CONTROL AND SAFETY IN THE OPERATION OF THE NRX AND NRU REACTORS

Technical Report · Sun Apr 01 04:00:00 EST 1962

OSTI ID:4810987

Breckon, D G; Collins, J J

Presented at International Atomic Energy Agency Symposium on Reactor Safety and Hazards Evaluation Techniques, Vienna, May 14--18, 1962. Safety in reactor operations is achieved through review and development of reactor control systems together with the exercise of sound administration controls. At Chalk River, the control and safety systems of the NRX reactor were developed over the 14-year history of the reactor to provide safer and more reliable operation. The original 18 boron carbide shut-off rods were replaced by 6 electrically operated rods of greater reliability. To augment this change an automatic dump of the heavy water moderator was included. Both devices function simultaneously but each is capable of shuttlng down the reactor independently. Control of reactor power was initially maintained through two manually operated devices; a cadmium control rod and an overflow weir by which the moderator level was adjusted. Later, automatic control of the cadmium rod was possible during power operation. Now, automatic start-up and power control is achieved by adjustment of the moderator level, eliminating the control rod and the weir. Incorporation of a two out of three coincidence system further improved the safety of the reactor. To assist in training, manuals and policy instructions are used. These form the basis for the operation and are augmented by the control procedures. Field work is controlled by work permits, entry to limited access areas through interlock systems and operation of valves through valve slips and flowsheets. Where feasible check-off systems are used to verify field operations. Scheduled checks made possible at power by the two out of three coincidence system permit a continual assessment of the reactor systems. When associated with well established maintenance procedures, they enhance the reliability and safety of the reactor. (auth)

• Research Organization: Atomic Energy of Canada Ltd., Chalk River, Ontario (Canada)
• NSA Number: NSA-16-026614
• OSTI ID: 4810987
• Report Number(s): AECL-1486
• Country of Publication: Canada
• Language: English

Related Subjects

AUSTRIA
BORON CARBIDES
CADMIUM
CIRCUITS
COINCIDENCE METHODS
CONFERENCE
CONTROL
CONTROL ELEMENTS
CONTROL SYSTEMS
HEAVY WATER MODERATOR
LEVELS
LOSSES
MAINTENANCE
NRU
NRX
OPERATION
PERSONNEL
REACTOR SAFETY
REACTOR TECHNOLOGY
RESEARCH REACTORS
SHUTDOWN
STARTUP
TRANSPORT
VALVES
VARIATIONS
VESSELS