143 research outputs found
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Blend Down Monitoring System Fissile Mass Flow Monitor and its Implementation at the Siberian Chemical Enterprise, Seversk, Russia
In this paper the implementation plans and preparations for installation of the Fissile Mass Flow Monitor (FMFM) equipment at the Siberian Chemical Enterprise (SChE), Seversk, Russia, are presented. The FMFM, developed by Oak Ridge National Laboratory, is part of the Blend Down Monitoring System (BDMS) for the U.S. Department of Energy Highly Enriched Uranium (HEU) Transparency Implementation Program. The BDMS provides confidence to the United States that the Russian nuclear facilities supplying the lower assay ({approx}4%) product low enriched uranium (PLEU) to the United States from down-blended weapon-grade HEU are meeting the nonproliferation goals of the government-to-government HEU purchase agreement signed between the Russian Federation and the United States in 1993. The first BDMS has been operational at Ural Electrochemical Integrated Plant, Novouralsk, since February 1999. The second BDMS has been operational at Electro Chemical Plant, Zelenogorsk, since March 2003. These systems are successfully providing HEU transparency data to the United States. The third BDMS was successfully installed on the HEU down-blending tee in the SChE Enrichment Plant in October 2004. The FMFM makes use of a set of thermalized {sup 252}Cf spontaneous neutron sources for modulated fission activation of the UF{sub 6} gas stream for measuring the {sup 235}U fissile mass flow rate. To do this, the FMFM measures the transport time of the fission fragments created from the fission activation process under the modulated source to the downstream detectors by detecting the delayed gamma rays from the fission fragments retained in the flow. The FMFM provides unattended nonintrusive measurements of the {sup 235}U mass flow of the UF{sub 6} gas in the blending tee legs of HEU, the LEU blend stock, and the resulting P-LEU. The FMFM also confirms that highly enriched UF{sub 6} gas identified in the HEU leg flows through the blending tee into the P-LEU leg. This report contains details of the SChE FMFM equipment characteristics as well as the technical installation requirements and the latest measurement results
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Blend Down Monitoring System Fissile Mass Flow Monitor Implementation at the ElectroChemical Plant, Zelenogorsk, Russia
The implementation plans and preparations for installation of the Fissile Mass Flow Monitor (FMFM) equipment at the ElectroChemical Plant (ECP), Zelenogorsk, Russia, are presented in this report. The FMFM, developed at Oak Ridge National Laboratory, is part of the Blend Down Monitoring System (BDMS), developed for the U.S. Department of Energy Highly Enriched Uranium (HEU) Transparency Implementation Program. The BDMS provides confidence to the United States that the Russian nuclear facilities supplying the lower-assay ({approx}4%) product low enriched uranium (P-LEU) to the United States from down-blended weapons-grade HEU are meeting the nonproliferation goals of the government-to-government HEU Purchase Agreement, signed between the Russian Federation and the United States in 1993. The first BDMS has been operational at Ural Electrochemical Integrated Plant, Novouralsk, since February 1999 and is successfully providing HEU transparency data to the United States. The second BDMS was installed at ECP in February 2003. The FMFM makes use of a set of thermalized californium-252 ({sup 252}Cf) spontaneous neutron sources for a modulated fission activation of the UF{sub 6} gas stream for measuring the {sup 235}U fissile mass flow rate. To do this, the FMFM measures the transport time of the fission fragments created from the fission activation process under the modulated source to the downstream detectors by detecting the delayed gamma rays from the fission fragments. The FMFM provides unattended, nonintrusive measurements of the {sup 235}U mass flow in the HEU, LEU blend stock, and P-LEU process legs. The FMFM also provides the traceability of the HEU flow to the product process leg. This report documents the technical installation requirements and the expected operational characteristics of the ECP FMFM
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Measurement Methodology of the Fissile Mass Flow Monitor for the HEU Transparency Implementation Instrumentation in Russia
The highly enriched uranium (HEU) Transparency Agreement between the U.S. and Russian Federation (RF) requires implementation of transparency measures in the Russian facilities that are supplying product low enriched uranium (LEU) to the U.S. from down blended weapon-grade HEU material. To satisfy the agreement's non-proliferation objectives, the U.S. DOE is implementing the fissile mass flow monitor (FMFM) instrumentation developed by Oak Ridge National Laboratory. The FMFM provides unattended non-intrusive measurements of {sup 235}U mass flow of the uranium hexafluoride (UF{sub 6}) gas in the process lines of HEU, the LEU blend stock, and the resulting lower assay product LEU (P-LEU) that is used for U.S. reactors. The instrumentation continuously traces the HEU flow through the blending point to the product LEU, enabling the U.S. to verify HEU material down blending. The FMFM relies on producing delayed gamma rays emitted from fission fragments carried by the UF{sub 6} flow. A thermalized californium-252 ({sup 252}Cf)-neutron source placed in an annular sleeve filled with moderator material that surrounds the pipe is modulated by a neutron absorbent shutter to induce fission in UF{sub 6}. For this technique to be effectively applicable the average range of resulting fission fragments in the UF{sub 6} gas must be smaller than the pipe diameter. The fission fragment range can be very large in low-density materials. Therefore, a methodology has been developed to determine the fission fragment range and its distribution to assess the fraction of the fission fragments that will remain in the flow; this methodology is the primary topic of discussions in this paper
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Characterization of an enriched uranyl fluoride deposit in a valve and pipe intersection using time-of-flight transmission measurements with {sup 252}Cf
A method was developed and successfully applied to characterize large uranyl fluoride (UO{sub 2}F{sub 2}) deposits at the former Oak Ridge Gaseous Diffusion Plant. These deposits were formed by a wet air in-leakage into the UF{sub 6} process gas lines over a period of years. The resulting UO{sub 2}F{sub 2} is hygroscopic, readily absorbing moisture from the air to form hydrates as UO{sub 2}F{sub 2}-nH{sub 2}O. The ratio of hydrogen to uranium can vary from 0--16, and has significant nuclear criticality safety impacts for large deposits. In order to properly formulate the required course of action, a non-intrusive characterization of the distribution of the fissile material within the pipe, its total mass, and amount of hydration was necessary. The Nuclear Weapons Identification System (NWIS) previously developed at the Oak Ridge Y-12 Plant for identification of uranium weapons components in storage containers was used to successfully characterize these deposits
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Calibration measurements using the ORNL fissile mass flow monitor
This paper presents a demonstration of fissile-mass-flow measurements using the Oak Ridge National Laboratory (ORNL) Fissile Mass Flow Monitor in the Paducah Gaseous Diffusion Plant (PGDP). This Flow Monitor is part of a Blend Down Monitoring System (BDMS) that will be installed in at least two Russian Federation (R.F.) blending facilities. The key objectives of the demonstration of the ORNL Flow Monitor are two: (a) demonstrate that the ORNL Flow Monitor equipment is capable of reliably monitoring the mass flow rate of {sup 235}UF{sub 6} gas, and (b) provide a demonstration of ORNL Flow Monitor system in operation with UF{sub 6} flow for a visiting R.F. delegation. These two objectives have been met by the PGDP demonstration, as presented in this paper
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Toroidal field ripple effects in TNS design
In the design of TNS, the choice of the number of TF coils has been made on the basis of trade-off studies among the plasma physics considerations and engineering design requirements. The theory of the magnetic field ripple effects has been studied to include the effects of noncircular cross sections such as those encountered in high-beta equilibria. A computer simulation model (RIPPLE) was developed to examine the field ripple effects on plasma transport and scaling. The magnetic field computer program BOVAL was used to calculate the magnetic field due to current flowing in a noncircular coil of finite rectangular cross section. The number of toroidal field (TF) coils is then determined by calculating the maximum magnetic field ripple that can be tolerated from plasma physics considerations
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ITER plasma safety interface models and assessments
Physics models and requirements to be used as a basis for safety analysis studies are developed and physics results motivated by safety considerations are presented for the ITER design. Physics specifications are provided for enveloping plasma dynamic events for Category I (operational event), Category II (likely event), and Category III (unlikely event). A safety analysis code SAFALY has been developed to investigate plasma anomaly events. The plasma response to ex-vessel component failure and machine response to plasma transients are considered
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Edge turbulence and transport: Text and ATF modeling
We present experimental results on edge turbulence and transport from the tokamak TEXT and the torsatron ATF. The measured electrostatic fluctuations can explain the edge transport of particles and energy. Certain drive (radiation) and stabilizing (velocity shear) terms are suggested by the results. The experimental fluctuation levels and spectral widths can be reproduced by considering the nonlinear evolution of the reduced MHD equations, incorporating a thermal drive from line radiation. In the tokamak limit (with toroidal electric field) the model corresponds to the resistivity gradient mode, while in the currentless torsatron or stellarator limit it corresponds to a thermally driven drift wave
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Configuration control, fluctuations, and transport in low-collisionality plasmas in the ATF Torsatron
In low-collisionality plasmas confined in tokamaks and stellarators, instabilities driven by particles trapped in inhomogeneities of the magnetic fields could be important in increasing plasma transport coefficients. In the Advanced Toroidal Facility (ATF), an {ell} = 2, M = 12 field-period stellarator device with major radius R = 2.1 m, average plasma minor radius a = 0.27 m, central and edge rotational transforms {chi}{sub 0} {approx} 0.3, {chi}{sub a} {approx} 1, the effects of electron trapping in the helical stellarator field are expected to be important in plasmas with {bar n}{sub e} {approx} 5 {times} 10{sup 12} cm{sup {minus}3}, T{sub e0} {approx} 1 keV. Such plasmas have already been sustained for long-pulses (20 s) using 150--400 kW of 53.2-GHz ECH power at B = 0.95 T. Transport analysis shows that for {rho} = r/a {le} 1/3, the electron anomalous transport is {le}10 times the neoclassical value, while at {rho} = 2/3 it is 10--100 times neoclassical; this is compatible with expectations for transport enhancement due to dissipative trapped-electron modes. 4 refs., 3 figs
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