[en] A description is given of the Omega West Reactor and associated experimental facilities, followed by a brief discussion of recent usage, new experiments, and future prospects

[en] One of the cooling towers at Los Alamos Scientific Laboratory is being operated intermittently. The cooling tower has been modified to restrict air flow and to keep the tower from drying out. The modifications are relatively inexpensive, simple to operate, and have proved effective. (U.S.)

[en] After the discovery of cooling system leak of about 284 liters per twenty-four (24) hour period, an investigation determined that the 76.2-cm diameter, 33.5-m long stainless-steel (304) OWR delay line was losing water at the same nominal rate. An excavation effort revealed that a circumferential crack, approximately 0.0025 cm in width, extended around the bottom half of the delay line. In addition, other evidence of what appeared to be microcracking and pitting that originated at random nucleated sites around the pipe were also found. Results of destructive analysis and nondestructive testing allowed Los Alamos staff to conclude that the direct cause for the main crack and other pitting resulted from stress-assisted, microbial-induced corrosion of the stainless steel primary piping. The results also indicated that microbial action from bacteria that are normally present in earth can be extremely harmful to stainless- steel piping under certain conditions. Other potential problems that could have also eventually led to a permanent shutdown of the OWR were discussed. These problems, although never encountered nor associated with the current shutdown, were identified in aging studies and are associated with: (1) the water-cooled, bismuth gamma-ray shield and, (2) the aluminum thermal column head seal that prevents reactor vessel water from entering into the graphite-filled thermal column

[en] A fail-safe, reliable, easy-to-use neutron shutter was designed, built, and put into operation at the Omega West Reactor, Los Alamos Scientific Laboratory. The neutron shutter will be used primarily to perform thermal neutron radiography, but is also available for a highly collimated source of thermal neutrons [neutron flux = 3.876 x 10⁶ (neutrons)/(cm².s)]. Neutron collimator sizes of either 10.16 by 10.16 cm or 10.16 by 30.48 cm are available

[en] This report presents neutron flux measurements carried out at the Omega West Reactor. 3 refs., 2 figs., 4 tabs

[en] The first RTNS-II irradiation of the Low Exposure Spectral Experiment has been completed. The dosimetry has been analyzed, and expressions have been determined that fit the data very well. The effects of including the angular variation of the neutron spectrum were investigated

[en] This paper reports on a Level 1 PRA performed on the Omega West Reactor at Los Alamos National Laboratory. A Master Logic Diagram was used to identify possible initiating events. A chi-square distribution was used to quantify initiating event frequencies given that no initiating events have occurred in 30 years of OWR operation. The PRA results are presented as both probability density function and cumulative distribution function curves

[en] An automated delayed neutron counting and instrumental neutron activation analysis system has been developed at Los Alamos National Laboratory's Omega West Reactor (OWR) to analyze samples for uranium and 31 additional elements with a maximum throughput of 400 samples per day

[en] Throughout its fifty year history, Los Alamos National Laboratory has conducted research and development in the production, isolation, purification, and application of radioactive isotopes. Initially this work supported the weapons development mission of the Laboratory. Over the years the work has evolved to support basic and applied research in many diverse fields, including nuclear medicine, biomedical studies, materials science, environmental research and the physical sciences. In the early 1970s people in the Medical Radioisotope Research Program began irradiating targets at the Los Alamos Meson Physics Facility (LAMPF) to investigate the production and recovery of medically important radioisotopes. Since then spallation production using the high intensity beam at LAMPF has become a significant source of many important radioisotopes. Los Alamos posesses other facilities with isotope production capabilities. Examples are the Omega West Reactor (OWR) and the Van de Graaf Ion Beam Facility (IBF). Historically these facilities have had limited availability for radioisotope production, but recent developments portend a significant radioisotope production mission in the future

[en] The Omega West Reactor (OWR) has been operated by the Los Alamos National Laboratory without accident or major operational incident since August, 1956. The OWR is, perhaps, one of the few remaining US reactors that was not built to a set of standards but was designed to the experience base of several reactors that had been operated during the late 1940's and early 1950's. In addition, physics parameters were measured during its lifetime in somewhat unusual but innovative ways. The design approach and physics measurements are summarized in this report