Cold shuts

Cold shuts Appear as distinct dark lines of variable length and smooth outline. This is due to interrupted pouring or slow rate of pouring or the low temperature of pouring... 

The method can locate discontinuities open to the surface in porous materials. It is possible to detect porosity, surface cracks and through leaks, which may result from fatigue cracks, shrinkage porosity, cold shuts, grinding and heat-treat cracks, seams, forging laps and bursts as well as improper bonding between joined metals. 

The true indications of the discontinuities may appear as continuous lines due to cracks, cold shuts, forging laps, scratches or die marks. 

Cold shuts Smooth, narrow straight lines... 

Cold shuts Inherent Ferrous and nonferrous cast material Liquid penetrant method Magnetic particle method for ferrous material Radiographic method... 

Reactn ity control CPS Active/Passive Cold shut down capability... 

Failure of the lower joint-column connection due to creep by the cold shut or due to shear at the upper end of column resulting from the shear component of the force of equivalent truss transferred by the infill of stmctnral mesh... 

The shear force exerted by the curtain wall can cause relevant damages to the joint, which, depending on the starting configurations and on the cold shut section, may show a cross-crack on the joint panel (Fig. 5.1 Oa), which is a semihorizontal crack close to the section joining the column and the joint panel (Fig. 5.10b), or, again, a failure due to cross-cracking at the column head). 

It is necessary to load 31 fuel assemblies with guide tubes for control rods (GT assemblies) to gain a satisfactory shutdown margin under cold zero power shutdown conditions. The Reactor Protection System comprises two independent fast acting shutdown systems. Shutdown System-1 (SDS-1) is based on mechanical shutdown rods with boron carbide based absorbers in 31 fuel assemblies it provides sufficient negative reactivity with all rods inserted, with one maximum worth rod not available, in the cold shut down condition. Shutdown system-2 (SDS-2) is based on liquid poison injection into the moderator. 

The mechanical system of reactivity control is based on conventional cylindrical control rods and electromagnetic drives. It includes 104 electromagnetic drives, of which 37 drives are used to compensate reactivity changes with fuel bum-up and to flatten power distribution in the core. Of them, 12 drives are used for the automatic control of power. The remaining 67 drives combine the functions of operation control and reactor shutdown. The mechanical system is capable to bring the VKR-MT to a cold shut down state at the beginning of life (BOL) only. Later on, the operation of liquid boron shutdown system should be added to achieve this state, while the mechanical system will be capable to bring the reactor to a shutdown state only at 250°C. 

Passive system Primary shutdown system (Control rods) Rod insertion by gravity Enough reactivity worth to move the reactor from power operation to a cold shut-down... 

Comer and Fillet RadiL Proper selection of comer and fillet radii is critical in avoiding metal flow problems such as laps, cold shuts, and flow-through defects in structural rib-web foigings and other parts with deep cavities. 

A cold shut is produced when two streams of metal flowing from different regions in the casting meet without union. The shuts appear as apparent cracks or wrinkles in the surface, together with oxide... 

Cold shuts Non-union of metal streams (i) Raise pouring temperature (ii) Preheat mould Relocate runners and ingates... 

Defects in casting, 166 et seq. blowholes, 166 cold shuts, 174 contraction cracks, 174 crossjoint, 178 flash, 178 hot tears, 174 misruns, 185... 

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