Isolation condensers

The AP600 passive safety system includes subsystems for safety injection, residual heat removal, containment cooling, and control room habitability under emergency conditions. Several of these aspects are in existing nuclear plants such as accumulators, isolation condensers as natural-circulation closed loop heat removal systems (in early BWRs), automatic depressurization systems (ADS - in BWRs) and spargers (in BWRs). 

Early BWRs used an isolation condenser, although such is not specific to the direct cycle. This device removes decay heat by steam flow through a heat exchanger the other side of which is water vented to the atmosphere. Discuss the relative merits of such a boiler. 

IC - Isolation condenser - used with some BWRs and the SBWR. 

Answer There are obvious merits in using an isolation condenser because it is being included in some of the advanced reactor designs. FTAP INPUT... 

In another process [20] phthalonitrile, dissolved in an alcohol is reacted with a base and, without isolating, condensed with barbituric acid in a mixture of formic acid and water. 

Giner-Chavez BI, Van Soest PJ, Robertson JB et al (1997) A method for isolating condensed tannins from crude plant extracts with trivalent ytterbium. J Sci Food Agric 74 359-368... 

James Watt was a discoverer. He discovered the great principle of condensation - instantaneous isolated condensation. He discovered that vacuum was a commodity that could be housed, garnered, stored, husbanded, set apart, kept at hand ready for instantaneous use. .. [This discovery] was enough to have made him celebrated as a philosopher, even if he had been ignorant as an inventor, and incapable as a mechanic.48... 

The Isolation Condenser System removes decay heat after any reactor isolation during power operations. Decay heat removal limits further pressure rises and keeps the RPV pressure... 

Isolation condenser system X Passive high pressure decay heat removal (3 independent heat exchanger loops)... 

Coolant mventory (high pressure) - Control rod dnve system - Feedwater system - Isolation condenser pool active active passive 4 ICS loops... 

Isolation makeup water RCIC RCIC Isolation condensers, passive... 

This reactor also has 100% heat removal by natural circulation, and passive safety is ensured by engineered safety features like gravity-driven water pool, isolation condenser, and large volumes of water that can totally submerge the core in the event of an accident. 

This small BWR concept (Figure 1) uses an isolation condenser to improve transient response. Gravity-driven control rods and gravity-driven borated water injection are used to simplify and provide diversity to the shutdown function. Core cooling and decay heat removal are provided by depressurizing the reactor to an elevated suppression pool. The drywell and pool gas spaces are inert. 

Reactor pressure is normally controlled with turbine throttle and bypass valves. When the reactor vessel is isolated from the turbine condenser, an isolation condenser controls pressure. This device was selected because of its simplicity and because it provides high-pressure reactor water inventory control. A failure of the isolation condenser to control reactor pressure, is not expected during the plant live. If such a failure occurs, safety and depressurization valves provide a backup depressurization to the suppression pool which is positioned above the reactor vessel. When the reactor pressure is sufficiently low, check valves open in the suppression pool-to-vessel fill lines and water flows by gravity into the reactor vessel to keep the core covered. The response to a loss-of-coolant accident and transient with failure to scram is similar. 

The high-pressure loop consisted primarily of Vin (6.4 nun) stainless-steel tubing and had a total volume of 170 cm . Initially, the loop was contaminated with oxygen and chlorine, which were removed by cooling an isolable condenser section with liquid nitrogen while circulating hydrogen gas at 6... 

The passive safety systems of the AFPR include passive containment cooling system reactor isolation condenser, core flood tanks and suppression chamber tanks. 

IC ISOLATION CONDENSER LOCA LOSS OS COOLANT ACCIDENT UHS ULTIMATE HEAT SINK SG STEAM GENERATOR... 

Figure 4. Isolated condensed phase products from the liquid TNT thermochemical decomposition process. ...

Large experimental facility (Integral Test Loop, ITL) is imder constmction the tests will include validation of the isolation condensers, large passive heat sink located within containment, passive valves, steam driven poison injection, passive ECCS of enhanced effectiveness, passive containment isolation, etc. 

The combination of a high pressure resistant containment and the upper entry CRD can facilitate the compact PCV without a suppression pool and the simplified safety systems with only an isolation condenser (IC) and an equalizing injection system. The adoption of simplified safety systems contributes to the reduction of O M costs. 

In summary, the isolation condenser has the heat removal capability sufficient to reduce the pressure in the containment, and the reactor core remains covered with the coolant all the time following a feedwater line break. 

Shutdown cooling Residual heat remover (RHR) 3 RHR/Clean up water system (CUW) 1 Isolation condenser (IC) Adopting passive systems can reduce the redundancy of active systems. 

Coolant inventory (high pressure) Control rod drive system Feedwater system Isolation condenser system. 

Heat removal Water wall Isolation condenser system. 

Since the drain piping is located at the bottom of the pressure vessel, this accident is the most severe one with respect to core flooding. The results show that the accumulator injection system can keep the water level above the top of the core for one day after initiation of the LOCA. Although the active component of the FLS is not activated in the present analysis to show the performance of the ACC, the FLS is supposed to be activated to maintain long-term core cooling by injecting water from the suppression pool, even one day after initiation of the LOCA. For isolation of the reactor, the passive isolation condenser (IC) is introduced for core cooling whereas the RCIC system driven by the steam turbine is eliminated. 

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