ML20027C678
| ML20027C678 | |
| Person / Time | |
|---|---|
| Site: | 07106639 |
| Issue date: | 09/07/1982 |
| From: | Prichard R ENERGY, DEPT. OF |
| To: | Macdonald C NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| Shared Package | |
| ML20027C679 | List: |
| References | |
| 21240, NUDOCS 8210270074 | |
| Download: ML20027C678 (4) | |
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Qign I fSS Department of Energy Washington, D.C. 20545
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2 I p.,g g j Mr. C. E. MacDonald, Chief SN.7 t
Transportation Certification Branch p#-
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Division of Fuel Cycle and s
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Material Safety
" '3 U.S. Nuclear Regulatory Commission Washington, D.C.
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Dear Mr. MacDonald:
Enclosed are eight copies of the following documents for USA /6639/BF(D0E/AL),
the FN-IA spent fuel cask:
1.
Safety Analysis Report 2.
Engineering Evaluation Report 3.
Certificate of Compliance There are two of these casks, and they are suitable for use by many research reactors including NRC licensed facilities such as the National Bureau of Standards reactor in Gaithersburg, MD. The spent fuel at this NBS reactor is ready for shipment, and we propose that you give the NRC evaluation for certification high priority.
Please advise T. L. Dunckel if you need further information.
Sincerely, i
Reuben P. Prichard Acting Director Safety Engineering and Analysis Division
Enclosure:
cc:
R. R. Rawl, 00T w/ DOE cert
& Engr Eval J. N. Maddox, ER-70 w/o encl R. B. Chitwood, NE-340 w/o enci j
R. F. Garrison, DP-122 w/o encl E. L. Barraclough, AL w/o encl e s,s a., 7:7 m f;a,
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e, 2124D 8210270074 820907 PDR ADOCK 07106639 B
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I EVALUATION OF MH-1A SARP l
1.
Structural - Structural characteristics of the MH-1A cask were evaluated by calculation rather than tasts. Basic data for the materials which are used in cask construction were tabulated and appear to be selected from appropriate sources and to have values which are commonly used. Equations used for stresses, deflections, accelerations, forces and other conditions are either those which are well known or have also been selected from ap-propriate handbooks or references. Weights of the various cask components
.have been tabulated and the most conservative (with TRIGA fuel) weight was used in calculations.
Evaluation against general standards for all packages showed that there is little or no possibility for chemical or galvanic reactions between the materials that make up the cask. Lifting devices were found to be adequate both for the cask and for the lid. Tiedown lugs were found to be a possible weak spot in the tiedown system. The bearing stress and yield stress are essentially equal, indicating that the holes in the lugs could tear out under extreme loads. Load resistance as a simple beam and the requirement to meet an external pressure of 25 psig were evaluated e
and the essk was found to be satisfactory.
The normal conditions of transport posed no problems for the cask.
Thermal conditions (including brittle fracture), pressure, vibration, j
water spray, free drop, penetration and compression will cause no des-radation of cask performance.
Hypothetical accident conditions were considered in relation to the structure of the cask. The 30-foot free drop included end, side, center of gravity over a corner, and slapdown orientation. It was found that the impact limiters had sufficient redwood to absorb the kinetic energies involved and the cask would suffer no disabling damage. Stresses in the 30 foot drop, 1000F ambient and maximum decay heat and insolation were extensively investigated and found to be well within allowable limits.
The 6-inch diameter puncture pin tests and immersion test were also found to be well within the capabilities of the cask. Analysis of the TRIGA fuel basket, the MURR basket, the HFBR and NBSR baskets showed that the baskets, under end drop and side drop conditions, were adequate to main-tain their geometry and provide fuel separation.
2.
Thermal - The MH-1A cask thermal evaluation utilized MH-1A spent fuel parameters since these are more restrictive than those of TRIGA or MTR spent fuels. No auxiliary cooling systems or fire shields are used in the MH-1A design. It is aircooled and no liquids are used in the cask.
Shipments are made in a dry condition. Maximum temperature attained I
by the silicone seal (4830F) is within the capability of this material and no leakage is expected. Maximum pressures ir.volved are less than design pressures.
Under normal conditions of transport the decay heat load is 1.73 kw, based on MH-1A spent fuel. Added to this is a solar heat load of 0.40 kw l
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_y-for a total of 2.13 kw.
The cask is modeled by a one-eighth section based on symmetry considerations. The analysis was done using the THT-D heat j
transfer computer program. A degree of conservatism is injected into the analysis by leaving out the thermal capacities of the fuel basket and its contents. Normal operations at the maximum and minintaa temperatures (1300 to -40 F ambient) were found to pose no problems. The cask and components 0
were well able to withstand the pressures and stresses resulting from these conditions.
The hypothetical thermal accident evaluation used the same thermal model as previously noted. Since the end and side drop analyses predicted no significant damage, no effects of damage were included in the thermal i
analysis. Though temperatures involved are higher than for normal opera-tions, it was found that fuel elements did not reach unacceptable tempera-tures. Seals of the lid and component flanges were within temperature ranges acceptable for short time durations and pressures are well within the design pressure of the cask. It was found that some 64 in3 of lead would melt at the corners of the cask as a result of the thermal test.
Adequate expansion space is provided for such an eventuality and no rupture of the shell is expected. The lead is expected to begin to re-solidify in about 3 minutes.
3.
Shieldina - Shielding material in the NH-1A cask is 7 5/8 inches of lead encased in inner and outer shells of 1/2 inch steel. In the shielding analysis no credit was taken for self-attenuation of the basket or fuel elements. Cases evaluated included 48 TRIGA elements, 48 NBS half-ele-ments, 32 HFBR elements and 12 MURR elements. The heat load of 1.73 kw and shielding pose the major constraints to loading of the cask with the j
shielding usually determining the earliest shipping times. Tables are presented which indicate that some 13 to 16 months are required from i
reactor discharge to shipping date, depending upon the fuel involved.
l Decay heat source terms were generated using the well established ORIGEN code.
i The QAD point kernel shielding code was used to determine shielding 1
adequacy. Results obtained indicate that dose rates at accessible pack-ages surfaces are approximately 80 ar/hr under normal conditions. Under accident conditions the dose rate is about 18 mr/hr at 3 feet from acces-sible surfaces. These doses are well within the regulatory rates of 200 ar/hr and 1000 ar/hr respectively. The loss of lead (0.2 weight percent) as found in the accident thermal analysis was considered in the accident dose rate.
4.
Criticality - The criticality safety of the MH-1A cask was investigated to determine that the various fuel loadings would meet the requirements for a Fissile Class III shipment. Fuel baskets considered included the 48 TRIGA fuel element basket, the 48 NBS half MTR-element basket, the 32 HFBR fuel MTR-element basket and the 12 NURR fuel MTR-element basket.
A notable feature of the basket designs is the inclusion of boral plates 1
as. neutron absorbers. It was found that the cask with the above mentioned baskets provided adequate assurance of criticality safety for fresh as well as spent fuels in both normal and accident conditions.
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The models investigated included geometries for normal and accident con-ditions as well as the orientation of the. fuel with respect to the baskets.
The analysis for normal conditions included consideration of water inisak-age., as well as two casks in contact with one another and closely reflected on all sides. The accident condition considered oce cask, optimally moder-ated and fully reflected on all sides. It was further assumed that the fuel elements stayed in the fuel element cavity as under normal conditions.
Should the MTR elements collapse, the system was found to be under-moderated.
The KENO IV code was used in the criticality avsluation with several other,
code packages being used to obtain neutron cross ashtions. Presh fuel was assumed in the analysis and no credit was taken for the presence of fission s
product neutron poisons. Benchmark comparisons were made by use of.several criticality experiments with SPERT-D MTR fuel and a bias of 0.036 *.n'keff was found. If the uncertainty in the bias is considered, a bias of 'O.025 in keff is established at 99% confidence ILvel.
s 5.
Quality Assurance - There is a brief description of the QA pro $ rams as carried out in previous years, from when the cask'vas fabricated in 1964 up to the time of this SARP submittal. A QA plan for future years is n
outlined which is to be applied to the design, fabrication and testing of the MTR fuel baskets and modifications to the MH-1A cask top and bottom impact limiters. Sections are presented for all the required activities from " Organization" to " Audits". fIf this plan is implemented a's presented, there should be no QA problems with theiresults of the cask' modifications and the new MTR fuel baskets.
't,J 6.
General - Operating procedures are provided for loading and univading spent '
fuels of interest. A checklist gives' sequential, stepsby-step.. directions for all necessary operationc. A similar checklist is prorided for the preparation of an empty package for transport. A table of specific dimen-sions, weights and other pertinent data is provided as an aid in fulfilling shipment requirements such as shippintspapers, placards, etc. An appendix describing the procedure for establishing the presence of boral is included.
l Acceptante tests and a maintenance program'are described. Theacceptency tests were those used when the cask was modified in 1971. Thc QA program carried out at that time met regulatory requirements.
Based on the data presented in this Safety Analysis Report for Packcging, it is concluded that the NH-1A cask will meet regulatory requirement for
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the safe transport of radioactive materials ~when loaded and otherwise handled as described.
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