Coolant pressure

Location Commissioning Date Coolant Pressure (MPa) Reactor Vessel Rating [MW(e)l... 

Monitoring differential pressure between the primary and secondary cooling systems would be one of the candidates for detecting the heat transfer tube rupture. Meanwhile, the pressure varies even at normal operation and therefore there is a concern of malfunction of CV isolation valves. In case of primary helium gas recovery flow rate, primary helium pressure control system only covers the rated operation since the system activates when the primary coolant pressure reaches about 3.95 MPa. On the other hand, the primary-secondary differential pressure control system covers start-up, shutdown and rated operations. The control system keeps supplying helium gas to the secondary cooling system during the scenario. Thus, monitoring the entire secondary helium gas supply would be an effective way to detect the tube rupture. 

The results are due to the difference in differential pressure behaviour at IHX. Figure 5 shows the influence of the isolation valves actuation sequence on the differential pressure behaviour at IHX, which is defined as a subtraction from secondary to primary coolant pressure. Though the profile of differential pressure behaviour at IHX is almost the same in all of the cases, occurrence time of the peaks and their intensity are different in each case because of the momentum change difference which are induced by the difference of isolation valves actuation time and occurrence time of secondary circulator trip. 

Figure 6 Calculation results of transient behaviour of primary coolant pressure, heat transfer tube temperature of PPWC and IHX, RPV temperature and fuel temperature...

Reactor type Percentage " I uch ) Canning Moderator Coolant Coolant temp. [< Ci Coolant pressure [MPaj Power iMW,i Burn-up IMWd per kg)... 

The high temperature reactors like VHTR holds the promise to be applied various chemical processes that need high temperature, especially for coal processes, to produce hydrocarbons and hydrogen. However, in high temperature reactors, due to material limitation at present, the pressure of chemical process should be in the same range as the primary coolant pressure, which may be a hindrance factor in some processes. 

In vibrating at such high frequencies, the liner metal is "jerked" away from cooling water contacting the surface so rapidly as to reduce local coolant pressure below the vapor pressure of the coolant fluid, forming minute vapor-filled cavities, or "bubbles."... 

Ihe operating ejqjerience has shown that abnqit changes in a primary pressure can be the reason of damages in internal structures made as semi-closed plena which walls were not designed for the primary coolant pressure. That was the reason of feilure of a partition in the reactor coolant pump of icebreaker "Arctica". 

Steam Generator Isolation Valves and Primary Coolant Pressure Relief Valves... 

The steam generator Isolation valves and primary coolant pressure relief valves must perform their mechanical motion during and after a seismic event. A qualification program consistent with Regulatory Guide 1.148 and comprising qualification tests and/or analyses of these valves assures operability during and after a seismic event. 

Ohere are many miscellaneous pressure gauges In the control room vhlch Indicate the pressures at various points In the primary secondary and last ditch coolant systems. Included In these measurements are top of riser pressure crossheader pressures, top of downcomer pressure, control rod coolant pressures, and high tank level and pressure. 

Cutting tool material. - Ductility, - Coolant pressure. 

With systems where a rapid increase in heat output can lead to a surge in coolant pressure, the whole of the reactor system can he surrounded hy a sealed containment system. There can therefore he several barriers to prevent or restrict the escape of radioactive fission products from the fuel to the surroundings ... 

Type Neutron reaction Fuel (% enrichment) Cladding Moderator Coolant pressure (bar) Primary inlet-outlet Temp. (X) Primary constraint Remarks... 

The immediate damage was the overturning of the top shield, fracturing all of the coolant pressure tube connections and allowing air to come into contact with the hot fuel and graphite, leading to a graphite fire. 

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