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This document was printed on recycled paper. SummaryThe Pacific Northwest National Laboratory (PNNL) conducted neutron measurements at Hanford's Plutonium Finishing Plant (PFP). The measurements were performed to evaluate the performance of the Hanford Standard Dosimeter (HSD) and the 8816 TLD component of the Hanford Combination Neutron Dosimeter (HCND) in the neutron fields responsible for worker neutron exposures.For this study, TEPC detectors and multisphere spectrometers were used to measure neutron dose equivalent rate, and multispheres were used to measure average neutron energy. Waterfilled phantoms holding Hanford dosimeters were positioned at each measurement location. The phantoms were positioned in the same location where a multisphere measurement was taken and TEPCs were also positioned there. Plant survey meters were also used to measure neutron dose rates at all locations.Three measurement locations were chose near the HC-9B glovebox in room 228A of Building 234-5.The multisphere spectrometers measured average neutron energies in the range of 337 to 555 keV at these locations. Personal dose equivalent, H p (10) n , as measured by the multisphere and TEPC, ranged from 2.7 to 9.7 mrem/h in the three locations. Effective dose assuming a rotational geometry (E ROT ) was substantially lower than H p (10), ranging from 1.3 to 3.6 mrem/h. These values were lower than the reported values from dosimeters exposed on a rotating phantom. Effective dose assuming an AP geometry (E AP ) was also substantially lower than H p (10), ranging from 2.3 to 6.5 mrem/h. These values were lower than the reported values from the dosimeters on slab phantoms. Since the effective dose values were lower than reported values from dosimeters, the dosimeters were shown to be conservative estimates of the protection quantities.iii

Executive SummaryThe Pacific Northwest National Laboratory (PNNL) Nondestructive Assay (NDA) Service Center was contracted to develop and demonstrate a simple and inexpensive method of assaying 110 gallon drums at the Hanford Site's T-Plant. The drums contained "pucks" of crushed old drums used for storage of transuranic (TRU) waste. The drums were to be assayed to determine if they meet the criteria for TRU or Low Level Waste (LLW).Because of the dense matrix (crushed steel drums) gamma measurement techniques were excluded and a mobile, configurable neutron system, consisting of four sequentially connected slab detectors was chosen to be used for this application. An optimum measurement configuration was determined through multiple test measurements with a californium source. Based on these measurements the initial calibration of the system was performed applying the isotopic composition for aged weapon-grade plutonium. A series of background and blank "puck" drum measurements allowed estimating detection limits for both total (singles) and coincidence (doubles) counting techniques. It was found that even conservative estimates for minimum detection concentration using singles count rate were lower than the essential threshold of 100 nCi/g. Whereas the detection limit of coincidence counting appeared to be about as twice as high of the threshold.A series of measurements intended to verify the technique and revise the initial calibration obtained were performed at the Waste Receiving and Processing (WRAP) facility with plutonium standards. Standards with a total mass of 0.3 g of plutonium (which is estimated to be equivalent of 100 nCi/g for net waste weight of 300 kg) loaded in the test "puck" drum were clearly detected. The ensuing measurements of higher plutonium loadings verified the calibration factors obtained in the initial exercise. The revised and established calibration factors were also confirmed within established uncertainties by additional measurements of plutonium standards in various locations in the test drum.Due to necessity to dispense the blank "test" drum an alternative method of baseline determination was established during field measurements. Count rates of ambient background were corrected by the differences between observed background and blank "test" drum count rates which were previously determined over a series of measurements.Only 31 drums out of 352 counted during the intensive measurement campaign at T-Plant were determined to be "Suspect TRU". 25 of these drums were re-measured at the WRAP facility using the SuperHENC. Of the 25 drums measured, 21 were confirmed to be TRU and the remaining four LLW.iii Acronyms and Abbreviations