Study of origin on tritium release into primary coolant for research and testing reactors; Tritium release rate evaluated from JMTR, JRR-3M and JRR-4 operation data

Ishitsuka, Etsuo; Motohashi, Jun; Hanawa, Yoshio; Komeda, Masao; Watahiki, Shunsuke; Mukanova, A.*; Kenzhina, I. E.*; Chikhray, Y.*

JAEA-Technology 2014-025, 77 Pages, 2014/08

JAEA-Technology-2014-025.pdf:43.46MB

It has been shown that tritium concentration in the primary coolant of the JMTR and JRR-3M increases during its operation. In this report, to clarify the tritium sources, the tritium release rate into the primary coolant in each operation cycle for the JMTR, JRR-3M and JRR-4 was evaluated. As a result, the tritium release rate is 8 Bq/Wd in the JRR-4, which has not the beryllium core components installed, and no increase in the tritium concentration during reactor operation is observed. In contrast, the tritium release rate is about 1095 and 60140 Bq/Wd in the JRR-3M and JMTR respectively, which cores contain beryllium components, and where the tritium content increases while reactor operates. It is also observed that the amount of released tritium is lower in the case of new beryllium components installation, and increases with the reactor operating cycle.

Resumption of JRR-4 and characteristics of the neutron beam for BNCT

Nakamura, Takemi; Horiguchi, Hironori; Kishi, Toshiaki; Motohashi, Jun; Sasajima, Fumio; Kumada, Hiroaki*

Proceedings of 14th International Congress on Neutron Capture Therapy (ICNCT-14) (CD-ROM), p.379 - 382, 2010/10

The clinical trials of BNCT have been conducted using JRR-4. The JRR-4 stopped in January 2008, because the graphite reflector was considerably damaged. For this reason, the specifications of graphite reflectors were renewal. All existing graphite reflectors of JRR-4 were changed by new graphite reflectors. The resumption of JRR-4 was carried out with new graphite reflectors in February 2010. We measured the characteristics of neutron beam at the JRR-4 Neutron Beam Facility. A cylindrical water phantom was put the gap for 1cm from the beam port. TLD and gold wire were inserted within the phantom when the phantom was irradiated. The results of the measured thermal neutron flux and the dose in water were compared with MCNP calculations. The calculated results showed the same tendency with the experimental results. These results are proceeding well and will be reported in full paper at July 2010.

Quantitative analyses of impurity silicon-carbide (SiC) and high-purity-titanium by neutron activation analyses based on k standardization method; Development of irradiation silicon technology in productivity using research reactor (Joint research)

Motohashi, Jun; Takahashi, Hiroyuki; Magome, Hirokatsu; Sasajima, Fumio; Tokunaga, Okihiro*; Kawasaki, Kozo*; Onizawa, Koji*; Isshiki, Masahiko*

JAEA-Technology 2009-036, 50 Pages, 2009/07

JAEA-Technology-2009-036.pdf:32.66MB

JRR-3 and JRR-4 have been providing neutron-transmutation-doped silicon (NTD-Si) by using the silicon NTD process. We have been considering to introduce the neutron filter, which is made of high-purity-titanium, into uniform doping. Silicon carbide (SiC) semiconductors doped with NTD technology are considered suitable for high power devices with superior performances to conventional Si-based devices. The impurity contents in the high-purity-titanium and SiC were analyzed by neutron activation analyses (NAA) using k standardization method. Analyses showed that the number of impurity elements detected from the high-purity-titanium and SiC were 6 and 9, respectively. Among these impurity elements, Sc detected from the high-purity-titanium and Fe detected from SiC were comparatively long half life nuclides. From the viewpoint of exposure in handling them, we need to examine the impurity control of materials.

Characterization measurement of JRR-4 utilization facility

Kishi, Toshiaki; Motohashi, Jun; Yamamoto, Kazuyoshi; Kumada, Hiroaki; Torii, Yoshiya

JAEA-Technology 2008-054, 99 Pages, 2008/08

JAEA-Technology-2008-054.pdf:3.22MB

JRR-4 had carried out modification works for the purpose of reducing the enrichment level of fuel. About utilization facilities, followings were installed new neutron beam facility, renewal irradiation facility that was modified pneumatic irradiation facility for activation analysis of short-lived nuclides. This report describes the characteristic measurement by initial core and equilibrium core in 2001 by renewal JRR-4. Utilization facilities had been identified equal performance before modify about neutron flux and cadmium ratio on 1998 and 2001. And we have achieved less than 5% of irradiation uniformity at N-pipe. The maximum neutron flux is about 2.210ms at the New neutron beam facility and the maximum neutron flux is about 110ms at the prompt -ray analysis facility got good quality performance for medical irradiation and fundamental examination of it.

Calculation of the pressure vessel failure fraction of fuel particle of gas turbine high temperature reactor 300C

Aihara, Jun; Ueta, Shohei; Mozumi, Yasuhiro; Sato, Hiroyuki; Motohashi, Yoshinobu*; Sawa, Kazuhiro

Proceedings of International Conference on Advanced Nuclear Fuel Cycles and Systems (Global 2007) (CD-ROM), p.416 - 422, 2007/09

In high temperature gas-cooled reactors (HTGRs), coated particles are used as fuels. For upgrading HTGR technologies, present SiC coating layer which is used as the 3rd layer could be replaced with ZrC coating layer which have much higher temperature stability in addition to higher resistance to chemical attack by fission product palladium than the SiC coating layer. The ZrC layer could deform plastically at high temperatures. Therefore, the Japan Atomic Energy Agency modified an existing pressure vessel failure fraction calculation code to treat the plastic deformation of the 3rd layer in order to predict failure fraction of ZrC coated particle under irradiation. Finite element method is employed to calculate the stress in each coating layer. The pressure vessel failure fraction of the coated fuel particles under normal operating condition of GTHTR300C is calculated by the modified code. The failure fraction is evaluated as low as 3.510.

Crystal nucleation behavior caused by annealing of SiC irradiated with Ne at liquid nitrogen temperature or at 573K

Aihara, Jun; Hojo, Kiichi; Furuno, Shigemi*; Hojo, Tomohiro; Sawa, Kazuhiro; Yamamoto, Hiroyuki; Motohashi, Yoshinobu*

Materials Transactions, 48(7), p.1896 - 1900, 2007/07

https://doi.org/10.2320/matertrans.MRA2007608

Silicon carbide(SiC) TEM specimens were annealed, in-situ, at 1273K for 30 minutes after amorphization with 30keV Ne irradiation to the fluence of 1.9 or 2.310Ne/m at 573K or about 98K. The crystal nucleation and bubble coalescence accompanied by recrystallization were observed in both specimens with the annealing after the irradiations. 2.310Ne/m irradiations in both specimens. The Debye-Sherrer rings of the nucleated crystals well fitted the net pattern of the matrix, even though no ring corresponding to (200) of -SiC appeared. Dependence of the crystal nucleation behavior on irradiation temperature was not observed within the present experimental range.

Practical use of control rod calibration system with the inverse kinetices method

Yamanaka, Haruhiko; Hayashi, Kazuhiko; Motohashi, Jun; Kawashima, Kazuhito; Ichimura, Toshiyuki; Tamai, Kazuo; Takeuchi, Mitsuo

JAERI-Tech 2001-084, 110 Pages, 2002/01

JAERI-Tech-2001-084.pdf:10.15MB

no abstracts in English

The Renewal plan of JRR-3 process control system

Nio, Daisuke; Ikekame, Yoshinori; Suwa, Masayuki; Isaka, Koji; Ouchi, Satoshi; Mineshima, Hiromi; Motohashi, Jun; Torii, Yoshiya; Kinase, Masami; Murayama, Yoji

no journal, , 

no abstracts in English

TEM/STEM observation of ZrC coating layer for the advanced high temperature gas-cooled reactor fuel

Aihara, Jun; Ueta, Shohei; Yasuda, Atsushi; Ishibashi, Hideharu; Sawa, Kazuhiro; Motohashi, Yoshinobu*

no journal, , 

Japan Atomic Energy Agency (JAEA) has started to study and develop ZrC coated fuel particles for advanced high temperature gas cooled reactors. The ZrC coating layers were fabricated with bromide process at JAEA. We report in this study the microstructures of the ZrC coating layers deposited in the second year of the project. We already reported the microstructure of the one deposited in the first year of the project last year. The ZrC coating layer deposited at lower temperatures contains less free carbons. The crystal grains of ZrC were columner in shape and oriented in the region containing less free carbons. The orientation was different from the one reported in the last year. In addition to the stoichiometry of the ZrC layer, the microstructure of PyC/ZrC boundary also depended on the deposition temperature. The fibrous carbon structure is observed at PyC/ZrC boundary when the ZrC layer is deposited at higher temperature but not when ZrC layer is deposited at lower temperature.

TEM observation and EELS measurement of ZrC coating layer for advanced high temperature gas cooled reactor

Aihara, Jun; Ueta, Shohei; Motohashi, Yoshinobu*; Sawa, Kazuhiro

no journal, , 

Development of ZrC coated fuel particles for advanced high temperature gas cooled reactors. As a basic study, the ZrC coating layer has been fabricated using the bromide process at JAEA. The coated particles were annealed at around 1800 C for 1h, under which compact sintering will be done in a practical process, in order to study effects of the heat treatment on their microstructure evolution. Then the microstructures of the ZrC layers in the batch of C/Zr = 1.35 were characterized by means of TEM. Certain changes in the shape and size of voids or free carbons region caused by the heat treatment were found. After the heat treatment, the voids or free carbons region have changed from a thin layered feature into a clod like feature with diameters of 50 to 100 nm. In addition, EELS measurements were carried out in the heat treated specimen. The * peak of carbon was observed in the spectrum from free carbons or voids region, but not in the spectrum from ZrC region.