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Journal Articles

Study on eutectic melting behavior of control rod materials in core disruptive accidents of sodium-cooled fast reactors, 1; Project overview and progress until 2019

Yamano, Hidemasa; Takai, Toshihide; Furukawa, Tomohiro; Kikuchi, Shin; Emura, Yuki; Kamiyama, Kenji; Fukuyama, Hiroyuki*; Higashi, Hideo*; Nishi, Tsuyoshi*; Ota, Hiromichi*; et al.

Proceedings of 28th International Conference on Nuclear Engineering; Nuclear Energy the Future Zero Carbon Power (ICONE 28) (Internet), 11 Pages, 2021/08

One of the key issues in a core disruptive accident (CDA) evaluation in sodium-cooled fast reactors is eutectic reactions between boron carbide (B$$_{4}$$C) and stainless steel (SS) as well as its relocation. Such behaviors have never been simulated in CDA numerical analyses in the past, therefore it is necessary to develop a physical model and incorporate the model into the CDA analysis code. This study focuses on B$$_{4}$$C-SS eutectic melting experiments, thermophysical property measurement of the eutectic melt, and physical model development for the eutectic melting reaction. The eutectic experiments involve the visualization experiments, eutectic reaction rate experiments and material analyses. The thermophysical properties are measured in a range from solid to liquid state. The physical model is developed for a CDA computer code based on the measured data of the eutectic reaction rate and the physical properties. This paper describes the project overview and progress of experimental and analytical studies conducted until 2019. Specific results in this paper are the validation of physical model describing B$$_{4}$$C-SS eutectic reaction in the CDA analysis code, SIMMER-III, through the numerical analysis of the B$$_{4}$$C-SS eutectic melting experiments in which a B$$_{4}$$C block was placed in a SS pool.

Journal Articles

Generation of particles and fragments by quasicontinuous wave fiber laser irradiation of stainless steel, alumina, and concrete materials

Daido, Hiroyuki*; Yamada, Tomonori; Furukawa, Hiroyuki*; Ito, Chikara; Miyabe, Masabumi; Shibata, Takuya; Hasegawa, Shuichi*

Journal of Laser Applications, 33(1), p.012001_1 -  012001_16, 2021/02

 Times Cited Count:0 Percentile:0(Materials Science, Multidisciplinary)

Journal Articles

Study on eutectic melting behavior of control rod materials in core disruptive accidents of sodium-cooled fast reactors, 1; Project overview and progress until 2018

Yamano, Hidemasa; Takai, Toshihide; Furukawa, Tomohiro; Kikuchi, Shin; Emura, Yuki; Kamiyama, Kenji; Fukuyama, Hiroyuki*; Higashi, Hideo*; Nishi, Tsuyoshi*; Ota, Hiromichi*; et al.

Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 10 Pages, 2020/08

One of the key issues in a core disruptive accident (CDA) evaluation in sodium-cooled fast reactors is eutectic reactions between boron carbide (B$$_{4}$$C) and stainless steel (SS) as well as its relocation. Such behaviors have never been simulated in CDA numerical analyses in the past, therefore it is necessary to develop a physical model and incorporate the model into the CDA analysis code. This study focuses on B$$_{4}$$C-SS eutectic melting experiments, thermophysical property measurement of the eutectic melt, and physical model development for the eutectic melting reaction. The eutectic experiments involve the visualization experiments, eutectic reaction rate experiments and material analyses. The thermophysical properties are measured in a range from solid to liquid state. The physical model is developed for a severe accident computer code based on the measured data of the eutectic reaction rate and the physical properties. This paper describes the project overview and progress of experimental and analytical studies conducted until 2018. Specific results in this paper are boron concentration distributions of solidified B$$_{4}$$C-SS eutectic sample in the eutectic melting experiments, which would be used for the validation of the eutectic physical model implemented into the computer code.

Journal Articles

A Portable radioactive plume monitor using a silicon photodiode

Tamakuma, Yuki*; Yamada, Ryohei; Iwaoka, Kazuki*; Hosoda, Masahiro*; Kuroki, Tomohiro*; Mizuno, Hiroyuki*; Yamada, Koji*; Furukawa, Masahide*; Tokonami, Shinji*

Perspectives in Science (Internet), 12, p.100414_1 - 100414_4, 2019/09

In this study, a portable radioactive plume monitor using a silicon photodiode was developed for the detection of a radioactive plume (e.g. $$^{131}$$I, $$^{134}$$Cs and $$^{137}$$Cs) in an emergency situation. It was found that the background count rate was proportional to ambient dose equivalent rate and the detection limit for the monitor at 20 $$mu$$Sv h$$^{-1}$$ as an ambient dose equivalent rate was evaluated to be 187 Bq m$$^{-3}$$ using the ISO11929 method. These results suggest that the detection limit for the system can be decreased effectively by lead shielding with optimized thickness.

Journal Articles

Study on eutectic melting behavior of control rod materials in core disruptive accidents of sodium-cooled fast reactors, 1; Project overview

Yamano, Hidemasa; Takai, Toshihide; Furukawa, Tomohiro; Kikuchi, Shin; Emura, Yuki; Kamiyama, Kenji; Fukuyama, Hiroyuki*; Higashi, Hideo*; Nishi, Tsuyoshi*; Ota, Hiromichi*; et al.

Proceedings of International Nuclear Fuel Cycle Conference / Light Water Reactor Fuel Performance Conference (Global/Top Fuel 2019) (USB Flash Drive), p.418 - 427, 2019/09

Eutectic reactions between boron carbide (B$$_{4}$$C) and stainless steel (SS) as well as its relocation are one of the key issues in a core disruptive accident (CDA) evaluation in sodium-cooled fast reactors. Since such behaviors have never been simulated in CDA numerical analyses, it is necessary to develop a physical model and incorporate the model into the CDA analysis code. This study is focusing on B$$_{4}$$C-SS eutectic melting experiments, thermophysical property measurement of the eutectic melt, and physical model development for the eutectic melting reaction. The eutectic experiments involve the visualization experiments, eutectic reaction rate experiments and material analyses. The thermophysical properties are measured in the range from solid to liquid state. The physical model is developed for a severe accident computer code based on the measured data of the eutectic reaction rate and the physical properties. This paper describes the project overview and progress of experimental and analytical studies by 2017. Specific results in this paper is boron concentration distributions of solidified B$$_{4}$$C-SS eutectic sample in the eutectic melting experiments, which would be used for the validation of the eutectic physical model implemented into the computer code.

Journal Articles

Development of risk assessment methodology against natural external hazards for sodium-cooled fast reactors; Project overview and margin assessment methodology against volcanic eruption

Yamano, Hidemasa; Nishino, Hiroyuki; Kurisaka, Kenichi; Okano, Yasushi; Sakai, Takaaki; Yamamoto, Takahiro*; Ishizuka, Yoshihiro*; Geshi, Nobuo*; Furukawa, Ryuta*; Nanayama, Futoshi*; et al.

Proceedings of 11th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, Operation and Safety (NUTHOS-11) (USB Flash Drive), 12 Pages, 2016/10

This paper describes mainly volcanic margin assessment methodology development in addition to the project overview. The volcanic tephra could potentially clog filters of air-intakes that need the decay heat removal. The filter clogging can be calculated by atmospheric concentration and fallout duration of the volcanic tephra and also suction flow rate of each component. In this paper, the margin was defined as a grace period to a filter failure limit. Consideration is needed only when the grace period is shorter than the fallout duration. The margin by component was calculated using the filter failure limit and the suction flow rate of each component. The margin by sequence was evaluated based on an event tree and the margin by component. An accident management strategy was also suggested to extend the margin; for instance, manual trip of the forced circulation operation, sequential operation of three air coolers, and covering with pre-filter.

Journal Articles

Development of risk assessment methodology of decay heat removal function against natural external hazards for sodium-cooled fast reactors; Project overview and volcanic PRA methodology

Yamano, Hidemasa; Nishino, Hiroyuki; Kurisaka, Kenichi; Okano, Yasushi; Sakai, Takaaki; Yamamoto, Takahiro*; Ishizuka, Yoshihiro*; Geshi, Nobuo*; Furukawa, Ryuta*; Nanayama, Futoshi*; et al.

Proceedings of 24th International Conference on Nuclear Engineering (ICONE-24) (DVD-ROM), 10 Pages, 2016/06

This paper describes mainly volcanic probabilistic risk assessment (PRA) methodology development for sodium-cooled fast reactors in addition to the project overview. The volcanic ash could potentially clog air filters of air-intakes that are essential for the decay heat removal. The degree of filter clogging can be calculated by atmospheric concentration of ash and tephra fallout duration and also suction flow rate of each component. The atmospheric concentration can be calculated by deposited tephra layer thickness, tephra fallout duration and fallout speed. This study evaluated a volcanic hazard using a combination of tephra fragment size, layer thickness and duration. In this paper, each component functional failure probability was defined as a failure probability of filter replacement obtained by using a grace period to a filter failure limit. Finally, based on an event tree, a core damage frequency was estimated about 3$$times$$10$$^{-6}$$/year in total by multiplying discrete hazard probabilities by conditional decay heat removal failure probabilities. A dominant sequence was led by the loss of decay heat removal system due to the filter clogging after the loss of emergency power supply. A dominant volcanic hazard was 10$$^{-2}$$ kg/m$$^{3}$$ of atmospheric concentration, 0.1 mm of tephra diameter, 50-75 cm of deposited tephra layer thickness, and 1-10 hr of tephra fallout duration.

Journal Articles

Development of risk assessment methodology against natural external hazards for sodium-cooled fast reactors; Project overview and strong wind PRA methodology

Yamano, Hidemasa; Nishino, Hiroyuki; Kurisaka, Kenichi; Okano, Yasushi; Sakai, Takaaki; Yamamoto, Takahiro*; Ishizuka, Yoshihiro*; Geshi, Nobuo*; Furukawa, Ryuta*; Nanayama, Futoshi*; et al.

Proceedings of 2015 International Congress on Advances in Nuclear Power Plants (ICAPP 2015) (CD-ROM), p.454 - 465, 2015/05

This paper describes mainly strong wind PRA methodology development in addition to the project overview. In developing the strong wind PRA methodology, hazard curves were estimated by using Weibull and Gumbel distributions based on weather data recorded in Japan. The obtained hazard curves were divided into five discrete categories for event tree quantification. Next, failure probabilities for decay heat removal related components were calculated as a product of two probabilities: i.e., a probability for the missiles to enter the intake or outtake in the decay heat removal system, and fragility caused by the missile impacts. Finally, based on the event tree, the core damage frequency was estimated about 6$$times$$10$$^{-9}$$/year by multiplying the discrete hazard probabilities in the Gumbel distribution by the conditional decay heat removal failure probabilities. A dominant sequence was led by the assumption that the operators could not extinguish fuel tank fire caused by the missile impacts and the fire induced loss of the decay heat removal system.

Journal Articles

Development of risk assessment methodology of decay heat removal function against external hazards for sodium-cooled fast reactors, 1; Project overview and margin assessment methodology against snow

Yamano, Hidemasa; Nishino, Hiroyuki; Kurisaka, Kenichi; Okano, Yasushi; Sakai, Takaaki; Yamamoto, Takahiro*; Ishizuka, Yoshihiro*; Geshi, Nobuo*; Furukawa, Ryuta*; Nanayama, Futoshi*; et al.

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 10 Pages, 2015/05

This paper describes mainly snow margin assessment methodology development in addition to the project overview. For the snow margin assessment, the index is a combination of a snowfall rate and duration. Since snow removal can be expected during the snowfall, the developed snow margin assessment methodology is such that the margin was regarded as the snowfall duration up to the decay heat removal failure which was defined as when the snow removal rate was smaller than the snowfall rate.

Journal Articles

Development of margin assessment methodology of decay heat removal function against external hazards, 1; Project overview and snow PRA methodology

Yamano, Hidemasa; Nishino, Hiroyuki; Kurisaka, Kenichi; Okano, Yasushi; Sakai, Takaaki; Yamamoto, Takahiro*; Ishizuka, Yoshihiro*; Geshi, Nobuo*; Furukawa, Ryuta*; Nanayama, Futoshi*; et al.

Proceedings of 10th International Topical Meeting on Nuclear Thermal Hydraulics, Operation and Safety (NUTHOS-10) (USB Flash Drive), 12 Pages, 2014/12

This paper describes mainly snow probabilistic risk assessment (PRA) methodology development in addition to the project overview. In snow hazard category, the accident sequence was evaluated by producing event trees which consist of several headings representing the loss of decay heat removal. Snow removal action and manual operation of the air cooler dampers were introduced into the event tree as accident managements. The snow PRA showed less than 10$$^{-6}$$/reactor-year of core damage frequency.

Journal Articles

Development of margin assessment methodology of decay heat removal function against external hazards; Project overview and preliminary risk assessment against snow

Yamano, Hidemasa; Nishino, Hiroyuki; Kurisaka, Kenichi; Sakai, Takaaki; Yamamoto, Takahiro*; Ishizuka, Yoshihiro*; Geshi, Nobuo*; Furukawa, Ryuta*; Nanayama, Futoshi*; Takata, Takashi*

Proceedings of 12th Probabilistic Safety Assessment and Management Conference (PSAM-12) (USB Flash Drive), 11 Pages, 2014/06

This paper describes mainly preliminary risk assessment against snow in addition to the project overview. The snow hazard indexes are the annual maximum snow depth and the annual maximum daily snowfall depth. Snow hazard curves for the two indexes were developed using 50 year weather data at the typical sodium-cooled fast reactor site in Japan. In this paper, the snow risk assessment showed less than 10$$^{-6}$$/reactor-year of core damage frequency. The dominant snow hazard category was the combination of 1-2m/day of snowfall velocity and 0.75-1.0 day of snowfall duration. Sensitivity analyses indicated important human actions, which were the improvement of snow removal velocity and the awareness of snow removal necessity.

Journal Articles

Modeling of atomic processes of multiple charged ions in plasmas and its application to the study of EUV light sources

Sasaki, Akira; Nishihara, Katsunobu*; Sunahara, Atsushi*; Furukawa, Hiroyuki*; Nishikawa, Takeshi*; Koike, Fumihiro*

Plasma and Fusion Research (Internet), 6(Sp.1), p.2401145_1 - 2401145_4, 2011/12

Atomic processes and radiation from multiple charged ions in plasmas are of the interest in the investigation of plasma wall interaction and transport of impurity ions in the fusion devices. The emission from multiple charged ions is also investigated for the development of extreme ultra violet light (EUVL) sources at $$lambda=13.5 nm$$. Efficient emission through the 4d-4f + 4p-4d transition array is obtained from tin ions. An optimization of pumping conditions of laser produced plasma sources is carried out theoretically and experimentally. We also investigate an extension of the plasma light sources to short wavelength to $$lambda=6.5 nm$$ using Gd and Tb plasmas. We discuss requirements to the atomic structure, rate coefficient and collisional radiative codes to determine ion abundance and level population as a function of plasma temperature and density, to calculate the radiation intensity as well as emission spectrum.

Journal Articles

Target system of IFMIF-EVEDA in Japanese activities

Ida, Mizuho; Fukada, Satoshi*; Furukawa, Tomohiro; Hirakawa, Yasushi; Horiike, Hiroshi*; Kanemura, Takuji*; Kondo, Hiroo; Miyashita, Makoto; Nakamura, Hiroo; Sugiura, Hirokazu*; et al.

Journal of Nuclear Materials, 417(1-3), p.1294 - 1298, 2011/10

 Times Cited Count:3 Percentile:27.67(Materials Science, Multidisciplinary)

Engineering Validation and Engineering Design Activities (EVEDA) of the International Fusion Materials Irradiation Facility (IFMIF) was started. As a Japanese activity for the target system, EVEDA Lithium Test Loop simulating hydraulic and impurity conditions of IFMIF is under design and preparation for fabrication. Feasibility of thermo-mechanical structure of the target assembly and the replaceable back-plate made of F82H (a RAFM) and 316L (a stainless steel) is a key issue. Toward final validation on the EVEDA loop, diagnostics applicable to a high-speed free-surface Li flow and hot traps to control nitrogen and hydrogen in Li are under tests. For remote handling of target assemblies and the replaceable back-plates activated up to 50 dpa/y, lip weld on 316L-316L by laser and dissimilar weld on F82H-316L are under investigation. As engineering design of the IFMIF target system, water experiments and hydraulic/thermo-mechanical analyses of the back-plate are going.

Journal Articles

Theoretical investigation of the spectrum and conversion efficiency of short wavelength extreme-ultraviolet light sources based on terbium plasmas

Sasaki, Akira; Nishihara, Katsunobu*; Sunahara, Atsushi*; Furukawa, Hiroyuki*; Nishikawa, Takeshi*; Koike, Fumihiro*

Applied Physics Letters, 97(23), p.231501_1 - 231501_3, 2010/12

 Times Cited Count:14 Percentile:52.5(Physics, Applied)

Emission spectrum and conversion efficiency of laser produced terbium plasmas are investigated theoretically on the basis of computational atomic data. It is shown that calculation reproduces the main peak of the experimental spectrum at $$lambda=6.5$$nm, which originates from 4$$d$$-4$$f$$ transitions of near palladium like ions (Tb$$^{19+}$$). Simple model of the isothermal expansion of plasma suggests that efficient emission can be obtained by pumping a plasma with a laser pulse with an intensity approximately one order of magnitude grater than in the case of tin sources at $$lambda=13.5$$nm.

Journal Articles

Modeling of radiative properties of Sn plasmas for extreme-ultraviolet source

Sasaki, Akira; Sunahara, Atsushi*; Furukawa, Hiroyuki*; Nishihara, Katsunobu*; Fujioka, Shinsuke*; Nishikawa, Takeshi*; Koike, Fumihiro*; Ohashi, Hayato*; Tanuma, Hajime*

Journal of Applied Physics, 107(11), p.113303_1 - 113303_11, 2010/06

 Times Cited Count:33 Percentile:77.65(Physics, Applied)

Atomic processes in Sn plasmas are investigated for application to extreme-ultraviolet (EUV) light sources used in microlithography. An atomic model of Sn is developed on the basis of calculated atomic data using the Hebrew University Lawrence Livermore Atomic Code (HULLAC). Resonance and satellite lines from singly and multiply excited states of Sn ions are identified. The wavelengths of the 4$$d$$-4$$f$$ + 4$$p$$-4$$d$$ transitions of Sn$$^{5+}$$ to Sn$$^{13+}$$ are investigated. Results of calculation are compared with those of the charge exchange spectroscopy, measurement of the emission spectrum of the laser produced plasma EUV source, and the opacity measurement of a radiatively heated Sn sample. A reasonable agreement is observed between calculated and experimental EUV emission spectra. The spectral emissivity and opacity of Sn plasmas are calculated using a full collisional radiative (CR) model as a function of electron temperature and ion density.

Journal Articles

Recent progress in the energy recovery linac project in Japan

Sakanaka, Shogo*; Akemoto, Mitsuo*; Aoto, Tomohiro*; Arakawa, Dai*; Asaoka, Seiji*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2338 - 2340, 2010/05

Future synchrotron light source using a 5-GeV energy recovery linac (ERL) is under proposal by our Japanese collaboration team, and we are conducting R&D efforts for that. We are developing high-brightness DC photocathode guns, two types of cryomodules for both injector and main superconducting (SC) linacs, and 1.3 GHz high CW-power RF sources. We are also constructing the Compact ERL (cERL) for demonstrating the recirculation of low-emittance, high-current beams using above-mentioned critical technologies.

JAEA Reports

Estimation of acceptable beam trip frequencies of accelerators for ADS and comparison with performances of existing accelerators

Takei, Hayanori; Nishihara, Kenji; Tsujimoto, Kazufumi; Furukawa, Kazuro*; Yano, Yoshiharu*; Ogawa, Yujiro*; Oigawa, Hiroyuki

JAEA-Research 2009-023, 114 Pages, 2009/09

JAEA-Research-2009-023.pdf:8.86MB

Frequent beam trips as experienced in existing high power proton accelerators may cause thermal fatigue problems in ADS components which may lead to degradation of their structural integrity and reduction of their lifetime. Thermal transient analyses were performed to investigate the effects of beam trips on the reactor components. Our results indicated that the acceptable frequency of beam trips ranged from 50 to $$2times10^{4}$$ times per year depending on the beam trip duration. In order to consider measures to reduce the frequency of beam trips on the high power accelerator for ADS, we compared the acceptable frequency of beam trips with the operation data of existing accelerators. The result of this comparison showed that the beam trip frequency for durations of 10 seconds or less was within the acceptable level, while that exceeding five minutes should be reduced to about 1/30 to satisfy the thermal stress conditions.

Journal Articles

Atomic modeling of the plasma EUV sources

Sasaki, Akira; Sunahara, Atsushi*; Furukawa, Hiroyuki*; Nishihara, Katsunobu*; Nishikawa, Takeshi*; Koike, Fumihiro*; Tanuma, Hajime*

High Energy Density Physics, 5(3), p.147 - 151, 2009/09

 Times Cited Count:9 Percentile:35.94(Physics, Fluids & Plasmas)

We study the radiative properties of the EUV source to address conditions to achieve an output power and efficiency required for its application to the next generation microlithography. An atomic model is developed based on the atomic data calculated by Hullac code, which is validated through detailed comparisons with experimental emission and a absorption spectra. The atomic model is improved with respect to the wavelength of the strong emission lines, and the number of satellite channels taken into account. As a result, the radiation hydrodynamics model is shown to successfully reproduce the experiments. We show Sn plasma is more efficient than Xe plasma because of the atomic number dependence of the emission wavelength, and the use of CO$$_{2}$$ lasers as a pumping source has an advantage to reduce satellite contribution and to have narrower emission spectrum to obtain higher conversion efficiency.

Journal Articles

Estimation of acceptable beam trip frequencies of accelerators for ADS and comparison with experimental data of accelerators

Takei, Hayanori; Nishihara, Kenji; Tsujimoto, Kazufumi; Furukawa, Kazuro*; Yano, Yoshiharu*; Ogawa, Yujiro*; Oigawa, Hiroyuki

Proceedings of International Topical Meeting on Nuclear Research Applications and Utilization of Accelerators (CD-ROM), 9 Pages, 2009/05

Frequent beam trips as experienced in existing high power proton accelerators may cause thermal fatigue problems in ADS components which may lead to degradation of their structural integrity and reduction of their lifetime. Thermal transient analyses were performed to investigate the effects of beam trips on the reactor components, with the objective of formulating ADS design that had higher engineering possibilities and determining the requirements for accelerator reliability. These analyses were made on the thermal responses of four parts of the reactor components; the beam window, the cladding tube, the inner barrel and the reactor vessel. Our results indicated that the acceptable frequency of beam trips ranged from 43 to $$2.5times10^4$$ times per year depending on the beam trip duration to keep the plant availability 70%. In order to consider measures to reduce the frequency of beam trips on the high power accelerator for ADS, we compared the acceptable frequency of beam trips with the operation data of existing accelerators. The result of this comparison showed that the beam trip frequency for durations of 10 seconds or less was within the acceptable level, while that exceeding five minutes should be reduced to about 1/35 to satisfy the plant availability conditions.

Journal Articles

Atomic processes in the LPP and LA-DPP EUV sources

Sasaki, Akira; Nishihara, Katsunobu*; Sunahara, Atsushi*; Furukawa, Hiroyuki*; Nishikawa, Takeshi*; Koike, Fumihiro*

Alternative Lithographic Technologies (Proceedings of SPIE Vol.7271), p.727130_1 - 727130_8, 2009/03

We investigate characteristic feature of the atomic radiation from tin plasmas, which allow one to obtain high power EUV emission efficiently. We develop a collisional radiative model of tin ions to calculate steady-state and time dependent ion abundance, level population, and coefficients of radiative transfer of the plasma. The model, which is based atomic data calculated using the Hullac code is refined both theoretically and experimentally. Calculation of the spectral emissivity and opacity are carried out over a wide range of plasma density and temperature, and pumping conditions to obtain high conversion efficiency are discussed.

59 (Records 1-20 displayed on this page)