Effect of thermal aging on fracture toughness of RPV steel

The effect of thermal aging on mechanical properties and fracture toughness was investigated on pressure vessel steel of light water reactors. Submerged are welded plates of ASME SA508 C1.3 steel were isothermally aged at 350°C, 400°C and 450°C for up to 10,000 hrs. Tensile, Charpy impact and fracture toughness testings were conducted on the base metal and the weld heat affected zone (HAZ) material to evaluate whether thermal aging induced by the plant operation is critical for the integrity of the pressure vessel or not. Tensile properties of the base metal was not changed by thermal aging as far as the thermal aging conditions were concerned. Relatively distinct degradation was observed in fracture toughness J_IC and J-resistance properties of both the base metal and the weld HAZ material, while only slight changes were observed in Charpy impact properties for both of them. However, it was concluded that the effect of thermal aging estimated by 40–80 years of plant operation on fracture toughness of both materials is small.     

High-speed and precise monolithic multiplier with radiation hardness using silicon bipolar SST

A high-speed and precise monolithic analogue multiplier with radiation hardness for high-speed onboard modems has been developed using Si-bipolar SST (super self-aligned process technology). The developed multiplier achieves an amplitude error of less than 0.2 dB p-p and a phase error of less than 2 degrees p-p up to 1 GHz. Moreover, radiatio hardness tests have proved the multiplier has a total dose. immunity up to 106rad (Si).     

Immunological responsiveness and adjunct immunotherapy in lung cancer

Immunocompetency was assessed before and after the operation in 40 patients with lung cancer by skin reaction against tuberculin (PPD) and dinitrochlorobenzene (DNCB), lymphocyte response to PHA, proportion of T-cells, macrophage migration inhibition test (MIT) and the presence of blocking factor. MIT was positive in 27 per cent and blocking factor was positive in 42 per cent. Immune response paralleled the clinical stage of the lesion. In curative resection cases, the immune response rose postoperatively, but declined in non-resectable or recurrent cases. The influence of postoperative radiation therapy, cancer chemotherapy and host mediated agents on the patients was observed. The feasibility of adjuvant specific immunotherapy is discussed.     

Recent advance in life prediction for HTGR applications

Key issues in design methods at high temperatures for an HTGR regime are creep constitutive equations. The life in service of structural components is controlled by creep damage. A creep constitutive equation is then needed to calculate inelastic stress-strain components. The method for life prediction, applicable to this temperature regime, has been investigated. The ductility exhaustion rule in conjunction with the creep constitutive equation is confirmed to be useful from the point of view of methodology. Creep-fatigue damage for Hastelloy XRs was assessed by this method in conjunction with the Miner's rule. It is found that the ductility exhaustion for creep damage has a tendency to estimate creep damage larger than the time faction that is often used conventionally. Creep damage under compressive stress should be evaluated at high temperatures.     

Static frequency chirping in λ/4-phase-shifteddistributed-feedback semiconductor lasers: influence of carrier-densitynonuniformity due to spatial hole burning

An experimental and theoretical study of the effect of carrier-density nonuniformity on frequency modulation (FM) characteristics of 1.3-μm λ/4-phase-shifted distributed-feedback (DFB) lasers is discussed. The static frequency chirping is measured using a recently developed method that is free from dynamical chirping as well as thermal frequency shift. The amount of chirping shows a strong dependence on the bias current level. This is explained theoretically by considering the nonuniform carrier-density distribution due to the spatial hole burning effect     

A large vertebrobasilar junction aneurysm grown at the proximal end of basilar artery fenestration--usefulness of balloon occlusion test with 99mTc-HMPAO SPECT under induced hypotension and consideration in therapeutic strategies

A 48-year-old lady suffered a transient loss of consciousness. CT and MRI revealed a large vascular lesion compressing the left lower pons. Angiography revealed a large aneurysm at vertebro-basilar junction, dome of which projected anteriorly and left to midline. Her previous vertebral angiogram taken 10 years ago when she suffered a subarachnoid hemorrhage from the left MCA aneurysm, had showed a fenestration of lower basilar artery without apparent aneurysm. Bilateral super-selective vertebral angiograms revealed that the aneurysm arose at the proximal end of the fenestration, and vertebrobasilar junction was incorporated into the aneurysm indicating broad neck aneurysm. The left posterior communicating artery was well developed. Balloon test occlusion (BTO) of bilateral vertebral artery was performed under normotension and induced hypotension. 99mHM-PAO SPECT was used to examine cerebral blood flow (CBF) during hypotensive BTO. The patient tolerated the test and CBF imaging showed insignificant sight decrease in bilateral cerebellar hemispheres. Exploration of the aneurysm was carried out by the right far lateral suboccipital approach. Bilateral vertebral arteries and the right segment of the basilar artery fenestration were identified. Neck clipping of the aneurysm with reconstruction of the parent vessels were tried with fenestrate clip. However, narrow operative field and large dome of the aneurysm made it hard to identify the left segment of the fenestration. Neck clipping was given up and clipping of bilateral vertebral arteries were performed distal to posterior inferior cerebellar artery with three body clippings. The patient showed moderate postoperative left lower nerve palsy, which was gradually improved in several weeks. Follow-up angiography revealed no opacification of the aneurysm.(ABSTRACT TRUNCATED AT 250 WORDS)     

Liquid solidification in laminar tube flow with internal heat sources

The effect of liquid solidification (freezing) on the heat transfer characteristics for laminar flow of a heat-generating fluid in a cooled circular tube is investigated analytically. Steady-state conditions and a uniform wall temperature, which is lower than the liquid freezing temperature, are assumed. The radius of the liquid-solid interface and local Nusselt number are determined as a function of position along the tube for several different values of the wall temperature and internal heat-generating rate. The thickness of the solid-phase shell increases with distance down the tube and approaches to its fully developed value depending upon a single dimensionless freezing parameter which measures the relative rate of external cooling and internal heating. The local Nusselt number, however, first decreases rapidly, attains a minimum and then increases toward its fully developed value, which is identical with 6.