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Skip Navigation LinksFission gas measurement and analysis

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Instrument Description​

Fission gas puncture and sampling is performed using the HFEF gas assay, sample and recharge (GASR) system. The system comprises a 150-watt Nd-YAG pulsed laser, shielded optical feed-through, a mechanical vacuum pump, calibrated volumes, gauges and controls. Fuel elements or capsules are positioned on the laser by a clamp onto a gasket. The gasket provides a seal between the element and laser seal head. Void volume is determined by a series of backfills into the punctured fuel rod and expansions into the GASR system. The fuel rod internal gas pressure is derived from the void volume measurement and fission gas puncture pressure measurement. Fission gas samples are sent to the Analytical Laboratory, where they are analyzed by a gas mass spectrometer to provide krypton (Kr) and xenon (Xe) isotopic and total elemental composition. The rodlet void volume and internal gas pressure uncertainty is ≤ +/- 5% in the range of 0.03 to 60 liter-atmospheres. The isotopic and elemental analysis uncertainty is +/- 1-5%, depending on the relative abundance of the analyte.


Applications​

This equipment provides the ability to puncture cylindrical capsules or fuel elements in their plenum regions to measure free volume and pressure, and gather a sample for gas composition and isotopic analyses.


Specifications​

​Parameter

​Limit

​Element diameter range​0.174 to 0.832 in
​Element length range​1 to 152 in
​Cladding thickness​0.010 to 0.060 in
​Observed accuracy​Typically +/- 10% for volumes and pressures of plenums <1 in^3 and +/- 5% for volumes and pressures of plenums <1 in^3
​Laser tyle​Nd-YAG
​Maximum energy per pulse​20 Joules
​Rated average power​150 W
​Pulse repetition rate​1 to 100 pulses per second (pps)
​Pulse widthVariable from 0.12 to 8 msec
​Final lens focal length​4 in
​Minimum spot diameter​~0.005 in

​Pressure and Vacuum Instrumentation ​

​Sealing head pressure​0 to 50 +/- 0.1 psia
​Manifold pressure​0 to 50 +/- 0.01 psia
​Manifold vacuum​1 atm to 10 millitorr +/- 5 millitorr
​Sample line vacuum​1 atm to 10 millitorr +/- 5 millitorr
​Sample line pressure0 to 10 +/- 0.01 psia

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