ML20041C451
| ML20041C451 | |
| Person / Time | |
|---|---|
| Site: | 07109140 |
| Issue date: | 02/12/1982 |
| From: | Macdonald C NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Clay Johnson NAC INTERNATIONAL INC. (FORMERLY NUCLEAR ASSURANCE |
| References | |
| NUDOCS 8203010479 | |
| Download: ML20041C451 (9) | |
Text
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FEB 121982
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ATTN: Mr. Charles R. Johnson dd.g C/
24 Executive Park West 3
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Atlanta, GA 30329 a
Gentlemen:
This refers to your application dated December 8,1978 requesting approval of the Model No. NAC-3K packaging.
In connection with our review, we need the information identified in the enclosure to this letter. Please note that we have not reviewed the proposed t.>peratirg procedures, acceptance tests, and maintenance program at this tiae. This will be done after you have responded to this request for additlonal information and the design is firm.
Please advise us within thirty (30) days from the date of this letter when this infomation will be provided. The additional infonnation requested by this letter should be submitted in the form of revised pages.
If you have any questions regarding this matter, we would be pleased to meet with you and your staff.
Sincerely, aW orid#
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Charles E. MacDonald, Chie.f u
Transportation Certification 3 ranch l
Division of Fuel Cycle and gg Material Safety,IMSS
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Nuclear Assurance Corporation' Model No NAC-3K Docket No. 71-9140 FEB 121982 Enc 1 to ltr dtd:
STRUCTURAL 1.
The application does not adequately demonstrate the integrity of the containment vessel under the Normal Conditions of Transport or Hypothetical Accident Conditions specified in Appendices A and B of 10 CFR 71. The application should be revised to address all of the normal and accident load combinations specified in Regulatory Guide 7.8 and show that the stresses in the containment vessel are within the limits specified in Regulatory Guide 7.6.
In making this revision, the following information should be provided:
a.
A sketch of the containment vessel (including the end plates) showing the points at which the maximum stresses are expected to occur for various load cases and load combinations.
b.
A tabulation of the stresses at each of these points for each load case.
c.
A tabulation of the combined stresses at each of these points for each load ccmbination specified in Regulatory Guide 7.8.
d.
An explicit comparison for each load combination showing that stresses at each point meet all the applicable limits specified in Regulatory Guide 7.6.
e.
An explicit comparison showing that the range of stresses at each point are within the limits specified in C.3, C.4, and C.7 of Regulatory Guide 7.6.
State the stress concentration factors used for C.3 and C.7.
2.
The section on design criteria (1.1.2) should be revised to specify the allowable stress criteria used to design the closure fasteners and the fuel basket for normal and accident conditions. The application should also justify that these criteria are adequate to assure the package meets 10 CFR 71.
3.
Revise the analysis of closure bolt loading under Normal Conditions of Transport (Sect.1.4.4.1.6) to explicitly show that stresses in the fasteners meet the criteria specified in Section 1.1.2 for normal conditions. Justify the assumption that the 10-g tie-down condition produces the largest loads in the bolts under normal conditions. Show how the internal inertia loads of the cover (e.g., 1-foot side drop) are reacted.
Specify the manufacturer and model number of the heli-coils and show that they are capable of developing the full strength of the bolts.
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. 4.
The analysis of normal conditions of transport (1.6.3.1) should include an evaluation of the 130 F Heat Test-specified -in Appendix A of 10 CFR 71.
5.
The equations and symbols for rotation and displacement used in Section 1.6.1.3 are confusing (e.g., e, e e,
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W W, w, w, w Provide a sketch showing the pilysi8al bimen9 Ion eac8, symbol reilres8n)ts and the positive direction of each. Show the derivation of the equation used to calculate angular discontinuity (p47) and justify that assuming this value to be zero is appropriate.
Show how a moment reaction, and a horizontal shear reaction, could be developed at the shell-to-closure lid juncture. Justify that assuming this type of reaction is appropriate for a bolted closure (p47, p48A, and p48D). Justify that it is appropriate to analyze a bolted closure using equations 1.19,1.20, and 1.21. Note that these equations are based upon an assumption that radial displacement and rotation of the shell and bolted closure must be equal (pl67).
6 The containment vessel fatigue analysis (p52) should be revised to account for the maximum range of stresses produced throughout normal operations and Normal Conditions of Transport (Appendix A of 10 CFR 71). State the stress concentration factors that will be used at structural discontinuities.
Provide a table showing the i
stresses under each loading conditions for various locations on the cask and explicitly show the calculations for the maximum alternatina stress intensity (Sal t)
- 7.
Revise Section 1.6.6 to show explicitly that the package meets the requirements of 10 CFR 571.35 under one-foot drop test conditions.
Note that acceptance standards in 10 CFR 71 and allowable stresses in Regulatory Guide 7.6 are different for Normal Conditions of
- Transport and Hypothetical Accident Conditions.
8.
Either evaluate the effects ci.avity water freezing (Section 1.6.2) i or specify the operational controls that will prevent the occennce of freezing and justify that the controls are effective.
9.
The equations derived on pages 60 and 84 to calculate energy dissipated by redwood under enddrop conditions are confusing and apparently incorrect. Show that the inner and outer steel tubes will deform in compression, as assumed, rather than by buckling or bending.
t Also, justify that it is appropriate to use the equation for g-load on page 86 for systems where force varies with crush depth.
Clarify i
what effective diameter was used to evaluate the impact limiter for end impact and justify that this valve is appropriate, i
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- 10. With regard to the anslysis of side impact loading (Section 1.7.1.2).
a.
Either verify that the cooling fins and trunnions are not deformed under 30-foot side drop conditions or revise the analysis to account for the increased g-load.
b.
Show that the end plates will deform in compression as assumed (p91).
Consider other possible modes of deformation (e.g.,
buckling, bending). Note that the analysis in Section 1.7.1.2.1 is not adequate to support a conclusion that the rings will not buckle. The analysis did not consider all likely buckling modes or possible inelastic buckling.
c.
The curves, equations, and calculations of g-load and maximum deformation under side drop conditions are confusing and should be clarified with additional narrative, sketches and derivations. Also show the derivation of the equation for Gside.at the bottom of page 93.
- 11. Revise Section 1.7.1.3.4 (pl14) to include an analysis of the cover and bolts for the maxi um force that could act outward under top-corner or oblique angle impact conditions. Also note that the inward load under end-impact conditions (pil5) would be larger if the cask were transporting less than a full load of 12 assemblies.
Evaluate the closure bolts and seals under 30-foot side drop conditions.
- 12. The evaluation of side impact bending (Section 1.7.1.3.9) should be revised to justify analyzing the cask as a simple beam rather than as a shell. Also evaluate the cask for corner and obliaue angle drop orientations and show that the stresses in the shell meet -the criteria specified in Section 1.1.2 of the SAR. Justify that it is appropriate to assume the edges of the impact limiter would be effective in a corner or oblique angle impact. Note that a large portion of the impact limiter is not " backed-up" and does not bare against the cask (see Figure 1.17). Also note that the crush equation is not valid up to point "C" as assumed on page 100.
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. 13. Revise the package drawings to show the location and dimensions of the four stand-off plates analyzed in Section 1.7.1.3.9.5.
Clarify whether the plates are located at both ends of the basket. Also, the buckling analysis on page 125 apparently does not consider the holes shown in the plates on Drawing 115-4-Dll.
Describe the design provisions that have been made to station the active fuel region with respect to the bcral liner in the axial direction. Show that the fuel assemblies will not move longitudinally with respect to the poison materials under 30-foot end drop conditions.
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- 14. Revise the analysis of the structural support plates in the basket (p127) to consider.the actual pattern of contact between the fuel and the plate, rather than assuming fuel loads will be uniformly di-turbed over the entire plate area.
Note this also effects the assumption on page 133 regarding typical basket sections.
- 15. The evaluation of the fuel basket under 30-foot drop conditions (p128-143) should be revised to consider the following:
The ar.alysis should evaluate the effects that could be produced a.
with less than a full load of 12 fuel assemblies (e.g., rotation of the basket, eccentric axial loads, larger bending movements, j
etc.).
b.
The buckling analysis of stiffened plates (Section' l.7.1.3.9.8) assumes the two 0.315 inch thick plates act together as a structural section. The appropriateness of this assumption should be demonstrated.
Note the AISC specifications referenced in Section 1.7.1.3.9.7 are for plate girders.
The analysis of the corner gusset plate (Section 1.7.1.3.9.9.1) c.
should be revised to include a free-body diagram showing the forces and reactions that act on the plate and should also evaluate possible inelastic buckling.
i d.
The buckling analysis shculd either consider the member forces calculated in the finite element analysis or show they are less than those used to evaluate buckling.
The evaluation of the basket under 30-foot side drop conditions e.
t (Section 1.7.1.3.9.9.2) should show that other angular orientations would not be more damaging to the basket (i.e., other than 0 and 45 ).
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The evaluation should show that the stresses in the basket do not exceed the allowable values specified in Section 1.1.2 of the application.
g.
Revise the drawings to show the boral liner and its construction features in greater detail. Show how the boral liner is attached to the basket. Also, show that the boral liner would not be free to move longitudinally relative to the fuel assemblies following the 30-foot side drop test.
- 16. The evaluation of cask puncture (Section 1.7.2) should show that the stresses in the cask cover (pl45) and cask shell (p153) meet the allowable values specified in Section 1.1.2 of the application.
Note item 12 above, regarding analysis of the cask shell. The l
analysis of the closure bolts and cover (pl45) should also consider the 6-inch diameter pin to impinge at the edge of the closure plate in a top end test orientation. The relief and drain valve puncture analysis (Section 1.7.2.5) should be revised to consider the reduced effectiveness of the redwood (p151) that would result from the.
puncture test being preceeded by a 30-foot side drop (i.e., the redwood would be compressed before the puncture test). The analysis should also evaluate the effects that would result from the redwo6d and impact limiter shroud being compressed against the valves and rupture discs (p145).
- 17. Revise the engineering drawings of the package to include the cavity and basket radial tolerances referenced in the calculations on page 162 and the axial direction tolerances referenced in the calculations on page 162 and the axial direction tolerances referencod on page 163. The analysis of fuel pin axial expansion (pl64) should be revised to clearly show the dimensions and tolerances that assure a 0.59 inch gap for all fuel that will be transported.
Also, the thermal section of the application should be revised to show that no more than 6 fuel pins would be exposed at any inclination and to show that the fuel pin temperature would not exceed 900 F.
- 18. The analysis of discontinuity stresses in Section 1.7.3.3.2 and the anslysis of thermal stresses in Section 1.7.3.3.6 should consider the comments included in item 5, above.
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- 19. Revise Section 6.0 of the application and the engineering drawings of the package to specify the minimum and maximum value of torque that will be used to tighten the containment vessel bolts.
Revise Section 1.7.3.3.9.2 (p176) to show that the specified torque will-provide adequate clamping force to maintain a seal under the normal and accident test conditions in 10 CFR Part 71.
Show explicitly that under hypothetical accident conditions, the stresses in the fasteners would meet the criteria specified in Section 1.1.2.
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. 20. Show that the range of total stresses due to the initial and fabrication states and the normal operating and accident condition states of j
the containment vessel are within acceptable limits (refer to position 7 in Regulatory Guide 7.6). This should include an evaluation of the stresses caused by " heat-up" during the fire test (refer to Section 1.6.1.3.5 of the application). Note that the temperature of the outer wall changes from approximately 289 F (Table 1.5) to approximately 678 F (Table 1.9) within 30 minutes.
- 21. Specify the pressure at which the containment vessel relief system would be activated. Compare this pressure to the maximum pressures expected to occur under the normal and accident tests in 10 CFR 71 and show that the margin against relief is adequate.
Note that the effects of waterhammer should be included in this evaluation, as well as in the evaluation of the containment vessel under impact loads.
- 22. The engineering drawings of the containment vessel should be revised to specify a tolerance for roundness and straightness of the cavity.
- 23. The criteria and discussion in Section 1.6.2 (p54) are not adequate to show that the containment vessel materials and welds would not be subject to brittle fracture under cold temperature service conditions.
The application should demonstrate that the containment vessel materials
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and welds have adequate fracture toughness to withstand the normal and accident tests under cold temperature conditions (see Regulatory Guide 7.8).
- 24. Describe the procedures that will be used to fabricate and inspect the cask shell and end plates. This should include a detailed description of the procedures that will be followed for welding and stress relieving the vessel. Provide engineering drawings which show the location, size and details of the welds on the cask shell and end plates.
Show that the fabrication procedures are adequate to assure that the structural integrity of the vessel would not be degraded as a result of the fabrication process. Describe any procedures that will be used to assure the vessel materials will have their intended properties after fabrication is complete.
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- 25. Revise section 1.4.3.2 to clarify whether the lid lifting devices are a structural part of the lid.
If not, the provisions of 10 CFR 571.31(c)(2) do not apply.
If so, revise the analysis to consider the horizontal components (if any) of the lifting loads and revise the drawings to show the lifting devices.
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. 26. Describe the design provisions (if any) that have been made to accommodate differential thermal expansion between the package and the vehicle in the longitudinal direction. Justify the assumption (Section 1.4.4) that the tie-down loads will be equally distributed between four trunnions. Also, revise Drawing 115-4-D5 to show the dimension of the inside diameter of the trunnion.
- 27. Since 10 CFP,71 does not require packages to be evaluated for a one-foot drop test with theii impact limiters removed, Section 1.4.4.1.3 may be deleted.
Sections 1.6.5.1 and 1.6.9 regarding IAEA requirements may also be deleted.
THERMAL 1.
Provide assurances and correct application where necessary to reflect the fact that the normal conditions of transport used in the design are those of 130 F ambient air with direct sunlight and still air, not 100 F as stated in the application in several places.
(Example -Tables 1.2,1.5,1.6, and 2.11 as well as other locations within the application.)
2.
Differing values for the maximum temperatures and pressures resulting from both the normal and accident conditions are given in the application. Provide a summary of the resulting maximum temperatures and pressures as used in the cask design or provide explanation of these discrepancies as they appear in the application.
(Example -
maximum coolant pressure for hypothetical accident is given as both 3.54 MPa and 3.13 MPa and maximum coolant temperature is given as both 235 F and 228 F.)
3.
Provide an analysis of containment vessel maximum internal pressures for both the nonnal transport and accident damage conditions considering the maximum cavity pressure resulting from gases released from failed fuel pins, radiolytic decomposition of water, and steam.
4.
Provide the maximum internal coolant pressure which can be expected for conditions of normal transport in the event the cask is in the vertical position until steady state thermal conditions are reached.
5.
Identify all pressures as guage or absolute.
6.
Provide calculations which justify the 3 kw solar radiation values used in the thermal analysis. Consider the effect which the copper fins will have on the amount of solar energy absorbed by the cask.
. 7.
Provide more complete numerical results and curves that can be read accurately for the transient results of the thermal accident analysis.
8.
Specify the pressure relief valve setting and tolerances.
9.
Specify the quantity of coolant to be drained from the cask in preparation for shipment.
CRITICALITY Reanalyze the effective multiplication factor of the cask containing the twelve PWR fuel assemblies. The analysis in Section 5 of the applicativa needs to be revised because of the following deficiencies:
(a) The effective pitch of the homogenized fuel rods should be 1.496 cm rather than 1.41 cm when the 25 water holes are taken into accouat.
(b) The homogenized fuel assembly has dimensions of 24.31 cm (1.43 cm x 17 rods) rather than 22.97 cm and 22.87 cm.
(c) The proposed fuel assembly contains 19.3 kg U-235 but the analysis was for 17.0 kg U-235.
(d) Boron clumping (non-homogeneity) in the Boral sheets has not been taken into account.
(e) Figures 5.1 through 5.3 do not dimension the fuel region.
(f) Lack of KEN 0 input / output sheets.
(g) Analysis addresses only one specific fuel bundle, range of fuel loadings should be addressed.
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