On behalf of Ken Rosenberg (Kenneth.Rosenberg@inl.gov) :

I am serving as the project manager for new equipment being installed in a nuclear hot cell. A part of the project is to provide and install a 500 gram analytical balance that can be remotely operated and can survive in the inert (argon), high radiation environment of a nuclear hot cell.

The Laboratory recently prepared and installed a small analytical balance in an inert atmosphere nuclear hot cell. Unfortunately the balance did not survive. The balance did work when first installed but failed shortly after installation. It is estimated that the balance failed in less than 1 week.

The hot cell radiation levels present at the time of the failure were approximately 100 R/hr, which is significantly lower that the anticipated working levels.

The Laboratory is still planning to install an analytical balance but has not yet identified a candidate balance that would be suitable for modification and installation.

The Laboratory had prior success modifying an older model Mettler PR503/SE (a balance with separate electronics). The older model PR503/SE was modified, placed in a nuclear hot cell, and has survived for several years. The balance is still in service. The Laboratory has had success with the older model Mettler Industrial balances.

The failed balance was a (Laboratory modified) Mettler XP504/SE. The XP504/SE was selected based on the success of the previous PR503/SE.

The Laboratory’s installation required the instrumentation cables between the balance platform and the separate electronics (out-of-cell) be lengthened approximately 50’ and routed into the cell using a sealed feed thru.

Any feedback on balances that you use that have survived prolonged exposure to high radiation environments would be appreciated. thanks.