Tensile properties of modified 316 stainless steel (PNC316) after neutron irradiation over 100 dpa

Yano, Yasuhide; Uwaba, Tomoyuki; Tanno, Takashi; Yoshitake, Tsunemitsu; Otsuka, Satoshi; Kaito, Takeji

Journal of Nuclear Science and Technology, 9 Pages, 2023/00

https://doi.org/10.1080/00223131.2023.2243943

The effects of fast neutron irradiation on tensile properties of modified 316 stainless steel (PNC316) claddings and wrappers for fast reactors were investigated. PNC316 claddings and wrappers were irradiated in the experimental fast reactor Joyo at irradiation temperatures between 400 and 735 C to fast neutron doses ranging from 21 to 125 dpa. The post-irradiation tensile tests were carried out at room and irradiation temperatures. Elongations of PNC316 measured by the tensile tests were maintained at an engineering level, although the material incurred significant irradiation hardening and softening. The maximum swelling of PNC316 wrappers was about 2.5 vol.% at irradiation temperature between 400 and 500C up to 110 dpa. Japanese 20% cold-worked austenitic steels, PNC316 and 15Cr-20Ni, had sufficient ductility and work-hardenability even after above 10 vol.% swelling, while they had very weak plastic instabilities.

Measurement and analysis of in-vessel component activation and gamma dose rate distribution in Joyo, 2

Yamamoto, Takahiro; Ito, Chikara; Maeda, Shigetaka; Ito, Hideaki; Sekine, Takashi

JAEA-Technology 2017-036, 41 Pages, 2018/02

JAEA-Technology-2017-036.pdf:7.86MB

In the experimental fast reactor Joyo, the damaged upper core structure (UCS) was retrieved into the cask in May 2014 The dose rate on UCS surface was quite high due to the activation for over 30 years operation. In order to attain the optimum safety design, manufacture and operation of equipment for UCS replacement, the method to evaluate UCS surface dose rate was developed on the basis of C/E obtained by the in-vessel dose rate measurement in Joyo. In order to verify the evaluation method, the axial gamma-ray distribution measurement on the surface of the cask, which contained UCS, was conducted using a plastic scintillating optical fiber (PSF) detector. This paper describes the comparison results between calculation and measurement as follows. (1) The measured axial gamma-ray distribution on the cask surface had a peak on proper location with considering the cask shielding structure and agree well with the calculated distribution. (2) The C/E of axial gamma-ray distribution on the cask surface was ranged from 1.1 to 1.7. It was confirmed that the calculation for UCS replacement equipment design had a margin conservatively. Then, the results showed that the developed evaluation method for UCS replacement equipment design was sufficiently reliable.

Inspection and repair techniques in the reactor vessel of the experimental fast reactor Joyo; Observation technical development in a reactor vessel of the fast reactor, 3

Okuda, Eiji; Sasaki, Jun; Suzuki, Nobuhiro; Takamatsu, Misao; Nagai, Akinori

JAEA-Technology 2016-017, 20 Pages, 2016/07

JAEA-Technology-2016-017.pdf:5.75MB

In-Vessel Observation (IVO) techniques for Sodium Cooled Fast Reactors (SFRs) in service are important for confirming their safety and integrity. Since IVO equipment for an SFR has to be designed to tolerate the severe conditions (high temperature, high radiation dose and limited access route), fiberscopes used to be used in previous IVO for SFRs. However, in order to attain an IVO with higher quality and resolution, IVO using a radiation resistant camera was conducted in the fast experimental reactor Joyo and obtained some results. The demonstration results provided valuable insights for use in further improving and verifying IVO techniques in SFRs.

Design and manufacture of Joyo upper core structure for replacement

Ota, Katsu; Ushiki, Hiroshi*; Maeda, Shigetaka; Kawahara, Hirotaka; Takamatsu, Misao; Kobayashi, Tetsuhiko; Kikuchi, Yuki; Tobita, Shigeharu; Nagai, Akinori

JAEA-Technology 2015-026, 180 Pages, 2015/11

JAEA-Technology-2015-026.pdf:79.87MB

In the experimental fast reactor Joyo, it was confirmed that the top of the irradiation test sub-assembly of "MARICO-2" (material testing rig with temperature control) had bent onto the in-vessel storage rack as an obstacle and had damaged the upper core structure (UCS). The replacement of the UCS was conducted from May to December 2014. The design and manufacture of UCS was started from 2008, and the installation of UCS was completed successfully in November 21th 2014. The major results gained during the design and manufacture of UCS is as follows.

Inspection and repair techniques in the reactor vessel of the experimental fast reactor Joyo; Observation techniques development in a reactor vessel of the fast reactor, 2

Okuda, Eiji; Sasaki, Jun; Suzuki, Nobuhiro; Takamatsu, Misao; Nagai, Akinori

JAEA-Technology 2015-005, 36 Pages, 2015/03

JAEA-Technology-2015-005.pdf:44.42MB

In-Vessel Observations (IVO) techniques for Sodium cooled Fast Reactors (SFRs) are important in confirming its safety and integrity. In order to secure the reliability of IVO techniques, it was necessary to demonstrate the performance under the actual reactor environment with high temperature, high radiation dose and remained sodium. The IVO equipment for the Upper Core Structure (UCS) fitting area was specifically developed in the experimental fast reactor "Joyo". And the IVO was successfully completed as shown below. (1) Improvement of picture quality and resolution. The IVO of UCS fitting area with the gap of 5mm in minimum was achieved using the IVO equipment with video-scope under the actual reactor environment. The picture quality and resolution could be improved comparing with the radiation resistant fiberscope which was used in past IVO. (2) Prevention of video-scope hypofunction by high temperature / radiation dose. Since video-scope is inferior in thermal and radiation resistance, the IVO equipment was designed to be able to withdraw and insert video-scopes with cooling gas. This measure could achieve the observation in short radiation time with available temperature under the actual reactor environment. The IVO equipment for UCS fitting area provided useful information on UCS replacement. In addition, the experience provided valuable insights into further improvements for IVO techniques in SFRs.

None

JNC TN1400 2001-014, 437 Pages, 2001/10

JNC-TN1400-2001-014.pdf:23.1MB

no abstracts in English

Post irradiation examination of (U,Pu) C and (U,Pu) N fuel for fast reactor; Non-destructive examination result of the fuel pin

; ; ; Matsumoto, Shinichiro

JNC TN9410 2000-009, 65 Pages, 2000/09

JNC-TN9410-2000-009.pdf:4.36MB

In order to evaluate irradiation behavior of(U, Pu) C and (U, Pu) N fuel using fast reactor, (U, Pu) C and (U, Pu) N fuel pins were irradiated in JOYO for the fist time in Japan. In this study, one (U, Pu) C fuel pin and two (U, Pu) N fuel pins were irradiated to maximum burn up about 40GWd/t. Post irradiation examination of (U, Pu) C and (U, Pu) N fuel pins started in Fuel Monitoring Facility (FMF) at JNC from October 1999, and it ended in March, 2000. The results of non-destructive post irradiation examination reported in this document. Main results are shown in the following. (1)The soundness of all (U,Pu) C and (U,Pu) N fuel pins were confirmed from the non-destructive examination result. (2)The fuel stack elongation of (U,Pu) C and (U,Pu) N is bigger than it of the MOX fuel for fast reactor. (3)The singular behavior from the gamma ray scanning measurement in the stack area was not confirmed. The migration of Cs137 to lower insulator pellet and outside of the pellet was confirmed in (U,Pu) N B9NO2 pin. In (U,Pu) C fuel, the migration of Cs137 was not confirmed. (4)In (U,Pu) C B9CO1 pin and (U,Pu) N B9NO2 pin in which the gap width was small, diameter of cladding increase around 50 m in the stack area which originates for FCMI was confirmed. In (U,Pu) N B9NO1 pin in which the gap width was wide, the ovality which originates from the relocation of the pellet was confirmed. (5)Fission gas release rate of (U,Pu) N were 3.3% and 5.2%, and the low value compared to the MOX fuel was shown.

None

*

JNC TN1400 2000-003, 252 Pages, 2000/07

JNC-TN1400-2000-003.pdf:13.33MB

None

Analysis of Cm contained in irradiated fuel of experimental fast reactor "JOYO"; Development of the analytical technique and measurement of Cm

Osaka, Masahiko; Koyama, Shinichi; Mitsugashira, Toshiaki; Morozumi, Katsufumi; Namekawa, Takashi

JNC TN9400 2000-058, 49 Pages, 2000/04

JNC-TN9400-2000-058.pdf:1.22MB

The analytical technique for Cm contained in a MOX FUEL was developed and analysis of Cm contained in irradiated fuel of experimental fast reactor "JOYO" was carried out, to contribute to evaluation of transmutation characteristics of MA nuclide in the fast reactor. The procedure of ion-exchange separation of Cm with nitric acid-methanol mixed media essential for the isotopic analysis in irradiated MOX fuel was adopted considering for being rapid and easy. The fundamental test to grasp separation characteristics of this procedure, such as Cm elution position and separation capacity between Cm and Am or Eu, was carried out. ln applying this procedure to the analysis of Cm contained in actual specimen, separation condition was evaluated and optimized, and the procedure consist of impurity removal and Am removal process was devised. This procedure resulted in high recovery rate of Cm and high removal rate of Am and impurity which becomes a problem in sample handling and mass-spectrometry such as Eu and Cs. The Cm separation test from irradiated MOX fuel was carried out using this technique, and Cm isotopic ratio analysis was enabled. The analytical technique for Cm contained in irradiated MOX fuel was established using the procedure of ion-exchange separation with nitric acid-methanol mixed media. The analysis of Cm contained in irradiated MOX fuel of experimental fast reactor "Joyo" was carried out. As a result, it was revealed from measured data that Cm content rate was 1.4 4.0lO atom%, small amount of Cm was generated and Cm isotopic ratio was constant above burn-up 60GWd/t.

JOYO coolant sodium and cover gas purity control database (MK-II core)

; ; Saikawa, Takuya*; Sukegawa, Kazuya*

JNC TN9410 2000-008, 66 Pages, 2000/03

JNC-TN9410-2000-008.pdf:1.39MB

The experimental fast reactor "JOYO" served as the MK-II irradiation bed core for testing fuel and material for FBR development for 15 years from 1982 to 1997. During the MK-II operation, impurities concentrations in the sodium and the argon gas were determined by 67 samples of primary sodium, 81 samples of secondary sodium, 75 samples of primary argon gas, 89 samples of secondary argon gas (the overflow tank) and 89 samples of secondary argon gas (the dump tank). The sodium and the argon gas purity control data were accumulated from in thirty-one duty operations, thirteen special test operations and eight annual inspections. These purity control results and related plant data were compiled into database, which were recorded on CD-ROM for user convenience. Purity control data include concentration of oxygen, carbon, hydrogen, nitrogen, chlorine, iron, nickel and chromium in sodium, concentration of oxygen, hydrogen, nitrogen, carbon monoxide, carbon dioxide, methane and helium in argon gas with the reactor condition.