Characterization of In-Core Water Chemistry for Corrosion Control of LWRs

2014 ◽  
Author(s):  
Genn Saji
Keyword(s):  
Redox Potential ◽  
Water Chemistry ◽  
Single Point ◽  
Experimental Results ◽  
Potential Difference ◽  
Corrosion Mechanism ◽  
Recent Theory ◽  
Scientific Validity ◽  
Pile Test ◽  
Test Loop

This paper updates scientific bases of water chemistry in applying the author’s recent theory, which integrates the elemental radiation- and electro-chemistry reactions in the “Butlar-Volmer equation,” presented in ICONE21-16525. For the past several years the author has been trying to establish that the “long-cell” (a kin to macro-cell) corrosion mechanism is inducing practically all sorts of accelerated corrosion phenomena widely observed in water-cooled reactors, especially in aged plants. The theoretical electrochemical potential differences have been benchmarked with the published in-pile test results for both PWR- and BWR water chemistry environments. However the author’s previous verification efforts were limited to the extent that the curves were fitted with experimental results at a single point. The author re-formulated the basic theory and found that the redox potential difference consists of an electrochemical part (e.g., Nernst equation of dissolved hydrogen or oxygen) and radiation-induced perturbation term, the latter diminishes to zero without radiation. The author continued his studies to clarify whether our current scientific knowledge is sufficient to explain the in-core “chemistry” to reproduce the experimental results without the fitting parameter. Through his study he realized that the basic mechanism of the potential difference is still not sufficiently known. No fitting parameter was used for the PWR water chemistry in the DH region for practical engineering applications, although it is indispensable to confirm the results with an in-pile test loop. In the BWR-NWC the theoretical redox potential out of core was still necessary to be fitted with the experimental results, due to an effect of residual hydrogen peroxide detected by the reference electrode. In addition the calculated potential shift is several times larger than the experimental observation. With the reformulation the scientific validity of the author’s theory is further confirmed. He believes that there is no doubt that the “long-cell” takes place in LWRs, although details are still debatable.

Scientific Bases of Water Chemistry for Corrosion Control of NPPs by Integration of Radiation- and Electro-Chemistry

2013 ◽  
Author(s):  
Genn Saji
Keyword(s):  
Hydrogen Peroxide ◽  
Water Chemistry ◽  
Material Balance ◽  
Scientific Basis ◽  
Experimental Results ◽  
Basic Material ◽  
General Interest ◽  
Recent Theory ◽  
Radiation Chemical ◽  
Corrosion Science

In this paper, the author continues his investigation on the scientific basis of water chemistry specifications by applying his recent theory, which integrates the elemental radiation- and electro-chemistry reactions in the “Butlar-Volmer equation.” The B-V equation is well established as the basic material balance equation in corrosion science. The author’s new approach has been compared with the published in-pile test results of the electrochemical potential differences between the in-flux and out-flux regions for both the PWR- and BWR water chemistry environment. Although the theoretical estimation generally reproduced the experimental results, there remains significant deviation from the experimental results at the very low DH region (<10cc-STP/kg-water) in PWRs as well as the low DO region (<10ppb) in BWRs. Although these regions are outside of the water chemistry specifications of general interest, the scientific causes of the deviation must be clarified. In this paper, the author found that the deviations are due to the dominant radiation-chemical reactions involving hydrogen ions and hydrogen peroxide at the lower ends. Although the radiation- and electrochemical reaction was further exploited with respect to the potential differences induced by the hydrogen peroxide, the effects were disappointingly small, when estimated in terms of a mixed potential of the electrode reactions. This leads the author to suspect that hydrogen-ion-radical reactions should be the main causes. Currently further analyses are in progress.

A new method for monitoring the redox potential of fuel salt based on the deposition of 95Nb on Hastelloy C276

2021 ◽  
Vol 109 (5) ◽  
pp. 357-365
Author(s):  
Zhiqiang Cheng ◽  
Zhongqi Zhao ◽  
Junxia Geng ◽  
Xiaohe Wang ◽  
Jifeng Hu ◽  
...  
Keyword(s):  
Redox Potential ◽  
Molten Salt ◽  
Specific Activity ◽  
Chemical Reduction ◽  
Quantitative Approach ◽  
Experimental Results ◽  
New Method ◽  
Molten Salt Reactor ◽  
Fuel Salt ◽  
Well Correlation

Abstract To develop the application of 95Nb as an indicator of redox potential for fuel salt in molten salt reactor (MSR), the specific activity of 95Nb in FLiBe salt and its deposition of 95Nb on Hastelloy C276 have been studied. Experimental results indicated that the amount of 95Nb deposited on Hastelloy C276 resulted from its chemical reduction exhibited a positive correlation with the decrease of 95Nb activity in FLiBe salt and the relative deposition coefficient of 95Nb to 103Ru appeared a well correlation with 95Nb activity in FLiBe salt. Both correlations implied that the measurement of 95Nb activity deposited on Hastelloy C276 specimen might provide a quantitative approach for monitoring the redox potential of fuel salt in MSR.

scholarly journals Research on the Influencing Factors of "Scale Veins" of Single Point Incremental Forming Workpieces Surface

2015 ◽  
Vol 9 (1) ◽  
pp. 1025-1032
Author(s):  
Shi Pengtao ◽  
Li Yan ◽  
Yang Mingshun ◽  
Yao Zimeng
Keyword(s):  
Surface Quality ◽  
Incremental Forming ◽  
Single Point ◽  
Spindle Speed ◽  
Experimental Results ◽  
Feed Speed ◽  
Single Point Incremental Forming ◽  
Machining Parameters ◽  
The Mathematical Model

To furthermore optimize the machining parameters and improve the surface quality of the workpieces manufactured by single point incremental forming method, the formation mechanism of the sacle veins on the metal incremental froming workpieces was studied through experiment method. The influence principle of the spindle speed, the feed speed and the material of tip of tools on the length of scale veins was obtained through analyzing the experimental results and building the mathematical model among the length of scale veins were feed speed and spindle speed through measuring the roughness of surfaces and observing the appearance of the forming workpieces. The experimental results showed that, the spindle speed, the feed speed and the material of tool tips have a significant effect on the scale veins formation on the surface of forming workpieces. Therefore, an appropriate group of spindle speed and feed speed can reduce the effect of scale veins on the roughness of single point incremental forming workpieces and furthermore improve the surface quality of forming workpieces.

Radiation-Induced Electrolytic Corrosion of LWRS: (Part 2) — Verification of In- and Out-Core Redox Potential Differences

2016 ◽  
Author(s):  
Genn Saji
Keyword(s):  
Dielectric Property ◽  
Redox Potential ◽  
Single Point ◽  
Ionic Species ◽  
Nernst Equation ◽  
Radiation Chemical ◽  
Potential Shift ◽  
Reactor Water ◽  
Electrolytic Corrosion ◽  
Radiation Induced

The author recently identified that there should exist a “differential radiation cell” mechanism in the reactor water, prompting “radiation-induced electrolytic (RIE)” phenomena. This mechanism was identified while trying to theoretically reconstruct the potential differences observed in two in-pile test loops; NRI-Rez in Czech Republic and INCA Loop in Sweden. Part 2 of this series focuses on the theoretical reconstruction of the observed potential differences. Assuming a state of equilibrium, the author tried to develop a formalism by extending the Nernst equation to reproduce the observed redox potential differences. The radiological potential shift term is separated from the Nernst equation where the latter deals only with stable molecular and ionic species. The radiological effect is described as a perturbation term to the Nernst equation representing a potential shift due to radiation-chemical reactions which should diminish to zero without radiation. The theory generally reproduced the experimental results after fitting the theoretical curve at a single point of the potential for both PWR and BWR-NWC water chemistry environments. This discrepancy is likely due to the “conductive-dielectric property” of the reactor water.

Risk Analysis of Live Fire Shoot House Containment Systems Against Multiple Projectile Impacts

2020 ◽  
Author(s):  
Steven D. Andreen ◽  
Brad G. Davis
Keyword(s):  
Normal Distribution ◽  
Numerical Models ◽  
Single Point ◽  
Experimental Results ◽  
Risk Level ◽  
Triangular Distribution ◽  
Repeated Impact ◽  
Steel Panels ◽  
The Impact ◽  
Projectile Impacts

Abstract Many analytical and numerical models exist that can describe the effect of single projectile impacts on steel targets. These models are not adequate for the evaluation of live fire shoot house containment systems, which are subjected to repeated impact loading from small caliber projectiles over the lifetime of the structure. Models assuming perfectly rigid projectiles over-predict penetration depths. Models assuming rigid targets cannot predict any penetration, and hydrodynamic models are best suited to high velocity impacts well above the ranges of conventional ordinance. Development of sufficient analytical or numerical tools using traditional techniques would be either intractable, empirically based and unique to a given scenario, require unique material properties that are not commonly available, or require significant computational effort. Due to the limited amount of empirical data on multiple impact failure, classical reliability methods are not suitable for assessing the probability of containment system perforation. Using existing experimental results of .223 caliber ammunition against AR500 steel panels with 2-inch ballistic rubber, a commonly found protective system in these facilities, the cumulative effects of multiple projectiles were quantified to estimate the number of impacts required to perforate the target material. Impacts were simulated from normal distributions of the x and y coordinates describing the impact point using a cartesian coordinate plane. The impact resistance of the steel was also simulated from a triangular distribution to account for the variability of the experimental results. Monte Carlo Simulation was then used to estimate the expected number of impacts to cause failure at a single point on the target. Using this collective model, it was possible to determine that the distribution of the number of rounds to cause target failure approached a normal distribution. The results indicated that the mean impacts at failure was 11800 with a standard deviation of 800 impacts. Finally, targeting the allowable risk level for structural failure from the JCSS probabilistic model code from the simulated normal distribution, it was determined that the safe number of impacts was approximately 7996. Decision makers can utilize the safe number of impacts to inform training guidance for the future use of facilities and to develop effective inspection requirements. This model can also be adapted to evaluate similar training facilities and to assess how other small caliber projectile impacts would affect live fire shoot house containment systems, providing a useful tool for the design and analysis of future and the assessment of existing facilities for use with ammunition that did not exist during its design.

Chemico-Physical Causes of Radiation-Induced “Long Cell” Action Corrosion in Water Cooled Reactors

2010 ◽  
Author(s):  
Genn Saji
Keyword(s):  
Chemical Potential ◽  
Cooling System ◽  
Radiation Chemistry ◽  
Potential Difference ◽  
Equilibrium Potential ◽  
Corrosion Mechanism ◽  
Hydrated Electrons ◽  
Standard Chemical Potential ◽  
Radiation Induced ◽  
Reactor Types

In the previous overview papers [1, 2], the author has identified that ‘long cell action’ corrosion plays a pivotal role in practically all unresolved corrosion issues, irrespective of reactor types and operation. In trying to confirm the existence of radiation-induced ‘long-cell’ action (macro) corrosion cell in the primary cooling system of LWRs, the author attempted to theoretically reproduce the electrochemical potential difference demonstrated during experiments at the INCA Loop in Sweden and the NRI-Rez Loop in the Czech Republic [3, 4]. By performing a radiation chemistry kinetics study combined with electrochemistry calculations, the hydrated electrons, e−aq, reacting mainly with stable molecules, are found to be responsible for inducing a large portion of the potential difference both in the PWR and BWR water chemistry environment. Considering large uncertainties, the author used the standard equilibrium potential as a fitting parameter in the previous studies [3, 4]. The standard chemical potential of the hydrated electron estimated from the fitting parameter is far less than the generally accepted value of 2.86 V. In order to resolve the large discrepancy between the generally accepted values and the estimation from the fitting parameter, the author has developed a ‘mixed’ radiation-electrochemistry formalism, which enables theoretical reconstruction of the observed potential differences more clearly. The previous verifications are updated by using this approach. Through these studies, the author has confirmed the existence of the ‘long cell’ action corrosion mechanism existing in the water-cooled reactors.

Development of Water Radiolysis Code for the JMTR IASCC Test Loop

2006 ◽  
Author(s):  
Satoshi Hanawa ◽  
Tomonori Sato ◽  
Yuichiro Mori ◽  
Jin Oogiyanagi ◽  
Yoshiyuki Kaji ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Water Chemistry ◽  
Loop System ◽  
Water Radiolysis ◽  
Sampling Point ◽  
Water Sampling ◽  
Multiple Node ◽  
Irradiation Test ◽  
Test Loop ◽  
Irradiation Field

In order to evaluate the water chemistry in the irradiation field during IASCC irradiation test, a water radiolysis code for IASCC irradiation loop system was developed. In the water radiolysis code, a multiple node model was introduced since the irradiation loop system has a wide rage temperature distribution as well as the dose distribution. To investigate the applicability of developed water radiolysis code, water chemistry at the water sampling point of the irradiation loop system was measured and compared with analytical results under several water chemistry conditions. Further, water chemistry distribution in the in-pile region as well as in the out-pile region was calculated by the developed water radiolysis code.

scholarly journals THe proton-per-electron stoicheiometry of ‘site 1’ of oxidative phosphorylation at high protonmotive force is close to 1.5

1982 ◽  
Vol 204 (2) ◽  
pp. 515-523 ◽  
Author(s):  
P C de Jonge ◽  
H V Westerhoff
Keyword(s):  
Redox Potential ◽  
Redox State ◽  
Dynamic Equilibrium ◽  
Experimental Situation ◽  
Potential Difference ◽  
Protonmotive Force ◽  
Submitochondrial Particles ◽  
Output Force ◽  
Group Translocation ◽  
Static Head

The maximum redox potential difference between the NAD+/NADH couple and the succinate/fumarate couple generated during ATP-energized reduction of NAD+ by succinate in submitochondrial particles was measured, together with the electrochemical potential difference for protons (delta mu approximately H+). The presence of cyanide, the time-independence of the redox potential difference and the irrelevance of the initial redox state of the NAD+/NADH couple ensured that the experimental situation corresponded to a ‘static-head condition’ with delta mu approximately H+ as the input force and the redox potential difference as the output force, the flow of electrons having reached dynamic equilibrium. Consequently, the observed value of 1.6 for the ratio delta Ge/delta mu approximately H+ is interpreted as indicating that the leads to H+/e- stoicheiometry at ‘site 1’ is 1.5 and that therefore the mechanism of the proton pump at ‘site 1’ is not of the group-translocation type (no direct leads to e - leads to H+ coupling).

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