Secondary breaking

Accdg to Ref 5, the closed pit test is somewhat unreliable because of loss of very small fragments, and because of secondary break-up of fragments by the effect of surrounding sand... 

The relaxation phenomenon described herein is also called first-cycle effect, secondary break-in, waittime effect, memory effect, and hysteresis phenomenon which is in connection with the characteristic changes of the cyclic voltammograms obtained for -> polymer-modified electrodes [iii-vi]. 

Quantitative and (hopefully, at least) qualitative considerations are helpful in characterizing a liquid-liquid system for a potential extraction application. Batch shakeout tests are frequently the easiest way to determine basic feasibility by simply measuring the primary and secondary break times and by analyses to measure the compositions of the equilibrated phases. Such tests are readily conducted by mixing small volumes of each phase in a vial, which is then vigorously agitated and placed on a lab bench to settle. The resulting behavior of the liquid-liquid mixture depends on physical properties and system characteristics. The greater the density difference and interfacial tension between the two liquid phases, for example, the more rapidly the phases tend to separate. More viscous systems separate more slowly. 

The secondary break time is the time needed for the quiescent liquid-liquid mixture to achieve clarity in each of the bulk phases after rapid agitation. After initially breaking, the two liquid phases are usually hazy, especially if significant mass transfer has occurred. This haze is from very small droplets dispersed in each phase. Because of their small size, they move more slowly to the interface. After setthng overnight, the two phases may appear clear when examined in normal room lighting, but examination of such liquid phases in a darkened room with a laser beam will likely reveal the continuing presence of droplets in both phases, even after many weeks of quiescent equihbration. 

It is useful in such experiments to define a primary aad secondary break time. The primary break time is that tima required to form a clearly defined interface between the two phases. The secondary break time is that period needed for the quiescent liquid-liquid mixture to achieve clarity in ench of ihe balk phases after rapid agitation. Generally, the secondary break time is significantly greater then the primary break lime. 

Secondary breaking is required when boulders are produced which are too large to load or to feed into the crushing plant, and when toes are left by primary blasting. Over-sized boulders are broken by three techniques — hydraulic hammers, drop-balls and secondary blasting. 

S. Apte, M. Gorokhovski, P. Moin LES of Atomizing Spray with Stochastic Modeling of Secondary Break-Up, Int. J. Mnltiphase Flow 29, 1503—1522 (2003). 

E-2 Isolation of steam generator with secondary break . 

In addition to noting the primary and secondary break times, any change in the location of the interface after shakeout should also be noted. Such measurements are completed easily if standardized sample vials with flat bottoms are employed in the tests. Other changes, such as the transfer of color from one phase... 

Low compensated steam line pressure as reported by two out of four signals in any steam line. This protects against secondary breaks during power generation. 

A thermal-hydraulic analysis is performed to determine the plant response for a Design Basis SGTR, the integrated primary-to-secondary break flow, and the mass releases from the ruptured and intact steam generators to the condenser and to the atmosphere. This information is then used to calculate the radioactivity release to the environment and the resulting radiological consequences. 

The plant response following an SGTR until the primary-to-secondary break flow is terminated is analyzed with the LOFTTR2 program. The LOFTTR2 program is modified to model the PRHR system, core makeup tanks, and protection system actions appropriate for the APIOOO. 

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