Hydrogen water chemistry

BWR Water Chemistry Guidelines—1993 Revision, Normal and Hydrogen Water Chemistry," Report TR-103515, Electric Power Research Institute, Palo Alto, Calif., Feb. 1993. 

Using this approach, corrosion potentials have been calculated for various components in the heat-transport circuit of a BWR, as shown in Fig. 19, as a function of the concentration of hydrogen added to the feedwater. The calculations predict that the lower plenums and recirculation systems of many BWRs can be protected by hydrogen water chemistry, but that those components that are exposed to high radiation fields and/or high concentration of radiolysis products cannot be protected, at least under full-power operating conditions. Similar calculations have been carried out [46] for in-vessel materials in PWRs, in order to explore the susceptibility of various components to intergranular fracture. 

Normal water chemistry - — Hydrogen water chemistry — Normal to hydrogen water chemistry... 

C. P. Ruiz, C. C. Irvin, Modeling Hydrogen Water Chemistry for BWR Applications, EPRI-NP-6386, Electric Power Research Institute, June 1989. 

A more detailed study of N behavior under both BWR normal (NWC) and hydrogen water chemistry (HWC) conditions was performed by Lin (1989), using... 

Lin, C. C. Chemical behavior of radioiodine in boiling water reactor systems. II. Effects of hydrogen water chemistry. Nucl. Technology 97, 71-78 (1992)... 

The constants R and k obviously depend on the type of base material used, with molybdenum-containing stainless steel 316 SS having other values than the normally used 304 SS. To explain these differences, it was assumed that molybdenum ions present in the spinel oxide film are oxidized under normal water chemistry conditions, creating additional vacancies which may act as additional adsorption sites for cobalt and other transition metal ions. Under hydrogen water chemistry conditions, the difference in Co buildup rate between these two base materials vanishes, obviously due to the fact that no molybdenum oxidation occurs so that no additional vacancies in the oxide film are formed. 

Under hydrogen water chemistry (HWC) conditions, the Co deposition was observed to proceed faster than predicted from a logarithmic rate law, suggesting that under such conditions cobalt deposition is not controlled exclusively by the... 

Asakura, Y, Uchida, S., Ohsumi, K., Shindo, T., Aizawa, M., Usui, N., Amano, O., Yoshi-kawa, S., Otoha, K. Current operating experience with water chemistry in crud concentration suppressed boiling water reactors. Proc. 5. BNES Conf. Water Chemistry of Nuclear Reactor Systems. Bournemouth, UK, 1989, Vol. 1, p. 115-122 Asay, D. Radiation-field buildup at the Monticello BWR with hydrogen water chemistry. Report EPRI NP-7520 (1991)... 

Indig, M. E., SSRT for Hydrogen Water Chemistry Verification in Boiling Water Reactors, Slow Strain Rate Testing for the Evaluation of Enviromnentally Induced Cracking Research and Engineering Applications, ASTM STP 1210, R. D. Kane, Ed., ASTM International, West Conshohocken, PA, 1993. 

The EPRI guidelines for BWR primary coolant system water chemistry [4.3] is listed in Table 4-2a for Normal Water Chemistry (NWC) and Table 4-2b for HWC (Hydrogen Water Chemistry) or HWC+NMCA (Noble Metal Chemical Addition). The NWC guideline is also followed in Finland. 

The two most common methods currently being used to mitigate IGSCC/IASCC in BWR internals through water chemistry control are Hydrogen Water Chemistry (HWC) and Noble Metal Chemical Application (NMCA). Additional information about experience with... 

Implementing improvements such as Hydrogen Water Chemistry, Noble Metal... 

The comparison between the theoretical and observed crack growth rate-stress intensity relationships are shown for a sensitized stainless steel in a somewhat impure BWR environment (Fig. 16a) and a more modem hydrogen water chemistry BWR environment (Fig. 16b). The agreement between observation and theory is apparent, as is the inapplicability of a single life prediction law such as the NRC disposition line to a system which can exhibit a wide range of conditions within a nominal specification. 

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