单项选择题

Following the disaster at Chernobyl, nuclear experts proposed a program to make nuclear power around the world safer. At the top of the agenda were fundamental improvements in the training of operators and the design of control systems for reactors. The International Atomic Energy Agency also chose the meeting on the Chernobyl accident to announce it would step up its safety checks of nuclear power stations. Up to that time, with more than 300 nuclear power plants operating worldwide, the IAEA had sent safety review teams to inspect stations in only nine countries, mostly in the Third World. Now the emphasis would switch to reactors in the developed world, including the Soviet Union, US and Britain.
According to regulations, an international safety review could be undertaken by the IAEA only following a formal request from a member country. However, the meeting in Vienna produced a list of 14 recommendations for future action following the Soviet report on Chernobyl. The IAEA meeting said that better fire protection and more advanced techniques for firefighting were needed. The possibility of developing lightweight clothing to protect firefighters from radiation was of particular interest; so was the use of robot firefighters. The Soviet Union used minerals and sand to damp down the fires. Both Soviet and Western experts agreed there was no way of knowing in advance if this would work. Luckily, it did.
Decontamination (去除放射性污染) was another area where the international nuclear community was anxious to learn more from Chernohyl. The Soviet clean-up involved treating buildings and the ground around the reactor with special chemicals to reduce the spread of radioactive dust. Heavily contaminated soil was removed.
At the final press conference about the Chemohyl accident, the leader of the Soviet delegation (代表团) claimed that Chernobyl would not be repeated. There would have to be greater efforts to make sure that the design of nuclear plants eliminated the possibility of errors by operatorns. This would include making it difficult to override (使无效) safety systems, as happened at Chernobyl. It would also mean greater use of simulators (模拟装置) to train operators.

In the last two sentences of paragraph 2, both "this" and "it" refer to （）.

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