[en] Thermal conductivity values of 21-6-9 stainless steel over the temperature range of 5 K to 120 K are reported. Thermal conductivity integrals are measured using a steady-state heat flux method. The resulting data are fit with a polynomial and differentiated to obtain the conductivity. The derived conductivity is compared to published data for high-manganese stainless steels and to data for other stainless steels. A discussion of the methodology and its accuracy is included

[en] This report discusses the following topics related to the Superconducting Super Collider: Cryogenic system -- general requirements; cryogenic system components; heat load budgets and refrigeration plant capacities; flow and thermal characteristics; process descriptions; cryogenic control instrumentation and value engineering trade-offs

[en] The Superconducting Super Collider (SSC) will be the first proton machine in which synchrotron radiation significantly affects the cryogenic system and the beam tube vacuum. Synchrotron radiation represents the single largest heat load on the 4 K single-phase helium. It also provides a mechanism by which hydrogen can be desorbed from the beam tube wall, gradually worsening the vacuum. Insertion of a perforated and heated liner into the cold beam tube, together with a strip of cryosorber, effectively creates a distributed cryopump. Such an arrangement is an attractive solution to possible vacuum problems, provided it does not increase the heat load on the single-phase helium. In this paper, the primary mechanisms of heat transfer from an 90 K liner are considered, and the results of measurements on heat conduction through prototypical mechanical supports are presented

[en] The Superconducting Super Collider (SSC) consists of two stacked rings of superconducting magnets; each ring is about 86 km in circumference. The total mass to be cooled to liquid helium temperature amounts to about 1 x 10⁸ kg, and the total helium inventory under nominal operating conditions (4.15 K and 4 atm) is about 2.8 x 10⁵ kg. The cooldown and warmup process of a long string of magnets has to be well understood in order to design a cryogenic system that can satisfy the requirements of helium inventory handling, magnet temperature gradients, and process time for the different cooldown and warmup scenarios being planned for the SSC. A system that can be convincingly simulated can be understood, controlled, operated and improved in a systematic way. In this paper, we introduce two numerical models, a lumped model and a distributed model, for cooldown and warmup of the SSC ring, and present simulation results for an SSC string (4320 m long, or 1/20th of the full ring circumference). The models cover the temperature range between room and liquid helium temperature; the distributed model includes radial temperature distribution in the cold mass. Low temperature range simulations are particularly important to study inventory handling strategies because of the relationship between rapid changes in density and the system mass flow rate. 9 refs., 9 figs

[en] The HEATING6 heat conduction code is modified to (a) read the multigroup particle fluxes from a two-dimensional DOT-IV neutron- photon transport calculation, (b) interpolate the fluxes from the DOT-IV variable (optional) mesh to the HEATING6 control volume mesh, and (c) fold the interpolated fluxes with kerma factors to obtain a nuclear heating source for the heat conduction equation. The modified HEATING6 is placed as a module in the ORNL discrete ordinates system (DOS), and has been renamed DOS-HEATING6. DOS-HEATING6 provides the capability for determining temperature distributions due to nuclear heating in complex, multi-dimensional systems. All of the original capabilities of HEATING6 are retained for the nuclear heating calculation; e.g., generalized boundary conditions (convective, radiative, finned, fixed temperature or heat flux), temperature and space dependent thermal properties, steady-state or transient analysis, general geometry description, etc. The numerical techniques used in the code are reviewed and the user input instructions and JCL to perform DOS-HEATING6 calculations are presented. Finally a sample problem involving coupled DOT-IV and DOS-HEATING6 calculations of a complex space-reactor configurations described, and the input and output of the calculations are listed. 10 refs., 11 figs., 6 tabs

[en] Hydrogen desorbed from the beam tube of the super collider by synchrotron radiation may adversely affect the luminosity lifetime of the proton beam. One solution to this problem is to place a distributed cryopump within the beam tube which will pump desorbed gasses. Such a cryopump can be effected by attaching cryosorber to the cold (4 K) magnet bore tube. A concentric tube, or liner, centered within the magnet bore tube shields the cryosorber from the synchrotron radiation, and becomes the beam tube. By perforating a fraction of the liner surface with small (on the order of 1--3 mm) holes, the liner/cryosorber assembly becomes a distributed pump. The liner temperature may be allowed to equilibrate at a temperature close to that of the 4 K bore tube. However, actively stationing the liner at 80 K is of interest because the synchrotron radiation heat can then be deposited in the liquid nitrogen system. This, at least partially, decouples the allowable beam current from the helium cryogenic system. Active control is accomplished by means of 80 K helium flowing through a trace tube attached to the outside of the liner

[en] Republic of Turkey signed Non-Proliferation Treaty (NPT) in Vienna, Austria on January 28, 1969 and the Treaty was ratified by Turkish Parliament on March 29, 1979. International Atomic Energy Agency (IAEA) and Republic of Turkey signed the Safeguards Agreement on June 30, 1981. Turkey accepted the international safeguards administered by IAEA and at the same time its subsidiary arrangements and Facility attachments were enforced for all nuclear facilities as an Non-Nuclear-Weapon State party to NPT. Regulation on Nuclear Materials Accounting and Control, which was prepared in accordance with Agreement Between the Government of Turkey and IAEA for the application of Safeguard in Connection with the Treaty on NPT, has been put into force since it was published in Official Gazette on September 10, 1997. This study presents the essential futures of national system of accounting for and control of nuclear materials in Turkey

[en] As it is known, for the fact that the illicit trafficking and trading of nuclear materials are being increased over the past few years because of the huge demand of third world states. Nuclear materials like uranium, plutonium, and thorium are used in nuclear explosives that have very attractive features for crime groups, terrorist groups and, the states that are willing to have this power. Crime groups that make illegal trade of nuclear material are also trying to market strategic radioactive sources like red mercury and Osmium. This kind of illegal trade threats public safety, human health, environment also it brings significant threat on world peace and world public health. For these reasons, both states and international organizations should take a role in dealing with illicit trafficking. An important precondition for preventing this kind of incidents is the existence of a strengthened national system for control of all nuclear materials and other radioactive sources. Further, Governments are responsible for law enforcement within their borders for prevention of illegal trading and trafficking of nuclear materials and radiation sources

[en] The dynamic interaction between the beam-gas scattering induced energy deposition and the SSC cryogenic system is studied by integrating a cryogenic system dynamic simulator with an adsorption model and a beam-gas scattering and energy deposition model. Simulation results are obtained for a 1 km long SSC arc section where the beam tube pressure in one of the dipoles in increased up to 150 times its nominal operating pressure. The beam-gas scattering induced heat loads arising from such high pressure perturbations can be very locally but do not overload the cryogenic system. They are more likely to induce a magnet quench as they result in coil temperatures that largely exceed the desired operating limit. Simulations are also carried out for the case where a large external heat load of 1 W/m is imposed on the coldmass of a half-cell in the section. Results show that the coldmass temperatures rise significantly with the added heat load but the energy deposition in the coldmass due to beam-gas scattering remains low despite the increase in the beam tube temperature

[en] The superconducting Super Collider (SSC) will be the first proton machine in which synchrotron radiation significantly affects the cryogenic system and the beam tube vacuum. Synchrotron radiation represents the single largest heat load on the 4 K single-phase helium. It also provides a mechanism by which hydrogen can be desorbed from the beam tube wall, gradually worsening the vacuum. Insertion of a perforated and heated liner into the cold beam tube, together with a strip of cryosorber, effectively creates a distributed cryopump. Such an arrangement is an attractive solution to possible vacuum problems, provided it does not increase the heat load on the single-phase helium. In this paper, the primary mechanisms of heat transfer from an 80 K liner are considered, and the results of measurements on heat conduction through prototypical mechanical supports are presented