order to decrease the pressure in the primary system and to allow the use of the low pressure injection pumps for cooling the core. If the power is recovered after vessel break, flooding of the cavity will take place as an effect of the containment spray system and consequently the end of the accident destructive processes will occur. 

The assumption of the total transfer to the mixture of the energy released over time by the core is certainly cautious, while the assumption of an absence of delays in the phenomenon may or may not be cautious according to the aspects of the accident considered. In fact, what can be expected by the assumption of immediate transfer of the heat from the core is a pressure transient characterized at the start by higher values but having a shorter duration. Therefore this assumption is very likely to be conservative for the evaluation of the probability that a second pressure peak higher than the first one in the containment occurs. It will not necessarily be so for the evaluation of prolonged releases of activity from the containment in the absence of pressure abatement systems such as, for example, spray systems. 

The containment sump should be designed to permit mixing of emergency core cooling system (ECCS) and spray solutions. Drains to the engineered safety features sump should be provided for all regions of the containment which would collect a significant quantity of the spray solution. Alternatively, allowance should be made for dead volumes in the determination of the pH of the sump solution and the quantities of additives injected. 

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