For example, say I'm building a hotel with a conference room. The room is large enough for 1,000 people, and I assume everyone weighs 250 pounds ... So maybe we build a room that can take 2,000 people weighing 250 pounds ... Now I have reasonable assurance that this thing is not going to collapse.
ICN: And probabilistic risk assessment [now part of the NRC's 'risk-informed and performance-based' approach to safety planning]?
Lam: Probabilistic is, 'alright, outside of these predetermined parameters, there's something we have not thought about.' Of those we have not thought about, let us stack them up in terms of these things: One, how likely are they to occur? Two, how major are the consequences? And three, how effective are the remedies? All three need to come together.
For example, a meteorite comes in once every 5 million years, and nothing can defend against that, so I'm not going to consider that. Ah, but the flooding, once in 100 years, you'd better design against that. It's all a balance of how effective [the prevention measure] is and how cost-beneficial it is.
Looking at Fukushima, all they needed to do to avoid disaster was to elevate one or two diesel generators above the 50-foot tsunami level. And the cost, if they were to do it, would probably have been $10 million to $30 million. I'm just guessing, but let's say it's $100 million. If you knew about the tsunami coming, you would have spent the $100 million. Now [cleanup is] going to cost $100 billion, easy. So it's a matter of, 'Well, tell me what's going to happen? How much is it going to cost?" (Editor's note: The Japan Center for Economic Research put the accident's cost at between $71 billion and $250 billion.)
To be fair, a lot of things fall into that category besides a tsunami. And that's where probabilistic risk assessment comes in. What about a hurricane? The water ... would it hurt my diesel generators? Would it collapse my building? The building may not collapse on you, but if something else collapses and falls on a cable and cuts it, you are in equal jeopardy. What about a solar flare? These are the types of deliberations we need to go through.
ICN: Some people believe it's impossible to adequately protect the public from nuclear mishaps, and that belief forms the basis for opposing the technology altogether. What do you think?
Lam: They raise an interesting point. Are there any alternatives to this technology, so that if an accident were to happen, it would not cause so much harm? I think they're probably coming.
I would say that one should be really open minded as to what the future will bring, with or without nuclear power. And before we get there, our number one task is whatever nuclear power plants we have running, let's make sure they are safe.
ICN: Has the independent safety committee for Diablo Canyon affected things like safety culture at the plant?
Lam: I think the committee may play a part in enhancing that safety culture since three of us go down there nine times a year. We meet all the senior managers; we meet the rank and file, middle managers and first-line people. They probably know that the committee is there. They would not hesitate to tell us things that don't get appropriate attention.
The [NRC has] a program for whistleblowers. But perhaps we are a little bit more informal. We hear things. I usually meet with the site vice president behind closed doors. I would definitely let him know what I hear unless the people who told me things request confidential agreement. My job is to make sure, to the extent that we can contribute, that the plant operates safely.