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ZED-2 still relevant today

Observer reporter Stephen Uhler gets a tour of the ZED-2 reactor from Jerry McPhee, facility manager.

Observer reporter Stephen Uhler gets a tour of the ZED-2 reactor from Jerry McPhee, facility manager.

CHALK RIVER -A research reactor used by Atomic Energy of Canada to test its designs has reached its 50th year of service.

The Zero Energy Deuterium (ZED-2) nuclear reactor went on line Sept. 7, 1960, and has provided solid backing to the company's famed Candu reactor pro-g ra m ever since, providing a platform from which to test new designs, controls and configurations of its fuel bundles, the heart of the nuclear power generators.

Jerry McPhee, facility manager at Chalk River Laboratories, said the ZED-2 is still very relevant a half century later. It is low power, generating a maximum of only about 200 watts, yet operates on the same principles as the Candu fleet and the NRU reactor, all of which are heavy water reactors.

In fact, while NRU is far more powerful at 200 megawatts, essentially the two reactors operate in the same way, making the smaller ZED-2 a useful model in predicting how reactors of a similar type would behave.

"This is a remarkable piece of technology and feat of engineering," he said. "What we're celebrating is a reactor which was created 50 years ago, yet is still doing relevant work to support Canada's nuclear industry."

ZED-2, the replacement for the ZEEP research reactor, is used to study reactor physics and was initially built to test the fuel arrangement of Canada's first nuclear power plant, the NPD (Nuclear Power Demonstration), located on the Ottawa River about 20 kilometres upstream of Chalk River.

Since first operation, ZED-2 has supported development of the Candu industry by testing a wide range of fuel bundle designs and fuel arrangements at low power (usually between five to 100 watts) under a variety of operating conditions and simulated accident scenarios.

In fact, ZED-2 has been used to test reactor physics designs for all of Canada's power reactors, and it still continues to operate today, supporting develo p m e nt of the ACR-1000, (Advanced Candu Reactor), with further studies planned to begin in the near future. ZED-2 is also used to calibrate neutron detectors for use in power reactors.

Mr. McPhee said the key to its success is its flexibility in design.

Fuel assemblies are hung in the reactor from 14 steel beams spanning the top of it. An over-h ead crane is used to insert, remove, or reposition assemblies on the beams, while each beam itself can also be moved. This allows the fuel to be arranged in virtually any desired configuration.

How the fuel bundles are arranged within a reactor determines how efficient it is in generating power.

Mr. McPhee said this allows them to set up the reactor to test for almost any design and situation, making it an invaluable model for reactor research. Since it takes time to set up, on average the ZED-2 is used in one big experiment a month.

Stephen Uhler is a Daily Observer reporter

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