Effect of KOH and dissolved hydrogen on oxide film and stress corrosion cracking susceptibility of Alloy X-750
The replacement of LiOH with KOH for pH control in the primary water of pressurized water reactors (PWRs) is being considered due to the growing cost of enriched 7Li. This study aims to investigate the susceptibility of the primary water stress corrosion cracking (PWSCC) initiation in simulated prim...
| Main Authors: | , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
The Japan Society of Mechanical Engineers
2023-10-01
|
| Series: | Mechanical Engineering Journal |
| Subjects: | |
| Online Access: | https://www.jstage.jst.go.jp/article/mej/11/2/11_23-00317/_pdf/-char/en |
| _version_ | 1797206048551993344 |
|---|---|
| author | Kenta KAKITANI Wataru SUGINO Yusuke NAKANO Kenji SATO Yuichi SHIMIZU |
| author_facet | Kenta KAKITANI Wataru SUGINO Yusuke NAKANO Kenji SATO Yuichi SHIMIZU |
| author_sort | Kenta KAKITANI |
| collection | DOAJ |
| description | The replacement of LiOH with KOH for pH control in the primary water of pressurized water reactors (PWRs) is being considered due to the growing cost of enriched 7Li. This study aims to investigate the susceptibility of the primary water stress corrosion cracking (PWSCC) initiation in simulated primary water with KOH. Firstly, the susceptibilities in KOH and LiOH chemistries were compared by conducting uniaxial constant load tests on Alloy X-750 at 360°C. The results showed no significant difference in the time to initiation between the two chemistries. Secondly, the effect of dissolved hydrogen (DH) concentration in the KOH chemistry was examined. The DH concentration of the test water was varied at 5, 30 or 45 ml/kg-H2O. The results showed that the time to initiation of PWSCC was significantly extended under the low DH condition (5 ml/kg-H2O). This observed effect of DH concentration in the KOH environment agrees with the previously reported effect observed in the conventional LiOH environment. To investigate the mechanisms underlying the PWSCC tests, the oxide films on the test specimens were characterized using electron microscopes. The oxide films formed in the KOH and LiOH chemistries did not show significant differences. Additionally, under the low DH condition, the occurrence of selective internal oxidation under the inner oxide film was relatively minor. The results suggest that the use of KOH would not have an adverse effect on PWSCC initiation, and PWSCC initiation can be mitigated with a low concentration of DH in the KOH environment as well as in the LiOH environment. |
| first_indexed | 2024-04-24T09:00:49Z |
| format | Article |
| id | doaj.art-787a9f4cce32412fabe54589f79a2d05 |
| institution | Directory Open Access Journal |
| issn | 2187-9745 |
| language | English |
| last_indexed | 2024-04-24T09:00:49Z |
| publishDate | 2023-10-01 |
| publisher | The Japan Society of Mechanical Engineers |
| record_format | Article |
| series | Mechanical Engineering Journal |
| spelling | doaj.art-787a9f4cce32412fabe54589f79a2d052024-04-16T01:29:36ZengThe Japan Society of Mechanical EngineersMechanical Engineering Journal2187-97452023-10-0111223-0031723-0031710.1299/mej.23-00317mejEffect of KOH and dissolved hydrogen on oxide film and stress corrosion cracking susceptibility of Alloy X-750Kenta KAKITANI0Wataru SUGINO1Yusuke NAKANO2Kenji SATO3Yuichi SHIMIZU4Mitsubishi Heavy Industries, Ltd.The Japan Atomic Power CompanyThe Japan Atomic Power CompanyMitsubishi Heavy Industries, Ltd.Mitsubishi Heavy Industries, Ltd.The replacement of LiOH with KOH for pH control in the primary water of pressurized water reactors (PWRs) is being considered due to the growing cost of enriched 7Li. This study aims to investigate the susceptibility of the primary water stress corrosion cracking (PWSCC) initiation in simulated primary water with KOH. Firstly, the susceptibilities in KOH and LiOH chemistries were compared by conducting uniaxial constant load tests on Alloy X-750 at 360°C. The results showed no significant difference in the time to initiation between the two chemistries. Secondly, the effect of dissolved hydrogen (DH) concentration in the KOH chemistry was examined. The DH concentration of the test water was varied at 5, 30 or 45 ml/kg-H2O. The results showed that the time to initiation of PWSCC was significantly extended under the low DH condition (5 ml/kg-H2O). This observed effect of DH concentration in the KOH environment agrees with the previously reported effect observed in the conventional LiOH environment. To investigate the mechanisms underlying the PWSCC tests, the oxide films on the test specimens were characterized using electron microscopes. The oxide films formed in the KOH and LiOH chemistries did not show significant differences. Additionally, under the low DH condition, the occurrence of selective internal oxidation under the inner oxide film was relatively minor. The results suggest that the use of KOH would not have an adverse effect on PWSCC initiation, and PWSCC initiation can be mitigated with a low concentration of DH in the KOH environment as well as in the LiOH environment.https://www.jstage.jst.go.jp/article/mej/11/2/11_23-00317/_pdf/-char/enpressurized water reactorprimary waterpotassium hydroxide (koh)dissolved hydrogenoxide filmstress corrosion crackingalloy x-750nickel-based alloy |
| spellingShingle | Kenta KAKITANI Wataru SUGINO Yusuke NAKANO Kenji SATO Yuichi SHIMIZU Effect of KOH and dissolved hydrogen on oxide film and stress corrosion cracking susceptibility of Alloy X-750 Mechanical Engineering Journal pressurized water reactor primary water potassium hydroxide (koh) dissolved hydrogen oxide film stress corrosion cracking alloy x-750 nickel-based alloy |
| title | Effect of KOH and dissolved hydrogen on oxide film and stress corrosion cracking susceptibility of Alloy X-750 |
| title_full | Effect of KOH and dissolved hydrogen on oxide film and stress corrosion cracking susceptibility of Alloy X-750 |
| title_fullStr | Effect of KOH and dissolved hydrogen on oxide film and stress corrosion cracking susceptibility of Alloy X-750 |
| title_full_unstemmed | Effect of KOH and dissolved hydrogen on oxide film and stress corrosion cracking susceptibility of Alloy X-750 |
| title_short | Effect of KOH and dissolved hydrogen on oxide film and stress corrosion cracking susceptibility of Alloy X-750 |
| title_sort | effect of koh and dissolved hydrogen on oxide film and stress corrosion cracking susceptibility of alloy x 750 |
| topic | pressurized water reactor primary water potassium hydroxide (koh) dissolved hydrogen oxide film stress corrosion cracking alloy x-750 nickel-based alloy |
| url | https://www.jstage.jst.go.jp/article/mej/11/2/11_23-00317/_pdf/-char/en |
| work_keys_str_mv | AT kentakakitani effectofkohanddissolvedhydrogenonoxidefilmandstresscorrosioncrackingsusceptibilityofalloyx750 AT watarusugino effectofkohanddissolvedhydrogenonoxidefilmandstresscorrosioncrackingsusceptibilityofalloyx750 AT yusukenakano effectofkohanddissolvedhydrogenonoxidefilmandstresscorrosioncrackingsusceptibilityofalloyx750 AT kenjisato effectofkohanddissolvedhydrogenonoxidefilmandstresscorrosioncrackingsusceptibilityofalloyx750 AT yuichishimizu effectofkohanddissolvedhydrogenonoxidefilmandstresscorrosioncrackingsusceptibilityofalloyx750 |