Resin Overheating:
Since the potential for elevated temperatures exists in during most conditions of facility operation, that will summarize the output from the resin in an ion exchanger overheating. Primary the resin of an ion exchanger is an inert polystyrene structure along with ion exchange sites "loosely" attached. The simple structure is stable up to fairly high temperatures (around 300º F), but the active exchange sites are not. There are two categories of exchange sites: cation and anion. The anion resin starts to decompose slowly at about 140º F, and the decomposition becomes rapid above 180º F. The cation resin is stable up to about 250ºF. Since these temperatures are well below normal reactor coolant temperatures, a temperature of the coolant must be lowered before it passes by the ion exchange resin.
The decomposition of resin generates an alcohol form of the resin, that has no exchange capability, and trimethylamine (TMA), N(CH3)3. TMA is a weak base, same to ammonia which reacts along with water as follows.
N(CH3)3 + H2O ↔ NH(CH3)3+ + OH-
The pH might increase noticeably if large amounts of TMA are released to the coolant. For instance, 1 ppm of TMA in reactor coolant which uses lithium form resin will cause a noticeable rise in pH. TMA might also interfere along with the analysis for chloride ions (that is routinely performed on reactor coolant) through providing a false indication of high chloride concentration. The other significant property of TMA is its intense odor of dead fish. While the presence of like an odor from reactor coolant is not definitive for TMA, it might provide an indication of resin overheating.