Dismantlement Activities of Contaminated Glovebox and Tunnel with New Sealed Enclosure Methods

Gloveboxes that are contaminated with plutonium in the Plutonium Fuel Fabrication Facility of Japan Atomic Energy Agency are size-reduced and removed as a part of inactive fuel facilities decommissioning project. Recently, we have dismantled one glovebox that stood very near at the wall of a room and one transfer tunnel that penetrated another wall. The conventional tent enclosure cannot be applied to provide adequate containment boundaries in these two cases. We therefore developed new containment boundaries. Since the width between the glovebox and the wall was only 5 cm in the former case, we installed tent mounting plates on the wall and attached tents to create a working environment equivalent to a conventional plastic enclosure. As a result, negative pressure control and radiation control were performed as before. On the other hand, in the latter case, we attached a plastic bag with gloves to the tunnel to allow the cutting operation to be performed in an airtight space, resulting in a change to a less stressful face mask with coverall suit work instead of the air-fed suit work owing to access from outside the boundary. In this report, we present the features of new containment boundaries we have developed and the details of the dismantlement procedures we have implemented. We also analyze work performance of the methods by evaluating data achieve in these activities.