ML20042G884
| ML20042G884 | |
| Person / Time | |
|---|---|
| Site: | 07109789 |
| Issue date: | 05/15/1990 |
| From: | Macdonald C NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | |
| Shared Package | |
| ML20042G882 | List: |
| References | |
| NUDOCS 9005160225 | |
| Download: ML20042G884 (4) | |
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UNITED STATES
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'g NUCLE AR REGULATORY COMMISSION r 2 WALHING T ON, D. C. 20556
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j SAFETY EVALUATION REPORT Model No. AlW-3 Core Barrel and Thermal Shield Disposal Container Certificate of Compliance No. 9789 Revision No. 0 i
By application dated May 12, 1983, as supplemented, the Division of Naval j
Reactors, U.S. Department of Energy requested a Certificate of Compliance for i
the A1W-3 Core Barrel and Themal Shield Disposal Container (A1W 3 CB/TS DC).
PACKAGE DESCRIPTION The package is used for shipment and disposal of irradiated and contaminated AlW-3 shipboard or prototype components.
The shipment of shipboard components consists of an AlW-3 Core Barrel (CB), an AlW 3 Thermal Shield (TS), a Thermal Shield Lower Plate Plug, a Themal Shield Shock Ring, a Composite Ring (CR) and miscellaneous light weight shock ring items enclosed in the AlW-3 CB/TS DC. The composite ring provides spacing and support between the CB and TS.
The l
calculated shipboard package shipping weight is approximately 243,000 pounds.
The shipment of prototype components consists of an A1W-3 CB, an AlW-3 TS, a Thermal Shield Lower Plate Plug, and a Spacer Ring which provides spacing and support between the CB and TS. The calculated prototype package shipping weight is approximately 235,000 pounds.
The container is a 6-inch thick steel cylinder (ASTM A737), measuring 104 inches in outside. diameter, 92 inches in inside diameter, and 171 inches long.
The I
container has 12-inch thick top and bottom plates, which are welded to the container body during a shipment with the cargo. A support flange,122 inches in outside diameter, is welded to the outside of the container body near the top end of the container, and provides a means of attaching the top plate with bolts during an empty shipment.
A side crush ring, 122 inches in outside diameter, is welded to the outside of the container bcdy near the bottom end of the container, and provides a means for energy absorption during a side drop accident.
A bottom crush ring is also welded to the underside of the bottom plate for energy absorption during a bottom drop accident. Two shield rings are welded to the outside of the container body to provide additional shielding protection on the lower two thirds of the container.
-STRUCTURAL EVALUATION
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The applicant perfomed detailed structural analyses to show that the lifting and tie-down devices of the package are adequately designed to meet the requirements of 10 CFR 6 71.45. No significant themal stresses can be developed u
due to differential thermal expansions of the various components. The disposal container was also evaluated-for the maximum internal pressure and increased external pressure loads. The resulting stresses due to these pressure loads were very low and would have no effect on package safety.
The. applicant performed 100% nondestructive inspection of the container and 900516022G 900515 gDA ADOCK 071097G9 PDC s
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performed fracture mechanics calculations to obtain the critical fracture stress.
Since the critical fracture stress obtained in this manner are greater than the dynamic yield stress of the material, brittle fracture failure of the container 1
is precluded, j
Both static linear-elastic finite element analyses and dynamic plastic finite i
j-element analyses were performed to evaluate the structural responses of the J
disposal container under the normal and hypothetical accident conditions in 10 CFR Part 71. The linear-elastic static analyses were used to predict stresses resulting from the impact loading at locations away from the points of impact.
The dy'namic plastic DYNA 30 analyses were performed for the flat top drop and the 75 top corner drop accidents. These dynamic plastic finite element analyses have shown that high strains only occur in the top plate directly under the lifting lugs and there is large margin to failure of the top plate. Results of DYNA-3D analyses have also shown that strain in the cylinder to-top plate weld from the 75' top corner drop is circumferential1y localized to the crush zone and is much less than the failure strain for the material. The deformations of the container during the drop and puncture events are small and there will be l
no significant rearrangement of the contents. The staff agrees with the structural analyses included in the application.
l THERMAL EVALVATION Normal Conditions The applicant evaluated the AlW 3 CB/TS DC for the normal-heat condition of transport assuming an ambient temperature of 13.0*F and an internal heat source
- of 200 watts.
The maximum temperature calculated anywhere within the package was approximately 202'F. The mimimum temperature assumed for the cold condition of transport was -40'F.
In this temperature range, -40' to 202'F, there were no I
significant problems with either material properties or thermal stresses.
Accident Conditions
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The applicant evaluated the CB/TS DC for accident conditions assuming a maximum of 12 gallons of residual water. The maximum temperature calculated within the containment vessel was approximately 346*F.
The maximum package surface l
temperature was about 626 F.
None of the package components will melt or be damaged at these temperatures.
There are no gaskets or 0-ring seals as the containment vessel and all penetrations are welded shut. The maximum pressure l
within the package was calculated assuming the volumetric expansion of heated air and steam pressure resulting from the 12 gallons of residual water.
Thg maximum pressure based on a temperature of 346'F and a package volume of 424 ft is approximately 108 psia or 93 psig.
The package meets the thermal requirements of 10 CFR Part 71.
I CONTAINMENT EVALUATION The containment boundary for the A1W 3 CB/TS DC is comprised of the container i
body, and top and bottom end plates.
The bottom end plate is welded to the L
container body with a full penetration weld. The top end plate is field welded
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to the container body prior to shipment. The top end plate weld penetrates approximately 5.2 inches of the 6-inch thickness of tht container body wall.
The vent lines in the top cover and the drain lines in the bottom plate are plugged and welded prior to shipment.
There are no other penetrations in the 1
containment boundary. No seals are used in the A1W-3 CB/TS DC.
The package contents consist of irradiated metallic hardware. The only potential sources for radioactive release are crud and activated corrosion products. The total amount of crud and activated corrosion products adhering to the core barrel and thermal shield is estimated to be about 2.2 curies.
Shock tests performed l
by DOE /NR indicate that only about 0.1% of the crud and corrosion products would be released under accident conditions. Since the total amount of material that could be released under accident conditions is less than an A, quantity, the package meets the containment requirement of 10 CFR Part 71 for accident conditions.
Based on the limited quantity of releasable material and the fact that the package is welded shut, staff has concluded that the package meets the l
containment requirements specified in 10 CFR 6 71.51 for both normal and accident l
conditions of transport.
SHIELDING EVALUATION The applicant used the SPAN 4 3D shielding computer program to demonstrate that a shipment of an irradiated AlW-3 core barrel and thermal shield disposal container is in compliance with the radiological limits of 10 CFR Part 71.
The results of the applicant's calculations are given in the following table.
I GAMMA DOSE RATE (MREM /HR) l lidg Igg Bottom Normal Conditions Package surface 50.2 51.9 2.1 Two meters from package surface 9.5 8.9 0.73 Accident Conditions One meter from package surface 465 l
The staff reviewed the SPAN-4 shielding analysis for the above dose rate estimates and finds it acceptable. In addition, the staff used the Microshield personal computer program to check one of the applicant's results in the table.
The source term was taken from the information provided by the applicant.
The source was distributed in a cylindrical void. The contents' self shielding and the cask's shield were modeled as cylindrical shells.
The staff's calculated dose rate on the package surface at the side was-63.0 mr/hr.
This value is expected to be conservatively high because the source is actually distributed in a cylindrical shell.
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CRITICALITY No criticality evaluation is required.
The package contains only irradiated hardwares.
OPERATING PROCEDURES General operating procedures for use of the shipping container are specified in Chapter 7 of the application.
Separate procedures are given for loading of shipboard components and prototype components. The container will be buried at a disposal facility.
Thus, there is no procedure for unloading the container.
ACCEPTANCE TESTS AND MAINTENANCE PROGRAM Chapter 8 of the application specifies the acceptance tests to be performed prior to the first use of the container. These tests include visual inspections, ultrasonic test of 100% of the base materials, and magnetic particle test of all welds.
A maintenance program is not required because the container will be used for a single shipment.
CONCLUSIONS l
Based upon the information in the application, the staff concludes that the package design meets the requirements of 10 CFR Part 71.
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v Charles E. MacDonald, Chief Transportation Branch Division of Safeguards and MAY 15 1990 Transportation, NHSS
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