ML20149E133
| ML20149E133 | |
| Person / Time | |
|---|---|
| Site: | 07109268 |
| Issue date: | 06/30/1997 |
| From: | SIERRA NUCLEAR, INC. |
| To: | |
| Shared Package | |
| ML20149E111 | List: |
| References | |
| SNC-95-71SAR, SNC-95-74SAR-R02, SNC-95-74SAR-R2, NUDOCS 9707180114 | |
| Download: ML20149E133 (3) | |
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SNC-95-71SAR 1
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SAFETY ANALYSIS REPORT g
FOR TiiE TRANSTOR SHIPPING CASK SYSTEM i
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i PREPARED BY:
SIERRA NUCLEAR CORPORATION I
Scorrs VALLEY, CALIFORNIA ATLANTA, GEORGIA JUNE 1997 0
W 9707100114 970714 ADOCK071g28 PDR-C
SAR - TranStorm Shipping Cask Revision 2 Docket No. 71-9268 June 1997 nv; 5.0 SHIELDING EVALUATION The shielding analysis of the SNC TranStor Shipping Cask is described in this chapter.
The TranStor Shipping Cask may carry baskets with three types of payload: 24 PWR spent fuel assemblies,61 BWR spent fuel assemblies, or greater than Class C (GTCC) wa.ite. The PWR basket may also accommodate up to four fuel assembly size cans which may contain partial, damaged, or failed PWR fuel assemblies. The cans may also contain fuel debris (up to 10 kg of debris per basket). The BWR basket may accommodate up to eight fuel assembly size cans which may also contain partial, damaged or failed BWR fuel assemblies, or up to 10 kg of fuel debris, For each LWR fuel type, a wide range of burnup levels is evaluated. The minimum cooling time required to produce cask external dose rates below the 10 CFR 71 limits for normal and accident conditions is established as a function of bumup level. The minimum required cooling times for PWR and BWR fuel are presented in Figure 5.0-1.
A minimum required cooling time of 5 years applies for all burnup levels below those presented in Figure 5.0-1. For burnup levels between those specifically analyzed in the shielding analyses (i.e. the data points shown in Figure 5.01), the required cooling time is determined through linear interpolation between the points. After the required cooling time is determined, the value should be rounded up to the nearest integer ycar.
Gamma and neutron dose rates vary with fuel initial enrichment, with lower initial enrichments producing higher dose rates for a given burnup level and cooling time. For this reason, minimum allowable initial enrichment lev,els are established as a function of burnup level, based upon the initial enrichment levels assumed in the shielding analyses.
The minimum allowable initial enrichment is shown versus burnup level for PWR and BWR fuel in Figure 5.0-2.
For the bumup levels that were studied in the shielding analyses, the initial enrichment values shown in Figure 5.0-2 represent those assumed in the analyses. As discussed in Section 5.2, the gamma and neutron source terms used in the shielding analyses for the minimum burnup (30 GWd/MTU - 5 year cooling time) l cases are bounding for all lower burnup fuel which meets the initial enrichment requirements shown in Figure 5.0-2.
The TranStor cask may also transport stainless steel clad fuel. A maximum burnup level of 40 GWd/MTU and a minimum cooling time of 15 years is established for stainless steel clad PWR fuel. A maximum bumup level of 25 GWd/MTU and a minimum cooling time of 10 years is established for stainless steel clad BWR fuel.
Analyses presented in Section 5.5.2 show that any stainless steel clad fuel that meets the above requirements will not produce cask extemal dose rates that exceed any 10 CFR 71 limits.
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O SAR - TranStor Shipping Cask Revision 2 Docket No. 71-9268 June 1997 21 20 7 19
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FIGURE 5.0-1 REQUIRED COOLING TIME VS. BURNUP LEVEL FOR PWR AND BWR SPENT FUEL ASSEMBLIES (ZIRCALOY CLADDING) 5-2 l
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