NUREG-1537, Part 2 - NRC

REACTOpR CooLANT SyTms
requirements of1 0 CFR Part 20 and should be consistent with the facility
ALARA program., To ensure that facilities or components for controlling,
shielding, or isolating nitrogen-16 are acceptable, potential exposures
should not exceed the requirements of 10 CFRPart 20 and should be
consistent 'with the facility ALARA program. The nitrogen-I 6 control
system is discussed in Section 5.6 of this standard review plan.
Argon-41 is a ubiquitous radionuclide produced at non-power reactors.
Because this'ridionuclide may be the major release to the environment
during normal operation, special analyses and discussion of its production
and consequences should be given in Chapter II of the SAR. If any special
design or operational features of the primary coolant system modify or limit
exposures from argon-41, they should be discussed in this section ofthe
SAR. This discussion should demonstrate that any facilities or components
added to the primary coolant system to modify argon-l releases can limit
potential personnel exposures to the values found acceptable in Chapter 11.
Closed systems also may experience a buildup of hydrogen in air spaces in -
contact with the coolant. The discussion should show that it is not possible
to have hydrogen build up to concentrations that are combustible. This
may require gas sweep systems and hydrogen concentration monitoring.
These systems should be discussed in Chapter 9.
Because the primary coolant may provide essential fuel cooling and
radiation shielding, the system design should avoid uncontrolled release or
loss of coolant. Some design features to limit losses include locating
components of the primary coolant system above the core level, avoiding
drains or valves below core level in the pool or tank, providing syphonbreaks
in piping that enters the primary vessel or pool, and providing check
valves to preclude backflow. 'The designs and locations of such features
should provide reasonable assurance that loss of coolant that could uncover
the core is very unlikely. A potential accident of rapid loss of coolant
should be analyzed in Chapter 13 and summarized in this section of the
SAIPA - -
Heavy water systems require additional design features because of the
radiological hazards of tritium production in the coolant. These systems
should be designed with systems to'detect minor leakage; They also should
be designed so that heavy water, if lost from the system, will be contained
and not released to the environment.'
If contaminated coolant were lost from the primary coolant system, the
design and analyses should ensure that potential personnel'ecposures and
uncontrolled releases to the unrestricted environment do not exceed
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