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Journal Articles

Evaluation of fuel reactivity worth measurement in the prototype fast reactor Monju

Ohgama, Kazuya; Takegoshi, Atsushi*; Katagiri, Hiroki; Hazama, Taira

Nuclear Technology, 208(10), p.1619 - 1633, 2022/10

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

Journal Articles

Evaluation of fixed absorber reactivity measurement in the prototype fast reactor Monju

Ohgama, Kazuya; Katagiri, Hiroki; Takegoshi, Atsushi*; Hazama, Taira

Nuclear Technology, 207(12), p.1810 - 1820, 2021/12

 Times Cited Count:1 Percentile:30.57(Nuclear Science & Technology)

JAEA Reports

Prototype fast breeder reactor Monju; Its history and achievements (Translated document)

Mitsumoto, Rika; Hazama, Taira; Takahashi, Keita; Kondo, Satoru

JAEA-Technology 2019-020, 167 Pages, 2020/03


The prototype fast breeder reactor Monju has produced valuable technological achievements through design, construction, operation and maintenance over half a century since 1968. This report compiles the reactor technologies developed for Monju, including the areas: history and major achievements, design and construction, commissioning, safety, reactor physics, fuel, systems and components, sodium technology, materials and structures, operation and maintenance, and accidents and failures.

Journal Articles

Uncertainty evaluation of anticipated transient without scram plant response in the Monju reactor considering reactivity coefficients within the design range

Sotsu, Masutake; Hazama, Taira

Journal of Energy and Power Engineering, 13(11), p.393 - 403, 2019/11

This paper describes methods and results of the uncertainty evaluation of the significant plant response analysis of the reactor trip failure event, i.e. anticipated transient without scram of the Japanese prototype fast breeder reactor Monju. Unprotected loss of heat sink has a relatively large contribution to the core damage frequency due to reactor trip failure. The uncertainty of the allowable time to core damage in this event by plant transient response analysis, so far, has been estimated with considering the range of reactivity coefficients. There are some cases where core damage is considered to be avoided. Specifically, it is assumed that the core damage due to the ULOHS event would be avoided if the sodium temperature at the pump inlet stays below 650$$^{circ}$$C for 1 h; otherwise the possibility of cavitation occurring in the hydrostatic bearing increases. In this study, a method is developed to search for a solution as an inverse problem of multiple input variables that satisfy the temperature condition. This paper, as a first step, describes input conditions and probability to satisfy the temperature are evaluated through analyses treating input parameters, reactivity coefficients and kinetic parameters, as variables within the design range.

Journal Articles

A Validation study of a neutronics design methodology for fast reactors using reaction rate distribution measurements in the prototype fast reactor Monju

Ohgama, Kazuya; Takegoshi, Atsushi; Katagiri, Hiroki*; Hazama, Taira

Proceedings of 2019 International Congress on Advances in Nuclear Power Plants (ICAPP 2019) (Internet), 8 Pages, 2019/05

Journal Articles

Irradiation induced reactivity in Monju zero power operation

Takano, Kazuya; Maruyama, Shuhei; Hazama, Taira; Usami, Shin

Proceedings of Reactor Physics Paving the Way Towards More Efficient Systems (PHYSOR 2018) (USB Flash Drive), p.1725 - 1735, 2018/04

Irradiation dependence of the core excess reactivity was investigated for the Monju system startup tests at zero-power carried out in 2010. The excess reactivity basically decreases with the $$beta$$ decay of $$^{241}$$Pu in zero-power operation. However, the excess reactivity little changed in the two month period of the startup tests, which suggests a positive reactivity insertion during the period. The investigated irradiation dependence shows that the positive reactivity increases with reactor operation and mostly saturates by the fission-dose attained during the Monju zero-power operation in a month ($$sim$$10$$^{17}$$ fissions/cm$$^{3}$$). The saturated positive reactivity is equivalent to approximately 47% of the initially accumulated self-irradiation damage recovery assuming the defects were recovered by the fission-fragment irradiation in the reactor operation.

Journal Articles

Measurement and analysis of feedback reactivity in the Monju restart core

Kitano, Akihiro; Takegoshi, Atsushi*; Hazama, Taira

Journal of Nuclear Science and Technology, 53(7), p.992 - 1008, 2016/07

 Times Cited Count:6 Percentile:53.9(Nuclear Science & Technology)

A feedback reactivity measurement technique was developed based on a reactivity model featuring components that depend on the reactivity coefficients, denoted as reactor power (K$$_{R}$$) and reactor vessel inlet temperature (K$$_{IN}$$). This technique was applied to the feedback reactivity experiment conducted in the Monju system start-up test in May 2010. A thorough evaluation considering all possible biases and uncertainties revealed that the reactivity coefficients can be evaluated with a measurement uncertainty smaller than 3%. The evaluated reactivity coefficients were simulated considering the temperature distribution in the core. The C/E value of K$$_{R}$$ showed good agreement between calculated and measured values within the established uncertainty, and the value of K$$_{IN}$$ was consistent with that reported in a previous isothermal temperature coefficient experiment. The measured and calculated fuel subassembly outlet temperatures also agreed well within 0.2$$^{circ}$$C.

JAEA Reports

Development of the versatile reactor analysis code system, MARBLE2

Yokoyama, Kenji; Jin, Tomoyuki; Hirai, Yasushi*; Hazama, Taira

JAEA-Data/Code 2015-009, 120 Pages, 2015/07


The second version of the versatile reactor analysis code system, MARBLE2, has been developed. A lot of new functions have been added inMARBLE2 by using the base technology developed in the first version (MARBLE1). Introducing the remaining functions of the conventional code system (JOINT-FR and SAGEP-FR), MARBLE2 enables one to execute almost all analysis functions of the conventional code system with the unified user interfaces of its subsystem, SCHEME. In particular, the sensitivity analysis functionality is available in MARBLE2. On the other hand, new built-in solvers have been developed, and existing ones have been upgraded. Furthermore, some other analysis codes and libraries developed in JAEA have been consolidated and prepared in SCHEME. In addition, several analysis codes developed in the other institutes have been additionally introduced as plug-in solvers. Consequently, $$gamma$$-ray transport calculation and heating evaluation become available. As for another subsystem, ORPHEUS, various functionality updates and speed-up techniques have been applied based on user experience of MARBLE1 to enhance its usability.

Journal Articles

Nuclear data application in Monju

Hazama, Taira

JAEA-Conf 2014-002, p.26 - 31, 2015/02

Various nuclear data have been applied to the reactor physics test analyses in Monju. Good accuracy is confirmed with JENDL-3.3 for the analysis of reactor physics tests performed in 1994-1995. On the other hand, a clear discrepancy is observed for the reactivity loss caused by the $$^{241}$$Pu decay from 1994 to 2010. The discrepancy is resolved with JEDNL-4.0, where the revision of the $$^{241}$$Pu fission cross section and $$^{241}$$Am capture cross section contributes. Use of covariance data is promising application in the future design calculation. Based on the reactor physics test analyses, the reliability of the covariance data is investigated and covariance data that needs improvement are extracted. It is suggested that data on the average cosine of the scattering angle of $$^{23}$$Na need to be improved.

Journal Articles

Basic experiment for kinetics analysis in sub-critical sate

Kitano, Akihiro; Kishimoto, Yasufumi; Misawa, Tsuyoshi*; Hazama, Taira

KURRI Progress Report 2013, 1 Pages, 2014/10

The approach to criticality is conventionally performed by the inverse multiplication method. The method uses neutron count rate at a steady state attained in a certain waiting time after a reactivity insertion; thus it requires long time (for example, several hours from the startup in Monju reactor). We have developed a more efficient method based on Critical Index (CI) featuring the time behavior of delayed neutrons.

Journal Articles

IAEA benchmark calculations on control rod withdrawal test performed during Phenix End-of-Life experiments; JAEA's calculation results

Takano, Kazuya; Mori, Tetsuya; Kishimoto, Yasufumi; Hazama, Taira

Proceedings of International Conference on the Physics of Reactors; The Role of Reactor Physics toward a Sustainable Future (PHYSOR 2014) (CD-ROM), 13 Pages, 2014/09

This paper describes details of the IAEA/CRP benchmark calculation by JAEA on the control rod withdrawal test in the Phenix End-of-Life Experiments. The power distribution deviation by the control rod insertion/withdrawal, which is the major target of the benchmark, is well simulated by calculation. In addition to the CRP activities, neutron and photon transport effect is evaluated in the nuclear heating calculation of the benchmark analysis. It is confirmed that the neutron and photon transport effect contributes to the improvement of the absolute power calculation results in the breeder blanket region.

Journal Articles

Method development and reactor physics data evaluation for improving prediction accuracy of fast reactors' minor actinides transmutation performance

Takeda, Toshikazu*; Hazama, Taira; Fujimura, Koji*; Sawada, Shusaku*

Proceedings of International Conference on the Physics of Reactors; The Role of Reactor Physics toward a Sustainable Future (PHYSOR 2014) (CD-ROM), 15 Pages, 2014/09

A national project started in 2013 in Japan entitled "technology development for the environmental burden reduction". The present study is one of the studies adopted as the national project. We are aiming to develop MA transmutation core concepts harmonizing MA transmutation performance with core safety and to improve design accuracy related to MA transmutation performance. To validate and improve design accuracy of the high safety and high MA transmutation performance of SFR cores, we develop methods for calculating the transmutation rate of individual MA nuclides and estimating uncertainty of MA transmutation by using burnup sensitivity. Also we develop reliable reactor physics database to reduce the uncertainty of MA transmutation calculations. The overall consistency of the measured data is investigated by evaluating the usefulness of conventional static data as well as those related to MA transmutation obtained from various facilities like Monju, Joyo, FCA, BFS and PFR.

Journal Articles

Development of comprehensive and versatile framework for reactor analysis, MARBLE

Yokoyama, Kenji; Hazama, Taira; Numata, Kazuyuki*; Jin, Tomoyuki*

Annals of Nuclear Energy, 66, p.51 - 60, 2014/04

 Times Cited Count:13 Percentile:73.19(Nuclear Science & Technology)

A comprehensive and versatile reactor analysis code system, MARBLE, has been developed. MARBLE is designed as a software development frame-work for reactor analysis, which offers reusable and extendible functions and data models based on physical concepts, rather than a reactor analysis code system. From a viewpoint of the code system, it provides a set of functionalities utilized in a detailed reactor analysis scheme for fast criticality assemblies and power reactors, and nuclear data related uncertainty quantication such as cross-section adjustment. MARBLE covers all phases required in fast reactor core design prediction and improvement procedures, i.e. integral experiment database management, nuclear data processing, fast criticality assembly analysis, uncertainty quantication, and power reactor analysis. In the present paper, these functionalities are summarized and system validation results are described.

Journal Articles

Development of versatile nuclear heating calculation system in MARBLE

Hazama, Taira; Yokoyama, Kenji

Journal of Nuclear Science and Technology, 50(5), p.525 - 533, 2013/05

 Times Cited Count:2 Percentile:19.77(Nuclear Science & Technology)

A versatile nuclear heating calculation system is developed in MARBLE, a neutronics calculation platform based on the object-oriented language. The system provides a variety of heating calculation methods from the conventional simple methods based on energy-independent Q-values, to a detailed method based on NJOY. A particular feature is in hybrid methods that consider energy dependence employed in NJOY in the system. The hybrid methods provide tools to assess errors in the simple methods and to evaluate the heat transport property by neutrons and photons precisely. The accuracy of the hybrid methods and the errors in the simple methods are investigated in a Monju design calculation. It is confirmed that the hybrid methods realize the nuclear heating by the detailed method within an accuracy of 0.1%. The neglect of incident energy dependence of the fission Q-value in the simple methods causes clear overestimation in the Q-value but its influence on the total heating is less than 1%.

Journal Articles

Evaluation of feedback reactivity in Monju start-up test

Kitano, Akihiro; Miyagawa, Takayuki*; Okawachi, Yasushi; Hazama, Taira

Proceedings of International Conference on Fast Reactors and Related Fuel Cycles; Safe Technologies and Sustainable Scenarios (FR-13) (USB Flash Drive), 9 Pages, 2013/03

The feedback reactivity was measured in Monju start-up test conducted in 2010. The two reactivity components related either to power or to the core inlet coolant temperature were evaluated by fitting to a reactivity balance equation as a function of neutron count rate and coolant temperature. The measured feedback reactivity and the two components were compared with calculation taking account of the temperature distribution in the core. The calculated and the measured values of the feedback reactivity showed a reasonable agreement.

Journal Articles

Criticality evaluation for the Monju restart core

Hazama, Taira; Kitano, Akihiro; Kishimoto, Yasufumi*

Nuclear Technology, 179(2), p.250 - 265, 2012/08

 Times Cited Count:8 Percentile:54.86(Nuclear Science & Technology)

The Japanese prototype fast breeder reactor Monju restarted its system startup test in May 2010 after a 14-year interruption. In the first stage of the test, reactor physics parameters have been measured at a zero power level. The present paper describes the evaluation of the criticality data. The best-estimate value and its uncertainty are evaluated as accurately as possible. The restart core contains 1.5 wt% of $$^{241}$$Am which is three times larger than the previous test. To extract an influence of the $$^{241}$$Am accumulation on calculation accuracy, criticality data obtained in the previous test is evaluated in the same level of detail. The calculation accuracy is investigated with four major nuclear data libraries. It is confirmed that the accuracy is within 0.3%, 2$$sigma$$ value of experimental uncertainty, with JENDL-3.3, JENDL-4.0, and ENDF/B-VII.0. The reactivity change due to the $$^{241}$$Pu decay can be simulated within an accuracy of 1% with JENDL-4.0 and JEFF-3.1.

Journal Articles

Isothermal temperature coefficient evaluation for the Monju restart core

Mori, Tetsuya; Maruyama, Shuhei; Hazama, Taira; Suzuki, Takayuki

Nuclear Technology, 179(2), p.286 - 307, 2012/08

 Times Cited Count:9 Percentile:59(Nuclear Science & Technology)

The present paper describes the evaluation of the isothermal temperature coefficient data obtained in the Monju restart core. As in the preceding evaluations on the criticality and the control rod worth, the best-estimate value and its uncertainty are evaluated as accurately as possible. Data obtained in the previous test is evaluated in the same level of detail. The measured data shows that the fuel composition change from the previous test decreases the magnitude of the temperature coefficient by $$sim$$8%. Through a sensitivity analysis, it is confirmed that the decrease is mainly brought by the composition of $$^{241}$$Pu and $$^{241}$$Am. The best accuracy within the experimental uncertainty of 2% is attained for the previous core by a calculation with JENDL-4.0. Results for the restart core show inconsistent behavior and require a further investigation.

Journal Articles

Control rod worth evaluation for the Monju restart core

Takano, Kazuya; Fukushima, Masahiro; Hazama, Taira; Suzuki, Takayuki

Nuclear Technology, 179(2), p.266 - 285, 2012/08

 Times Cited Count:7 Percentile:50.57(Nuclear Science & Technology)

The present paper describes the evaluation of the control rod worth data obtained in the Monju restart core. The best-estimate value and its uncertainty are evaluated in detail. As in the criticality evaluation, data obtained in the previous test is evaluated in the same level of detail. The correlation in the uncertainties is also evaluated among different control rods and tests of the previous and the restart cores. Based on the evaluated data, calculation accuracy is investigated with JENDL-3.3 and JENDL-4.0. It is confirmed that the calculation accuracy is within the experimental uncertainty of 2% for each layer and $$^{10}$$B content. A reduction in the uncertainty related to the delayed neutron fraction is effective for a further improvement in the calculation accuracy.

JAEA Reports

Development of a standard data base for FBR core design, 14; Analyses of extensive FBR core characteristics based on JENDL-4.0

Sugino, Kazuteru; Ishikawa, Makoto; Numata, Kazuyuki*; Iwai, Takehiko*; Jin, Tomoyuki*; Nagaya, Yasunobu; Hazama, Taira; Chiba, Go*; Yokoyama, Kenji; Kugo, Teruhiko

JAEA-Research 2012-013, 411 Pages, 2012/07


Aiming at evaluating the core design prediction accuracy of fast reactors, various kinds of fast reactor core experiments/tests have been analyzed with the Japan's latest evaluated nuclear data library JENDL-4.0. Totally 643 characteristics of reactor physics experiments/tests and irradiation tests performed using the critical facilities: ZPPR, FCA, ZEBRA, BFS, MASURCA, ultra-small cores of LANL and power plants: SEFOR, Joyo, Monju were dealt. In analyses, a standard scheme/method for fast reactor cores was applied including detailed or precise calculations for best estimation. In addition, results of analyses were investigated from the viewpoints of uncertainties caused by experiment/test, analytical modeling and cross-section data in order to synthetically evaluate the consistency among different cores and characteristics. Further, by utilizing these evaluations, prediction accuracy of core characteristics were evaluated for fast power reactor cores that are under designing in the fast reactor cycle technology development (FaCT) project.

JAEA Reports

Preparation of fast reactor group constant sets UFLIB.J40 and JFS-3-J4.0 based on the JENDL-4.0 data

Sugino, Kazuteru; Jin, Tomoyuki*; Hazama, Taira; Numata, Kazuyuki*

JAEA-Data/Code 2011-017, 44 Pages, 2012/01


Fast reactor group constant sets UFLIB.J40 and JFS-3-J4.0 were prepared, which are based on the latest Japanese evaluated nuclear data library JENDL-4.0. Concerning UFLIB.J40, several fine group constant sets, which covered 70-group, 73-group, 175-group and 900-group structures, and the ultra fine group constant set were prepared. The number of nuclides for cross-sections of lumped fission products was extended so as to follow the extension of the number of fissile species for fission yield data.

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