L - KTH

68 C.J. Wo~,~
Comparative costs (LOMI) decontamination for IX resins, transport and burial are as
follows:
BWR recirc system $ 80,000
Full system - fuel out 1,300,000
- fuel in 6,400.000
PWR reclrc system $ 120,000
Full system - fuel out 635,000
- fuel in 1,300.000
Waste management is one of the key issues associated with full system decontamination.
Considerable progress is being made in improving waste disposal technology, including ion-
specific resins, volume reduction and interim storage, any of which could significantly
reduce costs. However, the high cost penalty associated with the fuel-in case is one of
the main reasons why most utilities will initially opt for fuel removal.
8.5 Materials compatibility
As a result of extensive corrosion test programs by the BWR Owners Group for
Intergranular Stress Corrosion Cracking research, the BWR position is considerably more
advanced than the PWR situation. Recently-completed tests on highly irradiated stainless
steels filled the last remaining gap in the BWR data base. These tests used 304 stainless
steel which is susceptible to Irradlation-asslsted stress corrosion cracking (IASCC).
Neither CAN-DECON nor LOMI had any adverse effects on these materials (30,37).
A recent evaluation of the corrosion data has led General Electric to conclude that the
risks associated with the use of the LOMI process for full system decontamination wlth the
fuel removed are low provided that a plant-speclfic material review of all LOMl-wetted
surfaces Is performed to verify the applicability of the existing data base (see Appendix
A).
Unfortunately the PWR data base is less complete. In particular corrosion data in the
presence of boric acid is lacking, and there are no data at the high flow rates expected
when the reactor coolant pumps are used to circulate the decontamination solvent. A two-
year industry-funded program has been initiated with Westinghouse to evaluate corrosion
issues.
8.6 Cost benefit
Cost-beneflt evaluations (56) for a number of decontamination scenarios are shown in
Figures 8-4 to 8-7, including estimates for BWR decontaminations using the LOMI and CAN-
DECON processes. The three options are (i) reclrculatlon piping system, (2) full system
Including fuel, and (3) full system with fuel removed. For these calculations the
reference plant was Quad Cities for an outage with above average maintenance requirements.
Figures 8-8 to 8-11 show estimates for PWR decontamination, using Zion as a reference
plant. The four options in this case are (1) steam generator channel heads, (2) full
system including fuel, (3) full system wlth fuel removed, and (4) as (3) but for the
special case of steam generator replacement.
For each example, costs include vendor charges, waste disposal and critical path time at
$624,000 per day. Savings include rents saved at $10,000/man-rem and critical path
savings. The net benefit is savings less costs. The second graph in each set shows the
estimates of the cost of each rem avoided.
Several interesting conclusions can be deduced from these graphs:
BWR reclrculatlon system decontaminations are more cost effective than P~R channel
head decontaminations.
The greatest net benefit is obtained from full system decontamination including
the fuel. However, radwaste disposal costs make this the most expensive option.
(Recent work suggests that radwaste costs might be significantly greater than the
costs used in this study because they assumed resin bed efflclencles orlglnally
are high.)