Reactor inventory

Reduction of reactor inventory by increasing temperature or pressure, by changing catalyst, or by better mixing... 

The reaction terms are evaluated at the outlet conditions since the entire reactor inventory is at these conditions. The set of component balances can be summarized as... 

Case B. Suppose, more realistically, that the catalyst undergoes a known, experimentally determined, rate of attrition as a function of particle size (Zenz, 1971 Zenz Kelleher, 1980). The particle loss rate from the cyclone system will now approach and finally equal the rate of production of 0 to 10 micron particles by attrition from all the larger sizes. To maintain reactor inventory, this loss rate will be replaced, at an equal rate, with fresh catalyst. Since the rate of attrition of any size particle depends on its concentration in the stream subjected to the attrition (as finer particles effectively cushion the coarser), and since the loss is replaced with fresh catalyst (containing the coarsest), the bed size distribution will reach a steady state between 10 and 150 microns in which the mean size, as well as all sizes smaller than the largest, will now be decreased from what would have prevailed under conditions of zero attrition. 

Radiochemical analysis of meta-studtite from an SNF test indicated that 237Np was associated with the U6+ peroxide (Table 3). Plutonium, Cm, and Am were found to be in lower concentration in the secondary U phases however, 5-6% of the available Pu and Am, based on reactor code estimates, was co-precipitated with the U phase. The radiochemical data for the collected alteration products from the SNF samples (Table 3) are presented as pg-analyte per g U for comparison to the reactor inventory code calculation for 30MW/d burn-up fuel at 20 y (extracted from Guenther et al. 1988). 

NV = Noi valid, fuel age no lakcn into account in reactor inventory code results. 

Nuclide Reactor inventory Stack filter(6) Environmental filters ... 

Nuclide Reactor inventory (EBq) to coolant or containment to atmosphere Activity to atmosphere (TBq)... 

Nuclide Reactor inventory (PBq) Release (PBq) Percentage release Release relative to 137Cs... 

The release of 131I and other fission products in reactor accidents has been considered in the previous chapter. In the Windscale accident, the temperature in the fire zone reached an estimated 1300°C and 8 tonne of uranium metal melted. Over 25% of the 1311 in the melted fuel escaped to atmosphere. In the Chernobyl accident, the fuel was U02, the temperature exceeded 2000°C, and about 25% of the total reactor inventory of 131I was released to atmosphere, as vapour or particulate aerosol. In the Three Mile Island accident, 131I remained almost completely in the reactor coolant. The activities of 131I released in reactor accidents, including that at Chernobyl, have totalled much less than the activities released from weapons tests (Table 2.3). 

The characterization of petroleum cracking catalysts, with which a third of the world s crude oil is processed, presents a formidable analytical challenge. The catalyst particles are in the form of microspheres of 60-70 micron average diameter which are themselves composites of up to five different micron and submicron sized phases. In refinery operation the catalysts are poisoned by trace concentrations of nickel, vanadium and other contaminant metals. Due to the replacement of a small portion of equilibrium catalyst each day (generally around 1% of the total reactor inventory) the catalyst particles in a reactor exist as a mixture of differing particle ages, poisoning levels and activities. 

Considering that aluminum trichloride is a very important commercial catalyst wifli over 25,000 tonnes produced annually in the USA alone, such hquids containing aluminum trichloride and allowing for differing levels of acidity have been extensively studied as first generation ionic catalytic solvents in a wide variety of synthetic and catalytic processes. Ionic liquids could therefore be used as substitutes for conventional solid or suspended sources of aluminum(III) chloride. As liquid phase catalysts, they allow for tremendous control of reactor inventories and can be cleaned and recycled with ease. Therefore, ionic liquids, in ideal cases, have no waste associated with them, whereas the supported alumi-num(III) chloride catalysts will require large (and annually rising) waste disposal costs. 

Reactivity Total Ih-reactor inventory very sensitive. Difficult for Inspector to verify Independently sup- plementary measurements required some fuel handling required., i ... 

QOmXimKSEB OP HELBASB OP H8SI0H PRODUCTS 9.1 The Reactor Inventory of Plgelon Paroducta... 

The reactor Inventory of fission products has been estimated from data... 

It should not be assumed that the total reactor Inventory of fission products will be available for release to environs It has been calculated... 

The control of inventory of main comjjonents and impurities are interrelated with the design of reactors and separators. For the main components the reactor inventory and the make-up policy plays the most important role. In handling the inventory of impurities the design of separators and the interactions through recycles are determinant. Snowball effects are possible if the positive feedback is not compensated. Chemical conversion of impurities in benign material is an efficient method to avoid their accumulation in recycles. 

A Phillips high-density polyethylene (HDPE) plant suffered a maintenance error that led to total loss of reactor inventory, causing a vapor cloud explosion resulting in 23 fatalities and 130 injuries. Loss estimated at 1.4billion. See Figure 6.2. 

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