Management of Commercially Generated Radioactive Waste - U.S. ...

3.11
wastes also result. These are described more fully in Section 4.2. After the HLW is solid-
ified (Section 4.3) it may be stored on-site (Section 4.4) for a period prior to shipment
(Section 4.5).
A mixed-oxide fuel fabrication plant (MOX-FFP) prepares fuel containing a mixture of
plutonium dioxide and uranium dioxide for recycle to a nuclear power plant. The reference
MOX-FFP receives U0 2 and Pu02 powders and Zircaloy cladding tubes and end plugs and pre-
pares hermetically sealed fuel rods ready for insertion into fuel assemblies. The reference
plant, described in DOE/ET-0028 Section 3.2, operates 300 days per year to produce 400 MTHM
of LWR fuel/yr; up to 5% of the heavy metal content is plutonium. The major process steps
involved include:
* Mechanical mixing of U0 2 and PuO 2 powders
* Preparation of dense fuel pellets by pressing, sintering, and grinding the mixed
powder
* Sealing the pellets in Zircaloy cladding to form fuel elements
* Scrap recycle. The following assumptions are made about the reprocessing fuel
cycle logistics:
* Spent fuel is stored until it is shipped to a reprocessing facility. As in the once-
through cycle, storage can occur either at the reactor site or at an AFR. Reactor
basin storage capacity is also seven annual discharges, but spent fuel is stored for a
minimum of one year once this accumulated backlog of stored fuel is worked off. The
reprocessing plant maintains a working inventory of 0.5-yr worth of spent fuel in stor-
age. Thus, the minimum fuel age at reprocessing is 1.5 years; however, because a large
accumulated inventory of spent fuel exists before the start of reprocessing, it is over
20 years after reprocessing starts before this minimum age is reached.
* The high-level waste is solidified immediately and then stored on-site for 5 years
prior to shipment to a repository or to an interim storage facility if a repository is
not available.
* TRU wastes are shipped immediately after treatment and packaging to either a repository
or interim storage.
* Spent fuel shipping distances are assumed to average 1000 miles from reactors to an FRP
or to an AFR, or from an AFR to an FRP.
* Treated waste shipping distances are assumed to average 1000 miles to interim storage
and 1500 miles from either an FRP or from an interim storage facility to a repository.
As in the once-through cycle, the actual distances will vary. No waste shipments
between an FRP and a MOX-FFP are assumed.
The logistical and storage requirements of this fuel cycle as well as the once-through
cycle for several nuclear power growth assumptions are discussed in Chapter 7.