D0 Control Room Argon Test Cell Placement

Due to the need of maintaining and providing high purity argon for the D0 experiment. it is necessary to have a purity verifying device readUy aVailable. The testing eqUipment used by the D0 cryo group is called the Argon Test Cell (ATC). It operates by taking a sample of the argon to be tested and running it through a test cell for purity determination. LiqUid nitrogen cooling loops are used to to keep the argon cold during the testing. The initial placement of the ATC was outside of the D0 Cryo Control Room. This was not a favorable place. mainly because of exposure to the elements on the operators and the device. A plan was made to move the ATe from outside to inside the control room. This would allow security. favorable environment conditions. and general overall improved access and operability. Havtng the ATC inside causes some concern over some issues. It is true that the ATC employs cryogenic piping components. so there is an ODH possibility ifthose components were to faU and leak. However. there are ways by which we can determine the ODH class fairly easily. Using the methods outlined in D0 EN-229. the components of the cryogenic pipelines are summed and grouped according to failure possibility and likely leakage upon failure. (Note that this is the reason that one type of component may be listed a multiple number of times in the appendix spreadsheet, as the different components have different possible leak rates. depending on position or size. etc.). The result is an ODH class 0. since the fatality rate has to be above 10{sup -7} for a hazard condition to be present. The fatality rates in this analysis only come within an order of magnitude of this safety limit due to using conservative estimates. Note that the 130 scfm fan must be active for the ODH status to remain O. The control room ventilation is on emergency power. An alarm attached to the fan will notify the operators of fan failure. but both the fan and the alarm can be turned off when they are not needed. The fan need not be active as long as there are no cryogens in the ATC, and the argon and nitrogen supply line valves have been secured closed. For ODH detection purposes, an ODH head has already been installed in the control room as a result of the DAB southSide ODH plan