The neutronic calculations for some fluids, libraries and structural materials in a hybrid reactor system

In the present investigation, a hybrid reactor system was designed by using 100 % Flibe, 90 % Flibe-10 % ThF4, 90 % Flibe-10 % UF4 fluids, ENDF/B-VII, JEFF-3.1, JENDL-4.0, ROSFOND, BROND-2.2, CENDL-3.1 evaluated nuclear data libraries and Ferritic Steel, 9Cr2WVTa, V4Cr4Ti, SiC structural materials. The fluids were used in the liquid first wall, liquid second wall (blanket) and shield zones of a fusion–fission hybrid reactor system. The nuclear parameters of a fusion–fission hybrid reactor such as tritium breeding ratio (TBR), energy multiplication factor (M), heat deposition rate were computed in liquid first wall, blanket and shield zones. Three-dimensional nucleonic calculations were performed using the most recent version MCNPX-2.7.0 the Monte Carlo code.

Neutronic performance calculations with alternative fluids in a hybrid reactor by using the Monte Carlo method

In this study, salt-heavy metal mixtures consisting of 93–85% Li20Sn80 + 5% SFG-PuO2 and 2–10% UO2, 93–85% Li20Sn80 + 5% SFG-PuO2 and 2–10% NpO2, and 93–85% Li20Sn80 + 5% SFG-PuO2 and 2–10% UCO were used as fluids. The fluids were used in the liquid first wall, blanket, and shield zones of a fusion–fission hybrid reactor system. A beryllium (Be) zone with a width of 3 cm was used for neutron multiplicity between the liquid first wall and the blanket. 9Cr2WVTa ferritic steel with the width of 4 cm was used as the structural material. The contributions of each isotope in the fluids to the nuclear parameters, such as tritium breeding ratio (TBR), energy multiplication factor (M), and heat deposition rate, of the fusion–fission hybrid reactor were calculated in the liquid first wall, blanket, and shield zones. Three-dimensional analyses were performed using the Monte Carlo code MCNPX-2.7.0 and nuclear data library ENDF/B-VII.0.

Investigation of (n,γ) reaction in hybrid reactor zones

In this study, the fluids were composed with increased mole fractions of a mixture of molten salt: heavy metals 99 – 95 % Li20Sn80−1 – 5 % SFG-Pu, 99 – 95 % Li20Sn80−1 – 5 % SFG-PuF4, 99 – 95 % Li20Sn80−1 – 5 % SFG-PuO2. In this study, the effect on conversion of each isotope (238–242Pu) in spent fuel grade plutonium by (n,γ) reactions was investigated in liquid first wall, blanket and shield zones of the designed hybrid reactor system. Beryllium (Be) is the neutron multiplier by (n,2n) reactions. The Be zone used was 3 cm thick. 9Cr2WVT, a ferritic steel, is used as structural material. Three-dimensional nucleonic calculations were performed by using the most recent versions of the MCNPX-2.7.0 Monte Carlo code and the nuclear data library ENDF/B-VII.0.

Investigation of (n,γ) reactions in fissionable fluids in a hybrid reactor system

In this study, the effect of (n,γ) reactions in spent fuel-grade (SFG)-PuO2, UO2, NpO2 and UCO contents was investigated in a designed hybrid reactor system. In this system, the molten salt-heavy metal mixtures 93 – 85 % Li20Sn80 + 5 % SFG-PuO2 and 2 – 10 % UO2, 93 – 85 % Li20Sn80 + 5 % SFG-PuO2 and 2 – 10 % NpO2, 93 – 85 % Li20Sn80 + 5 % SFG-PuO2 and 2 – 10 % UCO were used as fluids. Beryllium (Be) is used as neutron multiplier by (n,2n) reactions. Thence, a Be zone with a width of 3 cm was used in order to contribute on fissile fuel breeding between the liquid first wall and blanket. (n,γ) reactions were calculated in the liquid first wall, blanket and shield zones, which SFG-PuO2, UO2, NpO2 and UCO contents. 9Cr2WVTa ferritic steel with the width of 4 cm was used as the structural material. Three-dimensional nucleonic calculations were performed using the most recent version MCNPX-2.7.0 the Monte Carlo code and nuclear data library ENDF/B-VII.0.

Neutron flux investigation on certain alternative fluids in a hybrid system by using MCNPX Monte Carlo transport code

In this study, the molten salt-heavy metal mixtures 93 – 85 % Li20Sn80 + 5 % SFG-PuO2 and 2 – 10 % UO2, 93 – 85 % Li20Sn80 + 5 % SFG-PuO2 and 2 – 10 % NpO2, 93 – 85 % Li20Sn80 + 5 % SFG-PuO2 and 2 – 10 % UCO were used as fluids. The fluids were used in the liquid first wall, blanket and shield zones of the designed hybrid reactor system. Four centimeter thick 9Cr2WVTa ferritic steel was used as the structural material. In this study, the effect of mixture components on the neutron flux was investigated in a designed fusion–fission hybrid reactor system. The neutron flux was investigated according to the mixture components, radial flux distribution and energy spectrum in the designed system. Three-dimensional analyses were performed using the most recent MCNPX-2.7.0 Monte Carlo radiation transport code and the ENDF/B-VII.0 nuclear data library.

The production of 238–242Pu(n,γ)239–243Pu fissionable fluids in a fusion-fission hybrid reactor

In this study, the effect of spent fuel grade plutonium content on 239–243Pu was investigated in a designed hybrid reactor system. In this system, the fluids were composed of a molten salt, heavy metal mixture with increased mole fractions 99 – 95 % Li20Sn80-1 – 5 % SFG-Pu, 99 – 95 % Li20Sn80-1 – 5 % SFG-PuF4, 99 – 95 % Li20Sn80-1 – 5 % SFG-PuO2. Beryllium (Be) is a neutron multiplier by (n,2n) reactions. Thence, a Be zone of 3 cm thickness was used in order to contribute to fissile fuel breeding between the liquid first wall and a 9Cr2WVTa ferritic steel blanket which is used as structural material. The production of 238–242Pu(n,γ)239–243Pu was calculated in liquid first wall, blanket and shielding zones. Three-dimensional nucleonic calculations were performed by using the most recent version MCNPX-2.7.0 Monte Carlo code and nuclear data library ENDF/B-VII.0.

Investigation of neutronic effects in structural material of a hybrid reactor by using the MCNPX Monte Carlo transport code

In this study, 98–90% Li2BeF4-2–10% ThF4, 98–90% Li2BeF4-2–10% UF4, 98–90% Li2BeF4-2–10% UO2 and 100% Li2BeF4 molten salt-heavy metal was used as fluid. The fluids were used in the liquid first wall, liquid second wall and shield zones of the designed hybrid reactor system. A steel wall of 4 cm thickness is used as structural material. Proton, deuterium, tritium, He-3 and He-4 gas production rates are the parameters of radiation damage. In the study, the effect of liquid second wall thicknesses (20 cm, 30 cm, 40 cm, 50 cm) on the neutron flux distribution and the parameters of radiation damage according to neutron energy spectrum in the structural material were investigated for the selected fluids. A three-dimensional analysis was done by using the most recent version of the MCNPX-2.7.0 Monte Carlo code and the nuclear data library ENDF/B-VII.

Neuronal migration disorders presenting with mild clinical symptoms

Two children with neuronal migration disorders and unexpectedly mild clinical symptoms are reported. The first patient was followed with the diagnosis of febrile convulsion and seizures associated with fever for 14 years. Computed tomography scans were normal. Although periodic slow waves of the left parietal cortex were detected on the first two electroencephalograms, his latest examination was normal. Magnetic resonance imaging performed at 16 years of age disclosed a left parietal schizencephaly extending between the parietal cortex and corpus callosum. The second patient was followed with the diagnosis of febrile convulsion for 2 years and later experienced afebrile seizures. On his latest visit, a posterior parietal pachygyric region and a parieto-occipital island heterotopia on the left hemisphere were diagnosed by magnetic resonance imaging. We believe that review of these patients, at the mildest end of the clinical spectrum of neural migration disorders, will contribute to a new understanding of the correlation between clinical and pathologic findings of neuronal migration disorders.

Griscelli syndrome: report of three cases

The clinical features of three children with Griscelli syndrome and autopsy findings of two are presented. The patients were 5 years, 9 months, and 3 months old, respectively. Clinical features included partial albinism, hepatosplenomegaly, and various neurological symptoms. Light and electron microscopic studies of the skin were compatible with Griscelli syndrome. Postmortem examination of the viscera and central nervous system revealed lymphohistiocytic infiltration with erythrophagocytosis. Bilateral diffuse involvement of the central nervous system, cranial nerve, and spinal cord was detected in both cases.

Acute ascending myelitis and encephalopathy after intrathecal cytosine arabinoside and methotrexate in an adolescent boy with acute lymphoblastic leukemia

A 14-year-old boy with acute lymphoblastic leukemia developed acute ascending myelitis followed by encephalopathy after intrathecal administration of methotrexate 15 mg and cytosine arabinoside 50 mg. The patient had none of the risk factors noted previously in other patients with intrathecal therapy (IT) induced neurotoxicity. The doses administered were within the standard scales, and toxicity developed in the second boost of IT 20 days after the first one. There may not be any parameters to predict the occurrence of such severe and rare form of CNS neurotoxicity attributed to IT.

Neurologic features as initial presentations of childhood malignancies

Thirty patients were examined initially because of neurologic problems and later were diagnosed as having systemic malignant disorders. Acute leukemia was the most common malignancy (36.6%), followed by neuroblastoma (33.3%), non-Hodgkin lymphoma (13.3%), rhabdomyosarcoma (10%), Ewing tumor (3.3%), and Hodgkin lymphoma (3.3%). Four of the 11 acute leukemia patients had nervous system involvement due to meningeal, orbital, or cerebellar infiltration. The complaints of the remaining patients included back pain, weakness, and difficulty in walking, all of which were caused by anemia or bone pain. Neurologic involvement in systemic malignancies, other than acute leukemia, mainly appeared as spinal cord compression (7 with neuroblastoma, 3 non-Hodgkin lymphoma, 1 rhabdomyosarcoma, 1 Ewing tumor), orbital or cavernous sinus infiltration (3 with acute leukemia, 1 rhabdomyosarcoma), and VIIth cranial nerve involvement (2 with rhabdomyosarcoma). One patient had skull infiltration without any neurologic deficit. Cerebellar signs were caused by the remote effects of cancer. It is concluded that acute leukemia is the first and neuroblastoma is the second most common malignancy among childhood systemic malignancies presenting with neurologic involvement; however, neuroblastoma is the most common cause of spinal cord compression.

Autosomal recessive alobar holoprosencephaly with cyclops in three female sibs: prenatal ultrasonographic diagnosis at 18th week

A couple who were first cousins were referred for genetic counselling because of a previous spontaneous abortion and two female stillbirths with cyclopia. In the 18th week of the mother's fifth pregnancy a holoprosencephalic fetus was diagnosed by ultrasonography. The pregnancy was terminated. Postmortem computed tomography and pathological examination revealed that the female fetus had alobar holoprosencephaly with cyclopia. Chromosomal analysis of the fetus was normal.