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JNC TN1400 2000-006, 68 Pages, 2000/07
JNC-TN1400-2000-006.pdf:2.18MB
no abstracts in English
; Yamaguchi, Akira
JNC TN9400 2000-056, 150 Pages, 2000/05
JNC-TN9400-2000-056.pdf:6.67MB
[Purpose] The work was performed to make clear thermal-hydraulic issues resulting in the use of various coolants for fast reactors. [Method] Plant design features due to a use of working fluid other than sodium and design concepts relating a simplification of safety related systems were investigated. And based on the results, quantitative evaluation was made on the topical themal-hydraulic issues. Then both thermal stratification and striping phenomena were evaluated by the used of thermo-hydraulics computer programs. [Results] (1)Thermal-hydraulic issues Topical thermal-hydraulic issues of gaseous and heavy metal cooled reactors were extracted. (a)Gas cooled reactors : natural circulation,flow-induced vibration, depressurization accident (b)Heavy metal cooled reactors : thermal stratification, flow-induced vibration, sloshing And also the thermal-hydraulic issues relating compact reactor assembly and RVACS were extracted resulting from a simplification of safety related systems. (2)Evaluation of thermal stratification and striping phenomena. The following order of affects for the phenomena was obtained: (a) Thermal stratification: CO
Sodium Lead, (b) Thermal Striping: CO Lead Sodium
kasahara, Naoto
PNC TN9410 95-213, 38 Pages, 1995/08
In order to evaluate thermal transient strength of welded components in nuclear plants, conventional structural design codes provide conservative strength reduction factors, which are desired to be rationalized. Author extended the generalized clastic follow-up model to evaluate main causes of strength reduction of welded joints. As main causes of strength reduction of welded joints subjected to cyclic thermal transients, attention was given to (1)Metallurgical discontinuity in which the different deformation response between base metal and weld metal can result in nonuniform stresses and strain across the weldment, (2)Structural discontinuity at penetration beads of welded joints, and (3)Degradation of Weld Metal. In order to evaluate (1) and (2) of above factors, an elastic follow-up model was successfully applied. Thermal transient strength test results provide further substantiation of the validity of the elastic follow-up model for ensuring adequate life in elevated temperature component weldments. Author applied the creep-fatigue life prediction methods based on the elastic follow-up model to evaluate test results of a welded vessel model. Proposed method was proved to be adequate through comparison of predicted damagc with observed cracks data.
Tsukimori, Kazuyuki
PNC TN9410 95-203, 17 Pages, 1995/08
A mechanical hold down method is under discussion as the means to prevent fuel assemblies from being lifted up in the scope of investigation of the recycle reactor conception at Plant Engineering Section. The device of the mechanical hold down system is a coil spring. In this case it is necessary to maintain enough pressure force in high temperature region. Therefore, it is needed to analize creep behaviors of coil springs. At this stage it is desirable to survay parametrically the creep behaviors of various dimensions of coil springs rather than to analize detailed behaviors by FEM. This paper describes the investigation of a creep behavior analysis method of coil springs. In the development process of the method the torque of the spring is derived from the assumption of shear stress field and hear distribution of shear strain in the radius direction and the constitutive equation of creep, and finally the spring force can be obtained by the equilibrium equation as the function of time. For implementation of this method a simple program should be created since the shear stress distribution in the radius direction is nonlinear, however, a wide ranged parametric survay can be done on the creep behavior of coil springs of arbitrary shape, dimension and material.
kasahara, Naoto
PNC TN9520 93-009, 223 Pages, 1993/04
None
Kimura, Hidetaka; *; *; Kawasaki, Hirotsugu; Aoto, Kazumi;
PNC TN9450 91-003, 28 Pages, 1991/03
None
*
PNC TN9410 90-103, 126 Pages, 1990/07
Thermal transient strength tests of a Welded Vessel Model is carring out in Therma1 Transient Strength Test Facility for Structures. The objective of this test is to grasp the thermal transient strength of fast breeder reactor's components and to develop a life estimation method for creep fatigue failure. The model is designed and fabricated in order to grasp the thermal creep-fatigue life of SUS304 and modified SUS316 under the noteworthy typical stress distribution encountered in the structures design of Fast Breeder Reactors. This report shows the results of thermal stress analysis and creep-fatigue damage evaluation of the model. The analytical model was divided the test model into five portions, namely a inlet nozzle, an upper vessel, a lower vessel, an outlet nozzle and an inner shell ring. Thermal transient condition used in the analysis is the same that used in design of the model.
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.
*
PNC TN9410 90-053, 56 Pages, 1990/02
A series or multiaxial creep-fatigue tests (uniaxial fatigue, pure torsional fatigue, pure torsional creep-fatigue, proportional fatigue, proportional creep-fatigue) was conducted by Toshiba Corporation as a part of a joint study with PNC. The results of the tests were evaluated by the multi-axial creep-fatigue evaluation method which was developed by the authors in the previous report. The following observation were obtained. (1)Results of multiaxial creep-fatigue tests obtained by Toshiba Corporation coincide well with those obtained by PNC, except those of pure torsional fatigue/creep-fatigue tests. In the case of pure torsional fatigue/creep-fatigue, Toshiba data showed slightly longer lives, (2)Pure torsional creep-fatigue lives reduced as the peak strain hold time increased from 3 minites to 60 minites. A longer hold time would have redeced the creep-fatigue lives even more. (3)In pure torsional creep-fatigue tests with a peak strain hold of 15 minuites, recovery of life was not observed with an additional strain hold time (from 3 minites to 15 minuites) at the other strain peak. (4)It was shown that the multiaxial creep-fatigue evaluation method proposed by the authors could cvaluate the Toshiba data conservatively. Life predictionswere conservative for a factor of 5 and nonconservative for a factor of 2.
*
PNC TN9410 90-093, 68 Pages, 1990/01
The authors have conducted a series of axial and torsional biaxial fatigue/creep-fatigue tests with :304 stainless steel at 550 C and obtained the following conclusions, (1)A fatigue life under nonproportional loading reduces to 1/2-1/3 of that under proportional loading. (2)The life reduction under nonproportional loading can be accouted for by path-dependent Mises type equivalent strain range. In this report, the results of creep-fatigue tests under proportional and nonproportional loading are examined. The following results were obtained. (1)A creep-fatigue life under nonproportional loading reduces to 1/2-1/5 of that under proportional loading. (2)Stress relaxation occurs towards origin proportionally (to the point where axial and torsional loads are zero) even under nonproportional creep-fatigue loading. (3)A creep-fatigue life under nonproportional loading can resonably be evaluated based on the fatigue properties and the creep properties obtained under uniaxial loading conditions, using the path dependent Mises type equivalent strain range and Mises equivalent stress.
*
PNC TN9410 90-054, 125 Pages, 1990/01
A preliminary analysis was performed on the sodium thermal fatigue tests which are planned to be conducted with the "Sodium Thermal Fatigue Test Apparatus", which was recently constructed in the material development section. This test machine was constructed for the purpose of aquisition of data needed for sofistication of the evaluation method of creep-fatigue and crack propagation of welded joints. This preliminary analysis is concerned with thermal analysis and stress analysis on test specimens which are planed to be used in the machine. Effects of following parameters on temperature/stress distribution of test specimens under various conditions were analysed. Thcse parameters are considered to play significant roles in the analysis of the results of upcoming experiments. (1)Heat transfer coefficient (2)Thermal shock temperature (3)Speed of submerging specimen (4)Comparison of behavior of base metal and welded joint (5)Comparison of mechanical loading and thermal loading
; *; 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 10
8,000 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.
*; *
PNC TN9410 88-105, 206 Pages, 1988/04
KOM-MSS W/G studies to rationalize and revise "Elevated Temperature Structural Design Standard - Material Strength Standard - for Fast Breeder Reactor" based on new engineering techniques, knowledges of new structural materials and new evaluation method, furthermore, based on rationalized safety argorithm and design margines which have been investigated at the economical point of view. In 1987, five sub-groups organized in KOM-MSS W/G began to study on each main theme as followed. (1)1st S/G : To study material properties of Mod.9Cr-1Mo steel and its weldment at elevated temperature and to revise "Material Strength Standard (tentative in 1986)". (2)2nd S/G : To study material properties of Mod. austenitic stainless steels at elevated temperature. (3)3rd S/G : To study material properties of weldment of SUS304 at elevated temperature. (4)4th S/G : To extend the application of the usual elevated temperature structural design guide for class 1 components of prototype LMFBR. (5)5th S/G : To rationalize the evaluation method for creep-fatigue damage.