Operation and maintenance experience from the HTTR database

Shimizu, Atsushi; Furusawa, Takayuki; Homma, Fumitaka; Inoi, Hiroyuki; Umeda, Masayuki; Kondo, Masaaki; Isozaki, Minoru; Fujimoto, Nozomu; Iyoku, Tatsuo

Journal of Nuclear Science and Technology, 51(11-12), p.1444 - 1451, 2014/11

https://doi.org/10.1080/00223131.2014.946568

JAEA has kept up a data-base system of operation and maintenance experiences of the HTTR. The objective of this system is to share the information obtained operation and maintenance experiences and to make use of lessons learned and knowledge into a design, construction and operation managements of the future HTGR. More than one thousand records have been registered into the system between 1997 and 2012. This paper describes the status of the data-base system, and provides suggestions for improvement from four experiences: (1) performance degradation of helium compressors; (2) malfunction of reserved shutdown system in reactivity control system; (3) maintenance experiences of emergency gas turbine generators; and (4) experiences of the Great East Japan Earthquake. These experiences are extracted from the system as important lessons learned to be expected to apply for design, construction and operation managements of future HTGR.

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2011

Sumiya, Shuichi; Watanabe, Hitoshi; Nakano, Masanao; Takeyasu, Masanori; Nakada, Akira; Fujita, Hiroki; Isozaki, Tokuju; Morisawa, Masato; Mizutani, Tomoko; Nagaoka, Mika; et al.

JAEA-Review 2013-009, 195 Pages, 2013/06

JAEA-Review-2013-009.pdf:3.35MB

Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2011 to March 2012. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Plant on Tokyo Electric Power Co. in March 2011.

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2009

Sumiya, Shuichi; Matsuura, Kenichi; Watanabe, Hitoshi; Nakano, Masanao; Takeyasu, Masanori; Fujita, Hiroki; Isozaki, Tokuju; Morisawa, Masato; Mizutani, Tomoko; Kokubun, Yuji; et al.

JAEA-Review 2011-004, 161 Pages, 2011/03

JAEA-Review-2011-004.pdf:4.09MB

Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2009 to March 2010. Appendices present comprehensive information, such as monitoring program, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes.

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2007

Takeishi, Minoru; Matsuura, Kenichi; Watanabe, Hitoshi; Nakano, Masanao; Takeyasu, Masanori; Isozaki, Hisaaki; Isozaki, Tokuju; Morisawa, Masato; Fujita, Hiroki; Kokubun, Yuji; et al.

JAEA-Review 2008-057, 155 Pages, 2008/11

JAEA-Review-2008-057.pdf:2.15MB

Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of JAEA, Chapter IV; Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged to the atmosphere and the sea during April 2007 to March 2008. Appendices present comprehensive information, such as monitoring program, monitoring methods, monitoring results and its trends, meteorological data and discharged radioactive wastes.

Countermeasure to prevent residence nitrogen gas in Pressurized Water Cooling System

Furusawa, Takayuki; Saikusa, Akio; Hamamoto, Shimpei; Nemoto, Takahiro; Shinohara, Masanori; Isozaki, Minoru

JAEA-Technology 2007-066, 38 Pages, 2008/01

JAEA-Technology-2007-066.pdf:15.66MB

In the HTTR rise-to-power test which was performed from April in 2000 as phase 1 up to 10MW, nitrogen gas remained in the air cooler which release the heat to atmosphere. This residence nitrogen gas causes the reduction of the thermal performance of the air cooler. So, it was impossible that heat generated reactor core could not remove when reactor operated full power operation. A mockup test was carried out to investigate the occurrence mechanism of the residence nitrogen gas. From a result of the mockup test, we clarified that the marked wave rise in the water pressurizer and the melting velocity of the nitrogen gas into the pressurized water is thought to be higher than expected. Therefore, we installed a hollow type plate, multi-hole type plate and so on in the water pressurizer. As a result, it was confirmed that no residence nitrogen gas in the air cooler during rise-to-power test and normal operation. Consequently, the hollow type plate and multi-hole type plate were effective for prevention of the residence nitrogen gas in the air cooler. This paper describes the results of the mockup test and the improvement of the water pressurizer.

Annual report on the environmental radiation monitoring around Tokai Reprocessing Plant FY2005

Takeishi, Minoru; Miyagawa, Naoto; Nakano, Masanao; Takeyasu, Masanori; Isozaki, Hisaaki; Isozaki, Tokuju; Morisawa, Masato; Fujita, Hiroki; Kokubun, Yuji; Kato, Chiaki; et al.

JAEA-Review 2006-031, 155 Pages, 2006/10

JAEA-Review-2006-031.pdf:7.76MB
JAEA-Review-2006-031(errata).pdf:0.13MB

Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of JAEA, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged to the atmosphere and the sea during April 2005 to March 2006. Appendices present comprehensive information, such as monitoring program, monitoring methods, monitoring results and its trends, meteorological data and discharged radioactive wastes.

Environmental radiological monitoring around JNC Tokai works

Nakano, Masanao; Isozaki, Tokuji; Takeishi, Minoru

Koden Giho, (21), p.15 - 23, 2005/09

The regional environmental radiation monitoring and the dose calculation for the public were performed for the past 25-year operation of the Tokai Reprocessing Plant (TRP). For the environmental monitoring, various kinds of terrestrial and marine samples including air dust, surface soil, polished rice grain, leafy vegetable, milk, seawater, seabed sediments, fish, shellfish and seaweed were collected in the surrounding environment of the TRP. Radionuclides such as H, C ,Sr, I, Cs and Pu in the environmental samples were determined by radiochemical methods. However, they showed no significant short-term increase or long-term accumulation of radionuclides discharged from the TRP. Therefore, the public dose was evaluated by the mathematical models using the discharge data of radionuclides and the meteorological data. The estimated annual effective dose for the public was about 0.1% of the annual effective dose limit recommended by the ICRP.

Experience of HTTR construction and operation; Unexpected incidents

Fujimoto, Nozomu; Tachibana, Yukio; Saikusa, Akio*; Shinozaki, Masayuki; Isozaki, Minoru; Iyoku, Tatsuo

Nuclear Engineering and Design, 233(1-3), p.273 - 281, 2004/10

https://doi.org/10.1016/j.nucengdes.2004.08.014

From a viewpoint of heat leakage, there were two incidents during HTTR power-rise-tests. One was a temperature rise of the primary upper shielding, and the other was a temperature rise of the core support plate. Causes of the both incidents were small amount of helium flow in structures. For the temperature rise of the primary upper shielding, countermeasures to reduce the small amount of helium flow, enhancement of heat release and installation of thermal insulator were taken. For the temperature rise of the core support plate, temperature evaluations were carried out again considering the small amount of helium flow and design temperature of the core support plate was revised. By these countermeasures, the both temperatures were kept below their limits.

Data Book on the Current of Tokai Reprocessing Plant; From January to December in 2000

Takeishi, Minoru; Naoto, Miyagawa,; Nakano, Masanao; Isozaki, Hisaaki; Isozaki, Tokuju; Ao, Hidetoshi*; Nemoto, Masashi*

JNC TN8450 2004-005, 139 Pages, 2004/06

JNC-TN8450-2004-005.pdf:12.13MB

Current direction, velocity, water temperature, salinity and etc. were observed by the current meters which were set near the outlet (36 26' 51" N, 140 39' 02"E)of the discharge pipe of the reprocessing plant in JNC Tokai Works. Besides, the horizontal (26 points) and vertical (14 points) observation of water temperature and salinity were executed using the monitoring ship (Seikai). The observation region ranged from 36 22' N to 36 30' N and from 140 37' E to 140 42'E. The data, which were observed in 2000, were described in this report.

Data book on the current of Tokai Reprocessing plant; January - December, 1998

Shinohara, Kunihiko; Takeishi, Minoru; ; ; Isozaki, Tokuju; Ao, Hidetoshi*; *

JNC TN8450 2003-004, 99 Pages, 2002/11

JNC-TN8450-2003-004.pdf:4.64MB

Current direction, velocity water temperature, salinity and etc. were observed by current meters which were set near the outlet (36 26' 51" N, 140 39' 02" E) of the discharge pipe of the reprocessing plant in JNC Tokai Works. Besides, the horizontal (26 points) and vertical (14 points) observation of water temperature and salinity were executed using the monitoring ship (Seikai). The observation region ranged from 36 22' N to 36 30' N and from 140 37' E to 140 42'. The data, which were observed in 1999, were described in this report.