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Uesawa, Shinichiro; Shibata, Mitsuhiko; Yoshida, Hiroyuki
Konsoryu, 37(1), p.55 - 64, 2023/03
In decommissioning Fukushima Daiichi Nuclear Power Station, the issue is confinement of radioactive aerosols in the primary containment vessel. Although a High Efficiency Particulate Air (HEPA) filter is used to collect the aerosol particles, pretreatment equipment such as a scrubber may be applied to reduce the load of HEPA filters. In the scrubber, the aerosol particles are removed by moving from gas to liquid through gas-liquid interface. Since the collection efficiency (CE) depends on gas-liquid interfacial area, fine bubbles are necessary to obtain high collection efficiency. JAEA developed a new particle removal technique by using bubble breakup phenomenon in a Venturi tube. To confirm usefulness of the technique, we performed the CE measurements and observed gas-liquid two-phase flow in the Venturi tube. In comparison with a straight pipe type, the Venturi type can have removed particles more 1,000 than it. The CE is almost the same as a HEPA filter. In addition, the Venturi type has the enough CE as the pretreatment equipment for various materials of particles such as Kanto loam, SUS and oil. Besides, we clarified that the CE of the Venturi type depended on the gas and liquid flow rates. The CE increases with the increase of the liquid flow rate but decreases with the increase of the gas flow rate. This is because the CE is affected by the bubble breakup phenomenon in the Venturi tube. In the experiment, we confirmed that cavitation number which is the parameter of the bubble breakup was related to the CE of the Venturi type.
Tamakuma, Yuki*; Yamada, Ryohei; Iwaoka, Kazuki*; Hosoda, Masahiro*; Tokonami, Shinji*
Hoken Butsuri (Internet), 54(1), p.5 - 12, 2019/03
Airborne radioactivity measurements are necessary to know the contamination level and internal doses for residents after a nuclear accident. In addition, measurements of radon progenies in air, which are the risk factor of lung cancer, are also important to evaluate lung dose. In these measurements, a filter sampling is used to collect radioactive aerosols. However, it is well known that results of the measurement using a filter are strongly dependent on characteristics of the used filter. Selection of a suitable filter is important to achieve the high-resolution and long-term measurement. "Surface collection efficiency (SCE)" and "stability of air flow rate" were examined for six types of filter that are commercially available in Japan. In Japan, cellulose-glass fiber filter paper (HE-40T) is used for an environmental monitoring in Japan. In this study, it was found that the SCE of HE-40T was lower than that of mixed cellulose ester type membrane filter by Merck Millipore (DAWP02500). Attenuation ratio of flow rate for DAWP02500 was evaluated to be 2.9% which was lowest in six filters. The results suggest that the DAWP02500 is the most suitable for collecting radioactive aerosols for a long term.
Tamada, Masao
Hoshasen Kagaku (Internet), (100), P. 16, 2015/10
Collection of a rare metal form hot spring water attracted medias and had a public response by reports of numerous newspapers and television programs in my 35 years' research and development of radiation processing technologies and its technology management. Collection experiments of the rare metal were carried out in Kusatsu Onsen, Gunma prefecture, where discharge of hot spring water is the largest in Japan. We were on standby 6 am there when morning live broadcast started from 8 am. The invention of emersion grafting solved the problems in the cost reduction of adsorbent production owing to its high grafting yield and led the way for technology transfer of filter for the removal of metal ions in ppb level from semiconductor cleaning liquid and adsorbent for radio-active cesium.
-lactamase from the moderate halophile 
sp.560 and the discovery of a Cs
-selective binding siteArai, Shigeki; Yonezawa, Yasushi*; Okazaki, Nobuo*; Matsumoto, Fumiko*; Shibazaki, Chie; Shimizu, Rumi; Yamada, Mitsugu*; Adachi, Motoyasu; Tamada, Taro; Kawamoto, Masahide*; et al.
Acta Crystallographica Section D, 71(3), p.541 - 554, 2015/03
Times Cited Count：7 Percentile：50.76(Biochemical Research Methods)The crystal structure of halophilic -lactamase from sp.560 (HaBLA) was determined using X-ray crystallography. Moreover, the locations of bound Sr
and Cs ions were identified by anomalous X-ray diffraction. The location of one Cs specific binding site was identified on HaBLA even in the presence of 9-fold molar excess of Na (90 mM Na /10 mM Cs). This Cs binding site is formed by two main-chain O atoms and an aromatic ring of a side chain of Trp. An aromatic ring of Trp interacts with Cs by the cation-
interaction. The observation of a selective and high-affinity Cs binding site provides important information that is useful for designing artificial Cs binding sites useful in bioremediation of radioactive isotopes.
Seko, Noriaki; Kasai, Noboru; Shimizu, Takao*; Tamada, Masao
Nihon Kaisui Gakkai-Shi, 59(5), p.316 - 319, 2005/10
Braid adsorbent having functional group of amidoxime is a promising material for the recovery of uranium dissolved in the seawater. This long braid adsorbent was made by polyethylene multi-fibers in which amidoxime groups were introduced by radiation-induced graft polymerization and subsequent chemical treatment. The braid adsorbent obtained was moored at the offing of Okinawa Island. The average U adsorption of the adsorbent became 1.5 g-U/kg-adsorbent for 30 d soaking. The mooring system for braid adsorbent has possibility which reduced the cost for the recovery of uranium from seawater. Annual product of 1200 tons of uranium needs 134 km
of mooring area. In addition, there is 6000 km and more of suitable sea area for the collection of the uranium in the regions from Okinawa Islands to Tosa Bay in Japan.
Tamada, Masao; Seko, Noriaki; Kasai, Noboru; Shimizu, Takao*
FAPIG, (169), p.3 - 12, 2005/03
Braid adsorbent having functional group of amidoxime is a promising material for the recovery of uranium dissolved in the seawater. This braid adsorbent was made by polyethylene multi-fibers in which amidoxime groups were introduced by radiation-induced graft polymerization and subsequent chemical treatment. Reaction time for graft polymerization was 5 h and the resulted braid adsorbent had 2.8 mmol/g-adsorbent of amidoxime group. The braid adsorbent obtained was moored at the offing of Okinawa Island. The adsorption of uranium reached 1.5g/kg-adsorbent for 30 d soaking. The mooring system for braid adsorbent has possibility which reduced the cost for the recovery of uranium from seawater. It is shown that 134 km of mooring area is needed for annual product of 1200 tons of uranium. In addition, there is 6000 km and more of suitable sea area for the collection of the uranium in the regions from Okinawa Islands to Tosa Bay in Japan.
Seko, Noriaki; Kasai, Noboru; Tamada, Masao; Hasegawa, Shin; Katakai, Akio; Sugo, Takanobu*
JAERI-Tech 2004-076, 78 Pages, 2005/01
JAERI-Tech-2004-076.pdf:17.11MB
In September 1999, we have soaked 200 kg of fibrous amidoxime adsorbents, synthesized by radiation-induced graft polymerization, into seawater to evaluate their performance. Fractional elution facility was set effectively to elute the rare metals on adsorbents in Mutsu-Establishment. This facility consists of two parts of pre-washing and elution. The present report dealt with planning, manufacture and setting of fractional facility. Marine organism and slime on adsorbent cassette (290
290160 mm) were washed out and every 72 cassettes were set in elution unit (12101210H1460 mm) with nonwoven materials as a packing to avoid elution loss. In the elution process alkaline and alkaline earth metals were eluted with low concentration hydrochloric acid (0.01M) and rare metals were eluted with high concentration (0.5M) after the packing of elution unit into fractional elution facility.
Seko, Noriaki; Takeda, Hayato*; Kasai, Noboru; Tamada, Masao; Hasegawa, Shin; Katakai, Akio; Sugo, Takanobu*
JAERI-Tech 2004-075, 51 Pages, 2005/01
Fibrous adsorbent which is synthesized by radiation induced graft polymerization on the trunk polymers such as polymer nonwoven fabrics and woven cloths exhibits an excellent selective adsorption against heavy metal ions and toxic gases at extremely low concentrations. Two equipments were installed to synthesize the metal-ion and gas adsorbents by means of the radiation-induced graft polymerization in the liquid phase and the dipping, respectively. In the reaction chamber of the liquid phase reactor, the oxygen decreased to 100ppm. The inside temperature raised to 80
C. These characteristics satisfied the specification. The fabric transport can regulate the rate in the range from 1 to 10m/min. The reactor for the dip grafting could reduce the inside oxygen to 100ppm and inside temperature could reach to 80 C. The grafting of GMA was carried out as a characteristic test. The degree of grafting was controlled in the range from 40 to 70%.
Esaka, Fumitaka; Watanabe, Kazuo; Fukuyama, Hiroyasu; Onodera, Takashi; Esaka, Konomi; Magara, Masaaki; Sakurai, Satoshi; Usuda, Shigekazu
Journal of Nuclear Science and Technology, 41(11), p.1027 - 1032, 2004/11
Times Cited Count：60 Percentile：95.56(Nuclear Science & Technology)A new particle recovery method and a sensitive screening method were developed for subsequent isotope ratio analysis of uranium particles in safeguards swipe samples. The particles in the swipe sample were recovered onto a carrier by means of vacuum suction 8211; impact collection method. When grease coating was applied to the carrier, the recovery efficiency was improved to 48 %, which is superior to that of conventionally-used ultrasoneration method. Prior to isotope ratio analysis with secondary ion mass spectrometry (SIMS), total reflection X-ray fluorescence spectrometry (TXRF) was applied to screen the sample for the presence of uranium particles. By the use of Si carriers in TXRF analysis, the detection limit of 22 pg was achieved for uranium. By combining these methods with SIMS, the isotope ratios of 
U/
U for individual uranium particles were efficiently determined.
Takahashi, Manabu*; Tanaka, Kazuya*; Tamada, Masao; Aoi, Toru*
Kankyo Kogaku Kenkyu Rombunshu, Vol.41, p.229 - 235, 2004/11
Fibrous metal adsorbent having iminodiacetic acid was synthesized by radiation-induced grafting glycidyl methacrylate on nonwoven fabric and subsequent chemical treatment. The degree of grafting calculated by increasing weight after grafting reached 170 % for reaction time of 2h at 40 C. The adsorption characteristics of ferric and manganese ions were evaluated by using the resulting adsorbent with 2.1 mmol/g-adsorbent function group of iminodiacetic acid. Each distribution coefficient of ferric and manganese ion deceased with increase of another coexist ion. Both ferric and manganese ions were completely removed by the adsorbent column at the space velocity of 1000h
. Adsorption capacities of both ions were reduced to 80% after 5 times reputation of adsorption and desorption.
Tamada, Masao; Seko, Noriaki; Yoshii, Fumio
Radiation Physics and Chemistry, 71(1-2), p.223 - 227, 2004/09
Times Cited Count：71 Percentile：96.47(Chemistry, Physical)Graft polymerization and crosslinking in radiation processing were attractive techniques to modify conventional polymers. In the case of graftpolymerization, metal adsorbent was prepared by introducing the chelate function to trunk polymer like polyethylene. The obtained metal adsorbent was applied to the recovery of uranium in seawater. Three years' marine experiment revealed that 1kg of uranium could be collected by using graft-adsorbent. Natural polymers such as derivatives of starch and cellulose led irradiation crosslinking at paste-like condition and formed hydrogels. These hydrogels had degradability even after crosslinking. The mat of degradable hydrogel was effective to prevent bedsores as a healthcare product. After use, the hydrogel can be converted to fertilizer by decompositions.
Shimizu, Takao*; Tamada, Masao
Kaiyo Kaihatsu Rombunshu, 20, p.617 - 622, 2004/06
Recovery system of braid type adsorbent which stands straight with built-in float from sea bottom was proposed on the points of effective and economical view. The system scale for 1200 t/y recovery (demand for 6 atomic power plants) with braid type adsorbent was optimized by a model in which the efficiency of uranium adsorption was proportional to the uranium concentration surrounding the adsorbent. The recovery system of 2.67 millions adsorbents which were arranged with the distance of more than 60m intervals among the adsorbents could collect 1200t/y uranium. The system still collected 1000 t/y uranium when the interval distance decreased to 4 m. The area occupied by the adsorbents was 6.5 km square. The sea area on the coast of Japan was searched for recovery system of braid type adsorbent by considering the factors of the temperature, the depth, the fishery, and the territorial waters of Japan. The selected sea area was located form the South East Islands to the offing of Koch in the depth range from 100m to 200m, where the Japan Current flew.
Seko, Noriaki; Tamada, Masao; Kasai, Noboru; Yoshii, Fumio; Shimizu, Takao*
Kaiyo Kaihatsu Rombunshu, 20, p.611 - 616, 2004/06
Development of the recovery technology of uranium of storing all over seawater can stable supply of mineral resources over the future. The amidoxime adsorbents used by nonwoven fiber of the shape of cloth produced by the radiation graft polymerization technique. It became clear that their adsorbents of the high form of contact efficiency with seawater are important. Therefore, the braid adsorbents by which contact efficiency with seawater is improved were devised. Moreover, by the mooring system using braid adsorbents, since it counted upon lightweight-ization, i.e., rationalization of the marine structure which occupies the great portion of total cost, in this research, while developing the producing method, performance evaluation was performed, and the production method and the applicability of a recovery system were examined.
Tamada, Masao
Genshiryoku Hyakka Jiten ATOMICA (Internet), 15 Pages, 2004/04
no abstracts in English
Tamada, Masao
Kankyo Shigen Kogaku, 51(2), p.99 - 101, 2004/04
Fibrous chelate adsorbents have been synthesized by radiation-induced graft polymerization onto polyethylene nonwoven fabric. Graft polymerization was induced by electron beam irradiation to the trunk polymer. Then, irradiated trunk polymer was contacted with reactive monomer having function of chelate agent or its precursor. The precursor was chemically converted to chelate agent. The resulting fibrous chelate adsorbent gave the high space velocity more than 500 h in removal of lead from its solution. Such adsorbent was applied to the removal of cadmium from scallop processing waste and the removal of lead from the contaminated water which was produced by washing the inside of incinerator.
Seko, Noriaki; Tamada, Masao; Sugo, Takanobu
Kaiyo Kaihatsu Nyusu, 31(1), p.8 - 11, 2003/04
no abstracts in English
Tamada, Masao
Oyo Butsuri, 72(4), p.453 - 456, 2003/04
Radiation induced graft-polymerization is sophisticated technique which is capable of introducing aiming functions into conventional polymers. Especially, pre-irradiation method is available for industrialization owing to discrete processes of irradiation and grafting. The chelate adsorbents having high selectivity against metals were synthesized by the graft-polymerization. The recovery of uranium from seawater and the removal of toxic metals from wastewater were described as applicable examples of the graft adsorbents.
Shiraishi, Tomoyuki*; Tamada, Masao; Saito, Kyoichi*; Sugo, Takanobu
Radiation Physics and Chemistry, 66(1), p.43 - 47, 2003/01
Times Cited Count：50 Percentile：93.91(Chemistry, Physical)no abstracts in English
Basuki, F.*; Seko, Noriaki; Tamada, Masao; Sugo, Takanobu; Kume, Tamikazu
Nihon Ion Kokan Gakkai-Shi, 14(Suppl.), p.209 - 212, 2003/00
Radiation induced graftpolymerization is a sophisticated tool for introducing the aiming functional group into the conventional polymer. Adsorbent having phosphoric acid was directly synthesized by grafting methacrylate monomer having phosphoric acid onto polyethylene nonwoven fabric. Degree of grafting, which was estimated by increment weight after grafting, reached 185 % when the 10 % monomer in the mixture of 10 % methanol and 90 % water was reacted with 200 kGy-irradiated polyethylene nonwoven fabric. The resulting adsorbent revealed that adsorption capacities were 3 mmol/g-adsorbent for Pb and Cd. The removal of these metals could be performed with space velocity of 250 h.
Shimizu, Takao*; Tamada, Masao; Seko, Noriaki; Sakaguchi, Isamu*
Kaiyo Kaihatsu Rombunshu, 18, p.737 - 742, 2002/06
Total amount of uranium in seawater is 4.5 billion tons corresponding to 45,000 times of annual demand for nuclear fuel in the world, though its concentration is only 3.3 mg/m3. The target of this study is that the cost-down of uranium collection from the sea to three times of the market price. This price is cheaper than the recycle fuel by nuclear reprocessing. The present study proposed a high performance adsorbent made by means of both radiation induced graft polymerization and braid technique. The drag force of the braid type adsorbent in water channel was measured. In the west coast of Okinawa prefecture, the adsorption of uranium and the adhesion of sea creature were investigated. It was clarified that reduction of the drag force by the deformed braid adsorbent in the water flow, the increment of uranium adsorption owing to high temperature of seawater, and little adhesion of the creature.
