In PWRs - a different LWR system - control rods are withdrawn from the core, and the control is acheived with soluble B-10 in the coolant (which is buffered with LiOH) to maintain a pH above 6.9 or perhaps closer to 7.1 -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.
Repetition (rhetorical device) Repetition is the simple repeating of a word, within a sentence or a poetical line, with no particular placement of the words, in order to secure emphasis. This is such a common literary device that it is almost never even noted as a figure of speech.