CSER 96-014: Criticality Safety of Project W-151, 241-AZ-101 Retrieval System Process Test

Vail, T.S.

doi:10.2172/326847

Cited by 2 publications

(6 citation statements)

References 5 publications

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“…An initial volume of unexpectedly high plutonium concentration would be transformed into a thin layer of higher concentration. Vail (1997a) examines the possible range of variation in plutonium concentration in sludge in DST AZ-101 formed from discrete discharges of waste from the PUREX Plant. Vail modeled each discharge as forming a thin layer of uniform thickness on top ofthe existing waste surface.…”

Section: B73 Case Study Of Stratificationmentioning

confidence: 99%

Criticality Safety Evaluation of Hanford Tank Farms Facility

Weiss¹

2000

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Section: B73 Case Study Of Stratificationmentioning

confidence: 99%

Criticality Safety Evaluation of Hanford Tank Farms Facility

Weiss¹

2000

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“…As stated in Vail(1997), there are 6 in. of the sludge layer in the tank bottom that contain no plutonium solids.…”

Section: 9mentioning

confidence: 99%

“…Tank AZ-101 received plutonium-bearing PUREX aging wastes 262 times between 1983 and 1986 (Vail 1997). The average sludge thickness was 6 in.…”

Section: Initial Distribution Of Plutonium-bearing Solidsmentioning

confidence: 99%

“…The average sludge thickness was 6 in. before this slurry was received (Vail 1997). Since the current sludge thickness is 14.8 in., the 262 campaigns produced 8.8 in.…”

Section: Initial Distribution Of Plutonium-bearing Solidsmentioning

confidence: 99%

“…Assuming no mixing of the sludge within the tank by ALC operation during these campaigns, there could be 262 discrete sludge layers. Using the historical waste transfer records of the PUREX Material Balance Area log sheets and the Double-Shell Tank Plutonium Inventory Tracking System, a plutonium distribution was obtained without sludge mixing, as shown in Figure 3.5 (Vail 1997). It indicates significant variations in plutonium concentrations within the 8.8-in.…”

Section: Initial Distribution Of Plutonium-bearing Solidsmentioning

confidence: 99%

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Tank 241-AZ-101 criticality assessment resulting from pump jet mixing: Sludge mixing simulation

Onishi¹,

Recknagle²

1997

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Portions of thisThe tank contains a significant quantity of fissile materials, including an estimated 9.782 kg of plutonium. Before beginning jet pump mixing for mitigative purposes, the operations must be evaluated to demonstrate that they will be subcritical under both normal and credible abnormal conditions.The main objective of this study was to address a concern about whether two 300-hp pumps with four rotating 18.3-m/s (60-Ws) jets can concentrate plutonium in their pump housings during mixer pump operation and cause a criticality. The three-dimensional simulation was performed with the time-varying TEMPEST code to determine how much the pump jet mixing of Tank AZ-101 will concentrate plutonium in the pump housing.Tank Az-101 has 22 air lift circulators that have been operated continuously for years to mix the sludge during and after the period of plutonium-bearing waste additions. However, in these tests we neglected the mixing effects of the air lift circulators to obtain the conservative initial plutonium distribution within the sludge. Heterogeneous distributions of plutonium within the sludge might have been caused by two factors: the 262 sequential discharges of the plutoniumbearing wastes into AZ-101 and the preferential settling of heavier, larger solids affected by the three-dimensional, dynamic, interactive, flow/solid transport/rheological processes. Even though the dynamic slurry flow movements will not maintain the segregation caused by the sequential waste discharges totally intact, we added these two segregation factors together. This addition resulted in the initial maximum plutonium concentration of 1.88 g/L, which is 30 times greater than the actual average plutonium concentration in the AZ-101 sludge. The segregation factor of 30 is very conservative in light of the fact that even in the mining industry, the 10 to 20 pm size range is below the normal particle range for either gravity or flotation segregation processes without special chemical additives and very specialized equipment that would provide rhythmic shaking, thin liquid films, or high centrifugal forces coupled with selective collection and concentration to achieve the segregation. Furthermore, the total plutonium mass in the model is nine times higher than the actual amount stored in the tank, 9.782 kg.The AZ-101 model, with these very conservative initial plutonium conditions, predicted that the total amount of plutonium within the pump housing peaks at 75 g at 10 simulation seconds and decreases to less than 10 g at four minutes. The plutonium concentration in the entire pump housing peaks at 0.60 g/L at 10 simulation seconds and is reduced to below 0.1 g/L after four minutes. Since the minimum critical concentration of plutonium is 2.6 g/L, and the minimum critical plutonium mass under idealized plutonium-water conditions is 520 g, these predicted maximums in the pump housing are much lower than the minimum plutonium conditions needed to reach a criticality level.The initial plutonium maximum of 1.88 g L still results in s...

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CSER 96-014: Criticality Safety of Project W-151, 241-AZ-101 Retrieval System Process Test

Cited by 2 publications

References 5 publications

Criticality Safety Evaluation of Hanford Tank Farms Facility

Criticality Safety Evaluation of Hanford Tank Farms Facility

Tank 241-AZ-101 criticality assessment resulting from pump jet mixing: Sludge mixing simulation

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