Dose Consequence Evaluation

Each of these features provides a safety benefit, however not all of these features are necessary to mitigate dose consequences to acceptable levels. Only those features that are relied upon to function or actuate to prevent or mitigate uncontrolled releases of radioactive materials are so identified. Analyses accomplished to evaluate the consequences of release of radiological materials, described in Section 3.4, identify those SSC s that are part of the primary success path in each scenario. The SSC s so identified are associated with a significant mitigation of radiological releases in abnormal and accident scenarios and therefore perform a defense in depth Safety Function. 

These DBA s include those postulated events that pose the greatest risk and therefore bound the HCF operational risk. Failure of the ventilation system filters will be considered as a subset of each DBA by quantifying dose consequences with filtration as well as for a totally unmitigated release. Additionally, an accident from each of the major types of events identified in the hazard tables was selected even if the risk was evaluated to be low. 

Potential doses at the 3000-m. boundary have been evaluated using methodology described in Section 3.4.1. These techniques have been used to calculate the potential dose consequences resulting from the release of the inventory described in Table 3.4-1, under various multiple target scenarios and with various degrees of mitigation. These scenarios and associated probabilities derived in Appendix 3E are summarized in Table 3.4-2. 

The maximum potential dose consequence at the 3000 meter exclusion area boundary of 1.8 Rem for the process spill scenario is well below the evaluation guideline of 25 rem. 

The dose consequence to the public at the 3000 meters is calculated to be 44 mrem, which is well below the evaluation guideline of 25 rem CEDE. Since the 44 mrem dose represents a conservative upper bound on the dose from a radioactive material storage area fire, it can be concluded that all such fires would meet the evaluation guideline. 

In the event that the fan is not operating or the ventilation ducting is decoupled from the fan, there is no mechanism to draw contamination out of the SCBs. Release of hazardous material under these circumstances would occur at a rate determined by diffusion. Evaluations of transport of radionuclides under these conditions indicate that buildup of fission products in Zone 2 of the HCF several hours after the event is less than one microcurie. Transport of these fission products outside the confines of the HCF would be negligible, and dose consequences at 3000 meters would be negligible. 

Since dose to the pubiic from the reiease of the fission products from six in-process tai ets was calcuiated for two DBAs, the consequences for the resuits of multiple simultaneous events that affect multiple SCBs have already been assessed. They are bounded by the maximum potential dose consequences of 1.8 Rem for an unmitigated release. These dose values are lower than the evaluation guidelines (25 rem) so no additional safety-class SSCs or TSRs are identified. 

An evaluation of the confinement functions in the HCF must consider the state of the confinement structures, and the potential flow and/or leakage paths that would result in dose consequences to either on-site or off-site personnel. Two outside evaluations of the seismic performance of HCF SSCs form the basis for this DBE analysis. The first, performed by Walla Engineering Ltd in December 1998, was an evaluation of the east shield wall of Zone 2A. This wall has the greatest potential for failure in a seismic event of ail of the basement concrete structural elements, since it is unrestrained at the top. The second evaluation is a qualitative assessment of several SSCs performed by Chavez-Grieves based on an on-sHe inspection, reported in memorandum format dated May 18,1999. 

Thus, the distinction between the hazard (an inherent toxic property of a chemical that may or may not be manifested, depending on exposure potential) and risk (the consequences of being exposed to a hazardous chemical at a particular exposure level) is critical (Purchase, 2000). Each component of a risk assessment—hazard identification, dose-response evaluation, and exposure assessment—is essential for evaluating the potential risks associated with the use of a substance such as a nanomaterial. The components of a risk assessment are universal in their application for assessing the hazards and risks of chemicals or products for a variety of industries or environmental exposures, regardless of the types of chemicals of interest (such as solvents, fibers, particulates and nanomaterials). 

Potential offsite doses from hypothetical releases are of concern for any plutonium-based reactor facility. Offsite dose consequences may result from release of both fission products and heavy metals, especially uranium and plutonium. To compare differences in offsite dose impacts of 235 j and 239pu fueled reactors without developing specific reactor accident scenarios, simple aerosol releases were assumed. Appendix F presents an evaluation of offsite releases from a plutonium-burning reactor. Equivalent quantities of 235u and 2 Pu were assumed to be released along with the fission products associated with those heavy metals. In both cases the calculated dose impact from all pathways is dominated by the fission products. The total dose consequence from 2 Pu release is less than 1% of the fission product dose. 

MAPPscan is a manual ultrasonic testing system connected to an acoustic positioning system.. The system is developed as a consequence of the increased radiation doses in nuclear plants The system has the same flexibility as manual scanning with the same accuracy and the possibilties to collect, store and evaluate the UT data as with mechanised Ultrasonic systems The positioning system is based on spatial acoustic triangulation and have an accuracy of better than 1.0 mm within its recommended range. 

Despite stmctural similarities, the pharmacological consequences of excesses of these substances are quite different. Due to the interest in the effects of nicotinic acid on atherosclerosis, and in particular its use based on its abiUty to lower semm cholesterol, the toxicity of large doses of nicotinic acid has been evaluated. Eor example, in a study designed to assess its abiUty to lower semm cholesterol, only 28% of the patients remained in the study after receiving a large initial dose of 4 g of nicotinic acid due to intolerance at these large doses (70). 

Filter aids are evaluated in terms of the rate of filtration and clarity of filtrate. Finely dispersed filter aids are capable of producing clear filtrate however, they contribute significantly to the specific resistance of the medium. As such, applications must be made in small doses. Filter aids comprised of coarse particles contribute considerably less specific resistance consequently, a high filtration rate can be achieved with their use. Their disadvantage is that a muddy filtrate is produced. 

Vertex also put in clinical trial VX-765, another caspase-1 -specific, YVAD-derived peptidomimetic that is in vitro slightly more potent then pralnacasan (IC50 0.8 nM). Evaluation of VX-765 in a mouse model of oxazolone-induced dermatitis showed a dose-dependent (10-100 mg/kg) inhibition of ear inflammation. Consequently, VX-765 was enrolled in a 4-week phase Ila safety and pharmacokinetic study for psoriasis. However, Vertex has not communicated any results yet. 

Expert opinion is a source, frequently elicited by survey, that is used to obtain information where no or few data are available. For example, in our experience with a multicountry evaluation of health care resource utilization in atrial fibrillation, very few country-specific published data were available on this subject. Thus the decision-analytic model was supplemented with data from a physician expert panel survey to determine initial management approach (rate control vs. cardioversion) first-, second-, and third-line agents doses and durations of therapy type and frequency of studies that would be performed to initiate and monitor therapy type and frequency of adverse events, by body system and the resources used to manage them place of treatment and adverse consequences of lack of atrial fibrillation control and cost of these consequences, for example, stroke, congestive heart failure. This method may also be used in testing the robustness of the analysis [30]. 

In vivo microdialysis has been used to evaluate the persistent neurochemical consequences of MDMA exposure in rats.88114-116 Series et al.114 carried out microdialysis in rat frontal cortex 2 weeks after a 4-day regimen of 20 mg/kg s.c. MDMA. Prior MDMA exposure did not affect baseline extracellular levels of 5-HT, but decreased levels of the 5-HT metabolite, 5-hydroxyin-doleacetic acid (5-HIAA), to 30% of control. Moreover, the ability of (+)-fenfluramine to evoke 5-HT release was markedly blunted in MDMA-pretreated rats. In an analogous investigation, Shankaran and Gudelsky115 assessed neurochemical effects of acute MDMA challenge in rats that had previously received 4 doses of 10 mg/kg i.p. MDMA. A week after MDMA pretreatment, baseline levels of dialysate 5-HT and DA in striatum were not altered even though tissue levels of 5-HT were depleted by 50%. The ability of MDMA to evoke 5-HT release was severely impaired in MDMA-pretreated rats while the concurrent DA response was normal. In this same study, effects... 

Decision Analysis. An alternative to making assumptions that select single estimates and suppress uncertainties is to use decision analysis methods, which make the uncertainties explicit in risk assessment and risk evaluation. Judgmental probabilities can be used to characterize uncertainties in the dose response relationship, the extent of human exposure, and the economic costs associated with control policies. Decision analysis provides a conceptual framework to separate the questions of information, what will happen as a consequence of control policy choice, from value judgments on how much conservatism is appropriate in decisions involving human health. 

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