Prepared By
Planning Information Corporation
Denver, Colorado
September, 1996

5.   Shipment Groups

Spent Fuel Forms and Ages

Spent fuel discharged from boiling water reactors is in 52 different types of assemblies.¹³ As of July 1, 1996, 8.6 percent of the MTU discharged from boiling water reactors is over 20 years old, 41.4 percent is between 10 and 20 years old, and 50.0 percent is less than 10 years old.

Spent fuel discharged from pressurized water reactors is in 54 different types of assemblies. As of July 1, 1996, 5.3 percent of the MTU discharged from boiling water reactors is over 20 years old, 37.4 percent is between 10 and 20 years old, and 57.3 percent is less than 10 years old.

Under an oldest-fuel-first acceptance prioritization, spent fuel which is over 20 years old on July 1, 1996 would be picked up in the first and second acceptance years. Spent fuel which is between 10 and 20 years old would be picked up in the second through seventh acceptance years, while fuel less than 10 years old would be picked up in the seventh through twelfth acceptance years. If acceptance begins in January 1998, the 40 PWR assemblies discharged from the Trojan plant in May 1986 would be picked up in 2005—meaning that Portland General Electric will have stored these assemblies in an operating spent fuel pool for 19 years, and for 13 years after the Trojan plant shut down in 1992.

Criteria for Cask Loading

How would the discharges at various storage locations be grouped for loading into transportation casks for shipment in a particular acceptance year?

• Would discharges whose priority ranking places them in different acceptance years be mixed in the same transportation cask? Under an oldest-fuel-first acceptance prioritization, the assumption in this assessment is "no."

• Would BWR or PWR discharges of different assembly types be mixed in the same transportation cask? The assumption in this assessment is "yes, as necessary." Thus, for example, the 335 assemblies at Big Rock, which include seven BWR assembly types fabricated by three companies (General Electric, Siemens and Nuclear Fuel Services), could be mixed in the same transportation cask if they fall into the same acceptance year.

• Would BWR and PWR assemblies be mixed in the same transportation cask? The question arises at storage locations such as Brunswick and Harris, whose pools have sections for storage of BWR and PWR assemblies, and at locations such as Morris, West Valley, and INEL, where BWR, PWR, and (in the case of INEL) HTG assemblies have been shipped for temporary storage. The assumption in this assessment is "no"—BWR and PWR assemblies would not be mixed in the same transportation cask.

• Would BWR or PWR assemblies discharged from different reactors be mixed in the same transportation cask? The question arises at Morris, which stores BWR assemblies discharged from Cooper Station and Dresden 2, or at McGuire 2, which stores PWR assemblies discharged from the three Oconee reactors as well as the McGuire 2 reactor, or at INEL, which stores PWR assemblies discharged at TMI 2, Surry 1 and 2, Turkey Point 3, and Point Beach. The assumption in this assessment is "no"—BWR or PWR assemblies discharged from different reactors would not be mixed in the same transportation cask.

Among the four shipment grouping criteria discussed above, the last may be considered too restrictive in its application in certain cases. An example is the BWR assemblies stored in the joined Hatch 1 and 2 spent fuel pools, near the Altamaha River about 75 miles west of Savannah, Georgia. These pools contain about 900 BWR assemblies of the 8G5 type, about 750 of the 8GP type, and about 1,450 of the 8GB type,13 each of which has been discharged in substantial numbers from both the Hatch 1 and Hatch 2 reactors. There may be no impediment in mixing such assemblies in the same transportation cask, if they fall into the same acceptance year.

While shipment grouping is considered in this assessment, it is a factor which as a limited effect on the number of transportation casks shipped from a particular site in a particular acceptance year. More elaborate grouping criteria sometimes result in a few additional one or two partially-filled casks shipped from a particular site in a particular acceptance year.