The following information was received via e-mail:
The Plant Manager called the [Illinois Emergency Management] Agency to advise that a shutter on a gauge had failed. When staff went to close the shutter, [while performing] work in the immediate vicinity, the handle used to close the shutter, 'twisted off'. The shutter remained stuck in the open position. Radiation levels near the gauge did not change from the previous configuration. The area was posted to warn of the hazard and system maintenance personnel changed work procedures to account for the failure. No work is scheduled to be completed within the beam fan area in the lower portion of the vessel.
The company's radiation safety officer confirmed the steps taken and applied additional shielding to the front of the gauge to effectively render the gauge 'off' until such time as the vessel is once again filled with product to reduce the radiation levels or the manufacturer can be on-site. Current weather predictions are such that it may be a couple of days until a field engineer can be dispatched to the site.
This item remains open and may be further investigated depending on response by the manufacturer. This device experienced similar problems in October of 2009 which were addressed by the manufacturer. In that case, the gauge was 'upgraded' to include additional seals and replacement of others to prevent the infiltration of water which lead to corrosion of the shutter causing it to 'stick' in the open position unless sufficient force was applied to the handle.
The fixed gauge was manufactured by Ohmart Corp.; model number SH-F2; serial number 74932. The sealed source radionuclide is CS-137 with an activity of .08 Ci (2.96 GBq).
Illinois Event Number: IL10010.