ML19289C311
| ML19289C311 | |
| Person / Time | |
|---|---|
| Site: | 07109785 |
| Issue date: | 12/21/1978 |
| From: | Macdonald C NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Brodsky R ENERGY, DEPT. OF |
| References | |
| NUDOCS 7901040099 | |
| Download: ML19289C311 (3) | |
Text
lDC (f
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UNITED STATES f
g NUCLEAR REGULATORY COMMISslON 5
f WASHINGTON, D. C. 20555
%****/
DEC 211978 FCTR: RHO 71-9785 Department of Energy Division of Naval Reactors ATTN: Mr. R. S. Brodsky Wsshi.ngton, DC 20545 Gentlemen:
This refers to your application dated April 14,1976 (NR:RR: JBDubeckG#5204),
as amended, requesti_ng approval of the Model No. S2W/S2Wa Spent Cartridge Package.
In connection with our review, we need the information identified in the enclosure to this letter.
Dlease advise us within thirty (30) days from the date of this letter when this information will be provided. The additional information requested by this letter should be submitted in the form of revised pages to the application.
If you have any questions regarding this matter, we will be pleased to meet with you and your staff.
Sin'cerely, Charles E. MacDonald, Chief
~
Transportation Branch Divisica of Fuel Cycle and Material Safety
Enclosure:
As stated 79010400iC C
/
Department of Energy Division of Naval Reactors Model No. S2W/S2Wa Spent Cartridge Package 1
Encl to ltr dtd:
1.
Nonductile Fracture Show that the carbon steel components (impact limiter, shield container and its cover, including welds and bolts) are adequately designed against nonductile failure under the hypothetical accident 30-foot free-drop and 40-inch puncture loadings at low service temperature environments. The present evaluation of the packaging for nonductile fracture failure is incomplete.
2.
30-Foot Flat Top and Top Oblique Drops - Core Cartridge Hold-down Studs Revise the stud stability evaluation to show that the applied loads do not exceed either crush ultimate load limit or inelastic (elastic if stress is less than its yield value) buckling load limit.
According to the analysis shown in pages 1.99a-l.99c of SAR. the studs would begin to yield at about 18g (axial load = 56 kips) and buckle at 329 (axial load = 117.3 kips). Which are much less than the predicted q-loads.
In the inelastic buckling analysis, the eccentric loading effect, which is particularly important in an inelastic buckling case should be considered.
In the control rod withdrawal distance analysis (pp 1.103-1.107), scram shaft buckling analysis should be made by taking into account of additional load ircposed on the shaft due to held-down plate /R&S container top cover contacts either due to excessive crushing or buckling of the core cartridge hold-down studs.
(It should be noted that if the sleeve does not buckle, it can sustain stress much higher than the static yield stress (or limit load) due to material strain hardening, strain rate and mushrooming effects.
Hence, the conclusion in the application of no shaft buckling in a post-yield state based on the fact that the critical inelastic shaft buckling load is greater than the sleeve yield (limit) load is not justified).
The dynamic model used in finding dynamic amplification factors is not realistic because the core cartridge and scram shaft masses are mostly transmitted to the impact limiter through top cover assemblies of R&S and shielding containers rather than through the bottom-ends of these containers.
3.
30-foot Stable Bottom Oblique Drop The analysis should be revised or supported to consider the following:
) ** A.
Revise the g-load analysis to include the effect of additional work energy contributed by the lead crushing forces.
B.
Demonstrate that the g-load value of 360g used in R&S container shell stress analysis adequately takes care of possible dynamic amplification effects.by taking into account effects of fiexibility of structural elements of the system.
Include effects of lead crushing forces and core cartridge contact forces at the support shoe assemblies in the stress analysis /
evaluation at all affected critical locations.
C.
Appropriate measures should be taken to limit the R&S container wall stresses to that below the material ultimate strength (Su) at temperature. Note that the current standards on design criteria are contained in Reg. Guide 7.6 (also Appendix F of ASME Code III) which limit stress intensity of primary membrane stress not to exceed 0.7 Su and 2.4 S, where Sm = design stress m
intensity value given in Appendix I of ASME Code III; stress intensity arising from primary membrane stress and primary bending stresses should not exceed Su and 3.6 Sm.
In obtaining the stress intensity values, in addition to longitudinal and sheer stresses, other stress components (e.g., circumferential stresses in page 1.027T) should also be combined.
D.
Use. of lead flow stress of 3,200 psi should be justified noting that the static ultimate tensi,le strength of chemical lead may be as low as 600 psi at 250 F.
E.
In the scram shaft deceleration capability analysis, justify neglection of the portion of hold-down plate impact loading that is transmitted through scram shaft; also include thermal stress effects in the evaluation unless they are shown to be insignificant.
4.
30-foot ' Flat Bottom Drop The analysis should consider the following:
A.
R&S coltainer shell g-load and stress analysis - Revise the analysis to include effects of forces and work energies contributed by support shoe housing and lead crushing forces and the portion cf core cartridge loads (transmitted to the R&S container through the support shoe housing assemblies).
B.
Show that the dynamic amplification on the dynamic impact response of R&S container is not significant and may be ignored.
C.
See comment 3.C. above.
D.
Show that the R&S container shell does not buckle under the combined axial impact load and radial lead pressure.