ML20207H374
| ML20207H374 | |
| Person / Time | |
|---|---|
| Site: | 07109792 |
| Issue date: | 12/29/1986 |
| From: | Macdonald C NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Engel W ENERGY, DEPT. OF |
| References | |
| NUDOCS 8701070516 | |
| Download: ML20207H374 (3) | |
Text
~ * ')(-9 ) 9 L yJunsTo pachtin FCTC: RHO M 71-9792 EC19 Y Department of Energy Naval Reactors ATTN: Mr. W. P. Engel Washington, DC 20585 Gentlemen:
This refers to your application dated May 14, 1986, as amended, requesting approval of the Model No. DIG CB-TS Model 1 package.
In connection with our review, we need the information identified in the enclosure to this letter.
Please advise us within 20. days from the date of this letter when this infonnation will be provided. The additional information requested by this letter should be submitted in the form of revised pages. If you have any questions regarding this r,atter, we would be pleased to meet with you and your staff.
Sincerely, Orig'_31 C3med by mi.mcr ?. PvTDi1D Charles E. MacDonald, Chief Transportation Certification Branch Division of Fuel Cycle and Material Safety, NMSS
Enclosure:
As stated
, ,, Distribution: w/ encl SAF6 Docket File NRC PDR IE HQ Region I RH0degaarden (2) HWLee EPEaston CRMarotta NMSS R/F FCTC R/F OFC: FCTCO : :FCTC FCTC FCT 4 0 ____ _ '
NAME:RH0degaarden: alm HWLev EPEaston CR a ott CEMac onal DATE: 12/M/86 : :12/ff/86:12/c/86: 12/1//86: 12//f /86 : '
OFFICIAL RECORD COPY 8701070516 861229 PDR ADOCK 071**1**
C PDR
Department of Energy Naval Reactors Docket No. 71-9792 Encl to ltr dtd: DEC29 W
- 1. The' application did not show that the package meets the requirements of 10 CFR Part 71 under nomal conditions of transport. Because the cask is l made of cast steel and concrete, impact energy can only be absorbed by crushing the cask. The analysis of 2, 5, and 10 g load is inadequate to show the cask has sufficient structural integrity to meet the requirements of the " Normal Conditions of Transport" specified in 10 CFR 971.71.
- 2. The application does not demonstrate that the package meets the require-ments of 10 CFR.Part 71 under the accident conditions. The analyses of the container under the 30-foot free drop conditions were based on the assumption that the cask and the CB-TS assembly are rigid bodies. Thus, the analysis does not provide information on internal cask stresses or show that the stresses would be within acceptable limits. The application should be revised, taking into consideration the following comments:
- a. Stresses in the cask should be tabulated at a sufficient number of points to show the general stress state within the cask as well as the critically stressed points. Provide a sketch of the cask showing the locations at which stresses are tabulated. Separate points should be designated on the inside and outside of the shells at a given location to account for through wall bending.
- b. The details of the stress calculations should be presented for each of the various loads under nomal and accident conditions in 10 CFR Part 71 including the 30-foot free drop. The stresses calculated for various loads shn 'd be appropriately combined (see Regulatory Guide 7.8).
- c. The application should shew that the stresses at each point and for each load combination are within acceptable limits. Note that stress levels specified in Regulatory Guide 7.6 may not be applicable to the materials used to construct this cask. This is because the A352, Gr.LC2-1 cast steel is not an ASME code material for containment vessels. Revise the application to provide the allowable stress criteria that will be used to design the cask and justify that the criteria are appropriate.
- d. The dynamic stress factor and the confinement factor for the reinforced concrete shell should be justified. Also, the ability of the concrete to absorb energy after crushing should be justified.
Richard H. Odegaarden 2
- 3. For the 30-foot impact condition, the application should show that closure head bolt stresses are within the design stress limits. If the bolt is under the combined action of both tensile and shear forces, the interaction equation should be used. The analysis should provide free body diagram of the closure head to show that the forces satisfy the equilibrium condition.
- 4. The application indicates that the containment vessel is made from cast steel with a nil ductility transition temperature (TNDT) equal to -80*F.
This conclusion was reached based on test results. In the absence of knowledge with regard to flaw sizes and shapes, the fracture arrest criterien should be used in design of the cask. In accordance with the NRC Draft Regulatory Guide entitled " Fracture Toughness Criteria for Ferritic Steel Shipping Containers With a Wall Thickness Greater than Four Inches (0.1m)," TNDT for a lowest service temperature (LST) of -20 F at the cask wall thickness is approximately equal to -140*F. Thus, for TNDT = -80'F, the LST should not be lower than 40 F.
- 5. The outer concrete shell is connected to the inner containment vessel by 72 short rebars welded to the surface of the containment vessel. The rebars are not effective shear connectors and do not have sufficient length to develop full strength. In addition, high strength rebars may be susceptible to problems after welding depending upon the weld technique used. The effectiveness of the rebar as shear connector should be addressed which considers the above during the normal condition of transport.
- 6. The " equivalent" materials should be identified and their material properties listed.
- - - _ _ .