ML19331E023
| ML19331E023 | |
| Person / Time | |
|---|---|
| Site: | 07109508 |
| Issue date: | 08/05/1980 |
| From: | Brown W, Danni Smith LOS ALAMOS NATIONAL LABORATORY |
| To: | |
| Shared Package | |
| ML19331E021 | List: |
| References | |
| 17003, NUDOCS 8009050214 | |
| Download: ML19331E023 (5) | |
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O UrAINER FOR SHIPPING POLYSTYRESE-PLUTONIUM COMPAC*S i
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AUTHOR (S):
- o. R. Smith, cleo Byers, Q-14 W. K. Brown, TD-7 i
SUBMii iED TO:
Division of opera:ional Safe:y, Ato i
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By accectance of trus artic;e. the Duchsher recognates that the g
U.S. Government retains a nonetclus.ve, roya ty free hceme to puchsh of reDroduce the pud tshed form of inis contricu-i tson. Or to al ow ofners to do so, for U.S. Governrne91 Cur.
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O The Los Alamos Scientific Laboratcry reovests that the pue-Irsher identefy tnis article as work perf ormec under the aus-C pices of toe U.S. Department of Energv.
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Post Office Box 1663 Los Atamcs, New Mexico 67545 Tf m icyer E
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by D.
R., Smith, C. C.
Byers, and W.
K.
Brown ABSTRACT The LASL ONETRAN code has been used to provide values of plutonium-polystyrene load-5 ings f or the Depar tment of Transportation 6M Specification Container.
These values ccmply with Fissile Class 1 transport criteria.
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The need exists to ship a quantity of polystyrene that is loaded with plutonium oxide frca Richland, WA to Los Alamos to recover the plutenium from the plastic.
Th'e ma$erial is in the form of small cubes, and contains plutonium oxide at densities 3
between 0.03 and 4.1 gm/cm There exist no shipping containers approved for this pu,rpose, thcugh the DOT Scecification 6M ac. c. ears.to crovide ac. e. rce. riate saf et.y.
4 II.
n_ ?S v"R. T. :*.1 C".. Or. 6M The specification 6M container consists of an outer DCT Specificationi drum, between 10 and 110 gallon capacity, and an inner Specificatica 2R container supported in cane fiberboard insulation.
The 6M was originally intended for shipment cf fissile material, and to provide maximum reasonable loadincs all specified loadings are for unmoderated fissile material.
As a result of exposure cf pro:ctype 6M containers to the regulatorv h'.rothetical accident conditions, measurements demonstrated a maximum temperature fcr the 2R inner centainer Of 250 F.
The contents are therefore restricted.to caterials
which do not decompose at this temperature.
The decomposition temperature.of polystyrene is about 400 F, well.in excess of I
the allowable value.
III. ' CRITICALITY EVALUATION 2
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The only remaining' safety consideration is that of i
criticality.
To evaluate the criticality saf ety of these i
compacts if shipped in a 6M Specification container, cell 1
calculations used the LASL transport code ONETRAN with Hansen-Roach 16 group crcss sections.
The loadings that would provide a multiplication factor of unity were evaluated for a reflected cell, thus providing a value for Fissile Clast I loadings.'
Delta calculations were performed on spherical, cells having i
four regions.
The innermost region was filled with polystyrene 3
Ra t a density of 1.08 g/cm and plutonium at approp'riate d en s i ti e s.,, This was surrounded with a spherical steel shell of 0.66 en thickness, which is the,value correspending to 12.7 cm (5 in) schedule 40 pipe as used for fabrication cf the 2R inne:
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container of the 6M.
Outside this steel was CH at a density of 0.24 g/cm corresponding to the 15 pound per cubic feet cane fiberboard used as insulation in the 6M.
Outside the CH was a 0.1 cm steel, shell corresponding to the 18 ga. steel drum of the 15 gallon 6M.
The outer radius of the cell was constrained to 2
remain at 2'3.84 cm, providing a cell volume of 56.75 liters (15 As the volcme of the innermost regien was varied to gallon).
t achieve criticality, the radial thickness of the insulation alsc varied.to keep the cell radius constant.
The results of rhese i
calculations are tabulated below, with the radius and volume values applying to the fuel region at criticality, and the mass
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values representing the critical mass of plutonium, which was 230 assumed to consist of 100%
'Pu.
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H/Pu r(cm)
V(liters) mfe) l 1.0 20 8.89 2.95 2,927 0.5 40 9.46 3.55 1,774 0.3 67 9.85 4.00 1,201 0.1 200 10.83 5.33 533 0.08 250 11.10 5.73 458 0.066 30-0 11.36 6.53 406 0.057 350 11.60 6.53 372 0.050 400 11.82 6.93 346 0.044 450 12.05 7.34 324 0.040 500 12.28 7.75 308 Extension of these calculations to search for epti: mum modera-tion resulted in a minimum Fissile Class I loading of 250 g at a hydrogen-to-plutonium.r atie of 1200.
Several facters of conservatism are associated with application.of these values to a real situation.
9 The assumpticn of pure "] cpu underestimates th,e actual 240 situation, where the Pu content will act as a neutren poison, increasing critical values.
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Shipment will probably be in 30 cr 55 gallen 6M containers, for which larger cuantities of fissile material could be acccamodated.
The cylindrical radius of the inner 2P. container cf the 6M may not exceed 6. 67 cm (S.25 in diam).
The volumes derived from spherical radii substantially abcVe this value would, in the cylindrical. case, be increased by appropriate shape factors.
Consideration of these several effects would justify increased loadings, but,with attendant ccmplexity in the specification of allowable loadings.
The tabulated values support use of 6M containers, of 15 gallon or larger size, for the shipment of polystyrene compacts as Fissile Class 1.
Since this result provides generous shipping capacity, extension of the calculations does not appear to be justified.
Similarly, no calculations for Fissile Class II will be performed at this time.
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IV. RECO!'S. ENDED ALLOWABLE LOADINGS Maximur Quantity 237Pu, cra r Hvdrocen/Plutenium Ratio 2900 20 1750 40 1200 67 525 200 450 250 400 300 370 350 340 400 320 450 300 500 (CH),
These values apply to plutonium mixed with polystyrene when packaged in 6M Specification Containers of 15 gallon or greater size, and meet Fissile Class I criteria.
For any no a loading of 250,g ~~"Pu,will comply with moderation ratio, Fissile Class I.
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