Publications by authors named "Richaud J"

Annealing tests are of utmost importance in nuclear fuel research, particularly to study the thermophysical properties of the material, microstructure evolution, or the released gas as a function of temperature. As an alternative to conventional furnace or induction annealing, we report on a laser-heating experiment allowing one to heat a nuclear fuel pellet made of uranium dioxide, UO2, or potentially other nuclear fuel pellets in an isothermal and controlled manner. For that purpose, we propose to use an indirect heating method based on a two compartment tungsten crucible, one containing the sample and the other acting as a laser susceptor for efficient and homogeneous heating of the assembly.

View Article and Find Full Text PDF

We report on experimental development and qualification of a system developed to detect and quantify the deformations of the cladding surface of nuclear fuel pellet assemblies submitted to heat transient conditions. The system consists of an optical instrument, based on 2 wavelengths speckle interferometry, associated with an induction furnace and a model pellet assembly used to simulate the radial thermal gradient experienced by fuel pellets in pressurized water reactors. We describe the concept, implementation, and first results obtained with this system.

View Article and Find Full Text PDF

In the frame of minor actinide transmutation, americium can be diluted in UO and (U, Pu)O fuels burned in fast neutron reactors. The first mandatory step to foresee the influence of Am on the in-reactor behavior of transmutation targets or fuel is to have fundamental knowledge of the Am-O binary system and, in particular, of the AmO phase. In this study, we coupled HT-XRD (high-temperature X-ray diffraction) experiments with CALPHAD thermodynamic modeling to provide new insights into the structural properties and phase equilibria in the AmO-AmO-AmO domain.

View Article and Find Full Text PDF

The reduction of six mixed-oxide samples containing 14, 24, 35, 46, 54, and 62 mol % Pu was studied in situ by X-ray diffraction. The samples were first oxidized in air and subsequently reduced in a controlled atmosphere corresponding to a stoichiometric composition with an O/M = 2.00.

View Article and Find Full Text PDF

The oxidation products and kinetics of two sets of mixed uranium-plutonium dioxides containing 14%, 24%, 35%, 46%, 54%, and 62% plutonium treated in air were studied by means of in situ X-ray diffraction (XRD) from 300 to 1773 K every 100 K. The first set consisted of samples annealed 2 weeks before performing the experiments. The second one consisted of powdered samples that sustained self-irradiation damage.

View Article and Find Full Text PDF

Incorporating minor actinides (MAs = Am, Np, Cm) in UO2 fertile blankets is a viable option to recycle them. Despite this applied interest, phase equilibria between uranium and MAs still need to be thoroughly investigated, especially at elevated temperatures. In particular, few reports on the U-Np-O system are available.

View Article and Find Full Text PDF

Primary lymphoma arising in dura is exceedingly rare. We report the clinicopathologic findings of two patients with primary B-cell lymphoma of dura. Both were female, 38 and 45 years old.

View Article and Find Full Text PDF

A suprasellar location of a benign choroid plexus papilloma is reported. Local recurrence within the fourth ventricle was also present, 8 years after apparently complete removal. Imaging and histological findings were similar to those of the initial lesion.

View Article and Find Full Text PDF

Neurenteric cysts are cystic lesions lined by a columnar epithelium of endodermal derivation. They are rarely located in the central nervous system. We describe the case history of two recurrent neurenteric cysts located within the posterior fossa: one in the 4th ventricle and the second in the cerebellopontine angle.

View Article and Find Full Text PDF

Radiotherapy treatment planning needs optimum definition of the target volume in its relative position to normal tissue. The motion of the kidneys during respiration has not been well quantified. They move in a tilted coronal and sagittal plane.

View Article and Find Full Text PDF

The authors report the case of a 69-year-old woman with a brain metastasis from a cutaneous neuroendocrine carcinoma. The initial lesion was situated on the leg. No other secondary lesion was found.

View Article and Find Full Text PDF

Background: Potentiation of the antitumor activity of 5-fluorouracil (5-FU) by folinic acid has been demonstrated in patients with colorectal adenocarcinoma. Modulation is due to the interaction of thymidylate synthase (TS), fluorodeoxyuridylate (FdUMP), and methylene tetrahydrofolate (5,10-CH2-FH4), which leads to the formation of a stable ternary complex with concomitant enzyme inactivation. Folinic acid consists of a mixture of equal parts of two stereoisomers differing in chirality at the C6 carbon of the pteridine ring.

View Article and Find Full Text PDF

Background: Potentiation of the antitumor activity of fluorouracil (5-FU) by folinic acid has been demonstrated in patients with colorectal adenocarcinoma. Modulation is due to the interaction of thymidylate synthase, fluorodeoxyuridine monophosphate, and methylene tetrahydrofolate, which leads to the formation of a stable ternary complex with concomitant enzyme inactivation. Folinic acid consists of a mixture of equal parts of two stereoisomers differing in chirality at the C-6 carbon of the pteridine ring.

View Article and Find Full Text PDF

1,085 patients have been treated for intervertebral disc herniation with lombo-sciatica: in 751 cases surgical discectomy without laminectomy has been performed with or without microscope; 334 underwent papain nucleolysis. The two clinical groups were separated on clinical and radiographic backgrounds: nucleolysis was performed in patients with no motor disturbance, no stenosis of the lumbar canal, no displaced fragment; the other patients received surgical treatment. The results were evaluated according to MacNab's criteria with a follow-up of 12 to 84 months (mean 17.

View Article and Find Full Text PDF

To determine the concentration of renin inhibitors in plasma or other biological fluids, we developed an original approach to the already existing methods, such as HPLC or radio-inhibitor binding and enzyme inhibitor assays. We made an antigen-antibody complex by linking human renin (0.8 nM) to a specific monoclonal antibody fixed to magnetic spheres (3E8-magnogel).

View Article and Find Full Text PDF

The authors present 31 cases of spinal trauma affecting thoraco lumbar level with severe spinal canal stenosis secondary to compressive trauma of the anterior disco-corpereal region. Associated neurological disorders were of varying severity. 23 cases were investigated by computed tomography.

View Article and Find Full Text PDF

An 8-center, double-blind, placebo-controlled trial of 39 patients with benign prostatic hypertrophy was conducted to assess the effects of prazosin HCl treatment on functional urologic variables after a treatment period of 4 weeks. The randomized groups were comparable for demographic variables and symptoms, except for the mean residual urinary volume, which was significantly higher in the prazosin HCl group. Prazosin HCl elicited statistically significant improvements in the mean prostatic urethral pressure and prostate area (Mann-Whitney U test: p = 0.

View Article and Find Full Text PDF

3 cases of desmoid tumours of the mesentery occurring as part of Gardner's syndrome are reported. In 2 cases, CAT scanning was carried out. We underline the value of this examination compared to other imaging methods.

View Article and Find Full Text PDF

Multiple meningeal malformations are described: anterior or lateral meningoceles, extradural meningeal cysts, and intradural arachnoid cysts. All diverticulae appear to be extensions of the subarachnoid space, producing symptoms early or later. It is impossible to unify all these lesions because they cause multiple pathological conditions, depending upon the anatomical form or level, other systemic malformations, spinal abnormalities, or associated familial diseases.

View Article and Find Full Text PDF

The authors presented 15 cases of recent spinal cervical injuries treated with double approach procedure. Neurological disorders were variable but instability was severe in all cases. In 11 cases with severe neurological disorders the anterior procedure was made immediately, in 4 cases secondary with one or two sequences.

View Article and Find Full Text PDF