In PWRs - a different LWR system - control rods are withdrawn from the core, and the control is acheived with soluble B-10 in the coolant (which is buffered with LiOH) to maintain a pH above 6.9 or perhaps closer to 7.1 - 7.4 for purposes of minimizing the accumulation of crud (metal corrosion products) on the fuel.
Rhetorical patterns have an additional function of helping writers to organize information in ways their readers can understand easily (425). Another term for these patterns is topoi (commonplaces). Many of these topoi are useful in numerous situations.
1  Allusion, I suggest, functions like the trope of classical rhetoric. 2  A rhetorical trope is usually defined as the figure created by dislodging of a term from its old sense and its previous usage and by transferring to a new, proper, or 'strange' sense and usage.