ML23331A695

Appendix 4, Ujv Report: Z-1172- Amendment 2, SKODA MCNP Calculation of Cask Criticality for Atabor Internals of Thickness 4 Mm, Amendment 2

ML23331A695
Person / Time
Site:	07103103
Issue date:	08/01/2005
From:	Secured Transportation Services
To:	Boyle R Office of Nuclear Material Safety and Safeguards, US Dept of Transportation (DOT), Office of Hazardous Materials Safety
Shared Package
ML23331A280	List: ML23331A675 ML23331A681 ML23331A683 ML23331A684 ML23331A686 ML23331A688 ML23331A690 ML23331A692 ML23331A693 ML23331A695 ML23331A697 ML23331A698 ML23331A700 ML23331A702
References
CAC 001794, EPID L-2023-DOT-0004
Download: ML23331A695 (5)

Text

Ústav jaderného výzkumu ez a.s.

Divize reaktorových sluzeb

ÚJV Report: Z - 1172 - Amendment 2

MCNP Calculation of Cask Criticality for ATABOR Internals of Thickness 4 mm

- Amendment 2

Prepared by: Stanislav Flíbor

Department Manager: Ing. Milan Marek, CSc.

DRS Manager: Ing. Jan Kysela, CSc.

ez, August 2005

píloha 4Adod2-kritinost.doc

1. Fuel IRT-2M with 36% enrichment of 235U in a square stainless steel sheath

1.1 Material composition of fuel

Used library of effective cross-Enrichment 36,00% sections 235U weight portion 19,03% 92235.60c 238U weight portion 33,83% 92238.60c Al weight portion 40,00% 13027.60c O weight portion 7,14% 8016.60c

235U weight 230,00 g 238U weight 408,89 g Al weight 483,44 g O weight 86,27 g

Total 1208,61g

Active part length 60 cm Fuel volume 284,1281 cm3

U density 2,2486 g.cm-3 Fuel density 4,2537 g.cm-3

U atomic density 5,7146E+21 at.cm-3 Fuel atomic density 5,5120E+22 at.cm-3

235U mol. weight 235,0439 g.mol-1 238U mol. weight 238,0508 g.mol-1 Al mol. weight 26,9815 g.mol-1 O mol. weight 15,9994 g.mol-1

2 / 5 píloha 4Adod2-kritinost.doc

Fig. 1: Model of a basic cell with fuel IRT-2M 36% in a square stainless steel sheath

Fig. 2: Cross section of a cask with fuel IRT-2M 36% in a square stainless steel sheath

3 / 5 píloha 4Adod2-kritinost.doc

Fig. 3: Longitudinal section of a cask with fuel IRT-2M 36% in a square stainless steel sheath

4 / 5 píloha 4Adod2-kritinost.doc

1.2 Description of calculations The basic model of fuel IRT-2M 36% inserted in a stainless steel sheath of wall thickness 0,15 cm was used for the calculations. Internal sheath size is 7,15 x 7,15 cm. The sheath height is modified so that it could go in the internal space of the transport cask.

Two calculations were performed: a) the cask and sheath are completely flooded with water, and b) water only enters the cask, but not the sheath.

These two states have been selected as the two worst possible, resulting from the calculations for fuel not closed in sheath.

All calculations have been performed using MCNP 4C program, in mode KCODE. 50 non-active cycles of calculation (keff is not calculated) were used for the calculation of the initial distribution of points to start the calculation. A total number of 350 cycles with 5000 starting points in each cycle were used to determine the calculated value of keff.

1.3 Calculation results The resulting value of keff was determined at 95%/95% level of probability/reliability.

The resulting value of calculation for fuel without sheath in a flooded cask:

keff = 0,6439 0,0031 (see Report Z-1172, page 10).

The cask and the stainless steel sheath are filled with water:

keff = 0,6296 0,0012.

The cask is filled with water, but not the stainless steel sheath:

keff = 0,1164 0,0004.

1.4 Conclusion With respect to the fact that the resulting values of calculations for fuel IRT-2M 36% in stainless steel sheath are lower than the resulting values of calculations for fuel without a sheath, the calculations without a sheath can be considered to be conservative estimation of calculations.

5 / 5