Dynamic corrosion test loop

In view of the fractional filling of the toroid, which results in "slug flow, corrosion attack rates based on the elapsed time of operation may be corrected to account for the time of immersion in the circulating fluid. This is usually required when corrosion rates obtained in a toroid are being compared with those obtained in the dynamic corrosion test loops described below. 

Dynamic corrosion test loops. Dynamic solution corrosion test loops designed to operate under the various conditions proposed for homogeneous reactor operation are the principal experimental equipment used for out-of-pile tests. One such loop is shown diagrammatically in Fig. 5-2, in... 

NACE TM-02-74 Dynamic Corrosion Testing of Metals in High Temperature Water Similar to TM-01-71, but uses circulating loop and heat exchangers Weight loss method. 

In the dynamic slurry corrosion test loop [7], shown in Fig. 5-4, the pump discharge flow is directed through the bottom portion of the pressurizer to minimize settling and accumulation of slurry particles which would occur in this region if the pressurizer were connected as in the solution test loop. As shown in this figure, a condenser is installed in the... 

Corrosion testing was continued for one additional week in the dynamic test loop at 500F, after which it was found that one plate,... 

Corrosion tests in uranyl fluoride solutions. In contrast to uranyl carbonate solutions, uranyl fluoride solutions are acid, and in general the corrosivity of the fluoride solutions is much greater than that of the carbonate solutions. To determine the relative corrosion resistances of many different metals and alloys, a 0.17 m UO2F2 solution was used. Te.sts were performed at 100 and 250°C in static systems and at 250°C in loops. The static tests were continued for periods up to 1000 and 2000 hr. The dynamic tests lasted for 200 hr, and the flow rate of the solution past the specimens was 10 to 15 fps. The results of the dynamic tests are shown in Table 5-4. 

Corrosion tests in uranyl sulfate solutions. Many corrosion tests discussed in detail in HRP progress reports [27] have been carried out in uranyl sulfate solutions under different conditions of temperature, uranium concentration, flow rate, etc. Table 5-5 shows representative corrosion rates of a number of materials obtained in 0.17 m UO2SO4 at 250°C in stainless-steel loops during a 200-hr. exposure. The flow rate of the solution past the specimens was 10 to 15 fps. Static tests, the results of which are not included in the table, have also been carried out at 100 and 250°C and generally lasted for 1000 to 2000 hr. The results obtained in static systems generally confirmed the dynamic results, although the corrosion rates observed in static systems were less than those measured in dynamic systems. 

Evaluation of loop-test results Although the thermal loop test approximates to the conditions which obtain in a dynamic heat-transfer system, in evaluating the results it is necessary to be aware of those aspects in which the test differs from the full-scale unit, as otherwise unwarranted confidence may be placed in the data. Assuming that adequate attention has been paid to the purity and condition of components, etc., the following factors will, according to ASTM G68 1980, influence the observed corrosion behaviour ... 

NACE TM0274 appears to be an outgrowth of the previously mentioned TM0171 test method. It is similar in many aspects. The major difference is the use of a dynamic recirculation loop which accommodates both a high temperature test station and a low temperature test station in which corrosion coupons can be placed. This method can be used for (1) the quantitative measurement of the general corrosion rates of metallic materials for consideration for use in high-purity water, (2) the determination of the effects of flow velocity, and (3) the estimation of the release rate of metallic elements to the aqueous medium. No provisions... 

Thus, In order to avoid the corrosion-exfoliation problems associated with cupronickel HP feed heaters, stainless steel was specified for the HP heaters In the SGHW reactor. Subsequently It was decided to use mild steel In No. 4 unit on an experimental basis to assess Its potentialities for future systems. Dynamic tests conducted In mild steel loops with the appropriate temperature and chemistry Indicated mild steel wastage rates of 2 mdd after 1000 h exposure with 30 release of corrosion products. While some pitting does occur It Is by no means as serious as the exfoliation which could be expected If cupro-nlckel tubes had been Installed In the HP units. 

Dynamic tests of the reaction between Bi and steel in the presence of a radiation field must be completed before a final selection can be made of materials for the LMFR. The effect of velocity on corrosion is not certain from the out-of-pile studies, so that no exact analogy can be made between out-of-pile forced circulation loops and in-pile capsules. There has been limited work done at Harwell [6] with thermal convection loops in and out of a radiation field. These loops had no U but did contain Ca and Zr inhibitors. The data suggest that pile radiation may have induced some acceleration of mass transfer. 

---