A method for producing a grain oriented electrical steel sheet includes a decarburization annealing process where an oxidation degree PH.sub.2O/PH.sub.2 is controlled, an annealing separator applying process where a mass ratio of MgO and MCl in an annealing separator is controlled, a final annealing process where an oxidation degree is controlled when atmosphere includes hydrogen or a dew point is controlled when atmosphere consists of inert gas, and an insulation coating forming process where a mass ratio of phosphoric acid and metal compound in insulation coating forming solution is controlled.

A method for producing a grain oriented electrical steel sheet includes a decarburization annealing process where an oxidation degree PH.sub.2O/PH.sub.2 is controlled, an annealing separator applying process where a mass ratio of MgO and Al.sub.2O.sub.3 in an annealing separator is controlled, a final annealing process where hydrogen in mixed gas atmosphere is controlled to 50 volume % or more, an annealing separator removing process where water-washing is conducted using solution with inhibitor and then pickling is conducted, a smoothing process where mixed gas and temperature are controlled for annealing, and an insulation coating forming process where a baking temperature and a heat treatment temperature are controlled.

A method for producing a grain oriented electrical steel sheet includes a decarburization annealing process where an oxidation degree PH.sub.2O/PH.sub.2 is controlled, an annealing separator applying process where a mass ratio of MgO and Al.sub.2O.sub.3 in an annealing separator is controlled, a final annealing process where hydrogen in mixed gas atmosphere is controlled to 50 volume % or more, an annealing separator removing process where water-washing is conducted using solution with inhibitor, a smoothing process where chemical-polished is conducted to control average roughness Ra, and an insulation coating forming process where insulation coating forming solution in which crystalline phosphide is included is applied.

A grain oriented electrical steel sheet includes a base steel sheet, an oxide layer, and a tension-insulation coating. When the iron oxide layer is analyzed by a fourier transform infrared spectroscopy, an absorbance A.sub.650 at 650 cm.sup.−1 and an absorbance A.sub.1250 at 1250 cm.sup.−1 satisfy 0.2≤A.sub.650/A.sub.1250≤5.0. Moreover, a magnetic flux density B8 in a rolling direction of the grain oriented electrical steel sheet is 1.90 T or more.

Provided is a grain-oriented electrical steel sheet including a base steel sheet, an intermediate layer which is disposed in contact with the base steel sheet and mainly includes silicon oxide, and an insulation coating which is disposed in contact with the intermediate layer and mainly includes phosphate and colloidal silica, in which the base steel sheet contains predetermined chemical composition, BN having an average particle size of 50 to 300 nm is present, when an emission intensity of B is measured using glow discharge emission analysis, predetermined conditions are satisfied, and a ratio of a major axis to a minor axis of BN is 1.5 or less.

The grain-oriented electrical steel sheet according to the present embodiment is a grain-oriented electrical steel sheet having a base steel sheet (1), an intermediate layer (4) disposed to be in contact with the base steel sheet (1), and an insulation coating (3) disposed to be in contact with the intermediate layer (4). The grain-oriented electrical steel sheet according to the present embodiment includes a surface of the base steel sheet (1) having a strain region (D) which extends in a direction intersecting a rolling direction of the base steel sheet (1), and a crystalline phosphorus oxide M.sub.2P.sub.4O.sub.13 present in the insulation coating (3) on the strain region (D) in a cross-sectional view of a surface parallel to the rolling direction and a sheet thickness direction of the base steel sheet (1). (M means at least one or both of Fe and Cr.)

A method for producing a grain oriented electrical steel sheet includes a decarburization annealing process where an oxidation degree PH.sub.2O/PH.sub.2 is controlled, a final annealing process where hydrogen in mixed gas atmosphere is controlled to 50 volume % or more, an annealing separator removing process where water-washing is conducted using solution with inhibitor, a smoothing process where mixed gas and temperature are controlled for annealing, and an insulation coating forming process where a baking temperature and a heat treatment temperature are controlled.

A grain-oriented electrical steel sheet is a grain-oriented electrical steel sheet which does not have an inorganic coating containing forsterite as a main component and which includes: a base steel sheet containing a prescribed chemical component; a silicon-containing oxide layer provided on the base steel sheet; an iron-based oxide layer provided on the silicon-containing oxide layer; and a tension-insulation coating provided on the iron-based oxide layer, having a thickness of 1 to 3 μm, and containing phosphate and colloidal silica as main components. When the tension-insulation coating undergoes elemental analysis using a glow discharge optical emission spectrometry in a sheet thickness direction from a surface of the tension-insulation coating, a peak Si emission intensity satisfies a prescribed requirement.

This grain-oriented electrical steel sheet includes a base steel sheet, an intermediate layer that is formed on a surface of the base steel sheet and mainly contains silicon oxide, and an insulation coating that is formed on the surface of the intermediate layer. A number density of the oxide particles in a region from the surface of the base steel sheet to a depth of 10 μm toward an inside of the base steel sheet is 0.020 oxide particles/μm.sup.2 or less. In the grain-oriented electrical steel sheet, an area rate of an intermediate layer-remaining region n which the intermediate layer does not peel off but remains in a region in which the insulation coating peels off after a bend test performed using a mandrel according to JIS K 5600-5-1 (1999) is 20% or more.

A method of preserving a nuclear fuel includes exposing a surface of a fuel element comprising aluminum to a phosphorus-containing acid and reacting the phosphorus-containing acid with the aluminum to form aluminum phosphate (AlPO.sub.4). A nuclear fuel element includes a nuclear fuel and a shell surrounding the nuclear fuel. The shell comprises aluminum phosphate.