The United States showed its closed-down nuclear reactor at the Hanford nuclear installation to a group of United Nations diplomats on Wednesday (Nov 16).
The United States showed its closed-down nuclear reactor at the Hanford nuclear installation to a group of United Nations diplomats on Wednesday (Nov 16). The visit was set up specifically to demonstrate a simple safe-guard device which would prevent a nuclear plant from being used between inspections visits under an international atomic weapons control agreement.
During disarmament talks in Geneva, the United States announced that it had developed a fool-proof system for verifying that a shut-down reactor had remained shut down between visits by an inspection team, and invited all United Nations members to visit the previously secret facility in Washington State to see the system. Fifty nations accepted, none of them Communist. The Soviet Union has expressed support for the principle of international inspection of atomic plants, but has thus far declined to place any of its reactors under inspection by the International Atomic Energy Agency.
The United Nations members were ushered into the Hanford "F" plant, which has been used to produce plutonium for nuclear bombs until it was shut down in June 1965, after having been "hot" since 1945. In front of them was the "face" of the central pile, essentially a cubical structure of graphite, honeycombed with tubes. Uranium in capsules was inserted into the tubes until a critical mass was reached and the chain reaction begun.
In the so-called safing system, special tapes are run through some of the tubes and fastened at each end to a large white shield. The tapes contain metallic cobalt wires which are twisted and then squashed, producing a unique pattern when the wires are x-rayed. In addition, the ends of the tapes are sealed into a transparent plastic that is sprinkled with iron filings while still liquid. An x-ray picture of the filing provides another unique fingerprint. Thus inspectors can easily tell if the tapes have been removed, cut, or replaced. If the reactors, on the other hand, is started up with the tapes in place, the cobalt wires become unconcealably radioactive.