Attached 1: Potential troubles likely to occur at Reprocessing Plant and their countermeasures (No.1-15)
[Case: Clogging In Instrumentation Piping of Dissolution Feed Vessel]

Case	Clogging In Instrumentation Piping of Dissolution Feed Vessel
Outline of Incident
(1) Where does it occur?	Dissolution feed vessel in the separation building;
(2) Outline of the Unit	Vessel which receives solution of dissolved Spent Fuel from the Head-End Building and stores it temporarily for feeding to the Separation Process.
(3) When does it occur?	During an operation of the separation building
(4) How does it occur?	The piping of the Liquid Level Meter installed inside the dissolution feeding vessel is clogged by sludge, causing the Meter to initiate a wrong signal "solution level high”. As a consequence, the feeding of dissolution to the dissolution vessel is stopped. * Similar incidents could occur in other facilities during the similar process
(5)Why does it occur?	Clogging occurs during continuous operation (whose procedures are defined in advance)
Impact due to the incident
(1) On the outside of the Plant	There is no impact outside of the Plant; This is an incident concerning dissolution feed vessel installed in the Separation Building where the VOG Treatment System with filters, etc. for removing radio-active material is available, and its related recovery work. ., so that there is no impact such as the release of radioactive material outside of the Plant. Further, this incident does not accompany leakage of any radioactive material.
(2) On safety	There is no impact on safety The dissolution level in the tank cannot be measured during the incident. However, since the equipment which feeds the dissolution to the coextraction tower is in normal operating condition, no impact on the safety is expected.
(3) On workers	There is no impact on workers; In the maintenance activities to remove the clogging, each task is conducted efficiently in accordance with the prescribed Radiation Management Plan.
(4) On other processes	Operation of Down-stream processes could be affected; Since the dissolution is stopped being sent, some impact on the following separation/partition process is expected. Furthermore, whether high-active liquid waste concentration and Uranium enrichment further down stream can be carried out or not is judged based on the volume of the residual dissolution in the temporary storage vessels installed between the two processes or systems.
Outline of Corrective Measures	(1) To confirm that the incident is due to the clogging in the piping of the Liquid Level Meter. (2) To remove the clogging in accordance with the relevant work procedure. (3) To re-start operation after confirming the normal function of the Liquid Level Meter.
Announcement Category	Compiled monthly, and announced once a month on Web.
Information Category	Trouble information Operational Information A Category B Category C Category Very minor function failure Function failure which need cleaning, adjustment, etc Non- conformity, etc