Heat removal from containment

In Russian WWER-640/V-407 concept [8], at the outer surface of the containment steel shell, rectangular pockets are arranged in rows and columns. The pockets of each column are interconnected by vertical lines. A NC flow of cooling water from an external pool near the roof will be established. Steam is condensed at the cooled parts of the inner surface of the steel shell. The condensate is collected in the sump to allow for post accident recirculation. 

A passive containment cooler (PCC) which is used in some designs primarily for severe accident prevention purposes will also mitigate severe accident consequences as it is foreseen in the design of the ESBWR, and some advanced PWR and CANDU designs. The PCC is a condenser immersed in a special PCC pool above the containment, using the design principles of an isolation condenser. It consists of a tube bundle connecting inlet (top) and outlet (bottom) collectors. The steam-gas mixture from the containment enters the inlet collector of the PCC and will be condensed inside the tubes. The condensate drains towards the RPV and the wet well [9]. 

In a PCC system for an advanced heavy water reactor design the condensate is collected in a water storage tank for gravity driven injection, and non-condensables are vented to a suppression pool [10]. A PCC proposed for application in a PWR (e.g. the CP-1300) utilises an external pool in a high elevation as a heat sink. The steam-Hi mixture passes Hi-ignitors before entering the heat exchanger. The condensate is collected in the IRWST and/or used for passive containment spray [7]. 

Passive containment cooling can also be ensured by internal plate condensers (PCs) that are fitted to the containment wall and connected with an external heat sink. One example for a PC utilises cooling elements made from ductile cast iron, containing fins at the side facing the containment atmosphere. These fins can absorb loads from fragments impact without any 

In-vessel core retention systems (IVORS) based on in-vessel cooling of the molten core materials can prevent the RPV from failure by melt-through utilising in-vessel flooding of the molten core materials [19]. Direct contact between corium and steel must be avoided and a cooling capability must be provided. TMI-2 experience showed, that a small gap between the 

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Now in such a reversible cyclic process a certain finite amount of external work will be supplied, which is given by the area contained between the four curves. Since no heat is taken up on the curves BC and DA, and since, by equation (1), no heat can be taken up over the curve CD because the latent heat disappears at the absolute zero, it follows that the external work must have been supplied at the cost of the heat removed from the heat reservoir at the temperature AT, which is very low perhaps, but still finite. But as this contradicts the Second Law, we arrive at the conclusion which was to be demonstrated. 

Direct-contact condensers (Fig. 15.14f). These are used for minimizing pressure drop in vacuum condensation. To accomplish this, the direct-contact zone contains low-pressure-drop internals such as packings, or is a spray chamber. Another common application is intermediate heat removal ("pumparounds ) in refinery fractionators. Here the main purpose is to maximize heat recovery at the highest possible temperature levels. A third common application is intermediate heat removal from absorbers or reactive distillation columns in which an exothermic reaction takes places. In all these applications, condensation... 

Use of the containment structure as a special system for keeping the core xmder water, and providing for passive heat removal from the reactor following primary circuit loss of integrity. 

Heating a container with a loosened cap or lid poses a significant risk. Microwave ovens can heat material (e.g., solidified agar) so quickly that, even though container lids may be loosened to accommodate expansion, the lid can seat upward against the threads and containers can explode. Screw-caps must be removed from containers being microwaved. If the sterility of the contents must be preserved, screw-caps may be replaced with cotton or foam plugs. 

Reactor water makeup and control of core coolant inventory Heat removal from the containment. 

The secondary circuit serves for heat removal from the primary circuit in the SGs, production of superheated steam, and its further delivery to the turbogenerator set. The secondary circuit is composed of two heat exchange loops each containing an SG made up of 9 sections, piping and valves. Should a primary coolant leak in the SG occur, it can be isolated on water and steam sides by double isolation valves. 

A Passive System for the Decay Heat Removal from a Double Containment of a LWR",... 

Reactor accidents that progress to the point that core debris penetrate the reactor vessel and cascades into the reactor containment are, of course, quite severe. At this stage in a severe accident, only the containment provides a barrier to the release of radioactive materials from the plant into the environment. Indeed, if decay heat removal from the contaimnent could not be realized in a sufficient way, the failure of this last barrier becomes inevitable. Severe accident management efforts must, then, focus on ... 

CFR 50.2, "Definitions", defines station blackout as the loss of the offsite electric power system concurrent with a turbine trip and unavailability of the onsite emergency AC power system. It does not include the loss of available AC power to buses fed by station batteries through inverters or by alternate AC sources. Since many systems required for core decay heat removal and containment heat removal depend on AC power, a station blackout can result in unacceptable consequences unless AC power is restored in a timely manner or AC power is supplied from an alternate source. The issue involves the likelihood and duration of station blackout and the potential for core damage as a result. 

A second application of the CPR is product enhancement for catalytic reactions, where the product spectrum is highly dependant upon catalyst temperature. In such an application, alternate channels contain a boiling heat transfer fluid to maintain an isothermal catalyst temperature. The hydrocarbon product spectrum produced by a Fischer-Tropsch catalyst is highly dependent upon catalyst temperature and rate of diffusion of reactants into the catalyst matrix. The reaction is highly exothermic and, if rates of heat removal from the catalyst are not sufficiently high, hot spots will form which result in degradation of the product spectrum. Studies have... 

Passive systems for heat removal from the containment and biological shielding tanks. 

Heat removal from outside of guard/containment vessel to inexhaustible atmosphere heat sink by natural circulation of air. 

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