vitmog

CASTOR-V/21 spent fuel cask

The next load of the CASTOR-V/21 fuel cask [1] is considered below:

10 spent $15 \times 15$ PWR fuel assemblies of 3.11 wt.% initial enrichment, 35.7 GWd/MTU burn-up, and 46 months cooling time;
7 quadratic combined absorbers which consist of two coaxial polyethylene and lead prizms of inradius 7 cm and 10.5 cm respectively;
4 empty positions.


Figure 1: Horizontal cross-section of the loaded cask

Computed flux functional - ambient equivalent dose H*(10) [2] rates.

Several computations cases results are provided:

Single cask (total running time - 13.5 hours);
Additional calculation for the single cask side surface primary gamma dose rates distribution (total running time - 25.2 hours);
The cask is located in the center of $10^5$ cm air sphere inside a hypothetical labyrinth-like absorbing either polyethylene or lead construction which is designed for domination of the skyshine effect in radiation transfer (total running time - 12.6 hours);
The same as above model but construction has an air-filled perforation of 100 cm radius on 2500 cm height above the cask bottom (total running time - 12.7 hours).

Below, results of neutron-gamma and gamma problems computations are performed.


Figure 2: Neutron axial dose rates distribution for a single cask (20 cm thick)


Figure 3: Neutron vertical dose rates distribution for a cask in the skyshine model (20 cm thick)


Figure 4: Neutron vertical dose rates distribution for a cask in the skyshine model (100 cm thick)


Figure 5: Neutron vertical dose rates for a cask in the skyshine model with a perforation (100 cm thick)


Figure 6: Neutron azimuthal dose rates for a single cask (20 cm thick)


Figure 7: Neutron horizontal dose rates for a cask in the skyshine model (50 cm thick)


Figure 8: Primary gamma axial dose rates for a single cask (20 cm thick)


Figure 9: Primary gamma vertical dose rates for a cask in the skyshine model (20 cm thick)


Figure 10: Primary gamma vertical dose rates for a cask in the skyshine model (100 cm thick)


Figure 11: Primary gamma vertical dose rates for a cask in the skyshine model with a perforation (100 cm thick)


Figure 12: Primary gamma azimuthal dose rates for a single cask (20 cm thick)


Figure 13: Primary gamma horizontal dose rates for a cask in the skyshine model (50 cm thick)


Figure 14: Primary gamma side surface dose rates for a single cask (the extended calculation for 25.2 hours)

B.L. Broadhead, J.S. Tang, R.L. Childs, C.V. Parks, and H. Taniuchi. Evaluation of shielding analysis methods in spent fuel cask environments.
International Commission on Radiological Protection., International Commission on Radiation Units, and Measurements. Conversion coefficients for use in radiological protection against external radiation. Annals of the ICRP ; v. 26, no. 3/4. Published for the Commission by Pergamon Press, Oxford ;, 1st ed. edition, 1996 - 1997.