Nuclear gauge

A nuclear gauge for making measurements of traveling webs in continuous sheet-making systems, comprising:

• an enclosure means formed from a material having a high atomic number;
• a cylindrical cavity formed in the enclosure means;
• an aperture which is formed through the enclosure means in a direction that intersects the cylindrical cavity;
• a wheel-like member rotatably mounted in the cavity;
• an encapsulated nuclear source which is mounted to be carried by the wheel-like member;
• and
• rotating means for rotating the wheel-like member from a second position whereat the encapsulated nuclear source is positioned to face a the wall of the enclosure to a first position whereat the nuclear source can emit radiation directly through the aperture onto a web that travels past the aperture;
• the sidewall at the second position including a plug which is formed from a material having a low atomic number for safely receiving radiation from the nuclear source at the second position.

A nuclear gauge for making measurements of traveling webs in continuous sheet-making processes, comprising:

• an enclosure means formed from a material having a relatively high atomic number;
• an encapsulated nuclear source;
• and
• rotatable means mounted in the enclosure means for carrying the encapsulated nuclear source between two angularly-displaced positions;
• wherein the two angularly-displaced positions comprise a first position whereat the encapsulated nuclear source is positioned for making measurements of a web that travels past the gauge, and a second position whereat the encapsulated nuclear source is positioned to face a sidewall of the enclosure means at a location remote from the first position;
• the sidewall of the enclosure means at the second position including a plug which is formed from a material having a relatively low atomic number for safely receiving radiation from the nuclear source at the second position.