The estimates of 99Mo production rates by the solution irradiation method are shown in cases using aqueous (NH4)6Mo7O24^4H2O and K2MoO4 solutions as irradiation targets, assuming the 99Mo production in JMTR.

1.3 Conditions for estimates of 99Mo production rates

The JMTR core arrangement is shown in Fig. 2. The capsule of the 99Mo production system with the solution irradiation method is installed into the irradiation hole, M-9 with maximum and average thermal neutron fluxes of 3.5X1018 n/(m2 • s) and 2.6X1018 n/(m2 • s) (Department of JMTR Project, 1994). The capsule consists of inner and outer tubes, and an aqueous molybdate solution is irradiated with neutrons in the inner tube to prevent the solution from leaking into the reactor coolant. Table 2 shows the conditions of the capsule and the two irradiation targets of the aqueous (NH4)6Mo7O24^ 4H2O and K2MoO4 solutions.

99Mo production rates are estimated based on the following conditions in addition to the conditions of Table 2: [23]

j.

_2

_3

_4

_5

_6

_7

_8

_9

10

11

12

13

14

15

■ Fuel element |2| Be frame

П Control rod with fuel follower ^ Oarai shroud facility-1 I I Al reflector element ггкя Gamma-ray shield plate

П Be reflector element

Fig. 2. JMTR core arrangement

Size and material of capsule________

Dissolved molybdenum in each irradiation target

• Aqueous (NH4)6Mo7O24‘4H2O solution (concentration: 90% of saturation):

372.8 g/1,663 cm3

• Aqueous K2MoO4 solution (concentration: 90% of saturation):

702.7 g/1,663 cm3

Table 2. Conditions of capsule and two irradiation targets of aqueous (NH4)6Mo7O24 • 4H2O and K2MoO4 solutions