An apparatus and method that allows a conventional trimmer of the type with flying cutting string or any other type blade to maintain a controllable height above the cutting plane and to swivel 360 degrees. Preferably, fixed information is stored depending on presenceabsence of an impurity diffusion layer formed in a surface portion of the semiconductor substrate directly under the tunnel insulating film, semi-fixed information is stored depending on an amount of charges in the charge storage layers, and charges opposite to the charges are induced in the surface portion. A plurality of auxiliary vibration-resistant grids respectively positioned between the main support grids in the middle third elongated dimension of the fuel elements, that are smaller in height and provide a larger fuel element contact area than the main support grids.