ML20058N385
| ML20058N385 | |
| Person / Time | |
|---|---|
| Site: | 07109019 |
| Issue date: | 11/29/1993 |
| From: | GENERAL ELECTRIC CO. |
| To: | |
| Shared Package | |
| ML20058N366 | List: |
| References | |
| NUDOCS 9312210366 | |
| Download: ML20058N385 (28) | |
Text
1 i
l APPENDIX F i
" CRITICALITY SAFETY ANALYSES FOR BU-7 SHIPPING CONTAINER FOR URANIUM SCRAP WITH ENRICHMENTS AT OR BELOW 5.0%"
1 i
SEPTEMBER 9, 1993 l
REVISION 1, DATED NOVEMBER 29, 1993 1
1 1
l l
O LICENSE SNM-1097 DATE 12/03/93 PAGE DOCKET 71-9019 REVISION O
F 9312210366 931203 PDR ADOCK 07109019 c
Pnn
O h
Criticality Safety Analysis for IlU-7 Shipping Container For Uranium Scrap with Enrichments at or llelow 5.0%
r i
September 9,1993 Revision 1, dated November 29,1993 O
Revisions marked by revision bars in the left margin 9
O l
September 9,1993 [ Rev.1, dated 11/29193 J Page I of 20 n
Criticality Safety Analysis: BU-7 Shipping Container For Uranium Scrap with U
Enrichments at or Below 5.0%
I.
INTRODUCTION Model BU-7 shipping containers are used by the General Electric Company for the transportation oflow-enriched unirradiated uranium dioxide powder, pellets and scrap. The BU-7 235U enrichment of container is a Fissile Class I package which is currently licensed for a maximum 5.0% for powder and 4.025% for pellets and scrap. In the previous case for enrichments below 4.0%, the containers were restricted to two 5 gallon pails or three 3 gallon pails which are limited in contents to no more than 70 kg of UO2 powder or two safe batches of UO pellets (or powder) per 2
package. Each package was also limited in the amount of hydrogenous moderation that may be present in the fuel.
In a prior analysis for UO gowder enriched in ce range of 4.0% to 5.0%, the BU-7 container 2
was demonstrated to comply with Fissile Class I requirements even with optimum moderation and I maximum geometry for the accident conditions specifieelin 10CFR71.57.
Each container was restricted to UO masslimits as follows: 35.0 kg UO foremichments greater than 4.0% but no more 2
2 than 4.25%,32.5 kg UO for enrichments greater than 4.25% Sut no more than 4.50%,30.0 kg UO2 2
enrichments greater than 4.50% but no more than 4.75%, and P.5 kg UO2 for enrichments greater than 4.75% but no more than 5.0%. The normal case restrictior, for the fuel contents to a H/U O
atomic ratie ef 0.45 was aggiied, bui the cenieets were iimited se tha< 1he tetai mas ef hydroseeee moderator in the inner containment vessel was no greater than 1000 gams or 3.6% of the weight of the uranium dioxide, whichever was smaller.
This analysis is performed to show the criticality safety of tie BU-7 packages containing no more than 17.63 kgs of uranium in compounds no more dense than UO but with no specific limits on 2
235 moderation. It applies to U enrichments up to 5.0% and for any degree of moderation by water, carbon or either of their equivalents.
Specifications for the geometry and materials of construction of the BU-7 container,5 and 3 g gallon pails are the same as those fer the reference Certificate [1] with one exception. A liner containing a strong neutron absorbing material has been added to the inside drum, surrounding the pails of UO powder. The liner is made from "Boral,' which is essentially a layered B4C and 2
aluminum compound. The liner is composed of 0.080 inches (rninimum,0.085 nominnl) of Boral, sandwiched between two sheets of 0.026 inch (minimum,0.030 nominal) stainless steel. The Boral liner has a minimum height of 26.0 inches and is designed to fit against the inner drum of the B U-7.
The Boral material has a minimum density of B10 atoms per unit surface area of '
2 O.Oli g/cm II.
ANALYSIS i
A. BU-7 Container i
O The BU-7 shipping container consists of a 55 gallon DOT Specification 17H outer drum f
3 constructed of I8-gauge steel which contains 7-9 lbs/ft fire-retardant phenolic resin insulation i
1
September 9,1993 [ Rev.1, dated 11/29/93 ]
Page 2 of 20 sandwiched between it and a 13.75 to 14.05 inch diameter by nominal 27 inch long 18-gauge steel inner drum. The inner drum (described as the "innner containment vessel"in the above paragraph),
is gasketed and sealed with a bolted metallid to insure water tightness, and nomially holds two 5 gallon pailsor three 3 gallon pails. A liner of Boral is included inside the inner containment vessel.
Figure 1 depicts the container with a cutaway section showing the internal container, liner and the phenolic resin.
B. General Requirements for Fissile Class I Shipping Containers As specified in Parts 71.55 and 71.57 of Reference 2, the criticality safety requirements for a Fissile Class I shipping container are that suberiticality be maintained for the following:
1.
Sin gle Containers - with the most reactive credible configuration of the package and contents, including moderation by water, and assuming close reflection by water on all sides.
2.
Infinite Arrays of Containers - undamaged, in any arrangement with optimum interspersed hydrogenous moderation.
3.
Arrays of Damaged Containers - two hundred and fifty " damaged" containers stacked together in any arrangement, closely reflected on all sides by water and with optimum interspersed hydrogenous moderation. " Damaged" means in the condition resulting from being subjected to the " Hypothetical Accident Conditions" specified in Part 71.73 of the Rules and Regulations.
The " Hypothetical Accident Conditions" tests were conducted for the BU-7 container in 1979-80 and are reported in Reference 3. The basic results of the tests wem that while deformation of the outer 55 gallon drum occurred at the points of contact, them was no evidence of punctures, fractures or separation of the container sides from the bottoms. No damage was found to the sealing features or the integrity of the inner container or the UO powder pails inside it. After the fire and 2
water immersion tests, the inner container mmained dry, the silicone rubber gasket sealing it was undamaged, and no significant increase in the moisture content in the powder was found. The report concluded that in the tests, the outer container did not suffer any significant damage that would affect criticality safety considerations.
The current analysis will consider normal conditions in which wateris assumed to be present in the inner containment vessel to the extent of optimum moderation. The UO scrap in the three or 2
l five gallon pails is further assumed to occupy the larger inner containment vessel and mix with the
]
water. For simplicity in modelling, the three and/or five gallon pails will conservatively be omitted from the analysis and the water and UO2 scrap will be modelled solely in the inner containment vessel. The phenolic resin will also be considered to absorb water and the same amount of water j
analyzed outside of the container will be assumed to be present in the resin. This includes full density j
water for water reflection of the single container.
)
l 9
September 9,1993 i Rev.1, dated 11129193 J Page 3 of 20 Figure 1. BU-7 Containcr I
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September 9,1993 l Rev.1, dated 11129/93 l Page 4 of 20 C. UO Particles and Water Material Definitions 2
Previous criticality safety analyses of the BU-7 container are documented in References 4,5, 6 and 7. For the present analysis, the contents of the container is taken to be the inner containment vessel with uranium oxide in pellet form, which is more reactive than powder fomi. The uranium is 235 assumed to be enriched up to 5.0% in U. The fuel is modelled as heterogeneous UO2 surrounded by water and therefore applies to all uranium oxide pellets, powders and other sized solid fonns 3
having densities no greater than 10.96 g/cm For the present analysis, the contents of the container is taken to be 17.63 kg of uranium (20.0 kg of UO ) in the form of cylindrical particles (similar to the pellet analysis of Reference 11),
2 enriched to 5.0% in 235U. Water is utilized as the moderating material since it is a more effective moderating material than carbon or any other hydrocarbon moderating material that might be present in the scrap. The fuel is modelled as 10.96 g/cc UO in water and therefore applies to all 2
uranium compunds (oxide, silicates, etc.) which might be present in GE BWR fuel manufacturing scrap.
Atom densities for for theoretical density UO used in this analysis are listed in Table 1.
2 Ilomogeneous mixtures of UO2 and water are less reactive than the heterogeneous case and so are bounded by the analysis where all the UO is in solid form.
2 Table 1 Atom Densities for Theoretical Density UO Particles h
2 Enrichment N235 N238 Nm atoms /b-cm atoms /b-cm atoms /b-cm 5.0%
1.23755E4)3 2.32165E4)2 4.89077E4)2 For the analysis of particles, the particles are taken to be theoretical density UO (10.96 g/cc) 2 3
surrounded by full density water where OH2O = 1.00 g/cm Ng = 6 6743E--02 atoms / barn-cm and No = 3.3372E4)2 atoms / barn <m. Varying water-to-fuel ratios for the analysis are given by pitch of the particle array in the container, particle diameter and total height of the fuel in the container.
D. Materials of Construction The major constituents of the BU-7 container are the carbon steel drums and phenolic resin.
3 Carbon steel has a density of 7.82 g/cm and its component atom densities are 3.921E4)3 atoms /bam-cm for carbon and 8.3491E-02 for iron. Stainless steel,if used for construction in the future,is a better neutron absorber than is the carbon steel. Thus, the analysis applies to the BU-7 container constructed of stainless steel as well as those constructed of carbon steel.
3 The density of phenolic resin compound with the minimum specification (i.e.,7 lbs/ft )is given below. One-hundred percent of the minimum specified phenolic resin density is used in this h
analysis, although no credit has been taken for boron which is present.
September 9,1993 [ Rev.1, dated 11129/93 ]
Page 5 of 20 0
Table 3.
Phenolic Resin Atom Densities in the BU-7 Container Element Atom Density (Atom / barn-cm)
Hydrogen 3.0140E-03 Boron 10 0.0000E+00 Boron 11 0.0000E400 Carbon 2.3050E-03 Oxygen 2.0510E4)3 Silicon 5.2890E-05 Table 4 gives the constituent elements and associated atom densities for the Boral liner. As an added conservatism in the treatment of the liner, only 75% of the minimum specified density is 10 used in the analysis (only 75% of the B atoms are included in the liner for the analysis).
Table 4.
Boral Liner Atom Densities Element Atom Density (Atom / barn-cm)
Carbon 3.0675E4)3 O
Bor " io 2 442 88">3 Boron 11 9.8285E-03 Aluminum 4.5406E4)2 E. Analytical Method Neutron multiplication factor calculations in this criticality analysis have been performed s
with the GEMER Monte Carlo code. GEMER is a modified version of the Battelle Northwest Laboratory's BMC Monte Carlo code which has been combined with the geometry handling submutines in KENO IV. Cmss section sets in GEMER are processed from the ENDF/B-IV library in 190 broadgroup and resonance pammeter formats except for thermal scattering in water which is represented by the Haywood Kernel in the ENDF/B library. In GEMER, the resonance parameters describe the cross sections in the resonance energy range and Monte Carlo sampling in this range is done from the resonance kemels rather than from the broad group cross sections. There is thus, a single unique cross section set associated with each available isotope and dependence is not placed on Dancoff (flux shadowing) correction factors or effective scattering cross sections. The cross section library includes fission, capture, elastic, inelastic, and (n,2n) reactions. Absorption is implicitly treated by applying the non-absorption probability to neutron weights at each collision point.
i GEMER's bias has been determined in an extensive validation against critical experiments 1
to vary from +0.006 to 4).021 over the range of moderation in the fuel mixtures considered in this I
analysis. For undermoderated mixtures with H/U atomic ratios less than about 5, the bias is positive i
denoting that neutron multiplication factors are over-predicted. The bias then decreases almost
)
1
September 9,1993 i Rev.1, dated 11129193 J Page 6 of 20 linearly to -0.015 at an H/U ratio of about 25. Beyond this point, the bias decreases slowly to an II/U of about 40. These values span the range considered for the BU-7 container since the highest degree of moderation relevant to this analysis conesponds to an H/U ratio of about 28. A value of-0.021 for the bias is conservative for all calculations considered here.
F. Modelling of Geometry The geometry model used in this analysis of the BU-7 container is illustrated in Figure 2 and the GEMER.4 geometry input is tabulated in Tables 5 through 7. The BU-7 was modelled with the 35.40 cm diameter,70.2 cm high inner containment vessel filled with UO2 Particles oriented perpendicularly to the axis of the BU-7 and water surrounding the pellets to the height specified in Table 8A-C. The heights were essentially determined by dividing the applicable UO mass limit 2
(e.g.,20.0 kg at 5.0% enrichment) by the product of the average UO mixture density (although the 2
particles are modelled explicitly) and the Boral liner's inside area. Note that due to a difference between the minimum liner height (26 inches or 66.04 cm) and the height of the inner containment vessel (27.6 inches or 70.2 cm), a 4.16 cm gap exists. This gap in height is conservatively modelled by aligning the liner against the top of the inner drum, so that the UO and water mixture is not 2
surrounded by boron in the bottom of the vessel. This small amount of volume is accounted for in the mixture height calculation.
The Boral liner is modelled as having a minimum thickness and maximum outer radius (i.e.,
the liner is treated as if it were flush against the wall of the inner containment vessel). This treatment maximizes the outer radius of the UO and water mixture. While this modelling results g
2 in the maximum mass ofliner material in the BU-7, the effect of the maximizing the Boral mass is relatively smallin comparison with the impact of the geometric buckling. Maximizing the radius of the liner is a conservative treatment in the calculations.
Orientation of the cylindrical particle axes makes no significant difference in multiplication, but they are modelled in this fashion to take advantage of the geometry features of teh GEMER.4 code. Note that the particles are explicitly modelled. This is, of course, the key difference between models with mixtures of powder and models containing particles. The heterogeneous case modelled here will be shown to be more reactive. Because of the heterogeneous effect, the most reactive particle size (diameter) must be considered. Therefore, cases are run to determine the most reactive particle diameter and the most reactive moderator content. This is done for the normal case which is unrestricted in terms of the amount of moderation which may be present. The optimum panicle diameter is then used in the single container analysis and the water-to-fuel volume ratio is again varied to find a new optimum moderation point for the single container. Although this is a computer-time intensive task, this method explicitly accounts for both moderator and heterogeneous effects in the determineation of the most reactive configuration of containers and contents.
The water-to-fuel volume ratio (WTOF) is determined by the ratio of volumes of the water sunounding the particle (determined by the pitch of the array) and the volume of the particle itself.
The water-to-fuel ratio is related to the pitch and diameter as:
(Pitch)2 _ 992 4(Pitch)2 WTOF =
-1
=
jD
- rD2 2
i Sep! ember 9,1993 i Rev.1, dated 11/29193 J
. Page 7 of 20 l
?
An average density of the materials may be calculated (although this is not explicitly used in v
any of the present calculations) for each of the water-to-fuel volume ratios calculated. This allows calculation of the total mass of the fuel and water in the contanment vessel as well as a height calculation. The average density in the container is given by:
WTOF + 10.96 U "*' "
(l + WTOF) i The height is the total height of the water / fuel array of particles in the inner containment i
vessel. This height is related to the average density of material and the total amount of UO2 n the containment vessel. The height may be calculated as:
ave (1 - wtfrif2o) :r rk, Mass (UO ) -
h;,, - h,,,, o 2
ii vessel Height =
^
' +
h,, - hgw, i
eave (1 - wifrit20) :r r, vesse!
~
l
- The heights were determined by dividing the applicable UO mass (eg.,20.0 kg UO at 5.0%
2 2
enrichment less the amount of mixture in the region which may not surrounded by the liner) by the
_q product of the average UO component density for the mixture and the inner containment vessel's 2
base area (equal to n x 17.70 cm ) as shown above. These heights are shown in Tables 6A--C as
-l 2
2 referenced from the base of the inner containment vessel, whereas the model has as its reference the O
center of the BU-7 inner containment vessel (a constant difference of 35.1 cm).
i For the case of Infinite Arrays of Normal Containers, the model in Figure 2 was placed in a l
triangular pitch anay and spatially reflected on all six sides with varying amounts ofinterspersed water in the phenolic resin (Regions 2,11,13,23 and 27 in Table 5) and in the regions outside of the j
outercontainer. TheUO contentsforthiscaseistaken tobe20kgU(5.00%)O +optimumH 0. It i
2 2
2 has been shown previously,9 that when the fuel mixture is " smeared" from the minimum to i
6 maximum volume, thereby occupying the entire volume but reducing the material densities, the effective multiplication value goes down. Therefore, the maximum fuel densities (given in Table 1) 1 and water densities and their corresponding heights (from Tables 8A-C) are used in this analysis.
For the accident case of the Arrays of Damaged Containers, the array was modelled as an 9 = 7
- 4 triangular pitch array of BU-7 containers tightly reflected on all six sides by at least 30.5 cm of water. The 9 = 7 = 4 triangular pitch array is the one having a minimam of at least 250 units whose dimension is closest to a cube and therefore has the minimum geometrical buckling. The geometry input for the array of damaged containers is shown in Table 6. Each BU-7 was modelled as in Figure 2 and the interspersed water was again added to the phenolic resin insulation (Regions 2,11, 13,23 and 27 in Table 3). Since the accident array is really a subset and therefore bounded by the infinite anay ofoptimally moderated BU-7s, only a single verifying case was run for the finite array accident case.
For the Single Container case, the BU-7's outer 55 gallon drum was tightly reflected on all 6 sides by at least 30 cm of full density waterand water was assumed to leak into the inner containment O
vessei. Feii dee ity water -a ei e added te th rh eeiic re in (Resiee,2. ii, i3. 23 and 27 in Table 7).
September 9,1993 [ Rev.1, dated 11/29/93 )
Page 8 of 20 0
17.70 28.575 7
45.3692 - - - - - -
r---------------------
- - - - - Interspersed Water 44.4167 - - - - - -
Carbon Steel 44.308 - - - - - -
Phenolic Resin '.
e 36.638 - - - - - -
InterspersedWater f C
35.5763 - - - - - -
a 35.10 - - - - - -
r b
o n
Boral Liner S
t e
O sa s s. saa a s
-ssa-JJJJJJJJJJJJJJJJ.
J J J. J. J. J. J. J. J. J. J. J. J. J J.,J, sa Heterogeneous 3 J J * * * * *2 + H2O region J.
JJ UO ********J-
-30.94- - - - - - - J J J J J J J J J J J J J J J J *b.
4JJJJJJJJJJJJJJJ'J,
-35.10 - - - - - -
CarNsn steel
-35.2087 - - - - - -
fl.
Phenolic Resin
-42.8287 - - - - - -
l
-4 2'9374 - - - - - -
Carbon Steel l
.................terspersE.d Water l
In
_44,g4.,4......
a a
O
- 17.808 23.495 28.684 17.363 Dimensions in em.
Figure 2 GEMER Geometry Model for BU-7 Container
~ September 9,1993 [ Rev.1, dated 11/29193 ]
~ Page 9 ef 20 O-Table 5 GEMER Geometry Model for Infinite Arrays of Containers i
-1.0
-1.0
-1.0
-1.0
-1.0
-1 0 BOX TYPE 1
/* LOWER' PORTION OF BU-7 1
CYLINDER 3
17.808
-35.10 -35.2087 16*0 5
+
2 CYLINDER 5
28.575
-35.10 -42.8287 16*0.5 l
3 CYLINDER 3
28.5755
-35.10 -42.9374 16*0.5 4
CYLINDER 2
28.576
-35.10 -44.8424 16*0.5 5
CYLINDER 3
28.684
-35.10 -44.8424 16*0.5 BOX TYPE 2
/* SINGLE BU-7 6
CUBOID 4
59.2
-59.2 59.2
-59.2 75.85
-75.33 16*0.5 l'
BOX TYPE 3 /* UPPER PORTION OF BU-7.
7 CYLINDER 4
17.364 35.10 height 16*0.5 8
CYLINDER 3
17.429 35.10 height 16*0.5 l
9 CYLINDER 6
17.632 35.10 height 16*0.5 10 CYLINDER 3
17.808 35.10 keight 16*0.5 11 CYLINDER 5
23.495 35.5763 neight 16*0.5 12 CYLINDER 2
23.4955 36.688 height 16*0.5 t
13 CYLINDER 5
28.575 44.308 height 16*0.5 14 CYLINDER 3
28,5755 44.4167 height 16*0.5 15 CYLINDER 2
28.576 45.3692 height
,16*0.5 16 CYLINDER 3
28.684 45.3692 height 16*0.5 O
BOX TYPE 4 /* FUEL CYLINDER CELL-WATER-TO-FUEL = 12.00 17 YCYLINDER 1
0.0952 17.70 -17.70 16*0.5 18 CUBOID 4
0.3040 -0.3040 17.70
-17 70 0.3040 -0.3040' 16*0.5 BOX TYPE 5 /* INTERMEDIATE DISK OF FUEL CYLINDERS 19 CYLINDER 4
17.364 pitch 0.0 16*0.5 20 CYLINDER 3
17.429 pitch 0.0 16*0.5 21 CYLINDER 6
17.632 pitch 0.0 16*0.5
]
22 CYLINDER 3
17.808 pitch 0.0-16*0.5
)
23 CYLINDER 5
28.575 pitch 0.0 16*0.5' 24 CYLINDER 3
28.684 pitch 0.0 16*0.5 BOX TYPE 6 /* INTERMEDIATE DISK OF FUEL CYLINDERS-BOTTOM, NO BORAL 25 CYLINDER 4
17.700 pitch 0.0 16*0.5 26 CYLINDER 3
17.808 pitch 0.0 16*0.5
)
27 CYLINDER 5
28.575 pitch 0.0 16*0.5 28 CYLINDER 3
28.684 pitch 0.0 16*0.5 BOX TYPE 7 /* PROBLEM BOX FOR TRIANGULAR ARRAY - ONE LAYER DEEP 29 CUBOID 2 215.15
-215.15 227.7 -227.7 45.3692 -44.8424 16*0.5 30 CORE-0 215.15
-215.15 227.7 -227.7 45.3692 -44.8424 16*0.5 l
7 111 111 111 1
')
BEGIN COMPLEX.
)
/
- PLACE PINS INI'O FLAT DISK COMPLEX 5 4
-17.70 0.0 0.3040.59 1 1 0.6080 0.0 0.0
/* WITH LINER COMPLEX 6 4
-17.70 0.0 0.3040 59 1 1 0.6080 0.0 0.0 /* NO LINER
/* PLACE BOTTOM, DISKS AND TOP PORTIONS INTO BU-7 COMPLEX 2 1 0.0 0.0 0.0 1 11 0.0 0.0 0.0 COMPLEX 2 6 0.0' O.0 -35.10 1 17 0.0 0.0 0.6081 /* NO LINER O
COMPLEX 2 5 0.0 0.0 -30.8433 1 1 34 0.0 0.0 0.6081 /* WITH LINER COMPLEX 2 3 0.0 0.0 0.0 1 1 1 0.0 0.0 0.0-
1 September 9,1993 l Rev.1, dated 11/29/93 J Page 10 of 20 Table 5 (cont'd)
GEMER Geometry Model for Infinite Arrays of Containers
/* PLACE BU-7S INTO PROBLEM BOX ONE HALF AT A TIME COMPLEX 7 2
-186.465 -199.015 0.0 7 51 57.37 99.50 0.0 i
COMPLEX 7 2
-157.78
-149.266 0.0 7 4 1 57.37 99.50 0.0 U O + 11 0
)
Materials:
1 2
2 2
Interspersed Water 3
Carbon Stect i
4 Water Reflector (Full Density Water) 5 Phenolic Resin (Minimum Density) and Interspersed Weser 6
Boral(75% Boron density)
Note: Region Numbers I through 30 noted on the left are for information only and r.e not part of geometry input i
Nx, Nzl, Nz2 are integers such that Nx 22x17.70/ pitch; Nzl=(h ner-htmn)/ pitch; N?2 = (remaining height)/ pitch in
- Determined from height of fuel mixture. See Table 8A-C.
i i
O-G
.~
l September 9,1993 l Rev.1, dated 11/29193 J i
Page 11 of 20
()
Table 6 GEMER Geometry Model for 9
- 7
- 4 Triangular Accident Array of Containers f
BOX TYPE 1
/* LOWER PORTION OF BU-7 1
1 CYLINDER 3
17.808
-35.10 -35.2087 16*0.5 2
CYLINDER 5
28.575
-35.10 -42.8287 16*0.5 3
CYLINDER 3
28.5755
-35.10 -42.9374 16*0.5 4
CYLINDER 2
28.576
-35.10 -44.8424 16*0.5 5
CYLINDER 3
28.684
-35.10 -44.8424 16*0.5 BOX TYPE 2
/* SINGLE BU-7 6
CUBOID 4
59.2
-59.2 59.2
-59.2 75.85
-75.33 16 0.5 BOX TYPE 3 /* UPPER PORTION OF BU-7 7
CYLINDER 4
17.364 35.10 height 16*0.5 8
CYLINDER 3
17.429 35.10 height 16*0.5 9
CYLINDER 6
17.632 35.10 height 16*0.5 10 CYLINDER 3
17.808 35.10 height 16*0.5 11 CYLINDER 5
23.495 35.5763 height 16*0.5 12 CYLINDER 2
23.4955 36.688 height 16*0.5 13 CYLINDER 5
28.575 44.308 height 16*0.5 14 CYLINDER 3
28.5755 44.4167 height 16*0.5 15 CYLINDER 2
28.576 45.3692 height 16*0.5 l
16 CYLINDER 3
28.684 45.3692 height 16*0.5 BOX TYPE 4 /* FUEL CYLINDER CELL-WATER-TO-FUEL = 12.00 O
17 YCYLINDER 1
0.0952 17.70 -17.70 16*0.5 18 CUBOID 4
0.3040 -0.3040 17.70
-17.70 0.3040 -0.3040 16*0.5 BOX TYPE 5 /* INTERMEDIATE DISK OF FUEL CYLINDERS 19 CYLINDER 4
17.364 pitch 0.0 16*0.5 20 CYLINDER 3
17.429 pitch 0.0 16*0.5 21 CYLINDER 6
17.632 pitch 0.0 16*0.5 22 CYLINDER 3
17.808 pitch 0.0 16*0.5 23 CYLINDER 5
28.575 pitch 0.0 16*0.5 24 CYLINDER 3
28.684 pitch 0.0 16*0.5 BOX TYPE 6 /* INTERMEDIATE DISK OF FUEL CYLINDERS-BOTTOM, NO BORAL 25 CYLINDER 4
17.700 pitch 0.0 16*0.5 26 CYLINDER 3
17.808 pitch 0.0 16*0.5 27 CYLINDER S
28.575 pitch 0.0 16*0.5 28 CYLINDER 3
28.684 pitch 0.0 16*0.5 BOX TYPE 7 /* PROBLEM BOX FOR TRIANGULAR ARRAY - ONE LAYER DEEP 29 CUBOID 2 215.15
-215.15 227.7 -227.7 45.3692 -44.8424 16*0.5 l'
30 CORE O 215.15
-215.15 227.7 -227.7 181.4768 -179.3696 16*0 5 31 CUBOID 4 246.15
-246.15 258.7 -258.7 212.4768 -210.3696 16*0.5 7 1 1 1 111 1 1 1 1
BEGIN COMPLEX
/* PLACE PINS INTO FLAT DISK COMPLEX 5 4
-17.70 0.0 0.3040 59 1 1 0.6080 0.0 0.0
/* WITH LINER COMPLEX 6 4
-17.70 0.0 0.3040 59 1 1 0.6080 0.0 0.0 /* NO LINER
/* PLACE BOTTOM, DISKS AND TOP PORTIONS INTO BU-7 COMPLEX 2 1 0.0 0.0 0.0 111 0.0 0.0 0.0 COMPLEX 2 6 00 0.0 -35.10 1 17 0.0 0.0 0.6081
/* NO LINER
()
COMPLEX 2 5 0.0 0.0 -30.8433 1 1 34 0.0 0.0 0.6081
/* WITH LINER COMP LEX 2 3 0.0 0.0 0.0 1 11 0.0 0.0 0.0 w
r,-
September 9,1993 [ Rev.1, dated 11/29193 J Page 12 of 20 Table 6 (cont'd)
GEMER Geometry Model for 9 7 = 4 Triangular Accident Arrays of Containers
/* PLACE BU-7S INTO PROBLEM BOX ONE HALF AT A TIME COMPLEX 7 2
-186.465 -199.015 0.0 751 57.37 99.50 0.0 COMPLEX 7 2
-157.78
-149.266 0.0 7 41 57.37 99.50
0.0 Materials
1 UO2 + H O 2
2 Interspersed Water 3
Carbon Steel 4
Water Reflector (Full Density Water) 5 Phenolic Resin (Minimum Density) and Interspersed Water 6
Boral(75% Boron density)
Note: Region Numbers I through 31 noted on the left are for infonnation only and are not part of geometry input.
Nx, Nzl, Nz2 are integers such that Nx 2 2x17.70/ pitch: Nzl=(h rmer-h mer)/ pitch; Nz2 = (remaining height)/ pitch i
i
- Determined from height of fuel mixture. See Table 8A-C.
r O
O
September 9,1993 [ Rev.1, dated 11/29193 ]
Page 13 of20 O
Table 7 GEMER Geometry Model for Single Container BOX TYPE 1
/* LOWER PORTION OF BU-7 1
CYLINDER 3
17.808
-35.10 -35.2087 16*0.5 2
CYLINDER 5
28.575
-35.10 -42.8287 16*0.5 3
CYLINDER 3
28.5755
-35.10 -42.9374 16*0.5 4
CYLINDER 2
28.576
-35.10 -44.8424 16*0.5 S
CYLINDER 3
28.684
-35.10 -44.8424 16*0.5 BOX TYPE 2
/* SINGLE BU-7 j
6-CUBOID 4
59.2
-59.2 59.2
-59.2 75.85
-75.33 16*0.5 BOX TYPE 3 /* UPPER PORTION OF BU-7 7
CYLINDER 4
17.364 35.10 height 16*0.5 8
CYLINDER 3
17.429 35.10 height 16*0.5 9
CYLINDER 6
17.632 35.10 height 16*0.5 l'
10 CYLINDER 3
17.808 35.10 height 16*0.5 11 CYLINDER 5
23.495 35.5763 height 16*0.5 12 CYLINDER 2
23.4955 36.688 height 16*0.5 13 CYLINDER 5
28.575 44.308 height 16*0.5 14 CYLINDER 3
28.5755 44.4167 height 16*0.5 15 CYLINDER 2
28.576 45.3692 height 16*0.5 i
16 CYLINDER 3
28.684 45.3692 height 16*0.5 i
BOX TYPE 4 /* FUEL CYLINDER CELL-WATER-TO-FUEL = 12.00 l
17 YCYLINDER 1
0.0952 17.70 -17.70 16*0.5 18 CUBOID 4
0.3040 -0.3040 17.70
-17.70 0.3040 -0.3040 16*0.5 BOX TYPE 5 /* INTERMEDIATE DISK OF FUEL CYLINDERS.
l 19 CYLINDER 4
17.364 pitch 0.0 16*0.5 O
20 CYL7NDER 3
17.429 pitch 0.0 16*0.5 21 CYLINDER 6
17.632 pitch 0.0 16*0.5 22 CYLINDER 3
17.808 pitch 0.0 16*0.5 23 CYLINDER 5
28.575 pitch 0.0 16*0.5 3
24 CYLINDER 3
28.684 pitch 0.0 16*0.5 BOX TYPE 6 /* INTERMEDIATE DISK OF FUEL CYLINDERS-BOTTOM, NO BORAL l
25 CYLINDER 4
17.700 pitch 0.0 16*0.5 26 CYLINDER 3
17.808 pitch 0.0 16*0.5 27 CYLINDER 5
28.575 pitch 0.0 16*0.5 28 CYLINDER 3
28.684 pitch 0.0 16*0.5 2 11 1 111 11 1 1 BEGIN COMPLEX l
/* PLACE PINS INTO FLAT DISK i
COMPLEX 5 4
-17.70 0.0 0.3040 NX 1 1 pitch 0.0 0.0
/* WITH LINER j
COMPLEX 6 4
-17.70 0.0 0.3040 NX 1 1 pitch 0.0 0.0 /* NO LINER I
/* PLACE BOTTOM, DISKS AND TOP PORTIONS INTO Bis-7 I
COMPLEX 2 1 0.0 0.0 0.0 111 0.0 0.0 0.0 j
COMPLEX 2 6 0.0 0.0 -35.10 1 1 NZ1 0.0 0.0 pitch /* NO LINER l
COMPLEX 2 5 0.0 0.0 -30 8433 1 1 NZ2 0.0 0.0 pitch /* WITH LINER l
COMPLEX 2 3 0.0 0.0 0.0 111 0.0 0.0 0.0 1
UO + H2O l
Materials:
-1 2
2 Interspersed Water 3
Carbon Stect i
4 Water Reflector (Full Density Water) l 5
Phenolic Resin (Minimum Density) and Full Density Water 6
Boral(75% Boron density) i Notc: Region Numbers I through 28 noted on the left are for information only and are not part of geometa input.
{
Nx. Nzl, Nz2 are iniegers such that: Nx 2 2x17.70/ pitch: Nzl=(hmner-huna)/P tch; Nz2 = (remaining height)/ pitch i
+
- Determined from height of fuel mixture. See Table 8A-C.
1 I
September 9,1993 i Rev.1, dated 11/29193 J Page 14 of 20 Table 8A.
Fuel / Water lleights and Pitches forTheoretical Density U(5.0)O2 Particles Surrounded by WTOF H O 2
MASS UO2 20 KG Enrichment 5.0?o wt%
Pellet radius 0.0635 cm WTOF WTFR pitch height
( c.m)
(cm) 1 0.08 0.1590 3.685 2
0.15 0.1940 5.613 3
0.21 0.2250 7.539 4
0.27 0.2510 9.466 i
5 0.31 0.2750 11.388 6
0.35 0.2970 13.312 7
0.39 0.3180 15.239 8
0.42 0.3370 17.169 9
0.45 0.3550 19.100 10 0.48 0.3730 21.019 11 0.50 0.3890 22.953 12 0.52 0.4050 24.873 13 0.54 0.4210 26.809 g
14 0.56 0.4350 28.730 Table 8B.
Fuel / Water Heights and Pitches forTheoretical Density U(5.0)O2 Particles Surrounded by WTOF H O 2
MASS UO2 20 KG Enrichment 5.07c wt%
Particle radius 0.0952 cm WT0F WTFR pitch height (cm)
(cm) 1 0.08 0.2380 3.686 2
0.15 0.2920 5.609 3
0.21 0.3370 7.535 4
0.27 0.3770 9.456 5
0.31 0.4130 11.382 i
6 0.35 0.4460 13.312 7
0.39 0.4770 15.246 1
8 0.42 0.5060 17.162 9
0.45 0.5330 19.100 10 0.48 0.5590 21.019 11 0.50 0.5840 22.938 12 0.52 0.6080 24.881 h
13 0.54 0.6310 26.801 14 0.56 0.6530 28.722
September 9,1993 [ Rev. I, dated 11/29/93 J Page 15 of 20 i
(J Taole SC.
yuel,wa,e, neighis ond ei,ches fo,1,eo,,,icai oensi,, U<3.o,0, earticles Surrounded by WTOF II 0 2
MASS UO2 70 KG Enrichment 5.0%
wt%
Panicle radius 0.15875 cm WTOF WTFR pitch height (cm)
(cm) 1 0.08 0.3150 3.681 2
0.15 0.3860 5.614 3
0.21 0.4460 7.532 4
0.27 0.4990 9.458 5
0.31 0.5470 11.389 6
0.35 0.5900 13.302 7
0.39 0.6310 15.241 8
0.42 0.6690 17.157 l
9 0.45 0.7060 19.101 10 0.48 0.7400 21.020 11 0.50 0.7730 22.939 12 0.52 0.8050 24.858 13 0.54 0.8350 26.811 14 0.56 0.8640 28.732 III.
CRITICALITY SAFETY ANALYSIS RESULTS Tables 9 through 12 present the results of the GEMER calculations performed with the fuel materials and geometry models described in Section II. The results are all suberitical, with the most limiting case being the normal condition array with zero interspersed water. Each of the three cases is discussed in more detail in the following sections.
A.
Results for Infinlic Arrays of Undamaged Containers The results of the analysis of the tr4 angular pitch infinite array of undamaged containers are shown in Table 9 for k m as a function ofinterspersed waterdensity and particle diameter. The most reactive particle diameter in the BU-7 configuration is 0.075". The results in Table 9 show a maximum k. ofless than 0.91 for the infinite array of(normal) BU-7 containers. Single container results have previously tended to be the most reactive because the fuel in the normal and accident s
cases have been dry -due to the integrity of the innercontainment vessel under hypothetical accident conditions. However, for conditions in which uncontrolled moderation (by water) of the containers is considered, the single container is less reactive than the mays since individual containers in the arrays with full density interspersed moderator between packages may not only interact with adjacent containers, but are practically fully reflected themselves. In this respect, the single container and the accident array both are subsets of the normal condition array.
-O Tebic 10 show the re,uits fer1he mesi reective particie diemeier aed internai medererien es a function of interspersed moderator density between the containers for the infinite triangular an ay.
September 9,1993 [ Rev.1, dated 1ll29193 J Page 16 of 20 Consistent with other analyses 11, the optimum interspersed water for the nomial case is 0.0. This 30 allows maximum interaction between the already optimally moderated containers. This is an indication that components in the liner, phenolic resin and steel are more effective as absorbers when the neutrons are slowed down outside of the container.
Since the maximum keg + 20 value is less than 0.9290 (the limit of suberiticality including the method bias), the BU-7 with up to 20 kg U(5.00)O2 Percontainer with the assumption ofloss of containment (in the pails) and no restriction on moderation meets the applicable requirements for a Fissile Class I package.
Table 9 GEMER Results for Infinite Arrays of Undamaged Containers with Theoretical Density U(5.0)O2 Particles as a Function of WTOF II 0 and Pellet Diameter 2
Pellet Diameter 0.050" 0.075" 0.100" Water-to-Fuel
(o)
(o) 10 0.9004 0.9020 0.8980
(.0026)
(.0032)
(.0027) h 12 0.9000 0.9038 0.8976
(.0027)
(.0026)
(.0027) 14 0.8978 0.8947 0.8843
(.0028)
(.0027)
(.0025)
- WTOF = Water-TO-Fuel ratio Table 10 GEMER Results for Infiinte Arrays of Undamaged Containers with Theoretical Density U(5.0)O2 Particles as a Function of Interspersed II 0 for Most Reactive Particle Diameter i
2 Interspersed Pellet Diameter =0.075" i
Water Keff a
0.00 0.9038 0.0026 0.05 0.8781 0.0027 0.10 0.8705 0.0029 0.25 0.8403 0.0025 0.50 0.8266 0.0028 1.0 0.8273 0.0023 O
i Fraction of full density water
September 9,1993 l Rev.1, dated 11129193 ]
Page 17 of 20 0
B.
Results for Arrays of Damaged Containers As noted above, the most reactive condition for the Fissile Class I BU-7 container is the triangular pitch array ofoptimally moderated containers. The accident array of 9 7 4 damaged containers is a subset of the infinite normal condition array and one would normally expect the results for the finite array to show a less reactive configuration than for the infinite array of Section III. A. This is demonstrated by the single calculation summarized in Table 11 which indicates a kerr+
20 of 0.8512 for the 0.075" diameter panicle case of theoretical density UO2 at a water-to-fuel ratio of 12. This clue is less than the infinite array value of 0.9090 given by Table 9. These tables verify that the treuds are as stated and shows consistency of the results within the analysis.
Inble 11 GEMER Results for 9 7 4 Triangular Array of Damaged BU-7 Containers with Theoretical Density U(5.0)O and WTOF 2
II 0 2
Water-TO-Fuel Dia.=0.075" Kerr
(
o) 12 0.8460
(.0026)
I C.
Results for Single Containers The analysis for the fully reflected, single container uses the optimum particle diameter results obtained in Section llI.A. The GEMER results in Table 12 show a maximum kerr + 20 of 0.8357 for the case in which the WTOF is 12 for 20 kg of UO at 5.0% enrichment. The_ single 2
container is therefore not the most limiting case as it has been in prior considerations of pellets in the BU-7 container. Current analyses for the pellets are, however, consistent with the present analysis ll insofar as the limiting cases are now the arrays of optimally moderated containers.- The results are also bounded by (less reactive than) the 5.0% enrichment case analyzed in Reference 10 and the infm' ite array of normal containers shown in Table 9. The neutron multiplication factor for the fully moderated and fully reflected single container is suberitical, including the bias of-0.021 which is consistent with this analysis.
In prior analyses of the BU-7 container, the Single Container results have tended to be the most reactive because the fuel in the nonnal and accident array cases were both accepted as dry.
Ilowever, for conditions in which uncontrolled moderation (by water) of the array of containers is considered, the single container is less reactive than the normal or accident arrays since individual containers in the accident array with full density interspersed water between packages not only l
interact with adjacent containers, but are practically fully reflected themselves. (This is evident by comparing the results in Table 9 with those in Table 12).
O
September 9, I993 [ Rev.1, dated 11/29193 ]
Page 18 of 20 Table 12 GEMER Results for Fully Reflected Single 11U-7 Containers h'
with Theoretical Density U(5.0)O and WTOF 110 2
2 WTOF Dia.=0.075" Keg
(
c) 9 0.8241
(.0029) 10 0.8267
(.0031) 11 0.8301
(.0028) 12 0.8245
(.0029) 13 0.8223
(.0025) 14 0.82(X)
(.0027) e i
1 el
September 9,1993 [ Rev.1, dated 11/29/93 ]
Page 19 of 20 O
i D.
Presence of Plastic Bags or Other Moderating Materials Around the Uranium Compound (or Uranium Compound Containers)
It is sometimes desirable to ship uranium-bearing scrap enclosed in plastic bags in the BU-7 i
container. The bags may be around the fuel either inside or out, side of the three or five gallon pails.
For the BU-7 container with the contents and assumptions described in the previous sections of this report, the presence of these bags is acceptable. Since the scrap is modelled as having optimum moderation by water, even under nonnal conditions, any amount of moderation, including plastic i
bags,is acceptable. Also, since the contents of the BU-7 container with uranium oxide particles has explicitly modeled hetemgeneous fuel regions, the geometry regions bordering the inner containment vessel are water regions. Since the water content is optimum for normal and accident cases, any additional moderators such as the plastic bag, are already accounted for by the model as it has been constructed and analyzed.
IV.
SUMMARY
AND CONCLUSION This analysis has demonstrated that the BU-7 shipping container meets the requirements of 10CFR71.55 and 57 for a Fissile Class I package with contents specified as follows:
Type and Form Scrap containing uranium oxide enriched to not more than 5.0 w/o in the 235 U isotope, and with no specific limit on moderation by water, carbon, or either of their equivalents.
Maximum Quantity per Package The maximum contents per package shall be as follows:
Maximum
)
Enrichment Uranium Mass
(%)
(kg) 5.00 17.63 i
V.
REFERENCES i
1 l.
U. S. Nuclear Regulatory Commission " Certificate of Compliance for Radioactive Materials Packages", Certificate Number 9019, Revision 18.
2.
" Packaging and Trarisportation of Radioactive Material", United States Nuclear Regulatory Commission Rules and Regulations, Title 10, Chapter 1, Part 71, Code of Federal Regula-tions,11/30/88.
3.
" Test Report for Model BU-7 Bulk Uranium Shipping Container",4/25/80.
4.
" Criticality Analysis of BU-7 Container for Theoretical Density Pellets",1/24/86.
September 9,1993 l Rev.1, dated 11/29193 J Page 20 of 20 5.
" Criticality Safety Analysis of BU-7 Shipping Container for UO Powder",3/6/80.
2 6.
" Criticality Safety Analysis for BU-7 Shipping Container for 4.0% to 5.0% Enriched UO2 Powder with Failure of Containment and Moderation Control",6/1/92.
7.
"The General Electric Model BU-7 Uranium Shipping Container-Criticality Safety Analy-f sis", 2/74.
8.
DEMER/ MONTE CARLO, User's Manual,9/15/81.
9.
" Criticality Safety Analysis for BU-7 Shipping Container for UO at 4.025% Enrichment",
2 7D/92, Transnuclear, Inc.
10.
" Criticality Safety Analysis for BU-7 Shipping Container For Enrichments Below 5.0%
UO Powder with Failure of Containment and Moderation Control",8/31/93.
2 11.
" Criticality Safety Analysis for BU-7 Shipping Container For Enrichments Below 4.1%
UO Pellets / Powder with Failure of Containment and Moderation Control",9/9/93.
2 G
1 I
O
40 r
E t
t APPENDIX G i
DESIGN, MANUFACTURE AND QUALITY CONTROL FOR THE BORAL LINER
{
i O
'l
)
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LICENSE' SNM-1097 DATE 12/03/93 PAGE DOCKET 71-9019
. REVISION O
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r
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.--m...
e-....
t APPENDIX G 7
G DESIGN, MANUFACTURE AND QUALITY CONTROL GR THE BORAL LINER I.
INTRODUCTION Boral is a thermal neutron poison material composed of boron carbide and 1100 alloy aluminum.
Boron carbide is a compound having a high boron content in a physically i
stable and chemically inert form.
The 1100 alloy aluminum is a light-weight metal with high tensile strength which is protected from corrosion by a highly resistant oxide film.
The two materials, boron carbide and aluminum, are chemically compatible and ideally suited for long-term use.
()
Boral is an ideal neutron absorbing / shielding material because of the following reasons:
1 1.
The content and placement of boron carbide provides l
I a very high removal cross section for thermal i
i neutrons.
2.
Boron carbide, in the form of fine particles, is homogeneously dispersed throughout the central layer of the Boral panels.
3.
The boron carbide and aluminum materials in Boral are totally unaffected by long-term exposure to gamma radiation.
LICENSE SNM-1097 DATE 12/03/93 PAGE
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DOCKET 71-9019 REVISION O
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4.
The neutron absorbing central layer of Boral is clad with permanently attached surfaces of aluminum.
llh 5.
Boral is stable, strong, durable, and corrosion resistant.
II.
DESIGN The Boral liner is a sandwich design consisting of.080" mininum thickness Boral surrounded and protected full length on both sides by 22 gauge (.030") 300 series stainless steel.
The liner maximum OD is 13.5" and the minimum is 12.875".
The liner is 26" minimum in height.
The minimum B10 content of the Boral is.011 grams /cm2, Two lifting holes are located in the top 1/2" of the liner and stainless steel eyelets inserted thru the holes provide for wear resistance as well as a secondary means of connecting the liner materials.
e.
Buckling calculations were performed on the liner using the two stainless steel layers only for strength for the hypothetical accident condition 30 foot drop tests.
The calculations showed the liner has a factor of safety of more than 2.
This design provides for complete protection of the Boral from any handling or shipping damage since it is protected from the powder pails on the inside and the walls of the inner container on the outside by the two layers of stainless steel.
In addition, the stainless steel provides for easy cleanup of any contamination.
The verification of the presence of the Boral is easily i
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l accomplished since its entire diameter is visible from
(
both ends.
III.
MANUFACTURE j
The first step in the liner fabrication is producing the inside layer of stainless steel.
A sheet of 22 gauge material sheared to correct length and width is formed into a diameter and fusion TIG seam welded full length on an automatic welder.
Next, Boral panels are formed into full-length semi-circles and fitted around the outside of the stainless steel.
The Boral is made of two pieces since its width exceeds the manufacturing capability to produce it in a single sheet.
The outside layer of precise length and width stainless is then formed tightly around the Boral halves and again seam welded full length.
The resulting fusion weld shrinkage tends to tighten the fit between the Boral
()
and stainless steel layers and results in a very tightly layered liner.
The final operation is to punch two holes at approximately 180 apart near the top of the liner.
A stainless steel eyelet is swaged into each hole which provides wearability and additional strength for lifting the liner out of the BU-7 A serial number is engraved near the top of the liner to provide traceability to the Boral.
i e
4
()
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4 IV.
QUALITY CONTROL Boral is produced by constructing an 1100 series aluminum box, filling the box with a mixture of baron carbide and aluminum powders, and rolling it under heat and pressure into a flat plate.
The rolled panel is characterized by a solid aluminum periphery and a center section of solidified B C/ aluminum matrix clad with a 4
thin section of aluminum.
The boron carbide particle in this central layer averages 85 microns in diameter and the average spacial separation is 1.25 to 1.50 particle diameters.
The control of boron content starts with a QC verification of each B C/ aluminum powder mixture prior 4
to the rolling operation.
Each batch of powder will t
make about 5 ingots where each ingot makes one rolled sheet of Boral or about 2 % BU-7 liners.
O The hot rolling operation is the critical operation in the fabrication of Boral.
The rolling mill produces a slightly concave lateral surface profile (thicker in the middle than on the edges) and a slight taper in thickness from one end to the other.
Therefore, the thinnest cross section of a Boral panel can be found at one of the four corners.
This observation is of primary importance in the quality control program since extensive testing has shown that B10 areal density is roughly proportional to thickness of the panel.
Destructive analysis of several panels with B10 areal density readings taken along the diagonals of the panel confirm the conclusion that boron areal densities are LICENSE SNM-1097 DATE 12/03/93 PAGE DOCKET 71-9019 REVISION O
G-5
1 1
highest in the center of the panel and sampling at the
)
()
corners locates the lowest boron areal density, f
The quality control sampling plan for B10 areal density utilizes a wet chemistry technique to determine B10 content and is based on 95% confidence that 95% of the population will exceed the specification minimum of.011 grams B10 per square centimeter.
In addition, if any o
B10 areal density result is below.011, the panel will be rejected and an investigation conducted to determine the extent of the anomaly.
Past experience predicts approximately a 5% variation in Bio areal density from the panel edge to the panel center and the test coupon average will be about 13%
greater than the specification lower limit of.011.
This translates into a target panel central average of
.013 grams B10 per square centimeter and an expected
()
coupon lower limit of about.0116 grams Ble per square centimeter.
j A serial number engraved on the surface of the inside layer of stainless steel will provide traceability to the B10 areal density laboratory results.
V.
SUMMARY
The Boral liner as discussed in this appendix provides an excellent means of utilizing the thermal neutron absorption capabilities of boron carbide.
The liner is removable, easily inspectable for presence of Boral, structurally sound, durable and is easily cleaned and decontaminated.
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The fabrication process for Boral is very predictable and proven with over 25 years of manufacturing llk experience.
The tight control of boron areal density combined with criticality analyses utilizing only 75% of the specification minimum of Bio results in an extremely reliable and effective neutron poison.
O B
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