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*
JNC TN1400 2001-013, 70 Pages, 2001/08
JNC-TN1400-2001-013.pdf:5.13MB
no abstracts in English
*; *; Kawasaki, Hirotsugu; Aoto, Kazumi
JNC TY9400 2000-010, 138 Pages, 2000/03
JNC-TY9400-2000-010.pdf:5.15MB
None
; kasahara, Naoto; ; ; Kamide, Hideki
JNC TN9400 2000-010, 168 Pages, 2000/02
JNC-TN9400-2000-010.pdf:8.78MB
Thermal striping is significant issue of the structural integrity, where the hot and cold fluids give high cycle fatigue to the structure through the thermal stress resulted from the time change of temperatur distibution in the structure. In the sodium cooled fast reactor, temperature change in fluid easily transfers to the structure because of the high thermal conductivity of the sodium. It means that we have to take care of thermal striping, The thermal striping is complex phenomena between the fluid and structure engineering fields. The investigations of thermal striping are not enough to evaluate the integrity directly. That is the fluctuation intensity at the structure surface is assumed to be temperature difference between source fluids (upstream to the mixing region) as the maximum value in the design. 0therwise, the design conditions are defined by using a mockup experiment and large margin of temperature fluctuation intensity. Furthermore, such evaluation manners have not yet been considered as a design rule. Transfer mechanism of temperature fluctuation from fluid to structure has been investigated by the authors on the view points of the fluid and structure. Attenuation of temperature fluctuation was recognized as a dominant factor of thermal fatigue. We have devdoped a numerical analysis system which can evaluate thermal fatigue and crack growth with consideration of the attenuation of temperature fluctuation in fluid, heat transfer, and structure. This system was applied to a real reactor and the applicability was confirmed. Further verification is planned to generalize the system. For the higher cost performance of the fast reactor, an evaluation rule is needed, which can estimate thermal loading with attenuation and can be applied to the design. An idea of the rule is proposed here. Two methods should be prepared; one is a precise evaluation method where mechanism of attenuation is modeled, and the other is simple evaluation method where ...
Maruyama, Tadashi; ; ; Onose, Shoji;
PNC TN9410 97-077, 177 Pages, 1997/07
Postirradiation examinations of JOYO MK-II control rods have been carried out since 1983, where 16 subassemblies with total 110 absorber pins of initial load to the fifth reload control rods have been subjected to a number of both non-destructive and destructive examinations. In the course of postirradiation examinations, a cracking of cladding tube was found in the total 15 absorber pins in five control assemblies. This paper indicates the results of postirradiation examinations and analysis of absorber pin performance using CORAL code to elucidate the cause of absorber pin cracking in JOYO MK-II control rods. No crack was found in absorber pins whose maximum burnup was lower than 39 
10
cap/m
, whereas all the cracked pins had burnup of higher than 43 10 cap/m with the initial gap between B
C pellet and cladding larger than 0.44 mm. The cracks were found at around positions corresponding to the lowest BC pellet in the stack. The ceramography analysis indicated that BC pellet exhibited extensive cracking and a part of gap between pellet and cladding closed. The cladding deformation had an ovality and the cracks tended to occur at the shorter diameter side. The cracked surface of absorber pin was of a typical grain boundary fracture. The result of He analysis for the cladding material indicated a substantial amount of He accumulation at the inner surface of cladding, but the bulk He content was not anomalously high compared with those in the neutron irradiated stainless steels. TEM observation indicated He bubbles was not clearly found in the as-irradiated cladding material. The cause of cladding failure was attributed to the ACMI where the gap closure due to relocation of BC pellet took place from early times of irradiation. The code analysis by CORAL indicated that the cladding strain due to ACMI was not fully absorbed by the irradiation creep and that the plastic strain became large enough to ...
Aoto, Kazumi; ; ; ; ; Hirakawa, Yasushi
PNC TN9410 97-076, 29 Pages, 1996/06
This report describes the check of the thermocouple well at the inlet of the intermediate heat exchanger (IHX) of C-loop of the secondary heat tansfer system of the prototype fast breeder reactor Monju, regarding the sodium leak accident of the thermocouple well at the outlet of the IHX of the same loop of the secondary heat transfer system of the same plant Monju. Various tests and inspections were performed to check damages at the part with rapid diameter change of the thermocouple well where stress concentration may occur, and to get the information about the integrity of the welded part between the thermocouple well and the attachment. The thermocouple well, the rapid diameter change part, larger and smaller part, respectively, of the thermocouple well, and welded part between the thermocouple well and the attachments were examined as written below. (1)Accurate measurement of the dimension. (2)Vibration test by tapping the thermocouple well. (3)Non destructive testing at some points. (4)Chemical composition analysis. (5)Microscopic observation of metalogical structure. (6)Detailed observation around the rapid diameter change part. (7)Hardness test. (8)Research on corrosion at the clearance. (9)Structure strength test of the thermocouple well. (10)Bending test of the thermocouple's sheath at high temperature.
Furuhashi, Ichiro*; Wakai, Takashi
PNC TN9410 95-080, 84 Pages, 1995/02
Revisions have been done on CANIS-J(2D) that calculates fracture mechanics parameters of 2-dimensional structures containing cracks or notches. (a)Evaluation of △K between arbitrary two steps on the basis of △
. (b)Evaluation of △J and △J
between arbitrary two steps on the basis of △, △ε and △u. (c)Evaluation of each terms of J (△J)-integral and J (△J)-integral. (d)Execution of following three mode calculations in one job run. Mode- 0 
calculation of K, J and J at any step. Mode- 1 calculation of △K, △J and △J between arbitrary two steps. Mode- 2 calculation of J and J between any continuous steps. To verify the validity of the revised code, we performed fracture mechanics analyses and crack growth simulations of thermal fatigue crack growth tests of circumferentially slitted cylinders subjected to cyclic thermal transients. And we got following results. (1)At thermal-elastic and at thermal-elasto-plastic conditions, J (△J) - integral is not path-independent and can not be properly evaluated. The reason is that J - integral is defined at elastic condition. (2)At thermal-elastic and at thermal-elasto-plastic conditions, J (△J) -integral is good enough path-independent and can be properly evaluated. The reason is that J -integral is defined at more generalized stress conditions. (3)△Jhat, thermal-elastic △K △ (or △ε) at near the crack tip, and net-section bending stress range S
at crack ligament, these take approximate maximum values between the common two steps. (4)Crack growth simulations based on △J agree well with the behaviors observed at tests. (5)These results assist that, on the fracture mechanics evaluations of flawed structures subjected to complicated thermal-elasto-plastic load cycles, J (△J) -integral will be a possible fracture mechanics parameter which corresponds to ...
Furuhashi, Ichiro*; *
PNC TN9410 94-201, 301 Pages, 1994/04
Development and revisions of simplified crack analysis code CANIS-system were done for fracture mechanics evaluation of FBR structures. CANIS-system is composed of CANIS-G, K and -I. Following revisions were done on CANIS-G that evaluate creep fatigue crack growth history. (1.1)0uter crack of cylinder can be treated, addition to inner crack. (1.2)Axial bending load on cylinder can be treated. (1.3)Displacement controlled load such as thermal stresses can be easily treated. (1.4)Libraly of shape functions for net section stress and libraly of stress intensity factor solutions were expanded to support above subjects. (1.5)Material properties such as elasto-plastic stress-strain relation, creep strain relation, creep rupture time and fatigue failure life of 7 kinds of materials those have been gotten in PNC were added on libralies. (1.6)Backward analysis can be done to estimate past time crack shapes. And now CANIS-K that evaluate fracture mechanics parameters and CANIS-I that evaluate crack initiation probability have been developped. CANIS-K can be used in the following subjects. (2.1)Calculate and print details of fracture mechanics parameters such as stress intensity factor K, J-integral and creep J-integral for given crack shapes, and maximum and minimum values and time histories of those parameters. (2.2)Calculate and print crack growth rates, crack opening area and leak rates. CANIS-I can be used in the following subjects. (3.1)Evaluate time dependant fatigue damage and creep damage. (3.2)Evaluate time dependant crack initiation probability with reference of statistical crack initiation data that caused by fatigue damage or by creep damage. Input data format and subroutine programs of these CANIS-G, -K and -I are commonly, so future expansions and revisions will be done easily and commonly. CANIS is very powerful computational tool in the following regions and can be employed in many practical applications. (4.1)Remaining life predictions of cracked ...
kasahara, Naoto
PNC TN9520 93-009, 223 Pages, 1993/04
None
Koi, Mamoru
PNC TN9410 90-105, 163 Pages, 1990/07
Fatigue and creep crack growth data of SUS304 stainless steel, 2.25Cr-1Mo steel and Mod.9Cr-1Mo steel, which were accumulated in PNC in last several years, were treated as a data base. Average trend equations of crack growth rate were proposed and also statistical analysis was carried out. Finite Elements analysis of center cracked tensioned plate was performed and simplified prediction method of modified J-integral J'(C 
) was developed. 0btained results are summerized as follows: (1)In all tested materials, fatigue crack growth rate and creep crack growth rate were successfully represented using cyclic J-integral range 
J and modified J-integral J', respectivery. (2)In all tested materials, meaningful difference of crack growth rate could not be detected between hot rolled plate and forged material, and also between base metal and welded material. (3)Averaged trend equations of fatigue crack growth rate and creep crack growth rate of all tested materials were proposed on the basis of power low with cyclic J-integral range and modified J-integral, respectively. (4)Assuming that the coefficient and exponent of the above power low obey joint normal distribution, statistical analysis of crack growth rate was carried out and relationship between variance and J, J' were obtained. (5)Simplified method was developed to predict modified J-integral of center cracked tensioned plate. Prediction results show good agreement with experimental results, and this fact suggests that J-integral evaluation method of 3-dimensional surface crack, which has been developed in PNC, has good prediction accuracy.
C*
PNC TN9410 90-086, 47 Pages, 1990/05
Since stainless steels like SUS 304 and SUS 316 tend to be carburized in sodiun, the grain boundary near surface may be degraded due to carbides precipitation. In order to clarify the effect of the grain boundary degradation upon creep fatigue strength, long term creep fatigue tests of SUS304 stainless steel were performed in carburized sodium, 0btained results are summarized as follows: (1)Creep fatigue life in carburized sodium was nearly equal to that in air, in spite of the fact that severe carburization and carbides precipitation on grain boundary were observed on tested specimen surface. (2)Creep fatigue life calculated using usual linear damage summation rule showed good agreement with experimental results, (3)It was revealed that crack initiation life in carburized sodium was almost the same as that in air, although crack initiated on degraded grain boundary in carburized sodium. (4)The above fact supplies an evidence to justify the concept that creep fatigue crack initiation life in sodium is longer than 1/20 of failure life obtained using small specimens in air, which is basic assumption of our creep fatigue evaluation method. It is conjectured from this study that FBR grade SUS316 stainless steel will show almost the same creep fatigue life as that in air, however, a few creep fatigue tests of FBR grade SUS316 in carburized sudium will be necessary to clarify this conjecture.
; *; Furuhashi, Ichiro*
PNC TN9410 88-147, 215 Pages, 1988/09
The present study includes the analytical work for of the stable crack growth of the finite plate with semi-elliptical surface defect by creep-fatigue loadings, and of the crack opening area for presumed leakage of cloolant to be considered in safety assessment. The objective of this study is to develop the basic inelastic fracture mechanics to the level in which the integrity of basic components, plate, vessel, piping, and so on, with crack would be able to be assessed analytically. CANIS code developed last year was used to analize the J integral for fatigue crack growth and J' integral for creep crack growth of SUS 304 plates with various shapes of semi-elliptical surface cracks at 500 C, then those distributions were arranged from the view point of crack growth assessment. An appricable range of these data is 
1.5 Sm of fatigue cycle and hold time of 108,000 hr creep. 0nly secondary stress including membrane, bending and combination of these stresses were considered in the data base. Evaluation of elbow with 42
diameter and 20.6mm thickness considered in the design of large loop type FBR were achieved based on the data base. Then calculated through wall crack lengths were applied to the calculation of opening areas of 42 elbow subjected of internal pressure of 2 atg and in plane bending moment corresponding to stress level of 1.5Sm. The results are (1)A numbers of cycles at penetration are 6,250 for membrane stress and 30,520 for bending stress in the case of fatigue, and 303 for memberane and 1,534 for bending in the case of creep-fatigue. (2)opening area against internal pressure is larger than that against bending moment, and is about 0.5mm
. (3)maximum leak rate from the opening area is about 23 
/hr. The level up of analytical method for stable crack growth was almost accomplished. In the near future, the experimental study would be needed for validation of this method.
Shimoyama, Kazuhito; Kuroha, Mitsuo; *
PNC TN9410 87-014, 103 Pages, 1987/01
Acoustic type water leak detectors have promising potentiality in short detection time for minimising the extent of tube failure propagation caused by water leakage from a heat transfer tube of an LMFBR steam generator. Two different methods as follows were studied in this program : (1)The method to compare effective values between water leak sound and back ground noise using a single channel. (2)The method to detect and locate the leak using cross correlation signal processing of multi-channel. In the former one, it was estimated from acoustic signals obtained in the 50 MW Steam Generator Test Facility that the back ground noise levels of the Prototype and the Demonstration reactor were 0.0093G and 0.012G (G=gravity), respectively. The water leak rates equivalent to those back ground levels were evaluated as approximately 0.7 and 7 g/sec. In the latter one, first a detection and location software was developed in a off-line analysis, and secondly an on-line signal processing hardware was manufactured as a trial. In the off-line analysis, the influence of the internals on detection performance was examined by horizontal and vertical measurement. As the result, it revealed that back ground noise interfered the leak detection and location and that the potential depended on the leak positions even without noise. In the on-line analysis, leaks in a lower plenum were detectable with the same accuracy as the off-line analysis.