• Title/Summary/Keyword: Nozzle inspection

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Development of Automated Nondestructive Inspection System for BMI Nozzles in Nuclear Vessel (원자로 BMI 노즐 검사를 위한 자동화 비파괴검사 시스템 개발)

  • Park, Joon Soo;Lee, Won Kun;Han, Won Jin;Lee, Sun Ho;Seong, Un Hak
    • Journal of the Korean Society for Nondestructive Testing
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    • v.33 no.1
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    • pp.26-33
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    • 2013
  • BMI nozzles in bottom head of the nuclear vessel are one of major components in nuclear power plants. The BMI nozzles have high possibility to generate PWSCC(primary water stress corrosion crack) according to recent foreign case although operation temperature is lower then the upper head of the nuclear vessel. Thus, nondestructive inspection of the BMI nozzles is required. But, inspection of BMI nozzles is not easy since the BMI nozzles placed in high radiated area and inside the nozzles filled with boric acid. Thus, in this study, a TOFD transducer for inspection of BMI and automated scanner system with water were developed. Also, validation of performance of the developed transducer and system are performed using specimens with artificial defects.

Current Status of an International Co-Operative Research Program, PARTRIDGE (Probabilistic Analysis as a Regulatory Tool for Risk-Informed Decision GuidancE) (국제공동연구 PARTRIDGE를 통한 확률론적 건전성 평가 기술 개발 현황)

  • Kim, Sun Hye;Park, Jung Soon;Kim, Jin Su;Lee, Jin Ho;Yun, Eun Sub;Yang, Jun Seog;Lee, Jae Gon;Park, Hong Sun;Oh, Young Jin;Kang, Sun Yeh;Yoon, Ki Seok;Park, Jai Hak
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.9 no.1
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    • pp.62-69
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    • 2013
  • A probabilistic assessment code, PRO-LOCA ver. 3.7 which was developed in an international co-operative research program, PARTRIDGE was evaluated by conducting sensitivity analysis. The effect of some variables such as simulation methods (adaptive sampling, iteration numbers, weld residual stress model), crack features(Poisson's arrival rate, maximum numbers of cracks, initial flaw size, fabrication flaws), operating and loading conditions(temperature, primary bending stress, earthquake strength and frequency), and inspection model(inspection intervals, detectable leak rate) on the failure probabilities of a surge line nozzle was investigated. The results of sensitivity analysis shows the remaining problems of the PRO-LOCA code such as the instability of adaptive sampling and unexpected trend of failure probabilities at an early stage.

A Study on Development of New Repair Method by High Pressure Spray (고압 스프레이 방식 신보수공법의 개발에 관한 연구)

  • Woo, Jong-Tae;Jang, Suk-Hwan;Kim, Yong-Chul
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.7 no.1
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    • pp.279-288
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    • 2003
  • This study is the development of method on repairing concrete structure for progressing the durability of reinforced concrete. This method is wet spray method which compress and conduct mortar pre-mixed with polymer powder to hose by high pressure pump and spray it on the section of concrete structure through nozzle made specially. Characters of this method are that materials are selected with the sort of structure and the cause of deterioration and macro pores are removed in repaired section by conducting with high pressure and spraying with high velocity for progressing the durability of concrete structure. This study has carried out that the minimum capacity of rebound was measured with various condition and physical properties of sample made by spray method were estimated in comparing with sample made by previous hand method. Also, properties of long-term have carried out after this method was applied on site. According to experimental study, the capacity of rebound showed below 5% and physical properties of sample made by spray method were superior to that of sample made by hand method and physical and durable properties of long-term showed excellence.

A Study on the Characteristics of Micro Deep Hole Machining in Micro Drilling Machine (마이크로 드릴링 M/C에 의한 미세구멍가공특성에 관한 연구)

  • 민승기;이동주;이응숙;강재훈;김동우
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2001.04a
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    • pp.275-280
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    • 2001
  • Recently, the trends of industrial products grow more miniaturization, variety and mass production. Micro drilling which take high precision in cutting work is requested more micro hole and high speed working. Especially, Micro deep hole drilling is becoming more important in a wide spectrum of precision production industries, ranging from the production of automotive fuel injection nozzle, watch and camera parts, medical needles, and thick multi-layered Printed Circuit Boards(PCB) that are demanded for very high density electric circuitry. This paper shows the tool monitoring results of micro drill with tool dynamometer. And additionally, microscope with built-in monitor inspection show the relationship between burr in workpiece and chip form of micro drill machining.

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Effect of Process Parameters on Bead Formation in Nd:YAG Laser Welding of Thin Steels (저탄소 박판 강재의 Nd:YAG 레이저 용접부 형성에 미치는 공정변수의 영향)

  • 김기철;허재협
    • Journal of Welding and Joining
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    • v.19 no.3
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    • pp.317-324
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    • 2001
  • This study deals with high power Nd:YAG laser welding of thin steels for small pressure vessels. Full penetration welding at the overlap joint was performed so as to assure sufficient weld strength. Results showed that mid-depth weld size reduced drastically with increasing the travel speed. Position of focus had little effect on the bead formation even though short focal system was used. However, the shape factor and the bead width had closely related with the position of focus. Based on the microstructural inspection, acceptable weld was obtained when the overlap clearance was controlled up to 20% of the base metal thickness. In the case that the joint contained more clearance than the critical value, both the tensile shear strength and the tear strength were reduced. Results also demonstrated that shielding gases were proved to play a key role as far as the bead formation characteristics was taken into consideration. Blowing dry air through 5mm in diameter nozzle produced narrower bead cross-section than that of argon or nitrogen shielding.

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A review of fatigue failures in LWR plants in Japan

  • Kunihiro, Iida
    • Proceedings of the KWS Conference
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    • 1996.10a
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    • pp.19-34
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    • 1996
  • A review was made of fatigue failures of nuclear power plant components in Japan, which were experienced in service and during periodical inspection. No case has been recently reported of a service fatigue failure of a reactor pressure vessel itself, excluding nozzle corner cracks, that occurred many years ago. But, service fatigue failures have been occasionally experienced in piping systems, pumps, and valves, on which fatigue design seems to have been inadequately applied. The causes of fatigue failures can be divided into two categories: mechanical-vibration-induced fatigue and thermal-fluctuation-induced fatigue. Vibration-induced fatigue failure occurs more frequently than is generally thought. The lesson gleaned from the present survey is a recognition that a service fatigue failure may occur due to any one or a combination of the following factors: (1) lack of communication between designers and fabrication engineers, (2) lack of knowledge about a possibility of fatigue failure and poor consideration about the effects of residual stresses, (3) lack of consideration on possible vibration in the design and fabrication stages, and (4) lack of fusion or poor penetration in a welded joint.

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Development of Hydraulic Testing Machine for Flexible Seal on Solid Rocket Motor (고체모터 플렉시블 씰을 위한 수압시험장치 개발)

  • Kwon, Tae-Hoon;Rho, Tae-Ho;Kim, Byung-Hun;Cho, In-Hyun
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2008.11a
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    • pp.227-230
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    • 2008
  • Movable nozzle with a flexible seal have been used for Thrust Vector Control of the Solid Rocket Motor. The Hydraulic Testing Machine is consisted of Chamber, Actuator, Counterpotentiometer, and evaluates performance of Flexible seal for spring torque and axial compression. The qualification test of Flexible seal was conducted on design condition. A study fix up method of formulation, operation, inspection on Hydraulic testing machine.

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Evaluation on Performance of Repair Mortar Used for Pre-wetting Spray Method (프리웨팅 스프레이 공법용 모르타르의 성능평가)

  • Nam, Yong-Hyuk;Chung, Young-Jun;Jang, Suk-Hwan;An, Young-Ki;Kim, Sung Chil
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.9 no.4
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    • pp.235-242
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    • 2005
  • This study is on the evaluation of performance of polymer cement mortar which is used for pre-wetting spray method. Pre-wetting spray method is an epoch-making method to repair concrete structures damaged, which is added a small quantity water preciously to dry mortar to reduce dust and rebound and spray mortar mixed with fixed quantity water at nozzle before spray. The result showed that physical performance such like compressive, flexural and adhesive strength of polymer cement mortar, TS 100 used for pre-wetting spray method was superior to other repair mortar. Also durable performance such as resistance on permeability of chloride ion, carbonation, chemical and freezing-thawing was excellent.

Evaluation on Strengthening Capacities and Rebound Rate of Structures with Sprayed FRP (분사식 FRP에 의한 구조물의 보강 성능 및 반발률 평가)

  • Han, Seung-Chul;Yang, Jun-Mo;Yoon, Young-Soo
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.12 no.1
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    • pp.193-202
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    • 2008
  • This paper investigates experimentally the confining effect, strengthening capacity and rebound rate of sprayed Fiber-Reinforced-Polymer (SFRP). From the method, resin and chopped fibers are sprayed separately from the nozzle with high pressure, and then they are attached to the concrete surface, so structure could be repaired. To evaluate the strengthening effect of sprayed FRP, cylindrical specimens and beam specimens were strengthening with SFRP. As main material of FRP, glass fiber and polyester resin are used. To investigate the optimum condition of sprayed FRP, the effects of fiber length, coating thickness, fiber volume ratio and concrete strength were examined. Capacities of sprayed FRP method were also compared to the FRP sheet method. In case of the sprayed FRP, rebound rate is important parameter considering economical efficiency and constructibility, so rebound rate of was discussed. From the test results, optimum conditions of sprayed FRP were determined. SFRP method showed superior strengthening capacities than FRP sheet method.

Automatic Ultrasonic Inspection on Heater Sleeves and J-Groove Welds of Pressurizer (가압기 전열기 슬리브 및 J-Groove 용접부의 자동 초음파검사)

  • Ryu, Sung Woo;Chang, Hee Jun;Kim, Sun Je;Lee, Sang Duck;Sung, Jong Hwan
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.6 no.2
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    • pp.20-27
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    • 2010
  • In order to prevent the corrosion of component contacted primary water designed alloy 600 material in the nuclear power plant. But the primary water stress corrosion cracking(PWSCC) of alloy 600 and weld area occurs continuously due to the residual stress. The leakage accident resulted from PWSCC in the drain nozzle of the steam generator of domestic power plants. Heater sleeves of the pressurizer are welded with alloy 600 weld material and therefore exposed to the primary water environment. PWSCC occurred in heater sleeve material and weld area of many foreign power plants. The current issue of domestic nuclear power plants are consequently concentrated to PWSCC of similar material. In order to improve the detection and the sizing of the PWSCC in the welding sleeve of the pressurizer, the automatic UT system and multi-directions probe sets have been developed. The experimental studies have been performed using the mock-up block containing artificial reflectors(ID connected EDM notch) and semi-artificial cracks made from thermal fatigue. The automatic UT System is applied in the detection and the length sizing of the ID/OD on the tube and the J-groove weld area of the artificial reflectors and results of the detection and the sizing are compared respectively. Also, the developed automatic UT system is successfully accomplished to inspect the heater sleeve and the J-groove weld area on the pressurizer for the detection of PWSCC.

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