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Effects of alternate pH control additives on PWR secondary cycle chemistry: Final report

Technical Report ·
OSTI ID:5580437

Use of morpholine as a pH control additive at Prairie Island and Beaver Valley significantly reduced iron levels in the condensate and feedwater. This impact is attributed primarily to the increase in liquid film pH in two-phase regions as a result of the lower steam/liquid distribution coefficient of morpholine compared to ammonia. Although results indicate that morpholine does not increase blowdown removal efficiency compared to ammonia, the reduction in feedwater iron transport is sufficient to significantly reduce sludge buildup in the steam generators. Decomposition of morpholine leads to formation of formic and acetic acids which increase blowdown cation conductivity. However, the observed increase is less than 0.2 uS/cm, and the sensitivity of cation conductivity to strong acid anions does not decrease significantly. Use of 2-amino-2-methyl-l-propanol and dimethyl-amino-propanol (AMP-DMAP) as an alternate pH control additive at Fort Calhoun (approximately 0.4 ppM in the feed-water) had no significant beneficial effect on corrosion product transport compared to ammonia. In addition, acetate concentrations and the elevation in cation conductivity were much greater than the use of morpholine at Beaver Valley and Prairie Island.

Research Organization:
NWT Corp., San Jose, CA (USA)
OSTI ID:
5580437
Report Number(s):
EPRI-NP-5594; ON: TI88920214
Country of Publication:
United States
Language:
English