Special studies

Two studies resolved the Unresolved Safety Issue A-44, Station Blackout. The first siudy, The Reliability of Emergency AC Power Systems in Nuclear Power Plants, when combined uh die lelevant loss-oToffsite-power frequency, provides estimates of station-blackout frequencies lor 18 nuclear power plants and 10 generic designs. The study also identified the design and operational features most important to the reliability of AC power systems. The second study, Station Blackout Accident Analysis (NUREG/CR-3226), focused on the relative importance to risk of laiion blackout events and the plant design and operational features that would reduce this risk. 

3 Precursors to Potential Severe Core-Damage Accidents 

This study (NUREG/CR-2497) applies PSA techniques using operating experience to identify the high-risk features of plant design and operation. The operating experience base is derived from die licensee event repoits (LERs) to find multiple events that, when coupled with postulated events, lead to plant conditions that could eventually result in severe core damage. 

In the first 2.5 years of the precursor study, 169 significant precursors were identified for ihe 4. i2 reactor-years of operating experience represented by LERs submitted from 1969 to 1979. preliminary findings show 56 precursors for 126 reactor-years of operating experience for 1980-1981. The results were used to analyze accident sequences to estimate core melt frequencies lor operating plants and to compare these results with the estimates in existing PSAs. 

The high risk POSs R6, RIO, and D6 have different decay heats and plant configurations  

Groups of 10 male and 10 female B6C3F1 mice were exposed to sodium chlorate at concentrations of 0, 0.125, 0.25, 0.50,1.0 or 2.0 g/l in the drinking-water for 21 days. The average doses were equivalent to 0, 20, 45, 90,175 and 350 mg/ kg bw per day for males and 0, 20, 45, 95, 190 and 365 mg/kg bw per day for females. All mice survived the duration of the study, and mean body weights and water consumption were similar between test and control groups. No treatment- 

Female B6C3F1 mice (six per group) were administered sodium chlorate at concentrations of 0, 0.5,1.0,2.0, 4.0 and 6.0 g/l in the drinking-water for 105 days, equivalent to about 0, 50, 100, 200, 400 and 600 mg/kg bw per day expressed as chlorate. There were no effects on thyroid histology, but no other details were provided (Hooth et al., 2001). 

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C. W. Hardy and co-workers. Committee on Technology—Special Study Team on Refractories, Refractory Materials for Steelmaking International Iron and Steel Institute, Bmssels, Belgium, 1985. 

Apart from the general study by Wait and Wesley on azanaphthalenes, including most of the pyridopyridazines (66JSP(19)25), more specialized studies have attempted to relate charge density calculations to various chemical and physical properties, with greater success in the latter case. 

Example The combustion process in large vapor clouds is not known completely and studies are in progress to improve understanding of this important subject. Special study is usually needed to assess the hazard of a large vapor release or to investigate a UVCE. The TNT equivalent method is used in this example other methods have been proposed. Whatever the method used for dispersion and pressure development, a check should be made to determine if any govern-mentaf unit requires a specific type of analysis. 

A long evolving use of PSA was for Anticipated Transients without Scram (ATWS) which extended over 15 years to culminate in NUREG-0460 which was upset by the Salem failure-to-scram incident and the subsequent SECY Letter 83-28. Other special studies have been (a) value-impact analysis (VIA.) studies of alternative containment concepts (e.g., vented containment, NUREG/CR-0165), (b) auxiliary feedwater studies, (c) analysis of DC power requirements, (d) station blackout (NUREG/CR-3220), and (e) precursors to potential core-damage accident.s (NUREG/CR-2497), to name a few of the NRC sponsored studies. 

Raymond-Hamet has made a special study of the vascular action of the harmala alkaloids and certain of their proximate derivatives, including their influence on the pressor and other effects of adrenaline in comparison with that of yobyrine and ketoyobyrine (pp. 505-6). 

The mechanism of the decarboxylation of isoxazole-3-car boxy lie acids has not yet been specially studied, but the available experimental evidence allows some suggestions to be made. It seems that on heating isoxazole carboxylic acids in solution, or in the presence of arylhydrazines, it is the acid anion (158) formed which is being de-... 

A special study [74] was commissioned by the American Petroleum Institute (API) entitled Mitigation of Explosion Hazards of Marine Vapor Control Systems. The report examines the effects of deflagradons and detonations in pipes in the region of detonation flame arrestors. The primary objective was to resolve potential... 

Crossley, H. E., External Boiler Deposits, Inst, of Fuel Special Study of the Ash and Clinker Industry, Paper No. 4 (1952)... 

Three of the rhodium(I) carbonyl complexes are particularly important and are selected for special study. 

Various other interactions have been considered as the driving force for spin-state transitions such as the Jahn-Teller coupling between the d electrons and a local distortion [73], the coupling between the metal ion and an intramolecular distortion [74, 75, 76] or the coupling between the d electrons and the lattice strain [77, 78]. At present, based on the available experimental evidence, the contribution of these interactions cannot be definitely assessed. Moreover, all these models are mathematically rather ambitious and do not show the intuitively simple structure inherent in the effect of a variation of molecular volume considered here. Their discussion has to be deferred to a more specialized study. 

Nevertheless, such special study protocols should be discussed with those regulatory authorities which are involved in the national registration and/or EU evaluation in advance. 

Monsanto. 1978. TSCA sect. 8(d) submission 40-7859047. A study of variables effecting the river die-away test. Special study 1978. Washington, D.C. Office of Toxic Substances, U.S. Environmental Protection Agency. EPA Doc Control No. OTS 84003A... 

An excellent review of various catalyst preparation methods has been published,1 and an earlier book devoted to patent literature preparations of hydrogenation catalysts is available.2 Special studies of the formation of metal nanoclusters appeared in 1997 and 1998.3-5 What follows is a general summary of methods of preparation. 

In specialized studies, chemical measurements achieve particular importance by their temporal and spatial resolution. In process control, the momentary value is interesting only in such exceptional situations in which a warning or control limit is passed. Much more information is contained in the time function of an analytical system, y = f(t), or y = f(z, t), in case of multicomponent systems as shown in Fig. 3.11. 

Proton and 13C NMR spectroscopy have been widely used to elucidate the structures of compounds discussed in this chapter. 1SN NMR investigations have been reported for some hetero tricyclic derivatives <2003JA10288>. Several more specialized studies are mentioned below. 

Banks, PM. Technical aspects of specimen preparation and special studies. In Surgical Pathology of the Lymph Nodes and Related Organs, ed. ES Jaffe, pp. 1-21. Philadelphia W. B. Saunders, 1985. 

A very serious problem was to clear up the formation of hydroperoxides as the primary product of the oxidation of a linear aliphatic hydrocarbon. Paraffins can be oxidized by dioxygen at an elevated temperature (more than 400 K). In addition, the formed secondary hydroperoxides are easily decomposed. As a result, the products of hydroperoxide decomposition are formed at low conversion of hydrocarbon. The question of the role of hydroperoxide among the products of hydrocarbon oxidation has been specially studied on the basis of decane oxidation [82]. The kinetics of the formation of hydroperoxide and other products of oxidation in oxidized decane at 413 K was studied. In addition, the kinetics of hydroperoxide decomposition in the oxidized decane was also studied. The comparison of the rates of hydroperoxide decomposition and formation other products (alcohol, ketones, and acids) proved that practically all these products were formed due to hydroperoxide decomposition. Small amounts of alcohols and ketones were found to be formed in parallel with ROOH. Their formation was explained on the basis of the disproportionation of peroxide radicals in parallel with the reaction R02 + RH. 

In studies of alkyl- or silyl nitronates, the problem of comparison of covalent and ionic stmctures is not urgent because it is impossible to imagine a stable product containing alkyl- or trialkylsilyl cations. However, this is not so evident for other elementorganic nitronates, and special studies were required to solve these questions (see, e.g., Ref. 232). 

In special studies, several procedures were developed (465-468) for the one-pot synthesis of the corresponding BENA in good yields from the overwhelming majority of various AN, the amounts of impurities being minimum (Table 3.18). 

The reactions of amines with BENAs were discussed in several publications (464, 499, 521-523). Although there are no special studies on the reaction mechanism, the available data combined with the results in Reference 502 suggest a mechanistic model for this process (Scheme 3.243). 

The most accepted among the qualitative theories of mass spectral fragmentation are the conception of charge and unpaired electron localization and the estimation of ions and neutral particles stability. Despite their qualitative character these approaches are quite useful to work with mass spectra. Both theories use the principle of the minimal structural changes at each stage of fragmentation, while the structure of the molecular ion is considered to be the same as that of the initial molecule. Certain isomerization processes of M+ before the fragmentation are usually a matter of special study. 

It is important to emphasize that stereochemical aspects in mass spectrometry are a matter of special studies. Those who are interested in this field should read Green [18], Mandelbaum [19, 20], and Splitter and Turecek [21]. 

Both qualitative and quantitative evaluation techniques may be used to consider the risk associated with a facility. The level and magnitude of these reviews should be commensurate with the risk that the facility represents. High value, critical facilities or employee vulnerability may warrant high review levels. While unmanned "off-the-shelf, low hazard facilities may suffice with only a checklist review. Specialized studies are performed when in-depth analysis is needed to determine the cost benefit of a safety feature or to fully demonstrate the intended safety feature has the capability to fully meet prescribed safety requirements. 

Specialized studies are investigations that attempt to verify the ability of a facility to perform effectively during an emergency, generally by mathematical estimates. They are used extensively to justify the necessity or deletion of a safety system. The most common studies are listed below however every facility is unique and may require it s own investigative requirements (e g., for an offshore facility - the potential for ship collisions). For example, for a simple unmanned wellhead... 

Additional specialized studies are sometimes specified for offshore facilities. These may include the following, depending on the type of facility under review ... 

Category Duration of human administration3 Phase 3 Subacute or chronic toxicity0 Special studies... 

Additionally, there are specialized studies designed to address endpoints of concern for almost all drugs (carcinogenicity, reproductive or developmental toxicity) or concerns specific to a compound or family of compounds (local irritation, neurotoxicity, or immunotoxicity, for example). When these are done, timing also requires careful consideration. It must always be kept in mind that the intention is to ensure the safety of people in whom the drug is to be evaluated (clinical trials) or used therapeutically. An understanding of special concerns for both populations should be considered essential. 

Category Duration of Human Administration Clinical Phase Subacute or Chronic Toxicity Special Studies... 

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