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JAEA Reports

Introduction of a new framework of safety, maintenance and quality management activities in Japan Atomic Energy Agency under the new nuclear regulatory inspection system since FY 2020

Sono, Hiroki; Sukegawa, Kazuhiro; Nomura, Norio; Okuda, Eiichi; Study Team on Safety and Maintenance; Study Team on Quality Management; Task Force on New Nuclear Regulatory Inspection Systems

JAEA-Technology 2020-013, 460 Pages, 2020/11

JAEA-Technology-2020-013.pdf:13.46MB

Japan Atomic Energy Agency (JAEA) has completed the introduction of a new frame work of safety, maintenance and quality management activities under the new acts on the Regulation of nuclear source material, nuclear fuel material and reactors since April 2020, in consideration of variety, specialty and similarity of nuclear facilities of JAEA (Power reactor in the research and development stage, Reprocessing facility, Fabrication facility, Waste treatment facility, Waste burial facility, Research reactor and Nuclear fuel material usage facility). The JAEA task forces on new nuclear regulatory inspection systems prepared new guidelines on (1) Safety and maintenance, (2) Independent inspection, (3) Welding inspection, (4) Free-access response, (5) Performance indicators and (6) Corrective action program for the JAEA's nuclear facilities. New Quality management systems and new Safety regulations were also prepared as a typical pattern of these facilities. JAEA will steadily improve these guidelines, quality management systems and safety regulations, reviewing the official activities under the new regulatory inspection system together with the Nuclear Regulation Authority and other nuclear operators.

JAEA Reports

The Investigation related to the study on the method to withdraw the in-vessel transfer machine; Observation of the structure in the reactor vessel of the fast breeder reactor Monju

Harigae, Hitoshi; Takagi, Tsuyohiko; Hamano, Tomoharu; Nakamura, Shoichi; Oba, Toshio; Ebashi, Masaaki; Okuda, Eiichi; Kinoshita, Tomonobu

JAEA-Technology 2013-014, 150 Pages, 2013/07

JAEA-Technology-2013-014.pdf:24.38MB

In-Vessel Transfer Machine (IVTM) came off from the gripper claw in the Auxiliary Handling Machine (AHM) and fell at a height of approximately two meters during a withdrawal work of the IVTM in the Fast Breeder Reactor (FBR) Monju. The withdrawal work of IVTM from the reactor vessel by AHM was performed. The work, however, was suspended due to the excessive load alarm. To grasp the situation of the IVTM fall, observation of the machine was necessary. An interior observation and an exterior observation of the dropped IVTM were performed. As a result of these observations, the radially deformed lower end of the upper guide tube was observed at the connection part, and it was jammed in the fuel throat sleeve when the dropped IVTM was withdrawn. Based on this information, the IVTM could be safely withdrawn from the reactor vessel with the fuel throat sleeve.

Journal Articles

Tolerance of anhydrobiotic eggs of the tardigrade ${it Ramazzottius varieornatus}$ to extreme environments

Horikawa, Daiki*; Yamaguchi, Ayami*; Sakashita, Tetsuya; Tanaka, Daisuke*; Hamada, Nobuyuki*; Yukuhiro, Fumiko*; Kuwahara, Hirokazu*; Kunieda, Takekazu*; Watanabe, Masahiko*; Nakahara, Yuichi*; et al.

Astrobiology, 12(4), p.283 - 289, 2012/04

 Times Cited Count:20 Percentile:70.08(Astronomy & Astrophysics)

We examined the hatchability of hydrated and anhydrobiotic eggs of the tardigrade ${it Ramazzottius varieornatus}$ to hatch after ionizing irradiation (helium ions), extremely low and high temperatures, and high vacuum. Anhydrobiotic eggs (50% lethal dose; 1690 Gy) were substantially more radioresistant than hydrated ones (50% lethal dose; 509 Gy). Anhydrobiotic eggs also have a broader temperature resistance compared with hydrated ones. Over 70% of the anhydrobiotic eggs treated at high and low temperatures, but all of the hydrated eggs failed to hatch. After exposure to high vacuum conditions, the hatchability of the anhydrobiotic eggs was comparable to that of untreated control eggs.

Journal Articles

Corrosion state of iron and bronze artifacts excavated from Nishizuka Mound, Fukui Prefecture

Mitsui, Seiichiro; Yoshikawa, Hideki; Tokuda, Masashi*; Seiki, Yuji*

Nihon Bunkazai Kagakkai Dai-28-Kai Taikai Kenkyu Happyo Yoshishu, p.54 - 55, 2011/06

Ancient iron and bronze artifacts (ca 1,500 year old) excavated from Nishizuka Mound, Fukui Prefecture, were studied as archaeological analogues for metal overpack corrosion. As for corrosion state, we analyzed corrosion volume with a X-ray CT and corrosion products with a portable XRD/XRF. As results, we found that corrosion volume of bronze artifacts were smaller than those of iron artifacts and that cassiterite (SnO$$_{2}$$) was present as one of corrosion products on the surface of the bronze artifacts. This suggested that the cassiterite inhibited corrosion reaction of the bronze artifact.

Journal Articles

Establishment of a rearing system of the extremotolerant tardigrade ${it Ramazzottius varieornatus}$; A New model animal for astrobiology

Horikawa, Daiki*; Kunieda, Takekazu*; Abe, Wataru*; Watanabe, Masahiko*; Nakahara, Yuichi*; Yukuhiro, Fumiko*; Sakashita, Tetsuya; Hamada, Nobuyuki*; Wada, Seiichi*; Funayama, Tomoo; et al.

Astrobiology, 8(3), p.549 - 556, 2008/06

 Times Cited Count:70 Percentile:89.07(Astronomy & Astrophysics)

We report the successful rearing of the herbivorous tardigrade, ${it Ramazzottius varieornatus}$, by supplying the green alga ${it Chlorella vulgaris}$ as food. The life span was 35 d, deposited eggs required 5.7 d to hatch, and animals began to deposit eggs 9 d after hatching. The reared individuals of this species had an anhydrobiotic capacity throughout their life cycle in egg, juvenile, and adult stages. Furthermore, the reared adults in an anhydrobiotic state were tolerant of temperatures of 90$$^{circ}$$C and -196$$^{circ}$$C and exposure to 99.8% acetonitrile or irradiation with 4000 Gy $$^{4}$$He ions. Based on their life history traits and tolerance to extreme stresses, ${it R. varieornatus}$ might be a suitable model for astrobiological studies of multicellular organisms.

Journal Articles

Radiation tolerance linked to anhydrobiosis in ${it Polypedilum vanderplanki}$

Nakahara, Yuichi*; Watanabe, Masahiko*; Kikawada, Takahiro*; Fujita, Akihiko*; Horikawa, Daiki*; Okuda, Takashi*; Sakashita, Tetsuya; Funayama, Tomoo; Hamada, Nobuyuki*; Wada, Seiichi*; et al.

JAEA-Review 2007-060, JAEA Takasaki Annual Report 2006, P. 113, 2008/03

We have shown that anhydrobiotic larvae of ${it Polypedilum vanderplanki}$ have higher tolerance against both high linear energy transfer (LET) radiation than hydrated larvae. We therefore examined effects of high-LET radiation on four kinds of larvae: (1) normal hydrated (intact) larva, (2) intermediates between the anhydrobiotic and normal hydrated state, (3) almost completely dehydrated (anhydrobiotic) larvae, and (4) immediately rehydrated larvae that are assumed to have a similar molecular profile to anhydrobiotic larvae. The intermediates and immediately rehydrated larvae survived longer after high-LET radiation than intact larvae, indicating that radiation tolerance could be enhanced even in hydrated larvae. Physiological changes toward anhydrobiosis, e.g. accumulation of protectants or increasing damage repair capacity, correlate with improved radiation tolerance in hydrated larvae.

Journal Articles

Physiological changes leading to anhydrobiosis improve radiation tolerance in ${it Polypedilum vanderplanki}$ larvae

Watanabe, Masahiko*; Nakahara, Yuichi*; Sakashita, Tetsuya; Kikawada, Takahiro*; Fujita, Akihiko*; Hamada, Nobuyuki*; Horikawa, Daiki*; Wada, Seiichi*; Kobayashi, Yasuhiko; Okuda, Takashi*

Journal of Insect Physiology, 53(6), p.573 - 579, 2007/06

 Times Cited Count:19 Percentile:67.58(Entomology)

We examined effects of high-LET radiation on 4 kinds of larvae: (1) normal hydrated (intact) larva, (2) intermediates between the anhydrobiotic and normal hydrated state, (3) almost completely dehydrated (anhydrobiotic) larvae, and (4) immediately-rehydrated larvae that are assumed to have a similar molecular profile to anhydrobiotic larvae. The intermediates and immediately-rehydrated larvae survived longer after high-LET radiation than intact larvae, indicating that radiation tolerance could be enhanced even in hydrated larvae. Physiological changes toward anhydrobiosis, e.g. accumulation of protectants or increasing damage repair capacity, correlate with improved radiation tolerance in hydrated larvae. In addition, almost complete desiccation further enhanced radiation tolerance, possibly in a different way from the hydrated larvae.

JAEA Reports

Study of ageing effect of long-term storage fuel in prototype fast breeder reactor Monju

Kato, Yuko; Umebayashi, Eiji; Okimoto, Yutaka; Okuda, Eiichi; Takayama, Koichi; Ozawa, Takayuki; Maeda, Seiichiro; Matsuzaki, Masaaki; Yoshida, Eiichi; Maeda, Koji; et al.

JAEA-Research 2007-019, 56 Pages, 2007/03

JAEA-Research-2007-019.pdf:6.79MB

In order to resume the System Startup Test (SST) of Monju, replacement fuel have to be loaded in exchange for some of initial fuel now loaded in the core to compensate core reactivity lost by decay of Pu-241 in them. The replacement fuel were being stored either in sodium in an ex-vessel storage tank or in air in a storage rack for about 10 years since their fabrication. The initial fuel were irradiated during the SST which was suspended in the end of 1995 and then stayed being loaded in the sodium-circulated core. As this long-term storage and loading may deteriorate mechanical integrity of the assemblies, a study has been made thoroughly on its thermal-hydraulic, structural and material effects on them that might be caused by irradiation in the core, sodium and mechanical environment. The study has shown that the mechanical integrity of them is well maintained even with this long-term storage and loading.

Journal Articles

Effects of heavy ions and $$gamma$$-ray on the tardigrade ${it Milnesium tardigradum}$

Horikawa, Daiki*; Sakashita, Tetsuya; Katagiri, Chihiro*; Watanabe, Masahiko*; Kikawada, Takahiro*; Nakahara, Yuichi*; Hamada, Nobuyuki*; Wada, Seiichi*; Funayama, Tomoo; Higashi, Seigo*; et al.

JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 116, 2007/02

no abstracts in English

Journal Articles

Radiation tolerance in the tardigrade ${it Milnesium tardigradum}$

Horikawa, Daiki*; Sakashita, Tetsuya; Katagiri, Chihiro*; Watanabe, Masahiko*; Kikawada, Takahiro*; Nakahara, Yuichi*; Hamada, Nobuyuki*; Wada, Seiichi*; Funayama, Tomoo; Higashi, Seigo*; et al.

International Journal of Radiation Biology, 82(12), p.843 - 848, 2006/12

 Times Cited Count:110 Percentile:99.11(Biology)

no abstracts in English

Journal Articles

Estimation of radiation tolerance to high LET heavy ions in an anhydrobiotic insect, ${it Polypedilum vanderplanki}$

Watanabe, Masahiko*; Sakashita, Tetsuya; Fujita, Akihiko*; Kikawada, Takahiro*; Nakahara, Yuichi*; Hamada, Nobuyuki*; Horikawa, Daiki*; Wada, Seiichi*; Funayama, Tomoo; Kobayashi, Yasuhiko; et al.

International Journal of Radiation Biology, 82(12), p.835 - 842, 2006/12

 Times Cited Count:15 Percentile:73.49(Biology)

The aim of this study is to characterize the tolerance to high-LET radiations of${it P. vanderplanki}$. Larval survival and subsequent metamorphoses were compared between anhydrobiotic (dry) and non-anhydrobiotic (wet) samples after exposure to 1 to 7000 Gy of three types of heavy ions with LET values ranging from 16.2 to 321 keV/$$mu$$m. At all LET values measured, dry larvae consistently showed greater radiation tolerance than hydrated larvae, due to the disaccharide trehalose in anhydrobiotic animals. Relative biological effectiveness (RBE) values based on the median inhibitory doses reached a maximum at 116 keV/$$mu$$m ($$^{12}$$C). Anhydrobiosis potentiates radiation tolerance in terms of larval survival, pupation and adult emergence of ${it P. vanderplanki}$ exposed to high-LET radiations. ${it P. vanderplanki}$ larvae might have more efficient DNA damage repair after radiation than other chironomid species.

Journal Articles

Biological effects of anhydrobiosis in an African chironomid, ${it Polypedilum vanderplanki}$ on radiation tolerance

Watanabe, Masahiko*; Sakashita, Tetsuya; Fujita, Akihiko*; Kikawada, Takahiro*; Horikawa, Daiki*; Nakahara, Yuichi*; Wada, Seiichi*; Funayama, Tomoo; Hamada, Nobuyuki*; Kobayashi, Yasuhiko; et al.

International Journal of Radiation Biology, 82(8), p.587 - 592, 2006/08

 Times Cited Count:30 Percentile:88.8(Biology)

The present study aims to evaluate effects of anhydrobiosis on radiation tolerance in an anhydrobiotic insect, Polypedilum vanderplanki. Larval survival (48 h), anhydrobiotic ability, metamorphosis and reproduction after exposure to 1 to 9000 Gy of $$gamma$$-rays at the larval stage were comparedbetween anhydrobiotic (dry) and normal (wet) phases. Wet larvae were killed in a dose-dependent manner at doses higher than 2000 Gy, and all died within 8 h after 4000 Gy exposure. In contrast, dry larvae survived even 5000 Gy, and some of them still tolerated 7000 Gy and were alive at 48 h after rehydration. Moreover, greater radiotolerance of dry larva, compared to wet ones, was demonstrated interms of metamorphoses. However, anhydrobiosis did not protect against radiation damage in terms of producing viable offspring. These results indicate that anhydrobiosis enhances radiotolerance, resulting in increases of successful metamorphoses.

Oral presentation

Keeping situation and use of the fuel of prototype FBR MONJU

Ito, Kazumoto; Ikeda, Hiroshi; Takayama, Koichi; Okuda, Eiichi

no journal, , 

no abstracts in English

Oral presentation

Radiation tolerance in water bears

Horikawa, Daiki*; Sakashita, Tetsuya; Katagiri, Chihiro*; Watanabe, Masahiko*; Nakahara, Yuichi*; Okuda, Takashi*; Hamada, Nobuyuki*; Wada, Seiichi*; Funayama, Tomoo; Kobayashi, Yasuhiko

no journal, , 

no abstracts in English

Oral presentation

Energetic heavy-ion beams and $$gamma$$-rays tolerance in water bears

Horikawa, Daiki*; Watanabe, Masahiko*; Nakahara, Yuichi*; Kikawada, Takahiro*; Okuda, Takashi*; Sakashita, Tetsuya; Funayama, Tomoo; Hamada, Nobuyuki*; Wada, Seiichi*; Kobayashi, Yasuhiko; et al.

no journal, , 

no abstracts in English

Oral presentation

Radiation tolerance in tardigrades

Horikawa, Daiki*; Sakashita, Tetsuya; Katagiri, Chihiro*; Watanabe, Masahiko*; Nakahara, Yuichi*; Kikawada, Takahiro*; Hamada, Nobuyuki*; Wada, Seiichi*; Funayama, Tomoo; Higashi, Seigo*; et al.

no journal, , 

no abstracts in English

Oral presentation

Developing the database on medical exposure to CT in NIRS in collaboration with WAZA-ARI

Akahane, Keiichi*; Ono, Koji*; Okuda, Yasuo*; Sato, Kaoru; Takahashi, Fumiaki; Ban, Nobuhiko*; Shimada, Yoshiya*; Endo, Akira; Kai, Michiaki*

no journal, , 

The WAZA-ARI is a dose calculator of medical exposures on X-ray CT examinations, which is the web-based program based on the simulation data of voxel phantoms of Japanese adults and a 4-y girl. After the development, the WAZA-ARI has been installed in a web server of National Institute of Radiological Sciences (NIRS), and opened to the public as trial uses on Dec 2012. The user authentication function and the data input pages by users have been adding to the WAZA-ARI to store the calculated data and the inputted data of doses and frequencies of X-ray CT examinations into the database on medical exposure in NIRS for the analyses of the CT exposures. The use of these functions and WAZA-ARI II, which can calculate the doses of different patients' body sizes, will provide the basic and useful data on the CT exposures for the radiation protection in medicine, because the portion of CT doses in the overall medical exposures are relatively high compared to other radiological diagnoses.

Oral presentation

Evaluation of the tube-voltage dependence of organ doses in X-ray CT scans using Monte-Carlo calculation

Koba, Yusuke*; Matsumoto, Shinnosuke*; Nakada, Yoshihiro*; Kasahara, Tetsuji*; Akahane, Keiichi*; Okuda, Yasuo*; Sato, Kaoru; Takahashi, Fumiaki; Yoshitake, Takayasu*; Hasegawa, Takayuki*; et al.

no journal, , 

Many of the CT devices are in Japan. It is guessed that exposure doses of Japanese derived from CT scans are higher than others. Thus, it is needed to properly manage scan conditions and exposure doses of individual patients. JAEA developed WAZA-ARI under the collaboration research project with the National Institute of Radiological Sciences (NIRS) and the Oita University of Nursing and Health Sciences. Practical use of new version WAZA-ARI named WAZA-ARIv2 began on January 30, 2015 at the web server in NIRS. In WAZA-ARIv2, users can calculate patients doses by using only standard condition (120 kV) of X-tube voltage. In recent years, CT scans at low tube voltage against pediatric patients with high radiosensitivity are increasing. In this study, spectrum of X-ray derived from CT scan at low tube voltage was examined, and was defined in "usrsors.f" file of PHITS. We reported the characteristics of X-ray and organ doses derived from CT scan at low tube voltage (80 kV).

Oral presentation

Calculating dose distribution from diagnostic CT depending on age and physique size of patients; Development of dose assessment web - system WAZA-ARI

Ono, Koji*; Koba, Yusuke*; Matsumoto, Shinnosuke*; Nakada, Yoshihiro*; Okuda, Yasuo*; Akahane, Keiichi*; Sato, Kaoru; Takahashi, Fumiaki; Yoshitake, Takayasu*; Hasegawa, Takayuki*; et al.

no journal, , 

In medical treatment, CT scan is useful diagnostic method. On the other hand, exposure doses derived from CT scans are dependent on body sizes of patients. Therefore, consideration of body sizes is essential for accurate dose assessment of individual patients. JAEA developed the CT dose calculator, WAZA-ARIv2 under the collaboration research project with the National Institute of Radiological Sciences and the Oita University of Nursing and Health Sciences. WAZA-ARIv2 enable users to accurately calculate exposure doses of patients with sexes, ages (0y, 1y, 5y, 10y, 15y and adult) and fatness (small, large and extra-large body sizes). In the future, we will be plans to add the dose calculation functions corresponding to the scan conditions at low tube voltage and multi-detector row (more 80) CT devices to WAZA-ARIv2. We reported the system and future plans of WAZA-ARIv2 corresponding to dose calculation of patients with various body sizes.

Oral presentation

Analysis of effects of body sizes on organ doses due to CT examinations by using voxel phantoms

Sato, Kaoru; Takahashi, Fumiaki; Koba, Yusuke*; Ono, Koji*; Yoshitake, Takayasu*; Hasegawa, Takayuki*; Katsunuma, Yasushi*; Kasahara, Tetsuji*; Okuda, Yasuo*; Nakada, Yoshihiro*; et al.

no journal, , 

JAEA is now developing CT dose calculator named WAZA-ARIv2 in cooperation with the National Institute of Radiological Sciences. WAZA-ARIv2 has been opened to the public as full-dress uses on January 2015. WAZA-ARIv2 can perform dose assessment against 4 different body physiques by using the organ dose database, which were constructed on the basis of adult Japanese phantoms with 4 body sizes (-2$$sigma$$, average, +2$$sigma$$, +5$$sigma$$). In this study, it was found that salivary gland doses are independent on BMI, whereas lung doses are dependent on BMI. The differences in the effects of BMI on absorbed doses between salivary glands and lungs might be caused by the difference in thickness of subcutaneous soft tissues between head and thorax.

22 (Records 1-20 displayed on this page)