30 Containment systems Dose limits

Batch fermentation is the most widely used method of amino add production. Here the fermentation is a dosed culture system which contains an initial, limited amount of nutrient. After the seed inoculum has been introduced the cells start to grow at the expense of the nutrients that are available. A short adaptation time is usually necessary (lag phase) before cells enter the logarithmic growth phase (exponential phase). Nutrients soon become limited and they enter the stationary phase in which growth has (almost) ceased. In amino add fermentations, production of the amino add normally starts in the early logarithmic phase and continues through the stationary phase. 

To calibrate the cobalt source, three systems are most often used ferrous sulfate, ferrous sulfate-cupric sulfate, and ceric sulfate. Dosimeters of these solutions are prepared by filling 5-ml. chemical-resistant glass ampoules with approximately 5 ml. of solution and flame-sealing the ampoules. The ampoules are then arranged in phantoms of Masonite or similar materials (Figure 13) to simulate the food items. These phantoms are placed in containers similar to those used for food products, and arranged in the conveyor carrier in which they are transported into the irradiation cell. Because of the upper dose limit of the ferrous sulfate and ferrous sulfate-cupric sulfate dosimeters (40,000 and 800,000 rads, respectively), these systems can be used only to establish the dose rate in the facility and not to monitor the total dose during food irradiation. The ceric dosimeter which... 

Exempt Radioactive Wastes. The radioactive waste classification system in the United States does not include a general class of exempt waste (see Table 1.1). Rather, many products and materials that contain small amounts of radionuclides (e.g., specified consumer products, liquid scintillation counters containing 3H and 14C) have been exempted from requirements for use or disposal as radioactive material on a case-by-case basis. The various exemption levels are intended to correspond to low doses to the public, especially compared with dose limits in radiation protection standards for the public or doses due to natural background radiation. However, the exemption levels are not based on a particular dose, and potential doses to the public resulting from use or disposal of the exempt products and materials vary widely. 

Intraperitoneal therapy has also been evaluated as salvage therapy in patients with relapsed and refractory ovarian cancer in many phase I and E clinical trials. Intraperitoneal cisplatin and carboplatin have achieved documented complete responses in relapsed patients initially treated with systemic platimun-containing regimens. In the salvage setting, most of the IP experience has been with cisplatin, either alone or in combination. The primary toxicity associated with IP cisplatin was bone marrow suppression neurotoxicity and nephrotoxicity have also been observed. At doses greater than 125 mg/m , the dose-limiting toxicity of pachtaxel IP is abdominal pain. ... 

If, as the result of leakages in components containing primary coolant, gas-bome radioactivity is released into the reactor building or the reactor auxiliary building, the facility is automatically switched over to the subpressure maintenance system with its activated carbon and aerosol filters. It has to be noted that these action are not necessary in order to meet allowable dose limits, but they are carried out as a matter of precaution due to the principle of minimization. 

The reactor coolant and containment atmosphere sampling systems used for post-accident sampling conditions shall permit sampling of the reactor coolant and containment atmosphere without personnel exceeding their individual dose limits. The systems shall permit analyses for radioactive noble gases, iodine, cesium and nonvolatile isotopes, and also boron and chlorides. 

Even, limited PSAs use and contain much information. This information may come as memos and process reports and flow sheets, equipment layout, system descriptions, toxic inventory, hazardous chemical reactions, test, maintenance and operating descriptions. From this, data and analyses are prepared regarding release quantities, doses, equipment reliability, probability of exposure, and the risk to workers, public, and environment. An executive summary analysis is detailed, and recommendations made for risk reduction. Thus the information will be text, calculations of envelope fracture stresses, temperatures, fire propagation, air dispersion, doses, and failure probabilities - primarily in tabular form. 

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