Molybdenum-99-producing 37-element fuel bundle neutronically and thermal-hydraulically equivalent to a standard CANDU fuel bundle

PHWR Reactivity Device Incremental Macroscopic Cross Sections and Reactivities for a Molybdenum-Producing Bundle and a Standard Bundle

“…The bare-lattice homogenized cross sections for the MPB and the SCB have been previously studied 3 and found to be virtually identical, for any practical purpose.…”

“…99 Mo has a half-life of ~4 days, which means that it reaches saturation activity in ~20 days, after which it needs to be harvested. 3 Pressure-vessel power reactors are ill-suited to 99 Mo production because a reactor shutdown is necessary for the harvesting of 99 Mo. Pressure-tube pressurized heavy water reactors (PHWRs), on the other hand, are refueled on-power which allows harvesting of 99 Mo without the need to shut down the reactor.…”

“…The authors of this study have previously proposed a new 37-element fuel bundle which can produce 99 Mo when irradiated inside a PHWR (Ref. 3), herein referred to as the 'Molybdenum Producing Bundle' or 'MPB'. The principal attribute of the MPB design is that it has been designed to be neutronically and thermal-hydraulically equivalent to the standard CANDU a bundle (SCB).…”

“…The authors' previous study 3 comprised static transport calculations for a two-dimensional cell and static transport and diffusion calculations for a 3-by-3-cell model. The study concluded that the reactivities, bundle-averaged twogroup homogenized cross sections and reaction rates at the fuel pin level during normal, steady-state, operation are quasi-identical for the MPB and the SCB.…”

“…Reactivity devices (e.g., rods) are vertical and located between fuel channels. It is anticipated that 4 MPBs will be present in the core at any given time, 3 usually located in central axial positions, such as positions 6 and 7 in two adjacent channels as shown in Fig. 1.…”