47 were arrested while 1,500 others showed support at a nearby rally. Activists did statewide teach-ins to educate the public about Diablo Canyon and nukes" (4). In September 1981,"the Abalone Alliance starts a blockade of Diablo Canyon that lasts two weeks. Over 1,900 people are arrested, while tens of thousands show up to support them" (4).  In any case Diablo Canyon was built (although it was alleged that the site suffered the risk of an earthquake) and it  functioned until 2016, when the decisions was taken to close it down.  Political and environmental presures lies behind this decisions. In October 2010 a major controversy had arisen when California enacted a new policy banning the use of antiquated "once-through cooling" systems, which allow coastal power plants to directly take in and discharge massive amounts of sea water -- causing significant damage to marine creatures and the environment. While all plants were supposed to comply with the policy by 2015, Diablo Canyon was given the opportunity to instead explain by 2015 why they should not comply with the policy or face compliance by 2024. As Diablo Canyon caused some 80 percent of the damage to the marine environment of all the coastal power plants combined, excluding Diablo from the policy would make a mockery of the program. (5). ========================================= == In June 2016, pro-nuclear analysts still lament that Diablo Canyon Nuclear Power Plant in San Luis Obispo County, California is closing down. They say that "the plant is safe, can withstand an large earthquake, tsunami and any other disaster, provides billions to the local economy, and produces more clean energy than all the wind turbines in California combined".(2)  For critics who have long insisted that nuclear power is inherently dangerous and too expensive, the prospect of delivering a death blow to Diablo was something to relish. "Two nuclear plants are down in California and we're working on a third  one which is Diablo Canyon," said Kathryn Phillips, director of Sierra Club California, referring to the San Onofre Nuclear Generating Station in early 2012 and the Rancho Seco plant near Sacramento in 1989.  (1).  PG&E claims that  nuclear energy will be replaced completely with gains in efficiency and renewables. "But the proposal’s details do not back this up. In fact, it calls for implementing renewables and efficiency equal to only about a quarter of Diablo Canyon’s generation. Instead, experts agree, the generation will mainly be replaced by natural gas, and attempts to buy energy from out-of-state." (2). Whether it is solar and wid, or increased efficiency, or natural gas that replaces Diablo Canyon, the fact is that its closing down signals the end of nuclear commercial energy in California. The decommisioning expenditures will be very high , and as usual there is no clear plan for coping with the nuclear waste. On the whole, however, the closure plan is a final blow for commercial  nuclear energy in California. The impending closure of Diablo Canyon would leave just one nuclear plant on the West Coast, the Columbia Generating Station, about 200 miles outside of Seattle.  To craft the closing down proposal, PG&E worked with the International Brotherhood of Electrical Workers Local 1245, the Coalition of California Utility Employees, the Natural Resources Defense Council, Environment California, Friends of the Earth and the Alliance for Nuclear Responsibility.

As required by California law, PG&E has established a trust fund created by ratepayers, through their electricity bills over the course of decades, to cover decommissioning costs. The trust fund for Diablo Canyon is nearly $2.8 billion. In PG&E's most recent submission to the California Public Utilities Commission, the utility estimated it would cost $3.779 billion to decommission Diablo Canyon. (3). The nuclear waste will be kept on site because, as in the case with all nuclear facilities in the US, companies are not liable for final disposal: it is the federal government's responsibility to ultimately find places to deposit nuclear waste. However, with the proposed depository at Yucca Mountain in Nevada scrapped, nuclear facilities keep spent fuel at their respective sites.

For nuclear's supporters, Diablo Canyon was seen as essential to deliver reliable, base-load power and an effective way to reach the state's ambitious goals to reduce greenhouse gas emissions. "Diablo Canyon is an absolutely necessary part of the energy mix in California," had said Eugene Grecheck, president of the American Nuclear Society. This was not to be, however. It's not just California. There are 99 nuclear reactors in the U.S. providing in 2016, 19 percent of the nation's electricity. But the majority of those 99 plants are over 30 years old.