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Journal Articles

Post irradiation experiment about SiC-coated oxidation-resistant graphite for high temperature gas-cooled reactor

Shibata, Taiju; Mizuta, Naoki; Sumita, Junya; Sakaba, Nariaki; Osaki, Takashi*; Kato, Hideki*; Izawa, Shoichi*; Muto, Takenori*; Gizatulin, S.*; Shaimerdenov, A.*; et al.

Proceedings of 9th International Topical Meeting on High Temperature Reactor Technology (HTR 2018) (USB Flash Drive), 7 Pages, 2018/10

Graphite materials are used for the in-core components of High Temperature Gas-cooled Reactor (HTGR). Oxidation damage on the graphite components in air ingress accident is a crucial issue for the safety point of view. SiC coating on graphite surface is a possible technique to enhance oxidation resistance. However, it is important to confirm the integrity of this material against high temperature and neutron irradiation for the application of the in-core components. JAEA and Japanese graphite companies carried out the R&D to develop the oxidation-resistant graphite. JAEA and INP investigated the irradiation effects on the oxidation-resistant graphite by using a framework of ISTC partner project. This paper describes the results of post irradiation experiment about the neutron irradiated SiC-coated oxidation-resistant graphite. A brand of oxidation-resistant graphite shows excellent performance against oxidation test after the irradiation.

Journal Articles

Enhancement of oxidation tolerance of graphite materials for high temperature gas-cooled reactor

Mizuta, Naoki; Sumita, Junya; Shibata, Taiju; Osaki, Takashi*; Kato, Hideki*; Izawa, Shoichi*; Muto, Takenori*; Gizatulin, S.*; Sakaba, Nariaki

Tanso Zairyo Kagaku No Shinten; Nihon Gakutsu Shinkokai Dai-117-Iinkai 70-Shunen Kinen-Shi, p.161 - 166, 2018/10

To enhance oxidation resistance of graphite material for in-core components of HTGR, JAEA and four Japanese graphite companies; Toyo Tanso, IBIDEN, Tokai Carbon and Nippon Techno-Carbon, are carrying out for development of oxidation-resistant graphite by CVD-SiC coating. This paper describes the outline of neutron irradiation test about the oxidation-resistant graphite by WWR-K reactor of INP, Kazakhstan through an ISTC partner project. Prior to the irradiation test, the oxidation-resistant graphite by CVD-SiC coating of all specimens showed enough oxidation resistance under un-irradiation condition. The neutron irradiation test was already completed and out-of-pile oxidation test will be carried out at the hot-laboratory of WWR-K.

Journal Articles

Irradiation test about oxidation-resistant graphite in WWR-K research reactor

Shibata, Taiju; Sumita, Junya; Sakaba, Nariaki; Osaki, Takashi*; Kato, Hideki*; Izawa, Shoichi*; Muto, Takenori*; Gizatulin, S.*; Shaimerdenov, A.*; Dyussambayev, D.*; et al.

Proceedings of 8th International Topical Meeting on High Temperature Reactor Technology (HTR 2016) (CD-ROM), p.567 - 571, 2016/11

Graphite are used for the in-core components of HTGR, and it is desirable to enhance oxidation resistance to keep much safety margin. SiC coating is the candidate method for this purpose. JAEA and four Japanese graphite companies are studying to develop oxidation-resistant graphite. Neutron irradiation test was carried out by WWR-K reactor of INP of Kazakhstan through ISTC partner project. The total irradiation cycles of WWR-K operation was 10 cycles by 200 days. Irradiation temperature about 1473 K would be attained. The maximum fast neutron fluence (E $$>$$0.18 MeV) for the capsule irradiated at a central irradiation hole was preliminary calculated as 1.2$$times$$10$$^{25}$$/m$$^{-2}$$, and for the capsule at a peripheral irradiation hole as 4.2$$times$$10$$^{24}$$/m$$^{-2}$$. Dimension and weight of the irradiated specimens were measured, and outer surface of the specimens were observed by optical microscope. For the irradiated oxidation resistant graphite, out-of-pile oxidation test will be carried out at an experimental laboratory.

Journal Articles

2016 Professional Engineer (PE) test preparation course "Nuclear and Radiation Technical Disciplines"

Takahashi, Naoki; Yoshinaka, Kazuyuki; Harada, Akio; Yamanaka, Atsushi; Ueno, Takashi; Kurihara, Ryoichi; Suzuki, Soju; Takamatsu, Misao; Maeda, Shigetaka; Iseki, Atsushi; et al.

Nippon Genshiryoku Gakkai Homu Peji (Internet), 64 Pages, 2016/00

no abstracts in English

Journal Articles

A Summary of sodium-cooled fast reactor development

Aoto, Kazumi; Dufour, P.*; Hongyi, Y.*; Glats, J. P.*; Kim, Y.-I.*; Ashurko, Y.*; Hill, R.*; Uto, Nariaki

Progress in Nuclear Energy, 77, p.247 - 265, 2014/11

 Times Cited Count:39 Percentile:1.82(Nuclear Science & Technology)

Much of the basic technology for the Sodium-cooled fast Reactor (SFR) has been established through long term development experience with former fast reactor programs, and is being confirmed by the Ph$'e$nix end-of-life tests, the restart of Monju, the lifetime extension of BN-600 and the startup of CEFR. Planned startup in 2014 for BN-800 and PFBR will further enhance the confirmation of the SFR basic technology. Nowadays, the SFR development has advanced to aiming at establishment of the Generation-IV system which is dedicated to sustainable energy generation and actinide management, and several advanced SFR concepts are under development. Generation-IV International Forum is an international collaboration framework where various R&D activities are progressing for the Generation-IV SFR development, and will play a beneficial role of promoting them thorough providing an opportunity to share the past experience and the latest data of design and R&D among countries developing SFR.

Journal Articles

Irradiation test plan of oxidation-resistant graphite in WWR-K research reactor

Sumita, Junya; Shibata, Taiju; Sakaba, Nariaki; Osaki, Hiroki*; Kato, Hideki*; Fujitsuka, Kunihiro*; Muto, Takenori*; Gizatulin, S.*; Shaimerdenov, A.*; Dyussambayev, D.*; et al.

Proceedings of 7th International Topical Meeting on High Temperature Reactor Technology (HTR 2014) (USB Flash Drive), 7 Pages, 2014/10

Graphite materials are used for the in-core components of High Temperature Gas-cooled Reactor(HTGR)which is a graphite-moderated and helium gas-cooled reactor. In the case of air ingress accident in HTGR, SiO$$_{2}$$ protective layer is formed on the surface of SiC layer in TRISO CFP and oxidation of SiC does not proceed and fission products are retained inside the fuel particle. A new safety concept for the HTGR, called Naturally Safe HTGR, has been recently proposed. To enhance the safety of Naturally Safe HTGR ultimately, it is expected that oxidation-resistant graphite is used for graphite components to prevent the TRISO CFPs and fuel compacts from failure. SiC coating is one of candidate methods for oxidation-resistant graphite. JAEA and four graphite companies launched R&Ds to develop the oxidation-resistant graphite and the International Science and Technology Center(ISTC) partner project with JAEA and INP was launched to investigate the irradiation effects on the oxidation-resistant graphite. To determine grades of the oxidation-resistant graphite which will be adopted as irradiation test, a preliminary oxidation test was carried out. This paper described the results of the preliminary oxidation test, the plan of out-of-pile test, irradiation test and post-irradiation test(PIE)of the oxidation-resistant graphite.

Journal Articles

R&D plan for development of oxidation-resistant graphite and investigation of oxidation behavior of SiC coated fuel particle to enhance safety of HTGR

Ueta, Shohei; Sumita, Junya; Shibata, Taiju; Aihara, Jun; Fujita, Ichiro*; Ohashi, Jun*; Nagaishi, Yoshihide*; Muto, Takenori*; Sawa, Kazuhiro; Sakaba, Nariaki

Nuclear Engineering and Design, 271, p.309 - 313, 2014/05

 Times Cited Count:7 Percentile:39.47(Nuclear Science & Technology)

A new concept of the high temperature gas-cooled reactor (HTGR) is proposed as a challenge to assure no event sequences to the harmful release of radioactive materials even when the design extension conditions (DECs) occur by deterministic approach based on the inherent safety features of the HTGR. The air/water ingress accident, one of the DECs for the HTGR, is prevented by additional measures (e.g. facility for suppression to air ingress). With regard to the core design, it is important to prevent recriticality accidents by keeping the geometry of the fuel rod which consists of the graphite sleeve, fuel compact and SiC-TRISO (TRIstructural-ISOtropic) coated fuel particle, and by improving the oxidation resistance of the graphite when air/water ingress accidents occur. Therefore, it is planned to develop the oxidation-resistant graphite, which is coated with gradient SiC layer. It is also planned that the experimental identification of the condition to form the stable oxide layer (SiO$$_{2}$$) for SiC layer on the oxidation-resistant graphite and on the SiC-TRISO fuel. This paper describes the R&D plan for un-irradiation and irradiation test under simulating air/water ingress accident condition to develop oxidation-resistant graphite and to investigate the oxidation behavior of SiC coated fuel particle.

Journal Articles

R&D plan for development of oxidation-resistant graphite and investigation of oxidation behavior of SiC coated fuel particle to enhance safety of HTGR

Ueta, Shohei; Sumita, Junya; Shibata, Taiju; Aihara, Jun; Fujita, Ichiro*; Ohashi, Jun*; Nagaishi, Yoshihide*; Muto, Takenori*; Sawa, Kazuhiro; Sakaba, Nariaki

Proceedings of 6th International Topical Meeting on High Temperature Reactor Technology (HTR 2012) (USB Flash Drive), 6 Pages, 2012/10

A new concept of the High Temperature Gas-cooled Reactor (HTGR), so-called the Naturally Safe HTGR, is proposed as a challenge to assure no event sequences to the harmful release of radioactive materials even when the design extension conditions such as the air/water ingress accidents occur by deterministic approach based on the inherent safety features of the HTGR. For the Naturally Safe HTGR it is important to prevent recriticality accidents by keeping the geometry of the fuel rod which consists of the graphite sleeve, fuel compact and SiC-TRISO coated fuel particle, and by improving the oxidation resistance of the graphite when air/water ingress accidents occur. This paper describes the R&D plan for un-irradiation and irradiation test under simulating air/water ingress accident condition to develop oxidation-resistant graphite and to investigate the oxidation behavior of SiC coated fuel particle.

Journal Articles

The Screening methodologies and/or achievement evaluation in Japanese FR cycle development program with the changing needs for evaluation

Shiotani, Hiroki; Uto, Nariaki; Kawaguchi, Koichi; Shinoda, Yoshihiko*; Ono, Kiyoshi; Namba, Takashi

Proceedings of 20th International Conference on Nuclear Engineering and the ASME 2012 Power Conference (ICONE-20 & POWER 2012) (DVD-ROM), 10 Pages, 2012/07

This paper argues the characteristics evaluation of Fast Reactor and fuel cycle concepts in the FS "Feasibility Study on commercialized fast reactor cycle systems" and the achievement of the performance evaluation conducted in FaCT (Fast Reactor Cycle System Technology Development) project in Japan. The methodologies and way of achievement evaluation has been changed according to the evaluation needs and objectives, etc. Some decision-making methodologies are tried to be applied in the FS, FaCT phase I evaluation put emphasis on the confirmation of the direction of FR cycle development. Although some items of respective facilities showed insufficient achievements because of the challenging design requirements to achieve higher performance, a comprehensive evaluation determined that the performance criteria set by the Japan Atomic Energy Commission were achieved in FaCT phase I evaluation in general.

Journal Articles

Thermal analysis on shipping cask for JSFR fresh fuel

Kato, Atsushi; Chikazawa, Yoshitaka; Uto, Nariaki; Hirata, Shingo; Obata, Hiroyuki*

Proceedings of International Conference on Fast Reactors and Related Fuel Cycles (FR 2009) (CD-ROM), 12 Pages, 2012/00

A basic feasibility of the helium gas cask has been evaluated by thermal analyses. There have been conducted two analyses: whole cask and detail inside subassembly analyses. The detail inside subassembly analysis has shown that the temperature distribution is mainly governed by thermal conductivity and natural convection of coolant helium hardly contributes heat removal. In the case of a cask with five subassemblies with 2.2 kW decay heat per each, the maximum cladding temperature is evaluated to be 361 $$^{circ}$$C satisfying cladding temperature limit of 395 $$^{circ}$$C. Those results have shown the basic feasibility of the helium gas fresh fuel shipping cask.

Journal Articles

Development of transfer pot for JSFR ex-vessel fuel handling

Hirata, Shingo; Chikazawa, Yoshitaka; Kato, Atsushi; Uto, Nariaki; Obata, Hiroyuki*; Kotake, Shoji*

Proceedings of International Conference on Fast Reactors and Related Fuel Cycles (FR 2009) (CD-ROM), 10 Pages, 2012/00

In Fast Reactor Cycle Technology Development (FaCT) project, Japan Sodium-cooled Fast Reactor (JSFR) is going to adopt an advanced fuel handling system. As for ex-vessel spent fuel handling, a pot which contains two fuel subassemblies simultaneously and is applicable size to compact reactor vessel, has been developing so as to shorten a refueling period leading to an improvement of plant availability. The pot is required to provide sufficient cooling capability even in case of transportation malfunction during transportation of spent fuel subassemblies with high decay heat. In the present study, experimental and analytical studies to evaluate the cooling capacity of the pot are summarized.

Journal Articles

JSFR design study and R&D progress in the FaCT project

Aoto, Kazumi; Uto, Nariaki; Sakamoto, Yoshihiko; Ito, Takaya*; Toda, Mikio*; Kotake, Shoji*

Proceedings of International Conference on Fast Reactors and Related Fuel Cycles (FR 2009) (CD-ROM), 11 Pages, 2012/00

In the FaCT project, SFR with 1,500 MWe is a target for the commercialization. R&D on innovative technologies to achieve the economic competitiveness and enhance the reliability and safety is carried out. A compact RV without wall-cooling layer is pursued in consideration of seismic reliability. For a two-loop cooling system with shortened high chromium steel piping, studies on the hydraulics in the pipe elbow and the fabrication capability of the pipes are being performed. A double-walled straight tube SG is investigated to enhance the reliability against sodium/water reaction, and developmental works are progressing including the thermal-hydraulic design and trial manufacturing for components. SASS is being developed with safety analysis of the applicability for JSFR and experimental demonstration in JOYO. An advanced fuel handling system is also pursued. Discussion on whether the innovative technologies can be adopted for JSFR is in progress to be finalized in 2010.

Journal Articles

Design study and R&D progress on Japan sodium-cooled fast reactor

Aoto, Kazumi; Uto, Nariaki; Sakamoto, Yoshihiko; Ito, Takaya*; Toda, Mikio*; Kotake, Shoji*

Journal of Nuclear Science and Technology, 48(4), p.463 - 471, 2011/04

In the FaCT project, SFR with 1,500 MWe is a target for the commercialization. R&D on innovative technologies to achieve the economic competitiveness and enhance the reliability and safety is carried out. A compact RV without wall-cooling layer is pursued in consideration of seismic reliability. For a two-loop cooling system with shortened high chromium steel piping, studies on the hydraulics in the pipe elbow and the fabrication capability of the pipes are being performed. A double-walled straight tube SG is investigated to enhance the reliability against sodium/water reaction, and developmental works are progressing including the thermal-hydraulic design and trial manufacturing for components. SASS is being developed with safety analysis of the applicability for JSFR and experimental demonstration in JOYO. An advanced fuel handling system is also pursued. Discussion on whether the innovative technologies can be adopted for JSFR is in progress to be finalized in 2010.

Journal Articles

Development of the JSFR fuel handling system and mockup experiments of fuel handling machine in abnormal conditions

Kato, Atsushi; Hirata, Shingo; Chikazawa, Yoshitaka; Uto, Nariaki; Obata, Hiroyuki*; Kotake, Shoji*; Uzawa, Masayuki*

Proceedings of 2010 International Congress on Advances in Nuclear Power Plants (ICAPP '10) (CD-ROM), p.692 - 699, 2010/06

In the JSFR design, a single rotating plug and an upper inner structure (UIS) with a vertically penetrating slit are proposed, so that the fuel handling machine (FHM) can access any subassembly by horizontal movement of the FHM arm in the slit space. As a result of a full-scale mockup test, excellent performance in normal operation has been shown. In this study, from the viewpoint of achieving reliability of the pantograph type FHM, behavior of the FHM mockup have been investigated under abnormal conditions.

Journal Articles

Development of advanced loop-type fast reactor in Japan

Kotake, Shoji; Sakamoto, Yoshihiko; Mihara, Takatsugu; Kubo, Shigenobu*; Uto, Nariaki; Kamishima, Yoshio*; Aoto, Kazumi; Toda, Mikio*

Nuclear Technology, 170(1), p.133 - 147, 2010/04

 Times Cited Count:32 Percentile:7.61(Nuclear Science & Technology)

Japan Atomic Energy Agency (JAEA) is now executing "Fast Reactor Cycle Technology Development (FaCT)" project in cooperation with the Japanese electric utilities. In the FaCT project, both the conceptual design study for Japan Sodium-cooled Fast Reactor (JSFR) and the developments of innovative technologies to be adopted to JSFR are now implemented with paying attention to the consistency between the design and the innovative technologies. The current target is that the development will be accomplished around 2015, after that a licensing procedure for the demonstration JSFR will be launched. This paper describes design requirements, design characteristics of JSFR and evaluation on the performances for economic competitiveness. Furthermore, the current status of the key technology development for JSFR is briefly introduced.

Journal Articles

Conceptual design for Japan sodium-cooled fast reactor, 3; Development of advanced fuel handling system for JSFR

Kato, Atsushi; Hirata, Shingo; Chikazawa, Yoshitaka; Uto, Nariaki; Obata, Hiroyuki; Kotake, Shoji

Proceedings of 2009 International Congress on Advances in Nuclear Power Plants (ICAPP '09) (CD-ROM), p.9281_1 - 9281_6, 2009/05

One of the most important challenges to commercialize a Fast Reactor is to increase economic competitiveness. For that purpose, Japan Sodium cooled Fast Reactor (hereafter JSFR) aims to simplify the plant system and reduce the raw and processed material by adopting innovative technologies. In the JSFR design, a single rotating plug and a reactor upper inner structure (hereafter UIS) with a vertically penetrating slit are proposed, so that the fuel handling machine (hereafter FHM) can access any subassembly by horizontal movement of the FHM arm in the slit space. The feature of this FHM enables no need for the UIS removal when the rotational plug moves round above the core, which can achieve a compact reactor vessel to enhance the economic competitiveness. We fabricated the full scale FHM test equipment to perform comprehensive tests in the air for demonstrating the feasibility of the key characteristics of this FHM concept.

Journal Articles

Conceptual design for Japan Sodium-cooled Fast Reactor, 1; Current status of system design for JSFR

Uto, Nariaki; Sakai, Takaaki; Mihara, Takatsugu; Toda, Mikio*; Kotake, Shoji; Aoto, Kazumi

Proceedings of 2009 International Congress on Advances in Nuclear Power Plants (ICAPP '09) (CD-ROM), p.9298_1 - 9298_11, 2009/05

A conceptual design for JSFR and developments of innovative technologies are implemented. A compact RV has been designed to enhance the economy. The regarding development results have been reflected to the RV design. An innovative CV design has been implemented with elemental tests to reduce the construction cost. SASS and the NC DHRS have been designed to enhance the safety, with the irradiation data acquired in Joyo and the development of a 3-dimensional thermal-hydraulic evaluation method. An approach for ISI/R has been provided to be applicable for FR characteristics, and the developmental studies on innovative inspection technologies have been progressed. Other technologies including double-walled pipes with short elbows, a pump-integrated IHX are also being developed. These results, together with a preliminary conceptual design study on a demonstrative reactor for JSFR, will be utilized as resources in 2010 to determine which innovative technologies should be adopted.

JAEA Reports

Design studies on small fast reactor cores, 5; Research results in JFY2005

Uto, Nariaki; Okano, Yasushi; Naganuma, Masayuki; Mizuno, Tomoyasu; Hayashi, Hideyuki

JAEA-Research 2006-060, 68 Pages, 2006/09

JAEA-Research-2006-060.pdf:3.98MB

A design study on "Long-life Type Concept" of a 50MWe sodium-cooled metal-fueled reactor core was performed with more emphasis on irradiation results regarding fuel smear density. The concept aims at no refueling in a core life time, and achieving higher core outlet temperature such as 550$$^{circ}$$C which is advantageous to hydrogen production. The restriction of upper fuel smear density limit to 75% along with adjustments of fuel specifications showed feasibility of attaining core life time of 30 years and core outlet temperature of 550$$^{circ}$$C. No indication of occurrence of absorber-cladding mechanical interaction (ACMI) was found in the evaluation of ACMI for a control rod element. A shielding with Zr-H was selected in view of enhancement of shielding performance, and the feasibility was shown to satisfy the target allowance level of the ratio of hydrogen to zirconium, more than 1.53, with PNC316 used as the cladding material.

JAEA Reports

Design Study on BN-600 Hybrid Core (II) - Evaluation of Fuel Integrity and Core Neutronic Characteristics by Japanese Analysis Methods -

Sugino, Kazuteru; Uto, Nariaki; Naganuma, Masayuki; Mizuno, Tomoyasu

JNC-TN9400 2004-042, 55 Pages, 2004/08

JNC-TN9400-2004-042.pdf:2.08MB

A program of disposal of Russian surplus weapon-grade plutonium by containing the plutonium in vibropacked MOX fuel subassemblies and burning them in the BN-600 hybrid reactor core has been progressed. The relevant design works on the BN-600 hybrid core have been carried out under the contract between Japan Nuclear Cycle Development Institute (JNC) and OKB Mechanical Engineering (OKBM), Russian public enterprise. JNC obtained a series of design technical reports. Japanese analysis methods were adopted to evaluate fuel integrity in the design basis transients and neutronic characteristics of the BN-600 hybrid core, based on the design technical data described in the obtained reports. The evaluation results of the key performances, such as maximum cladding and fuel temperatures, coolant (sodium) void reactivity, reactivity coefficient, were found to satisfy the design criteria and/or target provided by Russia, and meet the Russian rule. The results of this study showed that the core and fuel specifications determined by Russia can be considered reasonable and proper from the viewpoint of safety and neutronic designs, and that the Japanese analysis methods are expected to contribute to increasing reliability of the Russian design works.

JAEA Reports

Design Studies on Small Fast Reactor Cores(III)

Sanda, Toshio; Okano, Yasushi; Takaki, Naoyuki; Naganuma, Masayuki; Uto, Nariaki; Mizuno, Tomoyasu

JNC-TN9400 2004-031, 154 Pages, 2004/06

JNC-TN9400-2004-031.pdf:10.75MB

Some concepts of small fast reactors have been studied as part of the "Feasibility Studies on Commercialized Fast Reactor Cycle System (FS)", and the core design study has been performed at two main features of "long-life core " and "enhanced passive safety" in the FS phase II. Based on the previous study, 165MWe forced circulation sodium cooled reactor with control rods was studied as the promising concept from a viewpoint of economical efficiency in JFY 2003. In the present study, the fuel reloading interval of 20 years and outlet temperature of 550 deg-C are targeted under following condition as thicker metal fuel pin diameter (less than or equal) 15mm, lower pressure drop (less than or equal) 0.75kg/cm2, and smller core diameter (less than or equal) 3m by sodium void reactivity restriction relief into design conditions avoiding core melt without SASS at ATWS. The prospect of achievement of the fuel reloading interval of 20 years and outlet temperature of 550 deg-C was acquired for "Higher Temperature Core" and "Higher Temperature and Smller Core" without blanket fuels by using a sodium-cooled metal-fueled core with single Pu enrichment fuel which has high potential of small change of space distribution of power density and high breeding ratio. These cores have core height / diameter of 127/293cm and 164/260cm, fuel burnup of 77 and 80 GWd/t, burnup reactivity of 1.2 and 1.5% (delta)k/kk', breeding ratio of 1.06 and 1.07 and coolanat void reactivity of 6 and 8${$}$, respectively. Control rod reactivity balance, fuel soundness and shielding performance were checked that these were satisfied. Moreover, since the reactivity change due to burnup was small, the possibility of long-term operation which does not require a control rod movement was also examined. In addition, the "Higher Temperature Core" was recommended for a promising core of phase-II middle time since core melt would be avoided without SASS at ATWS. Furthermore, the applicability of the Feher heat cycl

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