Safety evaluation of fuel-rods storage rack in DCA facility; Criticality, earthquake-proof and dose equivalent rate

Yoshida, Mamoru; not registered; not registered; Aihara, Nagafumi

A new fuel-rods storage rack has been manufactured to store DCA and JOYO type fuel-rods in a fuel-rods storage house attached to the Criticality Engineering Section Facility. For the manufacture of fuel-rods storage rack, a safety design evaluation was performed about criticality safety, earthquake-proof and dose equivalent rate. The calculation of design evaluation was performed by using SCALE-4, SAP-IV and ANISN code system, respectively. We could understand the following informations from the safety design evaluation: (1)As a result of criticality evaluation, a maximum Keff value was 0.568 by the use of JOYO type fuel-rods with all number of 300 fuel-rods. This means that the sub-criticality is kept in any situation. (2)As a result of earthquake-proof evaluation, it was confirmed that the new storage rack showed less value than the permitted stress from an analytical result when the yield point against the earthquake power of standard earthquake oscillation or the static earthquake power was set as a permitted limit. (3)As a result of evaluation for the dose equivalent rate, a maximum dose equivalent rate was a case by the use of DCA 3.4% enriched MOX fuel-rods with all number of 300 fuel-rods.