NUREG-1537, Part 2 - NRC

CHAPTER S
The descriptions and discussions should show that sufficient
instrumentation, coolant parameter sensors, and control systems are
provided to monitor and ensure stable coolant flow, respond to changes in
reactor power levels, and provide for a rapid reactor shutdown in the event
of loss of cooling. There also should be instrumentation for monitoring the
radiation of the primary coolant because elevated radiation levels could
indicate a loss of fuel cladding integrity. There should be routine sampling
for gross radioactivity in the coolant and less frequent radioactive spectrum
analysis to identify the isotopes and concentrations found in the coolant.
This spectrum analysis may also detect cladding failure at its earliest stages.
* The primary coolant should provide a chemical environment that limits
corrosion of fuel cladding, control and safety rod surfaces, reactor vessels
or pools, and other essential components. Aluminum-clad fuel operated at
high power density will develop an oxide coating that could decrease heat
conductivity (Griess et al., 1964). Chapter 4 of the SAR should contain
discussion and analyses of the dependence of oxide formation on water
quality and other factors. Other requirements for water purity should be
analyzed in the SAR, and proposed values of conductivity and pH should
be justified. Experience at non-power reactors has shown that the primary
water conditions, electrical conductivity s5 ,umho/cm and pH between 5.5
and 7.5, can usually be attained with good housekeeping and a good filter
and demineralizer system. Chemical conditions should be maintained, as
discussed in Section 5.4 of this standard review plan.
* Most non-power reactors consist of a core submerged in a pool or tank of
water. The water helps shield personnel in the reactor room and the
unrestricted area from core neutrons and gamma rays. It also decreases
potential neutron activation and radiation damage to such reactor
components as the pool liner, beam port gaskets, in-pool lead shields, and
concrete biological shield. The applicant should discuss these factors in
Chapter 4 of the SAR. To ensure that the design of the primary coolant
vessel is acceptable, exposure limits on materials discussed in Chapter 4
should not be exceeded, and exposures to personnel, as discussed in
Chapter 11, "Radiation Protection Program and Waste Management,"
should not exceed the requirements of 10 CFR Part 20 and should be
consistent with the facility ALARA (as low as is reasonably achievable)
program.
* Radioactive species including nitrogen-16 and argon-41 may be produced
in the primary coolant. Additional radioactivity may occur as a result of
neutron activation of coolant contaminants and fission product leakage
from the fuel. Provisions for limiting personnel radiological hazards should
maintain potential exposures from coolant radioactivity below the
NUREG- 1S37, PT 2 5-4 REV. 0,2/96
NUREG-1537,PART2 54 REV. O. 2/96
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