NUREG-1537, Part 2 - NRC

CHAPTER 5
5.4 Primary Coolant Cleanup System
Areas of Review
Experience has shown that potable water supplies are usually not acceptably pure
for use as a reactor primary coolant without additional cleanup. Most licensed
non-power reactors contain solid fuel elements immersed in the primary coolant
water. Experience has also shown that oxide buildup on aluminum-clad fuel
operated at high power densities can reduce heat transfer (Griess et al., 1964).
The rate of buildup depends on several operational characteristics, including the
pH of the coolant. Therefore, this process should be discussed in Chapter 4 and
summarized in this section of the SAR if it contributes to establishing requirements
for primary coolant purity. The purity of the primary coolant should be maintained
as high as reasonably possible for the following reasons.
* to limit the chemical corrosion of fuel cladding, control and safety rod
cladding, reactor vessel or pool, and other essential components in the
primary coolant system
* to limit the concentrations of particulate and dissolved contaminants that
might become radioactive by neutron irradiation
* to maintain high transparency of the water for observation of submerged
operational and utilization components
Specific areas of review for this section are discussed in Section 5 4 of the format
and content guide.
Acceptance Criteria
The acceptance criteria for the information on the primary coolant cleanup system
include the following:
* The primary coolant quality should be maintained in the ranges established
as acceptable in Chapters 4 and 11 of the SAR. These analyses for highpower
reactors (> 2 MW) should include the buildup of an oxide film on
aluminum cladding. Experience has shown that quality water conditions,
electrical conductivity &5 gmholcm and pH between 5 5 and 7.5, can
usually be achieved by good housekeeping and a cleanup loop with
particulate filters and demineralizers. Such a system is acceptable unless
the SAR analyses establish other purity conditions as acceptable.
* Radioactively contaminated resins and filters should be disposed of or
regenerated in accordance with radiological waste management plans
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