Design and operation of the core topography data acquisition system for TMI-2

Beller, L.S.; Brown, H.L.

doi:10.2172/6837047

Cited by 13 publications

(8 citation statements)

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“…An ultrasonic sensor can remotely measure the shape of the object in both air and water, and can achieve high radiation resistance. In the former nuclear accident of Three-mile Island, the ultrasonic measurement was practically applied to inspect the reactor vessel [4]. In fact, we did a preliminary experiment by exposing an ultrasonic sensor to gamma-ray at the rate of 650 Gy/h by 60Co, and con rmed that the degradation of the sensor signal was less than 3% where accumulated radiation dose was approximately 10,000 Gy [5], suggesting the ten times higher radiation resistance than that of the camera installed on the PMORPH2.…”

Section: Ultrasonic Sensorsmentioning

confidence: 99%

Study of a robotic system to detect water leakage and fuel debris -System proposal and feasibility study of visual odometry providing intuitive bird's eye view

Wang

Endo

Takahashi

et al. 2020

Preprint

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To obtain the necessary information of the fuel debris and water leakages in the decommissioning task of Fukushima Daiichi nuclear power plants, an ultrasonic-based investigating method had been proposed towards the future internal investigation of the Primary Containment Vessel (PCV). In this article, we studied the assisting mechanisms and methods for the investigating method, as the rotatable winch mechanism and visual localization method. We used the rotatable winch mechanism to adjust the height and orientation of the ultrasonic sensor and localized the robot with cameras to localize the sensor, as assisting information for data combination. We studied the feasibility of the conventional visual odometry method of applying to the situation and performed localizing accuracy evaluating experiments with a mobile robotic platform prototype. Results showed that the visual odometry method could generate intuitive maps from bird’s eye view, and provided the average error rate of 35mm/1500mm, which met the required error rate for grating movement. The adjustable parameter ranges that could provide the required accuracy were also conducted.

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Section: Ultrasonic Sensorsmentioning

confidence: 99%

Study of a robotic system to detect water leakage and fuel debris -System proposal and feasibility study of visual odometry providing intuitive bird's eye view

Wang

Endo

Takahashi

et al. 2020

Preprint

View full text Add to dashboard Cite

show abstract

“…Ultrasonic sensors can remotely measure the shape of objects in both air and water, and can achieve high radiation resistance. In the Three Mile Island nuclear accident, ultrasonic measurement was practically applied to inspect the reactor vessel [8]. In fact, we performed a preliminary experiment by exposing an ultrasonic sensor to gamma rays at a rate of 650 Gy/h by 60Co, and con rmed that the degradation of the sensor signal was less than 3 % where the accumulated radiation dose was approximately 10,000 Gy [9], suggesting that the radiation resistance was ten times higher than that of the camera installed on PMORPH2.…”

Section: Ultrasonic Sensorsmentioning

confidence: 99%

Study of a robotic system to detect water leakage and fuel debris -System proposal and feasibility study of visual odometry providing intuitive bird's eye view-

Wang

ENDO

Takahashi

et al. 2020

Preprint

View full text Add to dashboard Cite

To obtain the necessary information on fuel debris and water leakages during the decommissioning task of the Fukushima Daiichi Nuclear Power Plant, an ultrasonic-based method was proposed for future internal investigation of the primary containment vessel (PCV). In this article, we describe the rotatable winch mechanism and visual localization method, which were used to aid the investigation. We used the rotatable winch mechanism to adjust the height and orientation of the ultrasonic sensor and localized the robot with cameras to localize the sensor, to provide assisting information for data combination. We studied the feasibility of the conventional visual odometry method for application to the situation and performed localizing accuracy evaluation experiments with a mobile robotic platform prototype. The results showed that the visual odometry method could generate intuitive bird’s-eye-view maps, and provided an average error rate of 35 mm/1500 mm, which met the required maximum error rate of 100 mm/1500 mm for the grating movement. Experiments were also conducted with adjustable parameter ranges that could provide the required accuracy.

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“…Previous inspections of the lower plenum debris have produced a wide range of debris particle sizes and textures, ranglng from rather uniform pea-sized gravel to larger, irregular-shaped pieces up to 6 in. in diameter.…”

Section: Because the Debris Was Relativelymentioning

confidence: 99%

TMI-2 core bore acquisition summary report

Tolman¹,

Smith²,

Martin³

et al. 1987

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Core bore samples were obtained from the severely damaged TMI-2 core A description of the TMI-2 core bore during July and August, 1986. drilling unit used to obtain samples; a summary and discussion of the data from the ten core bore segments which were obtained; and the initial results of analysis and evaluation of these data are presented in thls report. the accident scenario is also discussed.The impact of the major findings relative to our understanding o f t i DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document.This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.. SUMMARYExaminations of the TMI-2 core indicated that a hard, nearly impenetrable layer of material exists across the core at approximately the mid-core elevation. It was hypothesized that this hard, basically ceramic material extended downward to about the 0.6-m elevation. material were required to complete the end-state characterization of the core configuration, as well as to improve understanding of the physical and chemical materials interactions and fission product retention of the core materials. A core bore machine has been designed and utilized to safely and efficiently provide the desired samples prior to the commencement of bulk defueling of the core by General Public Utilities Nuclear Corp. (GPU). Samples of thisThe core bore machine drilled 6-ft "core" samples approximately 2.5 in. in diameter, 'which were later removed from the reactor vessel (RV) for detailed physical and chemical examination. The hole remaining after sample removal provided access for closed-circuit te evision (video) inspections of the surrounding region. The central regions of the CSA do not contain significant amounts of previously molten fuel, which suggests that the major crust failure location was not in the central region of the core. primary migration path o f the previously molten material into the lower plenum appears to be located on the east side of the core near the periphery, primarily at assemblies P-5 and P-6. The3. -Based.on the limited video inspection data, the CSA appears to be undamaged. in those areas where previously mol ten ceramic mate...

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Design and operation of the core topography data acquisition system for TMI-2

Cited by 13 publications

References 0 publications

Study of a robotic system to detect water leakage and fuel debris -System proposal and feasibility study of visual odometry providing intuitive bird's eye view

Study of a robotic system to detect water leakage and fuel debris -System proposal and feasibility study of visual odometry providing intuitive bird's eye view

Study of a robotic system to detect water leakage and fuel debris -System proposal and feasibility study of visual odometry providing intuitive bird's eye view-

TMI-2 core bore acquisition summary report

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