Cavity venting

It has been repeatedly shown in previous RBMK safety analyses that none of the DBAs would lead to MPTRs. Should analysis of any BDBA encounter a sequence of events with the possible rupture of more than one fuel channel, the extent of the MPTR should be determined and the maximum capacity of the reactor cavity venting system analysed in order to assess the likely structural and mechanical consequences of this BDBA, including the reactor cavity integrity. 

Phenomenological analysis of the effect of various parameters on the maximum venting capacity allows a classification of them into key parameters and those of secondary importance. Variation ranges are determined for the former, while the latter have the worst values set for them, i.e. the values detracting from the maximum capacity of the reactor cavity venting system. 

Cavity venting—machined-in passages at one or more locations along the parting line or along ejector pins— is vital to obtaining complete cavity fill in the shortest possible time. Air in the cavity must have a... 

D Cavity venting - critical with thin part a Water lines - parallel lines, diameter, and efficient cooling D Taper or draft... 

Self-cleaning vents can be located in the bottom of cavities by grinding flat surfaces 0.010-0.020 in. deep on the side of knockout pins, and cavity vents 0.002 in. deep as shown in Fig. 7-19. This self-cleaning type of vent can become clogged when mold release spray is used. If parts tend to burn, the knockout plate can be moved forward and the flats wiped clean. 

Most thermosetting resins are heat-activated, and their polymerization reaction ultimately cross-links the chains as the molecular weight of the material approaches infinity. Any polymerization via condensation reaction produces small amounts of gas or vapor (such as water) that dissolve under pressure within the hardening resin or must be vented out of the mold cavity. Venting ports may be provided within the... 

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