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Journal Articles

Impact hammer test of ITER blanket remote handling system

Noguchi, Yuto; Maruyama, Takahito; Ueno, Kenichi; Komai, Masafumi; Takeda, Nobukazu; Kakudate, Satoshi

Fusion Engineering and Design, 109-111(Part B), p.1291 - 1295, 2016/11

 Times Cited Count:2 Percentile:19.85(Nuclear Science & Technology)

This paper reports the impact hammer test of the full-scale mock-up of ITER Blanket Remote Handling system (BRHS). Since the BRHS, which is composed of the articulated rail and the vehicle manipulator which travels on the rail deployed in the vacuum vessel, is subjected to the floor response spectrum with 14 G peak at 8 Hz, evaluation of dynamic response of the system is of essential importance. Recently impact hammer testing on the full-scale mock-up of the BRHS was carried out to verify the finite element method seismic analysis and to experimentally obtain the damping ratio of the system. The results showed that the mock-up has a vertical major natural mode with a natural frequency of 7.5 Hz and a damping ratio of 0.5%. While higher structural damping ratios is predicted in a high amplitude excitation such as major earthquake, it was confirmed that the experimental natural major frequencies are in agreement with the major frequencies obtained by elastic dynamic analysis.

JAEA Reports

Development of early core anomaly detection system by using in-sodium microphone in JOYO; Fundamental characteristics test of in-sodium microphone in water and examination of improvement of detection accuracy

JNC TN9400 2001-075, 51 Pages, 2001/07

JNC-TN9400-2001-075.pdf:1.73MB

Fast reactor core anomalies can be detected in near real-time with acoustic sensors. An acoustic detection system senses an in-core anomaly immediately from the fast acoustic signals that propagate through the sodium coolant. 0ne example of a detectable anomaly is sodium boiling due to local blockage in a sub-assembly; the slight change in background acoustic signals can be detected. A key advantage of the acoustic detector is that it can be located outside the core. The location of the anomaly in the core can be determined by correlating multiple acoustic signals. This report describes the testing and fundamental characteristics of a microphone suitable for use in the sodium coolant and examines methods to improve the system's S/N ratio. Testing in water confirmed that the in-sodium microphone has good impulse and wide band frequency responses. These tests used impulse and white noise signals that imitate acoustic signals from boiling sodium. Correlation processing of multiple microphone signals to improve S/N ratio is also described.

JAEA Reports

Study on early core anomaly detection system using nuclear instrumentation; Study on core anomaly detection system based on fluctuation characteristics of neutron flux monitors in JOYO

; *

JNC TN9400 2001-057, 36 Pages, 2001/03

JNC-TN9400-2001-057.pdf:1.15MB

A neutron flux monitor can be effective for early detection of reactivity anomalies in a FBR core. For instance, when a local blockage causes a bubble, there is a slight reactivity change in the high frequency band. It is important to understand the fluctuation characteristics of neutron flux monitors. Analysis of the JOYO reactor showed that flux-monitoring fluctuations are pink noise. These noise characteristics drive the requirements for the JOYO reactor anomaly detection system. The system requires fast time resolution and analog to digital resolution with sufficient dynamic range. A real time arithmetic unit is needed to compare the flux monitor signal with signals from normal conditions. This report describes the characteristics of neutron flux monitor signals and the anomaly detection system designed to analyze them.

JAEA Reports

Developmentofmeasurementofdisplacementofthetopofsub-assembly using super sonic sensor

JNC TN9400 2000-062, 61 Pages, 2000/03

JNC-TN9400-2000-062.pdf:1.78MB

lt has been studied for safety plant test to demonstrate inherent safety of FBR core in JOYO. As a part of this study investigation of feedback reactivity was studied. And analysis code which can estimate the reactvity of core-bowing has been prepared. In post irradiation examination, remain bowing displacement of sub-assembly can only be measured, so development of measuring system of displacement of sub-assembly under operation is expected to improve estimation of core-bowing reactivity. lt is supposed that an on-line measurement system of displacement of the top of sub-assembly using super sonic sensor under operation is an effective means. ln this report, development of measurement of displacement of the top of sub-assembly using super sonic sensor was settled as follows. (1)Characteristic test of heat-resistant super sonic sensor (2)Design of adjustment device of super sonic sensor (3)Examination of in-water test for estimation of temperature fluctuation

JAEA Reports

Development of early core anomaly detection using nuclear instrumentation

; *

JNC TN9400 2000-001, 42 Pages, 1999/12

JNC-TN9400-2000-001.pdf:1.51MB

Neutron flux monitoring can be an effective method for the early detection of reactivity anomalies in a FBR core. This development required that the normal range of reactivity fluctuations at power should be well characterized. An analysis of Reactor noise showed that the low frequency power fluctuation was influenced by the coolant temperature fluctuation, and that the high frequency power fluctuation was caused by control rod vibration. But spectral resolution was not adequate to determine the normal range of power fluctuation quantitatively. Also, a transfer function for the coolant temperature to reactor power ratio was modeled with the time constants of the thermal expansion of the core support plate, coolant temperature measurements, and so on. This was necessary to clearly understand the cause of the normal power fluctuations. The calculated values of simulated reactor power were compared with typical power ratio data from JOYO and the comparison was good in the low frequency range. Hence, it is clear that the dynamic characteristics of reactor power are caused by coolant temperature fluctuations. The high frequency power fluctuation, which is caused by control rod vibration, can be separated from the normal reactor power fluctuation. This analysis has shown that the normal range of reactor power fluctuations can be quantitatively determined accurately, and that neutron flux monitoring can be applied to detect reactivity anomalies early in a FBR core.

JAEA Reports

Analytical study for the in-vessel acoustic detection test investigation of modeling of fuel-pins and positioning of soundsource

*; *; *; *

PNC TJ9164 98-006, 150 Pages, 1998/02

PNC-TJ9164-98-006.pdf:8.11MB

Feasibility of a in-vessel acoustic detection system, which is used to detect boiling noise of sodium in a reactor vessel of FBR, was evaluated by means of SOSUM (Sound source Super-imposed Method) code. In 1997 Fy propagation of abnormal sound (ex, boiling noise) was evaluated. In 1998 Fy, detail simulation model in which fuel pins with wire are involved, was evaluated. In order to reduce calculation time, dipole model was adopted in the simulation. Adequacy of the dipole simulation model was confirmed by comparison with the simulated result acquired by normal elements division model. With the result of this study, difference of propagation was less than about 6 %,. and detecting sound source's position in reactor vessel was evaluated to be possible by Synthetic Aperture Focusing Technique with about 4 detecting points.

JAEA Reports

Sound propagation analysis for in-vessel acoustic detection test

*; *; *; *

PNC TJ9164 97-014, 50 Pages, 1997/03

PNC-TJ9164-97-014.pdf:1.55MB

Feasibility of a in-vessel acoustic detection system which is used to detect boiling noise of sodium in a reactor vessel of FBR, was evaluated by means of SOSUM(Sound Source Super-imposed method) code. The whole simulation model is consist of two steps. First one is the analysis of the sound propagation within the fuel assemblies. The second one is the analysis of the sound propagation from the fuel assemblies outlet to the acoustic detector installed in the upper plenum in Reactor. First a pulse wave was used in the simulation of the sound propagation in order to confirm the adequacy of the simulation. The propagation of white noise, which is considered to be resemble to an actual boiling noise, was used as a sound source to evaluate and to extract subjects, the feasibility of the in-vessel acoustic detection system. Based on a result of the analysis, pressure deceleration of the sound source is about 1/25000, and wave shape can be preserved after propagation. So it is expected that the in-vessel acoustic detection system will be feasible.

JAEA Reports

In-water test of ultrasonic sensors for the in-vessel structure inspection equipment under sodium in JOYO; Investigation for the concept of experimental equipment

*; *; *; *; *

PNC TJ9164 97-004, 40 Pages, 1997/03

PNC-TJ9164-97-004.pdf:1.12MB

As a part of the development of ISI(In-Service Inspection), the investigations regarding the inspect ion equipment which can observe the distortion of core assemblies under operating condition with ultrasonic measuring technique were performed as follows. (1)The method in order to measure distortion of core assemblies under turbulent outlet sodium flow of the core assemblies was investigated. An improved arrangement of ultrasonic sensors on the equipment was also investigated in this study. (2)A conceptual design of a test rig and conditions of the in-water test, in which performance of the measuring system of core assemblies distortions will be evaluated, were investigated. (3)The conditions of irradiation test of the heat-proof ultrasonic sensors were revised according to the result regarding the ultrasonic sensor's arrangement. The neutron flux condition and the arrangement of the test elements in a test rig were also revised. So it was confirmed that the irradiation test conditions can be realized in the severance-rig within a fuel rack.

JAEA Reports

Evaluation of acoustic microphone for sensing in-vessel noise

*; *; *

PNC TJ9164 96-018, 48 Pages, 1996/03

PNC-TJ9164-96-018.pdf:2.27MB

Acoustic sensing technique is regarded as one of means of to detect the unusual conditions detection in-a reactor vessel of FBR. This study aims at investigating data which are useful to develop the microphone which can be used continuously under sodium in a reactor vessel, and have good sensitivity and high temperature resistance. The acoustic characteristics of the existing high temperature microphone was investigated. And the shape and fixation of element and the inner structure of the microphone were confirmed by means of X-ray photographing. The arrangement, materials and environment resistance of the existing microphone were conjectured and subjects of the future development were picked up based on the above investigation's results.

JAEA Reports

Investigation of application of acoustic sensor for the equipment of in-vessel structure's inspection to "JOYO"

*; *; *; *; *

PNC TJ9164 96-013, 62 Pages, 1996/03

PNC-TJ9164-96-013.pdf:2.78MB

As a part of the development of ISI (In-Service Inspection), the investigations regarding the inspection equipment which can observe the distortion of core assemblies under operating condition with ultrasonic measuring technique were performed as follows. (1)The test elements of high temperature ultrasonic sensor for the irradiation test in operating condition were manufactured. And it was confirmed that the elements had good performance under 500 $$^{circ}$$C air condition. (2)The specifications of drive mechanism, cable and connector were clarified. And structure of the inspection equipment was investigated in consideration to conditions of actual plant in JOYO. (3)As the condition of irradiation test, the neutron flux which should be irradiated and the arrangement of the test elements in a test rig were estimated. It was confirmed that the irradiation test condition can be realized in the severance-rig within a fuel lack.

Oral presentation

Development of new electromagnetic flow meter in Fast Reactor with heat and radiation, 2; Investigation of flow velocity measurement system to evaluate EMF performance

Hirabayashi, Masaru; Otaka, Masahiko; Ara, Kuniaki; Enomoto, Mitsuhiro*; Komai, Masafumi*; Ota, Hiroyuki*

no journal, , 

no abstracts in English

Oral presentation

In water observation of mock-up of the top of fuel pins using under sodium viewing system in the experimental fast reactor Joyo

Ishikawa, Takashi; Kawahara, Hirotaka; Yamashita, Takuya; Tagawa, Akihiro; Komai, Masafumi*

no journal, , 

no abstracts in English

Oral presentation

Recovery from failure of ITER blanket remote handling system

Maruyama, Takahito; Noguchi, Yuto; Komai, Masafumi; Takeda, Nobukazu; Kakudate, Satoshi

no journal, , 

no abstracts in English

Oral presentation

Development of radiation hard components for ITER remote maintenance robot

Komai, Masafumi; Anzai, Katsunori; Noguchi, Yuto; Saito, Makiko; Maruyama, Takahito; Takeda, Nobukazu; Kakudate, Satoshi

no journal, , 

$$gamma$$-ray Environment of ~250 Gy/hr in International Thermonuclear Experimental Reactor (ITER) requires a full remote maintenance of in-vessel components such as blanket modules. JAEA is carrying out development of radiation hard components for the ITER blanket remote handling system. The current status of the radiation hardness component development is presented.

Oral presentation

Progress of procurement activity of the ITER blanket remote handling system

Noguchi, Yuto; Maruyama, Takahito; Komai, Masafumi; Takeda, Nobukazu; Kakudate, Satoshi

no journal, , 

no abstracts in English

Oral presentation

Technological development of maintenance robot for ITER

Takeda, Nobukazu; Noguchi, Yuto; Maruyama, Takahito; Inoue, Ryuichi; Komai, Masafumi; Kozaka, Hiroshi; Tanigawa, Hisashi; Kakudate, Satoshi

no journal, , 

In general, nuclear fusion device requires remote maintenance system to avoid human access because of $$gamma$$-ray emitted from structural material, which is activated by neutron of fusion reaction. The remote maintenance system was first introduced in the Joint European Torus (JET) which was constructed in UK based on international cooperation in Europe. The JET used so-called "Boom type" remote handling system which introduces articulated arm from a port. The arm is supported from the port with canti-levered and therefore the capacity is relatively low: 300 kg in JET. On the contrary, the ITER uses different type of remote handling system. The JT-60SA, which is under construction in Japan, also considers remote maintenance. This paper describes outline of remote maintenance systems for the international fusion experimental reactor, ITER.

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