Boronic solubility

The annular complexer was modeled exactly except that the conical (bottom) section was represented by a series of cylindrical increments. This vessel was not critically safe by geometry. Boron soluble poison was required in the fuel solution to maintain keff < 0.95 for concentrations of above 80 g/C. Satisfactory experience with soluble poisons has been demonstrated. ... 

A number of tritium production processes add tritium to the reactor coolant. Fission product formation in the fuel (ternary fission) forms tritium that can diffuse through the fuel clad or leak through fuel clad defects. Also, neutron reactions with soluble boron, soluble lithium, and deuterium in the reactor coolant result in tritium. Tritium emits beta radiation and presents no hazard during power operation. 

No soluble boron Soluble boron-free core Boron dilution accident (BDA) Physically eliminates BDA... 

Quantitative metallography, XPD and magnetie measurements served to determine the boron solubility in FesC as well as the influenee on the magnetie properties of FesC. 

Guo] determined flie boron solubility in metal matrix of alloys contained about 12 mass% Cr, 1.4 mass% B, some other elements and Fe to balance as 0.185 to 0.515 mass% in as-cast martensite and 0.015 to 0.059 mass% after the 750°C tempering. According to [2001Cal] the indicated shifts in the phonon frequencies and identification of additional vibration modes of the melted Fe-8Cr-0.095B (mass%) alloy are the evidences for the interstitial nature of boron soluble in flie alloy. 

Guo] Guo, C., Kelly, P.M., Boron Solubility in Fe-Cr-B Cast Irons , Mater. Sci. Eng. A, A352, 40-45 (2003) (Crys. Stmcture, Morphology, Experimental, 8)... 

Boron trioxide is not particularly soluble in water but it slowly dissolves to form both dioxo(HB02)(meta) and trioxo(H3B03) (ortho) boric acids. It is a dimorphous oxide and exists as either a glassy or a crystalline solid. Boron trioxide is an acidic oxide and combines with metal oxides and hydroxides to form borates, some of which have characteristic colours—a fact utilised in analysis as the "borax bead test , cf alumina p. 150. Boric acid. H3BO3. properly called trioxoboric acid, may be prepared by adding excess hydrochloric or sulphuric acid to a hot saturated solution of borax, sodium heptaoxotetraborate, Na2B407, when the only moderately soluble boric acid separates as white flaky crystals on cooling. Boric acid is a very weak monobasic acid it is, in fact, a Lewis acid since its acidity is due to an initial acceptance of a lone pair of electrons from water rather than direct proton donation as in the case of Lowry-Bronsted acids, i.e. 

The solid appears to be a mixture of the complexes CH,COOH.BF, and 2CH COOH.BF,. The latter appears to be a liquid and is alone soluble in ethylene dichloride the former is a solid. The solid moiioocetic acid complex is obtained by saturating an ethylene dichloride solution of acetic acid with boron trifluoride, filtering and washing the precipitate with the solvent it is hygroscopic and should be protected from moisture. It may be used as required 0-75 mol is employed with 0-26 mol of ketone and 0 6 mol of anhydride. 

With sodium hydroxide as the base boron of the alkylborane is converted to the water soluble and easily removed sodium salt of boric acid... 

Aqueous mineral acids react with BF to yield the hydrates of BF or the hydroxyfluoroboric acids, fluoroboric acid, or boric acid. Solution in aqueous alkali gives the soluble salts of the hydroxyfluoroboric acids, fluoroboric acids, or boric acid. Boron trifluoride, slightly soluble in many organic solvents including saturated hydrocarbons (qv), halogenated hydrocarbons, and aromatic compounds, easily polymerizes unsaturated compounds such as butylenes (qv), styrene (qv), or vinyl esters, as well as easily cleaved cycHc molecules such as tetrahydrofuran (see Furan derivatives). Other molecules containing electron-donating atoms such as O, S, N, P, etc, eg, alcohols, acids, amines, phosphines, and ethers, may dissolve BF to produce soluble adducts. 

In addition, boron trifluoride and some of its adducts have widespread appflcation as curing agents for epoxy resins (qv), and in preparing alcohol-soluble phenoflc resins (qv) (41). 

Lead borate moaohydrate [14720-53-7] (lead metaborate), Pb(B02)2 H20, mol wt 310.82, d = 5.6g/cm (anhydrous) is a white crystalline powder. The metaborate loses water of crystallization at 160°C and melts at 500°C. It is iasoluble ia water and alkaHes, but readily soluble ia nitric and hot acetic acid. Lead metaborate may be produced by a fusion of boric acid with lead carbonate or litharge. It also may be formed as a precipitate when a concentrated solution of lead nitrate is mixed with an excess of borax. The oxides of lead and boron are miscible and form clear lead-borate glasses in the range of 21 to 73 mol % PbO. 

The second control mechanism is the soluble reactor poison boric acid [10043-35-3] Natural boron contains 20% boron-10 [14798-12-0] ... 

The third control is by use of a fixed burnable poison. This consists of rods containing a mixture of aluminum oxide and boron carbide, included in the initial fuel loading using the vacant spaces in some of the fuel assembhes that do not have control clusters. The burnable poison is consumed during operation, causing a reactivity increase that helps counteract the drop owing to fuel consumption. It also reduces the need for excessive initial soluble boron. Other reactors use gadolinium as burnable poison, sometimes mixed with the fuel. 

Control of the core is affected by movable control rods which contain neutron absorbers soluble neutron absorbers ia the coolant, called chemical shim fixed burnable neutron absorbers and the intrinsic feature of negative reactivity coefficients. Gross changes ia fission reaction rates, as well as start-up and shutdown of the fission reactions, are effected by the control rods. In a typical PWR, ca 90 control rods are used. These, iaserted from the top of the core, contain strong neutron absorbers such as boron, cadmium, or hafnium, and are made up of a cadmium—iadium—silver alloy, clad ia stainless steel. The movement of the control rods is governed remotely by an operator ia the control room. Safety circuitry automatically iaserts the rods ia the event of an abnormal power or reactivity transient. 

Unlike boron, aluminum, gallium, and indium, thallium exists in both stable univalent (thaHous) and trivalent (thaUic) forms. There are numerous thaHous compounds, which are usually more stable than the corresponding thaUic compounds. The thaUium(I) ion resembles the alkaU metal ions and the silver ion in properties. In this respect, it forms a soluble, strongly basic hydroxide and a soluble carbonate, oxide, and cyanide like the alkaU metal ions. However, like the silver ion, it forms a very soluble fluoride, but the other haUdes are insoluble. Thallium (ITT) ion resembles aluminum, gallium, and indium ions in properties. 

Crystalline boron is very inert. Low purity, higher temperatures, and changes in or lack of crystallinity all increase the chemical reactivity. Hot concentrated H2SO4—HNO at 2 1 ratio can be used to dissolve boron for chemical analysis but boron is not soluble in boiling HE or HCl. Boron is also unreactive toward concentrated NaOH up to 500°C. At room temperature, boron reacts with E2, but only superficially with O2. 

---