L - KTH

In the parallel approach (Fig. 5), the flow exits the decontamination equipment to a
header which feeds each of the channel heads being decontaminated through a manway cover
fitting. Once the fluid has circulated inside each one, it returns to a second header and
then back to the decontamination equipment. Level adjustment is achieved by adding and
removing system fluid at regular intervals from a supplementary tank which rides on the
system.
When Inventories have been correctly adjusted and operating temperatures reached, the
decontamination can proceed. Operations for steam generators are identical to those for
the RWR system except that oxidizing steps must be included in order to achieve
satisfactory decontamination factors.
3.3 Comparison of RWR and channel head decontaminations
The following subsections compare the similarities and differences between BWR RWR
system and PWR channel head decontaminations from an operational perspective.
3.3.1 Similarities
(a) Predecontamlnatlon Preparations. To prepare for any decontamination a certain
number of preliminary tasks must be performed. These include the preparation of
drawings and procedures to make them site specific, the procurement of chemicals,
resins and other consumables, and the maintenance and shipment of the equipment to
site. They differ somewhat In detail (as would two RWR system decontaminations) but
are fundamentally the same irrespective of whether or not the work is being performed
for a BWR or a PWR utility.
(b) Equipment Setup on Site. In order to perform the decontamination, temporary
equipment must be set up on site in the general vicinity of the component or system
being decontaminated. Even though the final location of individual pieces of equipment
varies from station to station (even from one BWR to another), the need to interconnect
essentially the same equipment remains. About the same number of personnel are
required, the basic tasks which they perform during setup are similar, and the amount
of time required to perform this task is about the same. The differences in equipment
locations between BWRs and PWRs have a relatively small effect on the total effort
involved in this task.
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Fig. 5. PWR channel head decontamination parallel flowpath