[en] In the early 1950's, the concept of the unit shield for the nuclear powered aircraft reactor changed to one of the divided shield concept where the reactor and crew compartment shared the shielding load. Design calculations for the divided shield were being made based on data obtained in studies for the, unit shield. It was believed that these divided shield designs were subject to error, the magnitude of which could not be estimated. This belief led to the design of the Tower Shielding Facility where divided-shield-type measurements could be made without interference from ground or structural scattering. This paper discusses that facility, its reactors, and some chosen experiments from the list of many that were performed at that facility during the past 38 years

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[en] In 1946, the U.S. Air Force selected the Fairchild Engine and Airplane Corporation as the responsible organization for directing the Nuclear Energy for Propulsion of Aircraft (NEPA) project. At about this time, the Oak Ridge National Laboratory (ORNL) was putting into operation a facility that used a beam hole through the graphite reactor shield as a source of neutrons into which shield samples could be inserted. Since the laboratory had this facility, it was asked to cooperate in NEPA's needs. As time passed, more and more NEPA personnel became involved in NEPA work occurring at the laboratory, and in September 1949, the U.S. Atomic Energy Commission (AEC) designated ORNL as the agency for continuing the AEC's share of a joint technical program that was established in conjunction with the U.S. Department of Defense and the National Advisory Committee for Aeronautics. The purpose of the program was to develop a nuclear-powered aircraft. The laboratory was asked to study the neutronics aspect of the project, which included the relatively new discipline of reactor shielding. Since the weight and distribution of the shields would substantially affect the shape and size of the plane, it was imperative that the shield design be accurate and timely. It was concluded that the surest, fastest, and most economical way to verify calculations was through the use of full-scale mock-ups. This decision led to the building of what has been known as the Tower Shielding Facility

[en] Verification of methods for analysis of radiation-transport (shielding) problems in Liquid-Metal Fast Breeder Reactors has required a series of experiments that can be classified as benchmark, parametric, or design-confirmation experiments. These experiments, performed at the Oak Ridge Tower Shielding Facility, have included measurements of neutron transport in bulk shields of sodium, steel, and inconel and in configurations that simulate lower axial shields, pipe chases, and top-head shields. They have also included measurements of the effects of fuel stored within the reactor vessel and of gamma-ray energy deposition (heating). The paper consists of brief comments on these experiments, and also on a recent experiment in which neutron streaming problems in a Gas-Cooled Fast Breeder Reactor were studied. The need for additional experiments for a few areas of LMFBR shielding is also cited

[en] During the period between 1975 and 1980 a series of experiments was performed at the ORNL Tower Shielding Facility in support of the shield design for a 300-MW(e) Gas Cooled Fast Breeder Demonstration Plant. This report reviews the experiments and calculations, which included studies of: (1) neutron streaming in the helium coolant passageways in the GCFR core; (2) the effectiveness of the shield designed to protect the reactor grid plate from radiation damage; (3) the adequacy of the radial shield in protecting the PCRV (prestressed concrete reactor vessel) from radiation damage; (4) neutron streaming between abutting sections of the radial shield; and (5) the effectiveness of the exit shield in reducing the neutron fluxes in the upper plenum region of the reactor

[en] This manual provides information necessary to operate and perform maintenance on the reactor systems and all equipment or systems which can affect their operation or the safety of personnel at the Tower Shielding Facility. The first four chapters consist of introductory and descriptive material of benefit to personnel in training, the qualifications required for training, the responsibilities of the personnel in the organization, and the procedures for reviewing proposed experiments. Chapter 8, Emergency Procedures, is also a necessary part of the indoctrination of personnel. The procedures for operation of the Tower Shielding Reactor (TSR-II), its water cooling system, and the main tower hoists are outlined in Chapters 5, 6, and 7. The Technical Specification surveillance requirements for the TSR-II are summarized in Chapter 9. The maintenance and calibration schedule is spelled out in Chapter 10. The procedures for assembly and disassembly of the TSR-II are outlined in Chapter 11

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[en] This report presents the Phase I measurements of the High-Temperature Gas-Cooled Reactor Bottom Reflector and Core Support Neutron Streaming Experiment conducted at the ORNL Tower Shielding Facility during FY-1983. In this phase the first four of eight segments that comprise the full experimental mockup were utilized. These were: (1) an upper boron pin layer (graphite matrix) followed by a boral shroud; (2) a graphite reflector layer; (3) a graphite coolant crossover layer; and (4) a graphite follow-on layer, all containing coolant holes. A collimated beam from the Tower Shielding Reactor II was used as the neutron source. In order to obtain a spectrum of neutrons more nearly like the spectrum expected from the HTGR, an iron and graphite spectrum modifier was inserted in the TSR-II beam ahead of the experimental mockup. The various experimental configurations tested resulted from the successive addition of the four graphite layers to the mockup. Neutron energy spectra were measured behind the spectrum modifier and the boron pin layer and integral neutron fluxes were measured behind the spectrum modifier and behind each of the four layers. The measurements were divided into two Parts, the two parts differing in the composition of the boron pin layer. During part I, a reference pin pattern was used which consisted of a combination of graphite and boronated graphite pins. During part II, a full pattern of boronated graphite pins was used. The experimental data are presented in both tabular and graphical form

[en] This report describes the integral flux, energy spectra, and dose rate measurements made for the Exit Shield Experiment at the Oak Ridge National Laboratory Tower Shielding Facility as part of the Gas Cooled Fast Breeder Reactor program. The source was the same mockup of fuel pins used in the previous Grid Plate Shield Experiment. Two mockups of the upper axial shield were studied: one with seven subassemblies prototypic of that portion of the Exit Shield without a control rod, and another that was representative of the shield region with a control rod. The experiment was performed to provide verification of: the shield design methods, the shield effectiveness of a prototypic mockup, the analytical ability to calculate streaming effects in the presence of a control rod, and the source term bias factors for the upper plenum