ML24338A189
| ML24338A189 | |
| Person / Time | |
|---|---|
| Site: | 07105797 |
| Issue date: | 11/13/2024 |
| From: | Ohio State University, US Dept of Agriculture |
| To: | Office of Nuclear Material Safety and Safeguards |
| Shared Package | |
| ML24338A187 | List: |
| References | |
| Certificate of Compliance No. 5797, EPID L-2023-LLA-0156 | |
| Download: ML24338A189 (1) | |
Text
OBS-M-1:
Explain how the polyethylene foam was neglected in the analysis as discussed on pg. 2-6 of the FSAR. Identify how the energy absorption characteristics of the foam were modeled and whether lock up was also considered.
This information is needed to determine compliance with 10 CFR 71.51(a) and 10 CFR 71.55(d) and 10 CFR 71.55(e).
Page 2-6 of the FSAR states, [b]ecause the foam will mitigate the actual deceleration of the fuel elements The polyethylene foam does not exhibit crush resistance properties; therefore, no energy absorption or effects of lock-up were considered in analysis of the HFIR design. While the foam may absorb a negligible amount of energy during impact conditions, its only purpose is to provide padding to the fuel elements for protection from the effects of vibration and shock during normal transport. As such, the forces imparted to the other packaging materials or contents are not assumed to be mitigated by its presence during Normal Conditions of Transport (NCT) or Hypothetical Accident Conditions (HAC) impact conditions.
Fuel element response to NCT and HAC loadings are analyzed in Reference 2.12.10. The foam is not considered in this analysis, and therefore neither the impact force nor the force resisted by the fuel plates are mitigated by the presence of polyethylene foam in the analysis. The fuel element deceleration during these scenarios is calculated by dividing the impact force by package weight (Section 6.1 of Reference 2.12.10). Section 6.3 of Reference 2.12.10 provides a detailed account of how the fuel elements react to these forces. The inner shell, or side plate, of the fuel elements is assumed rigid, and only the fuel plates along the bottom half of the element (i.e., the impact side) are assumed to resist the applied forces. The calculation then determines the max force developed in the plates to estimate the maximum expected plate bending, which is related to a Chapter 4, Containment, analysis that assumes the maximum bend angle a plate can undergo without rupturing and subjecting its radioactive contents to release.
The analysis and physical testing demonstrate that the packaging design provides protection for the fuel elements under NCT and HAC.
For clarification, the following changes are proposed to the FSAR:
1.
Page 2-5, first paragraph of Section 2.2.1, revise next-to-last sentence to state, A 1-inch-thick layer of polyethylene foam that lines the inside of the cavity provides padding and shock resistance during normal transport.
2.
Page 2-6, revise first full paragraph to state, Because the polyethylene foam does not provide appreciable energy absorption capability, its contributions during analyzed drop scenarios were not considered in the analysis.
Enclosure - Observation Response Certificate of Compliance No. 5797 Docket No. 71-5797 Page 1 of 4
OBS-M-2:
For the plywood yield strength values (in-plane), the Table 2.5, Mechanical Properties Used in Analysis lists 3250 psi Static, based on Unpublished data transmitted by J. W. Langhaar of E. I.
duPont de Nemours and Company, Inc. to L.B. Shappert and others, dated February 19, 1974. In addition, in FSAR 2.2.1 the applicant states that the data from actual tests support this assumption (Reference 2.12.11). The staff requests the applicant provide the data that supports the values chosen in Table 2.5.
This information is needed to determine compliance with 10 CFR 71.51(a) and 10 CFR 71.55(d) and 10 CFR 71.55(e).
The compressive strength values utilized in the analysis are discussed in FSAR Reference 2.12.10, Evaluation of Structural Integrity of HFIR Shipping Containers for Impact Forces Resulting from Normal and Hypothetical Accident Drop Conditions of 10 CFR 71. Therein (pg. 2-10), the U.S. Forest Service Agricultural Handbook No. 72, Wood Handbook: Wood as an Engineering Material (1974), is referenced for calculation of the compressive strength of plywood parallel to the face grain, FCW, and perpendicular to the face grain, FCX, through the following equations:
FCW = EW/ECL FCL FCX = EX/ECL FCL Where:
EW = modulus of elasticity of plywood parallel to the face grain EX = modulus of elasticity of plywood perpendicular to the face grain ECL = modulus of elasticity of the veneer parallel to the grain FCL = compressive strength of the veneer parallel to the grain The values for FCW and FCX are tabulated in Reference 2.12.10 as being within a range of 3262 and 3805 psi. Moreover, the Wood Handbook, Reference 8 of FSAR Reference 2.12.10, Table 4-2, provides a minimum range for compression parallel to the grain (max crushing strength) of 3110 to 6220 psi for Douglas fir. Therefore, the compressive strength of 3250 psi, as utilized in the FSAR, was judged as being a reasonable value.
To clarify this matter, it is proposed that Note b of Table 2.5 of ORNL/RRD/INT-180 be amended to state the following:
Value based on data from U.S. Forest Products Laboratory Handbook No. 72, Wood Handbook, 1974, Table 4-2, and as approximated in Reference 2.12.10, pp 2-10.
Enclosure - Observation Response Certificate of Compliance No. 5797 Docket No. 71-5797 Page 2 of 4
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