[en] The computerized emergency response dose assessment codes (ERDACs) used in the nuclear industry commonly rely on Gaussian plume dispersion techniques. In coastal zones, particularly within 15 km of the shoreline, complex four-dimensional mesoscale meteorological regimes often violate some of the basic assumptions of Gaussian dispersion. For example a land breeze will initially advect materials offshore into unpopulated areas. Such effluents may pool over water only to return to land in the next morning's onshore flow, but in locations and concentrations unknown and undeterminable from on-site data and standard Gaussian modeling techniques. Improving the performance of ERDACs for a given coastal site requires a climatographic inventory of that site and its surroundings. This involves identifying the coastal mesoscale regimes (CMRs) that affect the site, including their annual frequencies of occurrence and the meteorological conditions that characterize them. Such a climatographic analysis has been performed for the Zion nuclear power station (NPS), which is located just north of Chicago, Illinois, on the western shore of southern Lake Michigan. The purpose of this papers is to summarize the results of this study and its implications for radiological emergency response activities. A conceptual framework for allocating resources in developing an adequate emergency response system includes three major factors: (1) frequency of the mesoscale regimes; (2) extent to which the regime can result in high concentrations/doses; (3) ease with which it can be modeled, with due consideration given for input data requirements

[en] The accident at Three Mile Island Unit 2 (TMI-2) created circumstances that have seldom been encountered in the nuclear industry. These circumstances involved high radiation and contamination conditions in areas to which emergency access was required to maintain reactor control. The radiological conditions in the auxiliary building immediately following the accident, how those conditions varied from one location to another, and how they varied with time during the first 6 to 8 months required to return to some degree of normalcy are reviewed. The controls and methods used to maintain radiological exposures as low as reasonably achievable (ALARA) while the necessary work was completed, as well as the circumstances that led to non-ALARA exposures, are also described

[en] Instrumentation for near-real-time analysis of tritium is being developed for ambient air sampling. The technique involves separation of molecular hydrogen gas from air, dissociation of the molecules, resonance ionization of the resulting hydrogen atoms, and detection by mass spectrometry. The goal is to provide a rapid analysis of extremely small concentrations and to have complete discrimination between hydrogen, deuterium, and tritium isotopes over a very wide range of relative abundances. Applications include environmental monitoring of ambient air around reactors and other nuclear facilities

[en] The lethal effects of radiation on microorganisms was noted soon after the discovery of X rays in 1895. In 1904, it was shown that vegetative bacteria are more sensitive than spores; however, no industrial applications could be made as the radiation sources were too expensive. In the mid-1950s, it became economical and practical to sterilize medical products, and ever since sterilization has been a growing industry. Radiation sterilization technology has made possible users of new materials, such as plastics. Food irradiation is about to take off. Just as there was a resistance to pasteurization of milk when it was first introduced, there will be resistance to radpasteurization. Irradiated foods have been proven safe beyond reasonable doubt. Safety has been established through two independent methods: (1) through the most extensive multigeneration animal feeding studies ever carried out, and (2) by analyzing the radiolytic products formed and the chemical changes that take place when food is irradiated. The possible toxicity of these products has been evaluated by an independent group of toxicologists, who based their evaluation on the results of exposure of these products in large quantities either to humans or to animals

[en] Severe nuclear plant accidents can involve the degradation of the reactor core while the primary coolant system remains pressurized. Molten fuel reaching the lower head of the reactor pressure vessel (RPV) may attack and fail the instrument guide tube penetrations, allowing the tube to be expelled from the vessel. The resulting aperture allows the molten fuel to be ejected into the cavity, followed by the blowdown of the contents of the primary system (high-pressure-melt ejection). Entrainment of the core debris in the cavity by the blowdown gases may cause high-temperature fuel particles to be carried into the containment building. Energy exchange between the particles and the atmosphere may cause heating and pressurizing of the containment [direct containment heating (DCH)]. The complex phenomena associated with direct containment heating accident sequences are not well understood. This work describes a series of four experiments that have been performed to study and quantify the processes involved. The data from the experiments are used to guide the development of computer models to describe the response of containments under accident conditions

[en] This paper describes the initial design work to develop the reactor systems hardware concepts for the advanced neutron source (ANS) reactor. This project has not yet entered the conceptual design phase; thus, design efforts are quite preliminary. This paper presents the collective work of members of the Oak Ridge National Laboratory, Martin Marietta Energy Systems, Inc., Engineering Division, and other participating organizations. The primary purpose of this effort is to show that the ANS reactor concept is realistic from a hardware standpoint and to show that project objectives can be met. It also serves to generate physical models for use in neutronic and thermal-hydraulic core design efforts and defines the constraints and objectives for the design. Finally, this effort will develop the criteria for use in the conceptual design of the reactor

[en] Mixed waste is waste containing radionuclides regulated by the US Nuclear Regulatory Commission (NRC) under the Atomic Energy Act, as well as hazardous waste materials regulated by the Environmental Protection Agency (EPA) under the Resource Conservation and Recovery Act (RCRA). This has led to a situation of dual regulation in which both NRC and EPA regulate the same waste under requirements that at times appear conflicting. The NRC has been working with the EPA to resolve the issues associated with the dual regulation of mixed waste. Discussions between the two agencies indicate that dual regulation of mixed wastes appears technically achievable, although the procedures may be complex and burdensome to the regulated community. The staffs of both agencies have been coordinating their efforts to minimize the burden of dual regulation on state agencies and the industry. Three major issues were identified as sources of potential regulatory conflict: (a) definition and identification of mixed waste, (b) siting guidelines for disposal facilities, and (c) design concepts for disposal units

[en] US Ecology is the state of California's designee to site, develop, and operate a low-level radioactive waste disposal facility. The facility will meet the state's responsibilities under the Low-Level Radioactive Waste Policy Act as amended. By January 1988, US Ecology narrowed its efforts to two candidate sites. Strong local community support has been expressed for both sites. US Ecology will select a single proposed site for licensing in 1988 and anticipates receiving waste in late 1900 or early 1991. This schedule places California well ahead of the milestones identified in federal law. The success to date in California can be attributed in large part to the open process used to involve citizens' advisory committees (CACs) and the general public at critical stages of the projects

[en] Recorded process data from minirun campaigns conducted at the Barnwell Nuclear Fuels Plant have been utilized to study the suitability of computer-based artificial intelligence (AI) methods for process monitoring for safeguards purposes. The techniques of knowledge engineering were used to formulate the decision-making software. The computer software accepted as input process data customarily used for process operations that had previously been recorded on magnetic tape during the 1980 miniruns. The OPS5 AI language was used to construct an expert system for simulated monitoring of the process. Such expert systems facilitate the employment of the heuristic reasoning used by human observers to form reasoned conclusions from incomplete, inaccurate, or otherwise fuzzy data

[en] The safeguards world has focused on the technical aspects of accounting for nuclear materials, developing sophisticated measuring devices, analytical methods, standards programs, and statistical models for use by the operating facilities. These devices and techniques should permit facility manages to know and state the plant nuclear material inventory with a high degree of certainty. However, experience at the Hanford Purex plant has shown this is not always the case. It has been a challenge to overcome the personnel-related problems on a near-term basis and to ensure reliable, long-term performance in accounting for the plant's nuclear materials. It was determined that the primary problem was one of attitude, and it was prevalent in all levels of personnel in the plant. The prescription developed at Purex contained the following ingredients: commitment, training, resources, and follow up. These elements have been built into the accountability system for Purex and the results look very promising. A significant improvement in attitude is evident, and problems related to accountability have been reduced