ML20032D463
| ML20032D463 | |
| Person / Time | |
|---|---|
| Site: | 07109154 |
| Issue date: | 11/04/1981 |
| From: | Macdonald C NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | |
| Shared Package | |
| ML20032D458 | List: |
| References | |
| NUDOCS 8111170041 | |
| Download: ML20032D463 (8) | |
Text
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U.S. Nuclear Regulatory Commission Transportation Certification Branch Safety Evaluation Report Model No. 858 Docket No. 71-9154
SUMMARY
By application dated October 29, 1981, Technical Operations,- Inc. requested design approval of the Model No. 858 Gamma Ray Projector.
Shielding of the 110 curies of Cobalt-60 is provided by a minimum of 4.0" thickness of depleted uranium.
Containment is provided by the source capsule meeting.the requirements of special form.
Based on the statements and representations contained in the application, and the conditions listed below, we have concluded that the Model No. 858 package meets the performance requirements of 10 CFR Part 71.
REFERENCE Technical Operations, Inc. application dated October 29, 1981.
DRAWINGS The packaging is constructed in accordance with the following Technical Operations, Inc. Drawing Nos.:
85L90, Sheets 1, 2, 3, 4, 5, and 6 of 6, Rev. O 66025, Sheets 2 and 3 of 3, rev. A.
, PACKAGING DESCRIPTION A steel encased, uranium shielded Gamma Ray Projector.
Primary components consist of an outer steel shell (21" x 12" x 14.62"), internal bracing,.
polyurethane potting material, depleted uranium shield (4.0" min. thickness) and a zircalloy "S" tube (0.467" OD x 0.385" ID).
The contents are securely positioned in the zircalloy "S" tube by a source cable locking device and shipping plug. Tamper-proof seals are provided on the packaging and a 1/4-inch thick steel shipping plate is bolted over the source locking mechanism for additional protection during transport. The total weight of the package is approximately 502 pounds.
CONTENTS (1) Type and form of material Cobalt-60 as sealed sources which meet the requirements of special
' form as defined in 10 CFR 571.4(o).
1 (2) Maximum quantity of material per package 110 curies.
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{DRADOCK 07109154 PDR-
. CONTAINMENT The Cobalt-60 is encapsulated in either 304 or 304L stainless steel which meets the requirements of special form as defined in 10 CFR 571.4(o).
STRUCTURAL The applicant's evaluation of the Model No. 858 to meet the 30 foot drop test and 40-inch puncture test of 10 CFR Part 71 is based on comparison with similar models that were actually tested. The extended side frames of the test models and Model 858 afford adequate attenuation and protection to enable the units to sustain the 30 foot drop test recuirements. The 40-inch puncture test was performed on the side and shipping plate locations of the test models.
The applicant reports that these tests resulted in no reduction of shielding effectiveness or loss of radioactive material.
To eliminate loss of structural integrity-in the event of pressure buildup resulting from decomposition and gas generation of the potting foam, in the event of a fire, non-leak tight joint assemblies are incorporated in the design.
Internal bracing within the unit secures the uranium shield position, also in the event that the potting foam is dissipated through decomposition.
A.
General Standards for all Packaging Chemical and Galvanic Reaction Copper separators have been used at steel-uranium interfaces to prevent the possibility of the formation of iron-uranium eutectic all oy.
Therefore, there is no significant chemical, galvanic, or other reaction among the packaging components, or between the packaging components and the packaging contents.
Positive Closure Inadvertent opening of the package is prevented by means of positive closure devices.
Lifting Devices Two lifting eyebolts are shown by analysis to be capable of lifting three times the maximum package weight without exceeding material yield stress in any material of the packaging.
Tie-Down Devices The same eyebolts for lifting are used for tie-down.
As shown by analysis, these eyebolts are capable of withstanding the load combinations of 10 CFR 571.31.
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_m Tie-Down Devices An independent check has shown that the container end plate has enough weld strength and shearing capacity to resist separation from the container shell or shearing through the end plate due to excessive forces in the eyebolts.
It is concluded that failure of the lifting / tie-down devices under I
excessive loads would not result in any loss of packaging effectiveness or release of radioactive materials.
B.
Structural Standards for Type B and Large Quantity Packaging Load Resistance The package is shown by analysis to be capable of withstanding statically five times ~of its fully loaded weight uniformly distributed along its length without generating stress in any material of the packaging in excess of-its yield strength.
External Pressure 4
Applicant has shown by analysis that the packaging design meets the regulatory requirements.
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C.
Normal Conditions of Transport Heat The staff agrees with the applicant's conclusion that the package can safely withstand the normal heat transport conditions.
Cold The staff agrees with the applicant!s conclusion that the package 1
will withstand the normal. transport cold conditions.
Brittle fracture is judged not to have significant effects on packaging safety for the following reasons:
1)
Small quantity of radioactive materials as content (110 curies of Cobalt-60).
2)
Special form (fixed contamination; materials not readily dispersible),
3)
The container shell thickness is only 1/4 inch. For this thickness, no fracture toughness requirements are required
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for the package category.
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4).
The' total weight of the package is only about 502 pounds. The' 1/4 inch shell and the r.igid polyurethane form shall be.able to absorb the energy resulted.from the drop test even if the 1/2 inch side frames are ignored.
Pressure The containment vessel has been shown to withstand atmospheric pressure _ considerably greater than 0.5 times standard atmospheric 7
pressure.
- Vibration The vibration loading is-judged not to have significant effects on packaging safety.
Water Spray Water spray will have no effect on the package.
Free Drop The package can safely withstand the free drop requirement of 10 CFR Part 71 Appendix A as demonstrated by meeting the more stringent requirements specified in Appendix B of 10 CFR Part 71 for the hypothetical accident conditions.
Corner Drop
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Not applicable for this design case, Penetration i
By comparison with similar models that were actually tested, the i
staff agrees with the applicant's judgement that this regulatory loading has insignificant adverse effects on the package design.
Compression
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The staff agrees with the applicant's conclusion that this regulatory requirement will not adversely effect the package.
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Hypothetical Accident Conditions Free Drop The applicant's evaluation of the Model 858 to meet the 30 foot drop test is based on comparison with similar models that were actually tested.
It has been shown that the extended side frames of the container provide adequate attenuation and prntection to enable the container to sustain the 30-foot drop test.
The side frames of the Model 858 are 1/2-inch thick.
The side frames of the test model are one inch thick with large openings cutted in the extended region of the frames.
Because of these openings, the extended side frames of the test model are considered less effective than those of the Model 858.
Thus, based on the satisfactory performance of the test model, it is concluded that the Model 858 will suffer no loss of shielding or structural integrity as a result of the 30-foot free drop test.
Puncture By comparison with a similar model actually tested, it is concluded that the Model 858 can successfully sithstand the puncture condition of 10 CFR Part 71.
Thermal The applicant has shown that the temperature increase due to the fire test to 1475 F has no significant effects on Model 858 package.
Immersion Not applicable, fissile packages only.
THERMAL The source capsule with a maximum decay heat of 2 watts (actual estimate is 1.84 watts) is centered in the depleted uranium (D.U.) shield.
The shield assembly is surrounded by rigid polyurethane foam within the outer steel box assembly.
The D.U. shield is mounted to a steel collinator positioning tube; the D.U. shield and steel face are separated by copper disks; the 6.75-inen diameter steel plate is in direct contact with the ambient air. The polyurethane foam insulates the D.U. shield and internal heat is dissipated primarily through the 6.75-inch diameter steel disk; heat is transferred to the ambient environment by natural convection 6
' i and thermal radiation (180 F). The applicant has performed calculations to snow that the surface temperature will not exceed 50 C (122 F) in t
shade,.or 82*C (180*F) with insolation. for normal conditions with a 38*F (100 F) ambient and 2 watt internal heat; the actual-values for these conditions are reported as 40*F (104 F) and 62*C (144 F), respectively.
For ambient temperature cf 130 F a maximum of 174 F 'for 2 watts internal heat and insolation would be. expected.
The applicant assunes a maximum package temperature of 800*C (1475"F) for the 1/2 hour 800 C fire test; the polyurethane foam is assumed to decompose and escape through vent holes and assembly joints.
The applicant notes that none of the metal components (e.g., steel structure, D.U.
shield, copper, etc.) have melting points below 800*C.
Containment is provided by the source capsule which meets the special form requirements which includes a thermal. test.
The applicant has demonstrated that the packaging satisfies the thermal conditions specified in 10 CFR Part 71 for normal and accident conditions.
The staff also considered the thermal effects by enclosure of the package within a wooden protective packaging.
The staff concluded that enclosure of the package within a wooden overpack would not have a'significant effect on the above.
SHIELDING The applicant requests approval for shipment of a maximum source of.110 curies of Cobalt-60 in the subject package. This encapsulated source is to be containted in a zircalloy or titanium "S" tube in the geometric I
center of the package. The "S" tube is cast inside a depleted uranium assembly which is then enclosed in a 1/4-inch steel box.
The average thickness of the depleted uranium shield at mid-center and at closest (6 inches) distance to the steel box surface is of the order of 4 inches.
The applicant has performed a gamma radiation profile of the package containing 99 curies of Co-60 and have extrapolated dose rates for the requested 110 curies source.
The result of measurements at contact of the package were mrem /hr Side 156 Top 122 Bottom 133
All of the above dose rates meet the permitted maximum contact dose rate of 200 mrem /hr.
The staff has performed a check on the reasonableness of the dose rates reported by the following analysis 10 13 110 curies Co-60 = 110 x 3.7 x 10 x 2 x 1.25 MEV/sec = 10 MEV/sec I3 For such a point source, having an energy strength of 10 MEV/sec shielded by 4 inches of depleted uranium followed by 1/4-inch steel at a distance of 6 inches from the point source, the following contact dose rate was calculated to be 167 mrem /hr in good agreement with the applicant's measured value of 156 mrem /hr.
The d8se rate was calculated via:
13
, _ 10 exp (-10.16 x 1.15) exp (.635 x.414) x 4.3 4 x 3.14 (15.24)2 4
2
= 9.55 x 10 MEV/cm -sec This energy flux of 1.25 MEV photons converts to 4
9.55 x 10 x 1.75 x 10-3 = 167 mrem /hr.
To the extent that the source will not move from the geometric center (inflection pt of the "S" tube) and the shielos stay in place in the accident, approval is reconnended.
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- s. o CRITIChlITY Not applicable, no fissile material.
OPERATING, ACCEPTANCE, AND MAINTENANCE General operating, acceptance, and maintenance procedures and controls are given in Sections 7 and 8 of the application.
In addition to the requirements of 10 CFR 5 571.53, 71.54, and 71.55, Sections 7 and 8 provide adequate information for development of procedures to prepare the package for transport.
CONDITIONS 1.
The source must be secured in the shielded position of the packaging by tne shipping plug, source assembly, and locking device. The shipping plug, source assembly used must be fabricated of materials l capable of resisting a 1475"F fire environment for one-half hour.
and maintaining their positioning function. The bal.1 stop of the source assembly must engage the locking device.
The flexible cable of the source assembly and shipping plug must be of sufficient length and diameter to provide positive positioning of the source in the shielded position.
2.
'The nameplates must be fabricated of materials capable of resisting the fire test of 10 CFR Part 71 and maintaining their legibility.
f-CONCLUSION Based on our review, the statements and representations contained in the application and the conditions listed above, we find that the Model No.
858 package meets the requirements of 10 CFR Part 71.
Charles E. MacDonald, Chief Transportation Certification Branch Division of Fuel Cycle and Material Safety, NMSS NOV 0 41981 Date:
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