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Outside view of ZPPR |
Any reactor that was built in ZPPR was called a critical assembly. It was the same size as and had all the gross physical characteristics of the reactor that was being designed. The masses of all the materials were close to the design quantities. Only on a scale finer than two inches, the typical distance that a neutron travels between collisions, were there any differences.
One-half of the ZPPR critical assembly |
The facility's unique construction characteristics provide an ultrastable enviroment for precise measurements as well as the capability to meet stringent safeguards requirements. The reactors were assembled in a 14' x 14' x 10' stainless-steel honeycomb matrix that is split into two halves while not during operation.
The ZPPR critical assembly is put together from rectangular building blocks of fuel, coolant and structural materials. The facility had a very large inventory of these materials that could be assembled in various combinations to construct any reactor within just a few weeks. Because ZPPR was operated at very low power, the materials did not become very radioactive, and they were used over and over again. This feature, combined with the short time required to assemble a core, meant that nuclear reactors could be built and tested in ZPPR for about 0.1% of the capital cost of construction the whole power plant.
A look at the gas generation experiment |
ZPPR's versatility was demonstrated during a three-year period in the mid-1980's when four diverse reactor cores were tested; a 10 MW(e) uranium-fuelled military emergency power reactor, a 330 MW(e) uranium and plutonium version of an Integral Fast Reactor(IFR) design, a 0.3 MW(e) uranium-fuelled space reactor, and a 700-1100 MW(e) plutonium fuelled breeder reactor.
The ZPPR reactor has been shutdown, but the facility is used for a number of projects including the Gas Generation Experiment. The Gas Generation Experiment is designed to verify that waste going to the Waste Isolation Pilot Plant (WIPP) will not decompose into gases which could compromise the integrity of the repository.