Do we have a responsibility to warn the future about radioactivity? And if we have that responsibility, do we have a right to create radioactive materials that could harm future generations in the first place?

These are the questions posed by the new observational documentary Containment, which will air on PBS’ Independent Lens tonight at 10pm ET. Although directors Peter Galison and Robb Moss don’t offer clear answers, their interviews with nuclear waste experts, policy directors, and people associated with and affected by nuclear sites are thorough and sober.

Containment focuses exclusively on the dangers of nuclear waste from both nuclear weapons projects and nuclear energy, often lumping the two endeavors together in a way that can come across as unjustly censuring nuclear energy, whose benefits in the face of climate change are scarcely mentioned. But ultimately the message seems to be that a rational and pragmatic approach to storing waste, unclouded by delusion that any site can be completely and totally safe, is necessary.

Containment uses footage from the Savannah River Nuclear Site in South Carolina; the Waste Isolation Pilot Plant (WIPP) in Carlsbad, New Mexico; and the Fukushima Daiichi Nuclear Power Plant in Japan.

The film opens with Bob Forrest, former mayor of Carlsbad, New Mexico, talking about the WIPP—so far the only site in the US that has been approved to store radioactive waste long-term. The WIPP has seen a significant amount of controversy because of an explosion that occurred in 2014, effectively closing the plant for two years and causing billions of dollars in cleanup. Trace amounts of radiation did escape the underground waste facility, although no residents of Carlsbad were affected, according to the Department of Energy. The WIPP has been approved for re-opening in 2017 (PDF), but Containment contains footage of Forrest and other scientists saying that radioactive containment at the WIPP was virtually impenetrable, which has obviously proven not to be the case.

After Carlsbad, we see footage of the 2011 earthquake and subsequent tsunami that damaged the Fukushima Daiichi plant, causing evacuation of nearby residents en masse. We then turn to the Savannah River Site in South Carolina, built in 1950 to develop materials for nuclear weapons. Today, nuclear waste from here is shipped to WIPP. All along, documentary shows how managing the dangers of waste from nuclear weapons and nuclear energy has been an afterthought until recently.

One criticism of Containment is that it’s hard to tell when the footage was shot and when the interviews take place. Some of them seem to be recent, others must have happened years before. The liquid waste at the Savannah River Site is portrayed as the most dangerous of the three sites we visit. And at some point, an expert talks about encasing the liquid waste in molten glass to make storing it more stable. But the audience is left unsure how this project is progressing or if it's at all a significant part of the site's cleanup efforts.

”Keep Out” signs for a future world

Instead of focusing on the ever-developing present, a large portion of the documentary is dedicated to the fascinating question of whether and how to warn the far future of the dangers of radiation poisoning. Decades ago, Congress decreed that the WIPP couldn’t be built until warning markers were created to urge people living 10,000 years in the future to stay out of the site. In 1990, the Department of Energy convened a group of astrophysicists, futurists, architects, linguists, and so forth to develop “intrusion scenarios” so that the waste site could best prevent humans from accidentally entering.

Science fiction author and astrophysicist Greg Benford, who was part of the group dedicated to intrusion scenarios, talked about the challenge of thinking that far into the future. “10,000 years is the span of human civilization… no nation state has survived more than about 1,000 years," he said. "The United States is only a bit more than two centuries old. I know it seems like it should last forever but it won’t. Even languages don’t have a long life span. It’s about 1,000 years.”

The experts suggested that warnings should somehow encompass the entirety of the WIPP in order to, for example, prevent people building a Houston-to-Los Angeles underground train from boring a tunnel through the Carlsbad site. The site would also have to be marked from the surface to let aircraft and satellites know what’s there. The intrusion scenarios discussed by the panel are presented by illustration in the documentary, which gives a large chunk of it a graphic novel feel.

Carl Sagan collaborator and artist Jon Lomberg, who was also a part of the 1990 group, is interviewed about whether markings are necessary or ethical. “The urgent issues that we face today I would say are more important than the well-being of people in the far future, but the future is important too," he says. "It's not an either-or. I think protecting either helps the other one.”

Lomberg spoke of creating messages for 10,000 years in the future as analogous to trying to make contact with aliens, like we did on Voyager’s Golden Record. “We want to tell extra-terrestrials the best about ourselves, but we need to tell our descendants something about what was worst about ourselves,” Lomberg says.

Perhaps one of the most fascinating parts of the documentary involves an interview with Fumihiko Imamura, the director of the International Research Institute of Disaster Science. The filmmakers drive around Sanriku, Japan to see ancient markers that past residents left for future generations, warning them of devastating tsunamis. One stone says “High dwellings ensure the happiness of our descendants. A terrible tsunami reached this place. Never build your homes lower than this.” What is apparent is that trying to warn future generations of unseen dangers is hardly new. While a tsunami of the size of which the marker was warning may not come every generation, or even every other generation, those who lived through that particular disaster wanted to make sure that the third or fourth generation didn’t experience the horrors that they did.

Liquid waste and equitable living

Alison McFarlane, the former chair of the US Nuclear Regulatory Commission, is one of the strongest voices in the documentary. She plainly lays out the complex political and scientific problems we face in dealing with radioactive waste, especially the troubles associated with finding a place to store it. “Shoot it into the sun” is apparently not a great option because of our imperfect record of successfully launching rockets into space, and international waters aren’t viable because international consensus would be required.

Containment also acknowledges an oft-overlooked aspect of nuclear energy and waste storage: equity. Reverend Willie Tomlin, a community organizer and pastor in Waynesboro, Georgia (which is near the Savannah River Site), tells the viewers, “It appears to me that most reactors are built in poor communities or in communities that are not heavily populated. In Burke county, there are 22,000 people in the whole county. Even if we could bring everybody to bear, that’s not enough people to worry about. Ok? You can figure a way around 22,000... They’re stuck with a problem that’s getting larger. That’s really going to be handed off to my grandchildren and my great grandchildren.”

McFarlane’s interview puts that sentiment in a broader context: “When we made nuclear weapons, it wasn’t a societal decision. A few people decided. It wasn’t all of society that said ‘yes let’s let’s definitely build 40,000 nuclear weapons’… and in building nuclear power plants, you know, initially we didn’t get a say either.”

Ultimately though, the pragmatic approach to nuclear waste expressed by McFarlane towards the end of Containment is the one we’re left to agree with.“There’s no way to ensure that forever you will keep this material isolated from humans in the environment… But, we always have to keep in mind that the issue is: do we leave this stuff where it is? Or do we put it underground?" he says. "In my mind leaving it where it is for hundreds of years poses a much greater risk, because certainly it will start to degrade if not maintained. And you might say 'Well somebody will maintain it.' Well, will they? You are assuming that the institutions that guarantee your safety at this time will still be there hundreds of years from now, and I do not have that faith.”