Nuclear Applications for Inflatable Seals
Major nuclear engineering services contractors.
Periodically, nuclear power plants are idled for refurbishing or refueling operations. Under normal operating conditions the cooling water in the system is circulated. When a refueling or refurbishing activity takes place the nozzle passageways that provide the cooling water must be dammed off to contain the water. Usually these operations are accomplished in a period of hours to a day or two.
The pressure head of water that needs to be sealed is approximately 40 psig. The diameters of the water nozzles to be dammed can range from 28 inches to 45 inches. Obviously, the major focus on this critical operation is to have zero leakage of the cooling water.
The water nozzle passageways are designed and fitted with a metal ring to accept a metal dam device, which is designed to mechanically lock into the metal ring in the passageway. The metal dam is manufactured in segments in order to pass through a small access door. The challenge then is to provide a seal configuration that fits with the metal dam that will provide a watertight seal around the metal nozzle dam and also is sufficiently compact to also fit through the access door.
The solution is a combination of two inflatable seals, a passive lip seal, and a diaphragm. This combination of seals and diaphragm is vulcanized in one process to provide a single high integrity part that attaches to the metal nozzle dam. (Reference Figure A.) The part is manufactured from radiation-resistant EPDM compounds and Kevlar® fabric. The inflatable seals and the chamber between them are under constant remote monitoring for air pressure and airflow during the entire refueling/refurbishing operation.
Various sizes and configurations of Seal Master nozzle dam seals are utilized throughout the nuclear engineering services industry during refueling and refurbishing operations.