DESIGN OF DRY CASK STORAGE FOR SERPONG MULTI PURPOSE REACTOR SPENT NUCLEAR FUEL

DESIGN OF DRY CASK STORAGE FOR SERPONG MULTI PURPOSE REACTOR SPENT
NUCLEAR FUEL. The spent nuclear fuel (SNF) from Serpong Multipurpose Reactor, after 100
days storing in the reactor pond, is transferred to water pool interim storage for spent fuel
(ISFSF). At present there are a remaining of 245 elements of SNF on the ISSF,198 element of
which have been re-exported to the USA. The dry-cask storage allows the SNF, which has
already been cooled in the ISSF, to lower its radiation exposure and heat decayat a very low
level. Design of the dry cask storage for SNF has been done. Dual purpose of unventilated
vertical dry cask was selected among other choices of metal cask, horizontal concrete modules,
and modular vaults by taking into account of technical and economical advantages. The designed
structure of cask consists of SNF rack canister, inner steel liner, concrete shielding of cask, and
outer steel liner. To avoid bimetallic corrosion, the construction material for canister and inner
steel liner follows the same material construction of fuel cladding, i.e. the alloy of AlMg2. The
construction material of outer steel liner is copper to facilitate the heat transfer from the cask to
the atmosphere. The total decay heat is transferred from SNF elements bundle to the atmosphere
by a serial of heat transfer resistance for canister wall, inner steel liner, concrete shielding, and
outer steel liner respectedly. The rack canister optimum capacity of 34 fuel elements was
designed by geometric similarity method basedon SNF position arrangement of 7 x 6 triangular
pitch array of fuel elements for prohibiting criticality by spontaneous neutron. The SNF elements
are stored vertically on the rack canister. The thickness of concrete wall shielding was calculated
by trial and error to give air temperature of 30
o
C and radiation dose on the wall surface of outer
liner of 200 mrem/h. The SNF elements bundles originate from the existing racks of wet storage,
i.e. rack canister no 3, 8 and 10. The value of I
from the rack no 3, 8 and 10 are 434.307;
446.344; and 442.375 mrem/h respectively. The total heat decay from rack canister no 3,8 and 10
are 179.640 ; 335.2; and 298.551 watts. The result of the trial and error calculation indicates that
the rack canister no 3, 8 and 10 need the thickness of concrete shielding of 0.1912, 0.1954 and
0.1940 m respectively.