• Title, Summary, Keyword: calandria

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THERMAL AND STRUCTURAL ANALYSIS OF CALANDRIA VESSEL OF A PHWR DURING A SEVERE ACCIDENT

  • Kulkarni, P.P.;Prasad, S.V.;Nayak, A.K.;Vijayan, P.K.
    • Nuclear Engineering and Technology
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    • v.45 no.4
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    • pp.469-476
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    • 2013
  • In a postulated severe core damage accident in a PHWR, multiple failures of core cooling systems may lead to the collapse of pressure tubes and calandria tubes, which may ultimately relocate inside the calandria vessel forming a terminal debris bed. The debris bed, which may reach high temperatures due to the decay heat, is cooled by the moderator in the calandria. With time, the moderator is evaporated and after some time, a hot dry debris bed is formed. The debris bed transfers heat to the calandria vault water which acts as the ultimate heat sink. However, the questions remain: how long would the vault water be an ultimate heat sink, and what would be the failure mode of the calandria vessel if the heat sink capability of the reactor vault water is lost? In the present study, a numerical analysis is performed to evaluate the thermal loads and the stresses in the calandria vessel following the above accident scenario. The heat transfer from the molten corium pool to the surrounding is assumed to be by a combination of radiation, conduction, and convection from the calandria vessel wall to the vault water. From the temperature distribution in the vessel wall, the transient thermal loads have been evaluated. The strain rate and the vessel failure have been evaluated for the above scenario.

Development of Remote Visual Inspection Technology for Calandria & Internal of CANDU NPP (중수로 칼란드리아 내장품 원격 육안검사 기술 개발)

  • Lee, Sang-Hoon;Jin, Seuk-Hong;Moon, Gyoon-Young
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.6 no.1
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    • pp.72-77
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    • 2010
  • During the period of reinforcement work for the licensing renewal of CANDU NPP, the fuel channels, Calandria tubes and feeders of CANDU Reactor are replaced. The remote visual inspection of Calandria internal is also performed during the period of reinforcement work. This period is a unique opportunity to inspect the inside of the Calandria. The visual inspection for the Calandria vessel and its internals of Wolsong NPP Unit 1 was performed by Nuclear Engineering & Technology Institute(NETEC) of KHNP. To perform this inspection, NETEC developed equipment applied new technology such as the synchronization of 3D CAD, automatic alignment and control system. The inspection confirmed that the Calandria integrity of Wolsong NPP Unit 1 is perfect.

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Development of Remote Visual Inspection Technology for CANDU Calandria & Internals (CANDU형 원전 칼란드리아 및 내장품 원격 육안검사 기술 개발)

  • Lee, Sang-Hoon;Kim, Han-Jong
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.4 no.2
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    • pp.57-61
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    • 2008
  • During the period of retubing work for the licensing renewal, the fuel channels, calandria tubes and feeders of CANDU Reactors will be replaced, and calandria visual examination will be performed. This period is a unique opportunity to inspect the inside of the calandria. The visual inspection for the calandria vessel and its internals of Wolsong NPP is scheduled for confirming the calandria integrity. The first visual inspection for the calandria is planned in Pt. Lepreau led by AECL. The visual inspection for Wolsong NPP, led by NETEC(Nuclear Engineering & Technology Institute) of KHNP, will employ 3D laser scanner and 3D CAD Mock-up for the first time in the world, in addition to a conventional video camera. The inspection system is composed of a robot with the 3D laser scanner, a video camera and a hardness meter.

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Ultrasonic Measurement of Gap between Calandria Tube and Liquid Injection Nozzle in CANDU Reactor (초음파를 이용한 중수로내 칼란드리아관과 원자로 정지물질 주입관과의 간격 측정)

  • Sohn, Seok-Man;Kim, Tae-Rong;Lee, Jun-Sin;Lee, Young-Hee;Park, Chul-Hun
    • Proceedings of the KSME Conference
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    • pp.834-839
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    • 2001
  • Calandria tube wrapping each pressure tube is one of the key structural components of CANDU reactor(Calandria) which is consisted of many pressure tubes containing nuclear fuel assemblies. As the Calandria tube(made of zirconium alloy) is sagging due to its thermal and irradiation creep during the plant operation, it possibly contacts with liquid injection nozzle crossing beneath the Calandria tube, which subsequently results in difficulties on the safe operation. It is therefore necessary to check the gap for the confirmation of no contacts between the two tubes, Calandria tube and liquid injection tube, with a proper measure during the life of plant. In this study, an ultrasonic measurement method was selected among several methods investigated. The ultrasonic device being developed for the measurement of the gap was introduced and its preliminary performance test results were presented here. The gap between LIN and CT at site was measured using by this ultrasonic device at site.

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Numerical Analysis of Heat and Mass Transfer in a Calandria Based Reactor

  • Tupake Ravindra S;Kulkarni PS;Rajan NKS
    • 한국전산유체공학회:학술대회논문집
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    • pp.281-282
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    • 2003
  • Numerical investigations are carried out to study the mass flux and temperature distribution in a calandria using a 3-D RANS code. The computations made for simulations of flow and convective heat transfer with near-to working conditions. The work provides an estimate of the safe working limits of the heat dissipation by virtue of prediction of the 'hot spots' in the calandria. The work assumes significance for preliminary designs of the reactors and for detailed critical parametric analysis that would be otherwise more expensive.

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Inspection of Calandria Reactor Area of Wolsung NPP using Thermal Infrared and CCD Images

  • Cho, Jai-Wan;Kim, Chang-Hoi;Seo, Yong-Chil;Park, Young-Soo;Kim, Seung-Ho
    • 제어로봇시스템학회:학술대회논문집
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    • pp.96.4-96
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    • 2002
  • Thermal infrared imaging is a highly promising technology for condition monitoring and predictive maintenance of electronic, electrical and mechanical elements in nuclear power plants. However, conventional low-cost infrared imaging systems suffer from poor spatial resolution compared to commercial CCD cameras. This paper describes an approach to enhance inspection performances for calandria reactor area of Wolsung nuclear power plant through the technique of superimposing thermal infrared image into real CCD image. In the occurrence of thermal abnormalities on observation points and areas of calandria reactor area, unusual hot image taken from thermal infrared camera is mapped upon re...

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Inspection of Calandria Reactor Surface of Wolsung Nuclear Power Plant using Thermal Infrared Camera mounted on the Mobile Robot KAEROT/m2

  • Cho, Jai-Wan
    • Proceedings of the KSRS Conference
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    • pp.578-578
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    • 2002
  • Thermal infrared imaging is a highly promising technology for condition monitoring and predictive maintenance of electronic, electrical and mechanical elements in nuclear power plants. However, conventional low-cost infrared imaging systems suffer from poor spatial resolution compared to commercial CCD cameras. This paper describes an approach to enhance inspection performances for calandria reactor area of Wolsung nuclear power plant through the technique of superimposing thermal infrared image into real CCD image. In the occurrence of thermal abnormalities on observation points and areas of calandria reactor area, unusual hot image taken from thermal infrared camera is mapped upon real CCD image. The performance of the technique has been evaluated in the experiment carried out at Wolsung nuclear power plant in the overhaul period. The results show that localizations of thermal abnormalities on calandria reactor face can be estimated accurately.

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Monte Carlo Calculation of Thermal Neutron Flux Distribution for (n, v) Reaction in Calandria (몬테칼로 코드를 이용한 중수로 Calandria에서의 $(n,\;{\gamma})$ 반응유발 열중성자속분포 계산)

  • Kim, Soon-Young;Kim, Jong-Kyung;Kim, Kyo-Youn
    • Journal of Radiation Protection and Research
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    • v.19 no.1
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    • pp.13-22
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    • 1994
  • The MCNP 4.2 code was used to calculate the thermal neutron flux distributions for $(n,\;{\gamma})$reaction in mainshell, annular plate, and subshell of the calandria of a CANDU 6 plant during operation. The thermal neutron flux distributions in calandria mainshell, annular plate, and subshell were in the range of $10^{11}{\sim}10^{13}\;neutrons/cm^2-sec$ which is somewhat higher than the previous estimates calculated by DOT 4.2 code. As an application to shielding analysis, photon dose rates outside the side and bottom shields were calculated. The resulting dose rates at the reactor accessible areas were below design target, $6 {\mu}Sv/h$. The methodology used in this study to evaluate the thermal neutron flux distribution for $(n,\;{\gamma})reaction$ can be applied to radiation shielding analysis of CANDU 6 type plants.

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Inspection of Calandria Reactor Area of Wolsung NPP using Thermal Infrared and CCD Images (CCD와 적외선 열영상의 다중영상을 이용한 월성원자력발전소의 칼란드리아 전면부 점검)

  • Cho, Jai-Wan;Choi, Young-Soo;Kim, Chang-Hoi;Seo, Yong-Chil;Kim, Seung-Ho
    • Proceedings of the KIPE Conference
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    • pp.711-714
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    • 2002
  • Thermal infrared camera have poor image qualities compared to commercial CCD cameras, as in contrast, brightness, and. resolution. To compensate the poor Image quality problems associated with the thermal infrared camera, the technique of superimposing thermal infrared image into real ccd image is proposed. The mobile robot KAEROT/m2, loaded with sensor head system at the mast, is entered to monitor leakage of heavy water and thermal abnormality of the calandria reactor area in overhaul period. The sensor head system is composed of thermal infrared camera and cod camera In parallel. When thermal abnormality on observation points and areas of calandria reactor area is occurred, unusual hot image taken from thermal infrared camera is superimposed on real CCD image. In this inspection experiment, more accurate positions of thermal abnormalities on calandria reactor area can be estimated by using technique of mapping thermal infrared image into CCD image, which include characters arranged in MPOQ order.

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A Study of Nuclear Power Plant Inspection Tasks Using A Mobile Robot (이동로봇을 이용한 원전 내부 감시점검에 관한 연구)

  • 김창회;서용칠;조재완;최영수;김승호
    • Proceedings of the IEEK Conference
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    • pp.193-196
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    • 2002
  • In this paper, we presents the remote inspection activity with a mobile robot at the calandria face areas of the PHWR (pressurized heavy water reactor) nuclear power plants during full power plant operation.. The tele-operated mobile robot has been developed for this task. A 4 wheeled mechanism with the dual reconfigurable crawler arm has been adopted for the ease access to the high radiation area of calandria face. A specially designed extendable long reach mast attached on the mobile platform and the thermal image monitoring system enable human eyes to look into the calandria face. Application of robot will keep human workers from high radiation exposure and enhance the reliability of nuclear power plants.

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