ML20056G652
| ML20056G652 | |
| Person / Time | |
|---|---|
| Site: | 07105450 |
| Issue date: | 09/01/1993 |
| From: | Samders C WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP. |
| To: | Haughney C NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| CON-NRC-93-023, CON-NRC-93-23 NUDOCS 9309070016 | |
| Download: ML20056G652 (6) | |
Text
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NRC-93-023 Westinghouse Commercial Nuclear aee a cmma sun cana m50 Electric Corporation Fuel Division 803 776 2610 September 1,1993 U. S. Nuclear Regulatory Commission Charles J. Haughney, Chief 6H3 l
Storage and Transport Systems Branch Division of Industrial and Medical Nuclear Safety, IMNS 11555 Rockville Pike l
Rockville, MD 20852
Subject:
Docket 71-5450: Application for Approval of Packaging, RCC Shipping Containers l
Gentlemen:
l Westinghouse Electric Corporation hereby requests a letter amendment to our shipping l
container license, USA /5450/AF, to permit shipping fuel with enriched annular axial l
blanket pellets. We request this authorization for shipments continuing through December 31,1993.
l Details supporting this request are in the attached pages, if you have any questions concerning this submittal, please write to me at the above address; telephone (803) 776-2610, extension 3426; or fav. (803) 695-3964.
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$.5 C. F. Sanders, Manager Nuclear Materials Management and Product Records 0200?L.
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I APPLICATION DETAILS t
September 1,1993 i
1.
A total of 48 assemblies will be shipped to Northern States Power Company's Prairie Island 2 plant under this authorization.
i 2.
The shipments shall be made between September 6,1993, and December 31,1993.
3.
The shipments shall consist of Westinghouse-designed 14x14 OFA fuel assemblies.
4.
The fuel stack will consist of 144 inches (nominal) of UQ enriched to 4.95%
(t.ominal) "5U, with the tcp six inches of the fuel made of annular pellets; the middle 132 inches of fuel made of solid pellets; and the bottom six inches of fuel made of annular pellets. Figure 1 shows thi Annular pellet; Figure 2 shows the fuel stack in the rod. The solid pellets are the same length and OD as the annular pellets.
5.
All parameters for this fuel are the same as those listed in Certificate of Compliance 5450, Paragraph 5.b.iii, column 1, except that the top and bottom six inches of the fuel stack has annular pellets; due to the smaller amount of UQ in the annular n5 pellets, the maximum U per fuel assembly is reduced from 22.1 to 21.6 kgs. The weight difference was calculated using the fm
- W.w = ( W, + W, (
))W,2s n
where u5 W. = the new maximum U weight per assembly with annular blankets, W, = the portion of the stack which is solid pellets, or 11/12 of the stack, W. = the portion of the stack which is annular pellets, or 1/12 of the stack, N, = the nominal weight of cne annular pellet, or 0.0107 lbs.,
1 N, = the nominal weight of one solid pellet, or 0.0143 lbs., and n5 Wa = the maximum U' weight per assembly with all solid pellets.
6.
Figure 3 illustrates the KENO model used for the HAC.
t 7.
Reactivity differences are discussed in a following page.
C:\\WPDoC\\93CoRRES.NRC september 1,1993 Page 1 of 5 l
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e FIGURE 1 ENRICHED ANNULAR AXIAL BLANKET PELLET
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C:\\WPDOC\\93CORRES.NRC September 1,1993 rage 2 of 5
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FIGURE 2 PRAIRIE ISLAND 214X14 OFA FUEL STACK l
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REACTIVITY DIFFERENCES Calculations have been performed using the KENO Va criticality ude m evaluate the reactivity of the Westinghouse RCC shipping container when loaded with NSP 14x14 OFA fuel assemblies. The NSP assemblies include six inch, enriched, annular axial blankets on i
both the top and bottom ends of the active fuel zone. Fuel assembly enrichment was assumed to be 5.0 wt% for both the solid center pellets and the annular axial blanket pellets.
Two cases were modeled. The first case evaluates the RCC cask reactivity under the same bases and assumptions applied to all previous Westinghouse cask evaluations - namely, that the insides of the fuel rods are dry and are not subject to the water which is assumed to flood the open areas within the cask. The second case is identical to the first, except that the water is assumed also to penetrate into the inside of each fuel rod and flood the pellet-txlad gap areas and the annulus of the annular blanket pellets.
Both cases were modeled under the Hypothetical Accident Condition (HAC) scenario and with three-dimensional geometry to capture the effects of the axial blanket zones. Reactivity results for the two cases are:
Case 1:
Fuel Rod Insides Remain Dry Keno K,y = 0.92487 i 0.00490 (1-sigma)
K, with biases and 95/95 uncertainties = 0.94126 Case 2:
Fuel Rod Insides Are Flooded Keno K, = 0.93107 0.00425 (1-sigma)
K,y with biases and 95/95 uncertainties = 0.94646 As the results show, the ingress of water into the interict of the fuel rods does cause an increase in reactivity. However, since both cases are less than 0.95, the acceptance criteria for criticality are satisfied.
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l C:\\WPDoC\\93CoRRES.NRC September 1,1993 Page 4 of 5 l
r FIGURE 3 i
KENO MODEL OF FUEL ASSEMBLY WITIIIN COhTAINER FOR SQUARE LATI' ICE FUEL 1
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