Controlled confinment systems

Flooding Loss of off-site power and other utilities Reactivity control Confinement system Reactor in shutdown state High to moderate Monitoring system warning... 

The description of small scale turbulent fields in confined spaces by fundamental approaches, based on statistical methods or on the concept of deterministic chaos, is a very promising and interesting research task nevertheless, at the authors knowledge, no fundamental approach is at the moment available for the modeling of large-scale confined systems, so that it is necessary to introduce semi-empirical models to express the tensor of turbulent stresses as a function of measurable quantities, such as geometry and velocity. Therefore, even in this case, a few parameters must be adjusted on the basis of independent measures of the fluid dynamic behavior. In any case, it must be underlined that these models are very complex and, therefore, well suited for simulation of complex systems but neither for identification of chemical parameters nor for online control and diagnosis [5, 6],... 

Phreatic aquifers are often regarded as recharge zones feeding adjacent confined systems. A continuous through-flow is commonly envisaged, controlled by (and deduced from) water level gradients and transmissivities. However, in certain cases a discontinuity is observed between the phreatic and confined parts of a system, reflected in abrupt changes in the chemical... 

Certainly, novel numerical methods [115-120] have to be further developed to treat the confined model systems which include multiple electrons and/or atoms under a wider variety of boundary conditions and symmetry. While confined systems present many computational problems not found in free systems, systems prepared under controlled confinement will continue to have their own virtues. 

The deuterium plus tritium and deuterium plus deuterium reactions are of interest in the development of controlled fusion devices for producing energy. A number of designs have been proposed for these fusion reactors, with most attention given to inertial confinement and magnetic confinement systems. 

FIGURE 5.16 Enthalpy recovery results for o-terphenyl aged at Tj — 11°C in (a) bulk state and (b) confined in an 11.6-nm pore diameter controlled pore glass material showing much smaller buildup of enthalpy overshoot upon aging of the confined material. Originally, similar data were interpreted [McKenna et al. [1992] to imply reduced aging in confined systems. (Data from Simon et al. [2002].)... 

The capillary condensation phenomenon is of course not exclusive to water. It can be found in any confined system, where the surfaces prefer one phase over another and there is a first order phase transition between the phases of the material between the surfaces. A nematic liquid crystal is an example of such a system exhibiting a first order phase transition between the isotropic and the nematic phase. For this system, the nematic capillary condensation has been predicted by P. Sheng in 1976 [17]. Since the isotropic-nematic phase transition is only weakly first order, the phenomenon is not easy to observe. One has to be able to control the distance between the surfaces with a nanometer precision and the temperature within 10 K, which is unachievable to methods like NMR, SEA, DSC, etc., and very difficnlt to achieve in dynamic light scattering experiments [18,19]... 

Portions of the HCF structure, along with the steel confinement boxes (SCBs), gloveboxes, fume hoods, and the ventilation systems perform confinement functions. These confinement systems provide defense in depth by ensuring that hazardous materials are retained in specific designated areas within the HCF. They accomplish this function by maintaining an air pressure differential hierarchy from regions of greater contamination to those of lesser contamination within the facility. These differentials are described later in this section. This pressure differential controls the movement of contamination by diffusion and by adverse airflows. The Identified contamination zones in the HCF are as follows ... 

The confinement system instrumentation includes provision for measuring system flow, pressure and radioactivity, activation of the fog spray and fans,and alarms in the control room for off-standard conditions. 

The ventilation system section is comprised of seven subsystems airborne activity confinement system (AACS), central control room habitability (CCRH), Assembly Area ventilation (AAV) system, Disassc ty Area ventilation (DAV) stem. Purification Area ventilation (PAV) system. Building 108-K ventilation (V108) system, and nuscellaneous ventilation tystem. 

A confinement system is provided for the EFR to minimize and control the release of airborne fission products in the event of significant release of fission products into the reactor building. The most severe confinement problem would be associated with rupture of the primary loop. Vents are provided in the primary confinement zone to release the steam and reseal the building before fuel element melting could occur. Fog sprays are provided to maintain build ing pressures within tolerable values after the building has been resealed. When appropriate, building exhaiist ducts leading to the filter system may be opened. The filter system consists of particu-... 

The confinement system for NFR is based on separation of energy and controlled release concepts. The system Is designed so the thermal energy in the primary loop would be released from the building... 

The rupture of a major line in tha primary loop could reault in malting of fuel due to inadequate cooling even though the reactor ia iimadiataly shutdown by insertion of control rods. The confinamant system is designed primarily to handle this claas of accidenta. The approach is to vent the steam and reseal Zone I of the confinement system before any significant quantity of fission producta can be released from the fuel. 

This subsection should present relevant information on the containment (or confinement) systems incorporated to localize the effects of accidents, and should include, among other things the heat removal systems of the containment, the functional design of the secondary containment, the containment isolation system, the protection of the containment against overpressure and underpressure, where provided, the control of combustible gas in the containment, the containment spray system and the containment leakage testing system. Further discussion on matters to be covered in this subsection of the SAR is provided in Ref. [28]. 

Step 2 The safety classification of structures, systems and components reflects the internal postulated events and external events as set forth in the safety analysis of the plant (box (3) of Fig. 1). The definition of the defence in depth levels and barriers [2], the application of the single failure criterion and the assessment of the potential for common cause failures are identified in box (2) of Fig. 1 [19], bearing in mind the categorization of the facility. Next is the evaluation of the need for emergency procedures, both on and off the site. This is followed by identification of the internal events to be considered as a consequence of an external event or as contemporaneous to an external event, and therefore of the safety functions to be maintained in case of an external event (e.g. cooling of radioactive material, reactivity control, confinement). 

The purpose of the contaminated water removal and disposal system (CWRDS), i.e., the sump water removal system, is to remove and retain the emergency coolant or cooling water following a design basis loss of coolant accident (LOCA) or seismic event. This system operates in conjunction with the Airborne Activity Confinement System (AACS) to control the release of liquid and airborne contaminants. 

---