Abstract: A materials exposure program has been established in the Garigliano Nuclear Power Plant to measure the effect of neutron irradiation and time at temperate on the mechanical properties of the reactor pressure vessel steel. Base metal specimens were made from portions of the pressure vessel steel, and weld heat-affected zone and weld metal samples were taken from a weldment made from the pressure vessel steel and simulating a pressure vessel circumferential weld since there are no longitudinal welds in the forged ring shell. The specimens were sealed in helium-filled capsules and placed in the reactor vessel at locations where they will be exposed to a variety of conditions. Tensile property changes will be measured by pre- and post-irradiation tests on small tensile specimens. Fracture characteristic changes will be measured in similar fashion by Charpy V-notch impact tests. The program is planned to cover a 32-year period, with specimens to be removed for test at intervals of 1, 2, 4, 8, 16, and 32 years.

Summary: Data were obtained in a two-road test section which consisted of two 7/16-inch diameter heater rods inside a roughly rectangular flow area. The heated length of the rods was 30 inches, with a 15-inch unheated calming length preceding it. Heater wall temperatures were recorded while the heater tubes were trans-versing the critical heat flux and transition boiling; these temperatures were used to calculate heat transfer coefficients. The following general results were obtaining: (a) Pressure has very little effect on the heat transfer coefficient in transition an film boiling. (b) Heat transfer coefficients during film boiling increase with mass velocity and steam quality. (c) The range of film boiling convective heat transfer coefficients observed was 364 to 1150 Btu/h-ft(2)-degrees F. (d) Temperature oscillations occur during transition boiling with a magnitude of as much 700 degrees F, at a frequency of about 1/2 cps. These temperature oscillations are reduced in magnitude as the steam quality and mass velocity are increased, becoming small (~20 degrees F) at high qualities and mass velocity. (e) A preliminary correlation of heat transfer coefficient data correlates the experimental data within about 20 percent. (f) Temperatures rises during transition boiling can be described analytically.

An investigation was made of the neutron and gamma flux distribution along the entire length of a withdrawn control rod in the SRE in order to determine heating, activation and dose rates produced by the streaming neutrons and gammas.

Technical report describing that voids were measured in a ½-inch by 1-3/4-inch channel with the S-1 insert (B(0)/B(1) = 0.4, L(0) = 0.1 inch), at 2 inches ahead of the insert (position A), ½-inch past the insert (position B), 5 inches past (position C), and 12 inches past (position D). The conditions were: P – 1000 psia, G = 1.00 x 10(6) lb/h-ft(2), and x = 18.8 percent. Average void and void distribution at position A are the same as for flow in a straight channel. Void distribution at position B shows that the stagnation region downstream of the inserts contains a high fraction of voids. Average void and void distribution at positions C and d show that the two-phase mixture becomes strongly mixed (homogenized) as a result of passing through he contraction-expansion inserts. Distribution at position D approaches the distribution at position A; i.e., the straight channel distribution.

VARI solves on the IBM-650 a system of simultaneous, first-order, ordinary, differential equations. The program was written so that a large number of calculations could be done in a reasonable length of time. The program permits the consideration of the production of the isotope by absorption and/or decay of one or more of any of the other isotopes in the chain.

Technical report describing a UO2-Mo cermet fuel assembly fabricated for long-term irradiation performance testing in the Vallecitos Boiling water Reactor. The design and fabrication histories of this assembly are described and pre-irradiation data on each individual rod are presented. Molybdenum was added to improve the bulk thermal conductivity of the fuel, so that fuel temperatures would remain comparatively low during high-power level operation of the fuel element. The molybdenum was incorporated into the compacts either as fibers or as a thin coating on individual UO2 particles. Fuel pellets were produced from these materials by vacuum hot pressing. The distribution of the molybdenum in both types of cermet fuels appeared favorable to good heat transfer. The fibers were oriented predominantly in the radial planes of the pellet as a result of the uni-directional compaction during the hot-pressing operation. In the pellets made from the coated particles, a continuous network of molybdenum occurred as a result of the coating welding together during the hot-pressing operation. The test assembly contains eight fuel rods; three contain UO2-Mo cermet, three contain the cermet produced from the coated particles, and two are for reference and contain the conventional sintered UO2 pellet fuel. The nominal outside diameter …

The 300 series stainless steels had been selected originally as the reference fuel cladding material for utilization in several superheat reactor (SHR) systems being built as part of the United States Atomic Energy Commission (USAEC) program. The adequacy of the general corrosion resistance of Type-304 stainless steel for superheat fuel cladding was confirmed in the Phase I portion of the study reported previously. Fuel jacket failures that occurred in Type-304 stainless clad fuel elements exposed in the Vallecitos boiling water reactor superheated steam loop indicated the questionable dependability of such stainless steels for this SHX fuel cladding application. The following conclusions are based on the out-of-pile general corrosion evaluations completed to date on Incoloy-800 as a fuel cladding for nuclear superheat applications: 1. The corrosion data from 4000-hour heat transfer tests indicate good corrosion resistance up to at least a 1300°F metal temperature. By use of a devised method of data treatment, the general corrosion for three years exposure at 1300°F can be calculated to average 0.0016 inch with an upper 95 percent confidence limit of 0.0033 inch. 2. A compositionally-disturbed layer develops at the metal-oxide interface. The disturbed layer depth is a function of time and temperature of exposure. …

Quarterly report describing progress on the EVESR Nuclear Superheat Fuel Development Project.

The objective of the Accurate Nuclear Fuel Burnup Analyses program is to develop more accurate methods for burnup analysis for general use than the current method of analysis of Ca-137 or Sr-90. The program will require from three to five years of effort.

Writing the VARI-II Program was motivated by the need for a method of analyzing the results for the Absorber Burn-Up Experiment in progress at the Vallecitos Atomic Laboratory.

Experiments were carried out to determine the erosion, oxidation and dimensional characteristics of purposely defected fuel elements containing unsintered UO2 powder prepared by the swaging technique. The experiments were conducted in an out-of-reactor loop under superheat conditions of pressure, temperature, flow velocity and steam chemical composition.

Summary: The design, construction and assembly of all components were completed during the first contract year previous to December 1963. These efforts, defined by Tasks A-F, are document in (1), (2), and (3). Brief summaries of these completed efforts are given in the introduction to each of the tasks in the text of this report. The digest given below covers only the shakedown and analysis work carried out in the fourth quarter of the first contract year. Task G Shakedown Tests. The photographic procedure has been experimentally defined for the glass test section. Four automatic 35 mm cameras and four strobe light sources have been ordered on ATL funds and their respective mounting arrangements are in place. Roughly ten test runs were carried out in the glass test section during the course of the above work. Satisfactory recorder traces have been obtained on all measurement systems. These systems presently meet the accuracy and linearity specifications initially set. An x-ray void fraction signal adjustment and filtering circuit has been design and installed to provide equal resolution across the test section. Calibration disc inserts have been installed to permit satisfactory beam intensity calibration. Good agreement has been obtained between calculated and measured …