Corrosion of M5 in PWRs: Quantification of Li, B, H and Nb in the Oxide Layers Formed Under Different Conditions

Bossis, Philippe; Raepsaet, Caroline; Tupin, Marc; Bisor-melloul, C.; Khodja, H.; Blat, Martine; Ambard, Antoine; Miquet, A.; Kaczorowski, D.

doi:10.1520/jai103709

Cited by 2 publications

(17 citation statements)

References 37 publications

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“…The standards consisted of pieces of cladding with an outer oxide, grown by autoclave exposure. The standards were implanted with 7 Li ions at ETH (Swiss Federal Institute of Technology), and were of the same kind as those used for 7 Li calibration of the SIMS equipment at PSI. SIMS measurements and SRIM calculations (Stopping and Range of Ions in Matter) of the implanted depth profile showed a peak 7 Li content ∼2.1 mm inside the oxide.…”

Section: La-icp-ms Methodsmentioning

confidence: 99%

“…The standards were implanted with 7 Li ions at ETH (Swiss Federal Institute of Technology), and were of the same kind as those used for 7 Li calibration of the SIMS equipment at PSI. SIMS measurements and SRIM calculations (Stopping and Range of Ions in Matter) of the implanted depth profile showed a peak 7 Li content ∼2.1 mm inside the oxide. Reference [5] provides additional information on the SIMS analysis and on the use of the same type of implanted reference materials.…”

Section: La-icp-ms Methodsmentioning

confidence: 99%

“…Reference [5] provides additional information on the SIMS analysis and on the use of the same type of implanted reference materials. With the above information and the implanted dose, the calculated peak 7 Li oxide content was used for calibration. The ablation depth rate was obtained by transforming the ablation time from the first rise in 91 Zr signal to the time to reach the 7 Li peak in the implanted standards, resulting in a depth rate of 0.5 mm/s (in good agreement with the SEM results).…”

Section: La-icp-ms Methodsmentioning

confidence: 99%

“…No boiling is expected at this elevation during normal operation. -Last cycle reactor 7 Li concentration 5 ppm, decreasing to ∼2 ppm.…”

Section: Fuel and Operating History Datamentioning

confidence: 99%

“…The scope of investigation consisted of cutting of the sample, ∼10 mm long near the rod-to-rod contact point followed by LA-ICP-MS (Laser Ablation Inductively Coupled Plasma Mass Spectrometry) investigation of the 7 Li and 11 B content in the outer oxide.…”

Section: Scopementioning

confidence: 99%

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Lithium and boron analysis by LA-ICP-MS results from a bowed PWR rod with contact

Puranen

Tejland

Granfors

et al. 2017

EPJ Nuclear Sci. Technol.

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Abstract. A previously published investigation of an irradiated fuel rod from the Ringhals 2 PWR, which was bowed to contact with an adjacent rod, identified a significant but highly localised thinning of the clad wall and increased corrosion. Rod fretting was deemed unlikely due to the adhering oxide covering the surfaces. Local overheating in itself was also deemed insufficient to account for the accelerated corrosion. Instead, an enhanced concentration of lithium due to conditions of local boiling was hypothesised to explain the accelerated corrosion. Studsvik has developed a hot cell coupled LA-ICP-MS (Laser Ablation Inductively Coupled Plasma Mass Spectrometer) equipment that enables a flexible means of isotopic analysis of irradiated fuel and other highly active surfaces. In this work, the equipment was used to investigate the distribution of lithium ( 7 Li) and boron ( 11 B) in the outer oxide at the bow contact area. Depth profiling in the clad oxide at the opposite side of the rod to the point of contact, which is considered to have experienced normal operating conditions and which has a typical oxide thickness, evidenced levels of ∼10-20 ppm 7Li and a 11 B content reaching hundreds of ppm in the outer parts of the oxide, largely in agreement with the expected range of Li and B clad oxide concentrations from previous studies. In the contact area, the 11 B content was similar to the reference condition at the opposite side. The 7 Li content in the outermost oxide closest to the contact was, however, found to be strongly elevated, reaching several hundred ppm. The considerable and highly localised increase in lithium content at the area of enhanced corrosion thus offers strong evidence for a case of lithium induced breakaway corrosion during power operation, when rod-to-rod contact and high enough surface heat flux results in a very local increase in lithium concentration.

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Section: La-icp-ms Methodsmentioning

confidence: 99%