On April 14, California State Sen. Sam Blakeslee grilled Nuclear Regulatory Commission official Troy Pruett on the seismic hazards facing California's nuclear plants. It was roughly a month after a tsunami generated by a 9.0-magnitude earthquake swamped the Fukushima Daiichi nuclear plant in Japan. Blakeslee, whose Central Coast district includes Pacific Gas & Electric's Diablo Canyon nuclear power plant, wanted his colleagues on the Senate's Energy Committee to understand the seismic risks at both Diablo Canyon and the San Onofre plant farther south.

He posed a simple question: Does the Shoreline Fault, discovered in 2008 a few hundred yards from Diablo Canyon, pose a greater threat than the Hosgri Fault a few miles away, which produced a 7.1 in 1927? Pruett bobbed and weaved ("There's the new Hosgri Fault and the old Hosgri Fault"), then waffled. ("It's not a simple yes or no question.")

Finally, the senator put it plainly: "(The Shoreline Fault) represents the greatest danger to the site, yes?"

"In terms of ground acceleration?" Pruett responded, referring to the shaking that makes earthquakes damaging -- as if Blakeslee had asked whether an approaching fire was dangerous in terms of heat.

"No," Blakeslee fired back. "In terms of pixie dust."

A geophysicist with a Ph.D. in earthquake studies, Blakeslee, 55, admits he's "hardly what you'd think of as an environmental activist. I'm a Republican!" But throughout his seven years in the state Legislature, he has insisted that science outweighs economics when it comes to nuclear safety. Other legislators, such as U.S. Rep. Lois Capps, D-Calif., have also aggressively questioned the safety of California's nuclear plants. Diablo Canyon in particular has faced formidable anti-nuclear activism since long before it went live in 1984. The right-leaning and scientifically astute Blakeslee, however, has proved harder for utilities and regulators to ignore. "He has been," says Rochelle Becker of the California nonprofit Alliance for Nuclear Responsibility, "a tireless voice of reason."

Blakeslee, Becker and Capps are among a growing bipartisan chorus who believe that the NRC has done an inadequate job monitoring the country's 104 nuclear reactors, most of them built in the 1960s and 1970s and intended to last only 40 years. As the NRC renews those reactors' licenses, some observers wonder: Why is a lawmaker who represents fewer than a million people stepping into the role of a federal agency that represents us all?

Even Blakeslee wonders. "(Many of us) believe the NRC has taken away the safety role from the state of California," he told Pruett. "And so the NRC had darn well better do its job."

The NRC -- one of two agencies teased out of the boosterish Atomic Energy Commission in 1974 -- has long faced charges that concern for utility finances influences its decisions. ProPublica's John Sullivan recently found text written by industry lobbyists quoted verbatim in official NRC safety literature. But what worries Blakeslee is that NRC staffers rarely think skeptically before they relicense. "They only feel an obligation to assess and review data that exist," he says. "They never identify new hazards."

NRC spokesman Victor Dricks argues that the relicensing process is only for "evaluating the effects of aging on key plant systems"; regular safety inspections happen on an ongoing basis. "The NRC oversight process is highly intrusive," he says. "Every day, inspectors are walking through all the plants all over the country." NRC inspectors recently evaluated plant emergency systems in light of Fukushima, and flagged weaknesses in a special report.

But new evidence from fresh disasters rarely alters the NRC's aging-plant analysis. "Anything generic -- that applies to more than one reactor site -- can't legally be brought up in a relicensing process," says Michael Mariotte, executive director of the nonprofit Nuclear Information and Resource Service (NIRS). The design flaws in the nation's many General Electric Mark I reactors -- the same type damaged at Fukushima -- were never raised in the reviews, and 22 of 23 of them have been relicensed.

And on April 22, the NRC relicensed all three reactors at the Palo Verde Nuclear Plant near Phoenix, Ariz., without broaching the issue of the plant's meager water supply. The only nuclear plant in the world that doesn't draw cooling water from a major source, Palo Verde uses recycled municipal water. "That's not enough to handle a Fukushima-style situation where you have three meltdowns going on at the same time," Mariotte says.

Blakeslee is determined to compensate. In 2006, he pushed a bill through the Assembly directing the California Energy Commission to assess the seismic setting of the state's two plants. When Diablo Canyon broke ground in 1968, PG&E asserted that there was no seismic threat at all. "What other fault systems exist out there," Blakeslee wonders, "wholly unexplored or even undetected?"

Until such questions are answered, opponents suggest postponing attempts to renew Diablo Canyon's reactor licenses, which expire in 2024 and 2025. On April 10, PG&E capitulated, asking the NRC to delay until it could complete a series of 3-D seismic studies -- the "geological CAT scans" that Blakeslee recommended.

"My goal has never been to stop the plant from being licensed," Blakeslee says. "It's just part of my role as an elected official to make sure regulators are doing their jobs."