NUREG-1537, Part 2 - NRC

CHAbRM 9
* Design features and procedures ensure that the use of byproduct material
produced by the reactor and (ifapplicable) source and special nuclear
material and the auxiliary facilities where this material is stored or used is
covered by the emergency plan, physical security plan, and fire protection
provisions (as aWplicable).
* Technical specifications are proposed that will ensure that the use and
possession of byproduct material produced by the reactor and (if
applicable) source and special nuclear material and the use of the auxiliaiy
facilities where this material is stored or used will not endanger the health
and safety of the public, users, or the environment.
9.6 Cover Gas Control in Closed Primary Coolant
Systems
Areas of Review
Some non-power reactor designs include a reactor core tank as part of the primary
coolant loop that is sealed against the atmosphere. At some of these reactors,
heavy water (D)0) functions as a moderator, reflector, or coolant. The heavy
water must be protected to prevent the admixture of atmospheric water vapor and
the loss of the heavy water. At other non-power reactors, primary systems operate
with ordinary light water at or above atmospheric pressure. In these systems,
radiolytic decomposition of the water leads to a hydrogen-oxygen mixture that
could reach explosive concentration unless it is controlled or processed.
Areas of review should include the following:
* design bases for the closed systems, addressing the types of gases to be
contained and controlled in them
systems for assessing and maintaining any required pressure differential
between the external atmosphere and the coolant system
* systems for assessing the required purity or concentrations of the contained
gases
* methods and systems for circulating, processing, decontaminating,
recovering, and storing the contained gases
* methods for assessing and recombining hydrogen and oxygen gases that
could result from radiolysis of the coolant
NUREG-1537,PARr2 9-14 REV. 0,2/96
NUREG-1537,PART2 9-14 REV. 0, 2/9