Development of LBB Assessment Method for Japanese Sodium Cooled Fast Reactor (JSFR) Pipes: 3—Fracture Assessment Methods Considering Compliance at a Crack Part

2010 ◽  
Author(s):  
Takashi Wakai ◽  
Hideo Machida ◽  
Shinji Yoshida ◽  
Yasuhiro Enuma ◽  
Tai Asayama
Keyword(s):  
Thermal Expansion ◽  
Internal Pressure ◽  
Fast Reactor ◽  
Load Balance ◽  
Assessment Method ◽  
Assessment Methods ◽  
Piping System ◽  
Thin Wall ◽  
Fracture Assessment ◽  
Leak Before Break

This paper presents a fracture assessment methods used in leak before break (LBB) assessment of sodium piping system in the Japanese sodium cooled fast reactor (JSFR). Use of thin wall pipes and compact layout of piping system are features of the design in JSFR. Since the internal pressure of piping of JSFR is low, the critical load is thermal expansion. Supposing a through wall crack (TWC) in such piping, the stiffness of the crack part will decrease, the load balance of the piping system will change from the condition without crack. The fracture assessment methods paying attention to this stiffness change at the crack part were proposed and these methods enabled rational LBB assessment. The proposed methods are much effective to loosen LBB conditions for the piping system of which the compliance is low. These methods applied to the LBB assessment of the piping system of JSFR which has the compact layout, and it was checked that the validity of these methods to loosen the LBB conditions.

Development of Leak-Before-Break Assessment Method for Japan Sodium Cooled Fast Reactor Pipe—Part 1 Crack Opening Displacement Assessment of Thin Wall Pipes Made of Modified 9Cr-1Mo Steel

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
Takashi Wakai ◽  
Hideo Machida ◽  
Manabu Arakawa ◽  
Shinji Yoshida ◽  
Yasuhiro Enuma
Keyword(s):  
Crack Opening Displacement ◽  
Fast Reactor ◽  
Work Hardening ◽  
Crack Opening ◽  
Assessment Method ◽  
Leak Rate ◽  
Thin Wall ◽  
Opening Displacement ◽  
Leak Before Break ◽  
Small Work

This was carried out to establish crack opening displacement (COD) evaluation methods used in leak-before-break (LBB) assessment of sodium pipes of the Japan sodium cooled fast reactor (JSFR). For sodium pipes of JSFR, the continuous leak monitoring will be adopted as an alternative to a volumetric test of the weld joints under conditions that satisfy LBB. The sodium pipes are made of ASME Gr.91 (modified 9Cr-1Mo steel). Thickness of the pipes is small, because the internal pressure is very low. Modified 9Cr-1Mo steel has a relatively large yield stress and small work hardening coefficient comparing to the austenitic stainless steels which are currently used in the conventional plants. In order to assess the LBB behavior of the sodium pipes made of modified 9Cr-1Mo steel, the coolant leak rate from a through-wall crack must be estimated properly. Since the leak rate is strongly related to the COD, an appropriate COD assessment method must be established to perform LBB assessment. However, COD assessment method applicable for JSFR sodium pipes—thin wall and small work hardening material—has not been proposed yet. Thus, a COD assessment method applicable to thin walled large diameter pipe made of modified 9Cr-1Mo steel was proposed in this study. In this method, COD was calculated by classifying the components of COD; elastic, local plastic, and fully plastic. In addition, the verification of this method was performed by comparing with the results of a series of four-point bending tests at elevated temperature using thin wall modified 9Cr-1Mo steel pipe containing a circumferential through-wall crack. As a result, COD values calculated by the proposed method were in a good agreement with the experimental results for the uniform pipe without a weld. In the case that the crack was machined in the weld metal or heat affected zone (HAZ), the proposed method predicted relatively larger COD than the experimental results. The causes of such discrepancies were discussed by comparing with the results of finite element analyses. Based on these examinations, the rational leak rate evaluation method in LBB assessment was proposed.

Three-Dimensional Leak before Break Analysis of Nuclear Pipes Containing Cracks

2015 ◽  
Vol 750 ◽  
pp. 376-381
Author(s):  
Wen Fu Liang ◽  
Tong Liu ◽  
Min Shan Liu
Keyword(s):  
High Temperature ◽  
Fast Reactor ◽  
Waste Heat ◽  
Three Dimensional ◽  
Design Guidelines ◽  
Structural Safety ◽  
Piping System ◽  
Pipe Material ◽  
Crack Behavior ◽  
Leak Before Break

Three-dimensional crack behavior simulation analysis and anti-fracture design have been a main subject in fracture theory and engineering application. Piping system is a key part of nuclear power engineering. Utilizing the three-dimensional finite element analysis software ANSYS and the specialized crack analysis programs Franc3D, three-dimensional crack behavior and leak before break (LBB) case were simulated and evaluated of a pipe with a crack in waste heat exhaust system of China Experimental Fast Reactor ( CEFR ). In fast reactor, the piping is working under a high temperature. Therefore, the code RCC-MR.A16 was adopted that is suitable for materials and structural safety design at high temperature. Material used in this article is modified 9Cr1Mo-T91/P91. The analysis model of pipe section was built in three-dimensional entity structure containing a cracks and the high temperature and creep effects were considered. The simulation results show that creep contributes more effect on crack growth than fatigue. The evaluation results on LBB of studied T91 steel pipe with a crack-like defect can satisfy the need of LBB design guidelines. The research results can be referenced in pipe material choose, safety assessment and structural integrity evaluation of a pipe containing defects at high temperature in a fast reactor design.

Development of LBB Assessment Method for Japan Sodium Cooled Fast Reactor (JSFR) Pipes (4): Verification of Crack Opening Displacement Assessment Method for Thin Wall Pipes Made of Mod.9Cr-1Mo Steel

2011 ◽  
Author(s):  
Takashi Wakai ◽  
Hideo Machida ◽  
Shinji Yoshida ◽  
Fumiko Kawashima ◽  
Koichi Kikuchi ◽  
...  
Keyword(s):  
Crack Opening Displacement ◽  
Fast Reactor ◽  
Work Hardening ◽  
Crack Opening ◽  
Assessment Method ◽  
Experimental Results ◽  
Leak Rate ◽  
Thin Wall ◽  
Opening Displacement ◽  
Small Work

For sodium pipes of Japan Sodium cooled Fast Reactor (JSFR), the continuous leak monitoring will be adopted as an alternative to a volumetric test of the weld joints under conditions that satisfy Leak-Before-Break (LBB). The sodium pipes are made of ASME Gr.91 (modified 9Cr-1Mo) steel. Thickness of the pipes is small, because the internal pressure is very low. Modified 9Cr-1Mo steel has a relatively large yield stress and small work hardening coefficient comparing to the austenitic stainless steels which are currently used in the conventional plants. In order to discuss about the LBB of the sodium pipes made of modified 9Cr-1Mo steel, the coolant leak rate from a through wall crack must be estimated properly. Since the leak rate is strongly related to the crack opening displacement (COD), an appropriate COD assessment method must be established to perform LBB assessment. However, COD assessment method applicable for JSFR sodium pipes — thin wall and small work hardening material — has not been proposed yet. Therefore, the authors have proposed a COD assessment method applicable to thin walled large diameter pipe made of modified 9Cr-1Mo steel. In this method, COD is calculated by classifying into three components of elastic, local plastic and fully plastic. This paper describes the improved COD assessment method and verifies the validity of the method based on the results of a series of four-point bending tests at elevated temperature using thin wall modified 9Cr-1Mo steel pipe containing a circumferential through wall crack. As a result, COD values calculated by the proposed method were in a good agreement with the experimental results for the uniform pipe without weld. In the case that the crack was machined at weld metal or heat affected zone (HAZ), proposed method predicted relatively larger COD than the experimental results. The causes of such discrepancies were discussed comparing with the results of finite element analyses. Based on these examinations, the rational leak rate evaluation method in LBB assessment was proposed.

A Comparison of Fracture Assessment Methods in Several Structural Integrity Assessment Procedures

2009 ◽  
Author(s):  
Tiecheng Yang ◽  
Xuedong Chen ◽  
Zhichao Fan
Keyword(s):  
Structural Integrity ◽  
Limit Load ◽  
Assessment Method ◽  
Assessment Methods ◽  
Safety Factors ◽  
Specific Calculation ◽  
Integrity Assessment ◽  
Fracture Assessment ◽  
Partial Safety Factors ◽  
Assessment Procedures

For the fracture assessment method internationally used in different structural integrity assessment procedures, such as R6, BS 7910, FITNET API 579 and GB/T 19624, this paper gives the results of analytical comparisons in combination with specific calculation examples by comparing different assessment options or levels, the partial safety factors (PSFs), limit load solutions, stress intensity factor solutions, residual stress distribution and treatment methods, secondary stresses and ρ factor solutions etc., which provide a basis for improvement of fracture assessment methods.

Development of LBB Assessment Method for Japanese Sodium Cooled Fast Reactor (JSFR) Pipes: 2—Crack Opening Displacement Assessment of Thin Wall Pipes Made of Modified 9Cr-1Mo Steel

2010 ◽  
Author(s):  
Takashi Wakai ◽  
Hideo Machida ◽  
Manabu Arakawa ◽  
Yasuhiro Enuma ◽  
Tai Asayama
Keyword(s):  
Crack Opening Displacement ◽  
Fast Reactor ◽  
Work Hardening ◽  
Evaluation Method ◽  
Crack Opening ◽  
Piping System ◽  
Thin Wall ◽  
Opening Displacement ◽  
Element Analysis ◽  
Hardening Material

This paper presents crack opening displacement (COD) evaluation methods used in leak before break (LBB) assessment of sodium piping system in the Japanese sodium cooled fast reactor (JSFR). Thin wall and low work hardening material are features of piping of JSFR. Detectability of coolant sodium is very high, the target leak detection performance of leak detector of JSFR is 100g/hr. Internal pressure of JSFR piping is very low, and large through wall crack is allowable to satisfy LBB condition. The existing COD evaluation method cannot be applied to the piping of JSFR which has above-mentioned features. Finite element analysis (FEA) were performed to evaluate COD for thin wall and low work hardening material piping with a circumferential through wall crack. These analytical results were arranged into engineering evaluation formulae. Proposed method gives high accuracy COD estimation, and is applicable to LBB assessment of JSFR piping.

Development of LBB Assessment Method for Japan Sodium Cooled Fast Reactor (JSFR) Pipes (5): Crack Growth Assessment Method for Pipes Made of Mod.9Cr-1Mo Steel

2011 ◽  
Author(s):  
Takashi Wakai ◽  
Hideo Machida ◽  
Shinji Yoshida ◽  
Takumi Tokiyoshi ◽  
Koichi Kikuchi ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Crack Length ◽  
Crack Growth ◽  
Fast Reactor ◽  
Master Curve ◽  
Large Diameter ◽  
Creep Crack Growth ◽  
Assessment Method ◽  
Thin Wall ◽  
Creep Crack

For sodium pipes of Japan Sodium cooled Fast Reactor (JSFR), the continuous leak monitoring will be adopted as an alternative to a volumetric test of the weld joints under conditions that satisfy Leak-Before-Break (LBB). The vessels of JSFR are connected by thin wall pipes with a large diameter made of modified 9Cr-1Mo steel and the internal pressure of the pipes is very low. Modified 9Cr-1Mo steel has relatively large yield stress and small work hardening coefficient compared to the austenitic stainless steels which are currently used in the conventional plants. Therefore, these material characteristics of modified 9Cr-1Mo steel must be taken into account in LBB assessment, as well as geometrical and structural features of JSFR pipes. In order to demonstrate LBB aspects of the JSFR pipes, the authors have proposed a LBB assessment flowchart and developed assessment methods of unstable fracture and crack opening displacement (COD) for the thin wall pipes with large diameter made of modified 9Cr-1Mo steel. This paper studies the master curve to estimate the crack length when a postulated initial crack unexpectedly grows and penetrates the pipe thickness. In order to obtain the fatigue crack and creep crack growth characteristics of modified 9Cr-1Mo steel pipes, fatigue crack and creep crack growth tests were conducted using compact tension (CT) specimens and crack growth rates for both fatigue and creep at elevated temperature were obtained. Based on the obtained material characteristics and the results of a series of crack growth calculations, a relationship between the penetrated crack length and the ratio of membrane to total stress, so called as master curve, was proposed. In this study, master curves were proposed for pipes made of modified 9Cr-1Mo steel as a function of pipe geometry, i.e. the ratio of radius to thickness.

BS 7910: History and Future Developments

2009 ◽  
Author(s):  
Isabel Hadley
Keyword(s):  
Assessment Methods ◽  
Weld Strength ◽  
Assessment Procedure ◽  
Metallic Structures ◽  
History Of ◽  
Fracture Assessment ◽  
Offshore Industry ◽  
Crack Tip Constraint ◽  
The Uk ◽  
Assessment Procedures

BS 7910, the UK procedure for the assessment of flaws in metallic structures, was first published almost 30 years ago in the form of a fracture/fatigue assessment procedure, PD6493. It provided the basis for analysing fabrication flaws and the need for repair in a rational fashion, rather than relying on long-established (and essentially arbitrary) workmanship rules. The UK offshore industry in particular embraced this new approach to flaw assessment, which is now widely recognised by safety authorities and specifically referred to in certain design codes, including codes for pressure equipment. Since its first publication in 1980, PD6493/BS 7910 has been regularly maintained and expanded, taking in elements of other publications such as the UK power industry’s fracture assessment procedure R6 (in particular the Failure Assessment Diagram approach), the creep assessment procedure PD6539 and the gas transmission industry’s approach to assessment of locally thinned areas in pipelines. The FITNET European thematic network, run between 2002 and 2006, has further advanced the state of the art, bringing in assessment methods from SINTAP (an earlier European research project), R6, R5 and elsewhere. In particular, the FITNET fracture assessment methods represent considerable advances over the current BS 7910 methods; for example, weld strength mismatch can be explicitly analysed by using FITNET Option 2, and crack tip constraint through Option 5. Corrosion assessment methods in FITNET are also more versatile than those of BS 7910, and now include methods for vessels and elbows as well as for pipelines. In view of these recent advances, the BS 7910 committee has decided to incorporate many elements of the FITNET procedure into the next edition of BS 7910, to be published c2012. This paper summarises the history of the development of BS 7910, its relationship with other flaw assessment procedures (in particular FITNET and R6) and its future.

A Comparison of Disease Assessment Methods for Southern Stem Rot of Peanut

2002 ◽  
Vol 29 (1) ◽  
pp. 66-71 ◽  
Author(s):  
S. L. Rideout ◽  
T. B. Brenneman ◽  
K. L. Stevenson
Keyword(s):  
Alternative Assessment ◽  
Disease Incidence ◽  
Sclerotium Rolfsii ◽  
Correlation Coefficients ◽  
Assessment Method ◽  
Assessment Methods ◽  
Alternative Methods ◽  
Stem Rot ◽  
Disease Assessment ◽  
Time Required

Abstract Southern stem rot (caused by the soilborne fungus Sclerotium rolfsii Sacc.) of peanut (Arachis hypogaea L.) traditionally has been assessed based on the percentage of infected 30.5-cm row segments, commonly referred to as disease incidence. Several alternative disease assessment methods were evaluated in four fungicide trials during the growing season (aboveground ratings) and immediately after peanut inversion (belowground ratings). Pearson's correlation coefficients compared disease assessments and yields for all trials. Across all disease assessment methods, belowground assessments at inversion showed a stronger correlation with yield than in-season aboveground assessments. Several of the alternative assessment methods showed a stronger negative correlation with yield than did the traditional disease incidence rating. However, none of the alternative methods were consistently more precise across all assessment dates and trials. There was a significant positive correlation between many of the alternative methods and the traditional disease incidence method. Furthermore, none of the alternative methods was better than the traditional method for detecting differences among fungicide treatments when subjected to ANOVA and subsequent Waller-Duncan mean separation tests (k-ratio = 100). Based on comparisons of the time required to assess disease intensity, the traditional disease assessment method was found to be the most time efficient method of those tested in this study.

scholarly journals The Effect Assessment for Fast Reactor Fuel Cycle Deployment-improvement of the Assessment Method-

2013 ◽  
Vol 39 ◽  
pp. 43-51
Author(s):  
Kyoko Mukaida ◽  
Hiroki Shiotani ◽  
Kiyoshi Ono ◽  
Takashi Namba
Keyword(s):  
Fast Reactor ◽  
Fuel Cycle ◽  
Assessment Method ◽  
Reactor Fuel ◽  
Effect Assessment ◽  
Fast Reactor Fuel

Study on Prediction and Assessment Methods of Outdoor Wind Environment of Residential District - Taking “Letian Home” in Leshan, Sichuan for Example

2011 ◽  
Vol 71-78 ◽  
pp. 3868-3873
Author(s):  
Li Jin Ma ◽  
Hong Juan Zou ◽  
Jia Shun Zhu
Keyword(s):  
Fluid Mechanics ◽  
Composite Index ◽  
Assessment Method ◽  
Assessment Methods ◽  
Assessment System ◽  
Outdoor Environment ◽  
Computational Fluid Mechanics ◽  
Analog Computation ◽  
Wind Environment ◽  
Residential District

According to the micro-climate environment outdoor of the region, wind environment outdoor which is under planning programming can be done analog computation using computational fluid mechanics PHOENICS software. A set of comprehensive prediction and assessment system which is mainly focused on outdoor environment composite index WBGT can be established combining with assessment method on wind environment outdoor of predecessors in order to more accurately and humanly predict and assess the wind environment outdoor, bring safe, comfortable and healthy outdoor environment and provide references for the assessment and design of green residential district.

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