Pipe whip

The quencher arm shoiild be anchored to prevent pipe whip. It should also extend to the length (for horizontal vessels) or the height (for vertical vessels) of the vessel to evenly distribute the vapors in the pool. 

Missile impact equivalent static load on the structure generated by or during [a credible accident event], such as pipe whipping... 

Secondary or consequential failures caused by impacts from neighbouring systems are conceivable. For example, ejected missiles, pipe whip or impacts from fluid jets in a system may cause destructions in a neighbouring system. 

The treatment of secondary failures, also called consequential failures is illustrated by an example. The fault tree of Fig. 9.34 models the failure of two pipes geometrically arranged in parallel. Apart from a spontaneous failure of pipe 1 (primary event Xi) pipe 2 may fail spontaneously (primary event X2) and as a consequence damage pipe 1 (primary event X3) by pipe whip or impinging steam jets. 

Pipe Whip and Discharge of Fluid associated with postulated pipe ruptures may be excluded from the design basis when it can be demonstrated that ... 

Similarly, at the beginning of the 1970s, the possibility was demonstrated that the break of a pipe could damage other nearby pipes or other plant components, starting a chain of ruptures (known as the pipe whip effect). 

This logical completion of the safety analyses highlighted some negative consequences of having adopted the extreme assumption of the complete rupture of the largest pipe. In particular, for the protection of components from the pipe whip, many cumbersome plastic deformation restraints had to be designed and installed on the pipe runs, in order to prevent the excessive displacement of the pipes themselves. The space occupied by these restraints resulted in a further reduction of the already small space around components and made it more difficult... 

II.2.4 Dynamic effects (segregation of systems with internal energy, pipe whip, compartment pressurization)... 

Section 2 is dedicated to general considerations in dealing with internal hazards it covers the selection of PIEs, considerations on acceptability, analysis of consequences (including cascading and secondary effects) and considerations for protection and safety. In Section 3 the aforementioned internal hazards are reviewed. A section is dedicated to pipe failure, which is an initiating event common to pipe whip, jet effects and flooding. 

To preclude or to reduce the probability of large pipe breaks, and with them the consequences of missiles, pipe whip and jet impingement, for example, a comprehensive procedure should be performed to qualify certain piping systems. ... 

Three main phenomena that could be induced by pipe failures — pipe whip, jet effects and flooding — are discussed in the following sections. 

The phenomenon of pipe whip in its classical form can occur only as a consequence of a double ended guillotine type pipe break in high energy... 

The characteristics of the broken pipe should be taken directly from the design of the system and the location and type of the postulated rupture. In the case of pipe whip it is usually conservative to assume a full circumferential rupture and to assume that the pipe will form a hinge at the nearest rigid... 

Although the probability of a severe pipe rupture in the piping systems of a nuclear power plant is generally accepted to be low, it is usual practice to restrict the motion of possible broken pipes at selected locations by the use of physical restraints. If piping is equipped with a sufficient number of effective pipe whip restraints at appropriate locations, the phenomenon of pipe whip may be considered to be excluded. 

In addition to the prevention of pipe whip by means of a sufficiently low frequency of the double ended guiUotine type pipe break, and its exclusion by means of pipe whip restraints, it may be necessary to take protective measures to reduce the probability of safety related piping or equipment being hit or... 

No special measures for protection against the consequences of an impact due to pipe whip need to be provided if any one of the following conditions is met ... 

It should be demonstrated that the effects of pipe failures such as jet impingement forces, pipe whip, reaction forces, pressure wave forces, pressure buildup, humidity, temperature and radiation on components, building structures, electrical and instrumentation and control (I C) equipment are sufficiently taken into account. Specifically, it should be shown that ... 

If the initiating event is an energetic event, such as the failure of a pressurized system that leads to the release of hot water or pipe whip, the definition of the DBA shonld include failure of the equipment which could be affected. 

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