What does this mean for those of us who live near the plant? For the past 15 years or so, PG&E has been using high-burnup fuel – fuel that burns longer in the reactor, and so is much hotter (both in temperature and radioactivity) than the “traditional” nuclear fuel. When high-burnup fuel comes out of the reactor core and is placed in the cooling pools, it needs to have space around it, and it must stay in the cooling pools for AT LEAST 7 years. Even after 7 years, it is hotter than other fuel. (PG&E has not revealed how many of the improperly loaded fuel rods were high-burnup.)
The fuel rods are supposed to be spaced far apart when they are loaded into the dry casks. Here’s where the problem lies:
PG&E IMPROPERLY LOADED 19 OF THE 34 DRY CASKS AT DIABLO CANYON. Rather than spacing the fuel rods far apart, technicians loaded the fuel into the CENTER of the dry casks, which keeps the heat at a higher level than the dry casks are designed for. In 56% of the dry casks now stored on the fragile, earthquake-prone coastline at Diablo Canyon, fuel loading has VIOLATED TECHNICAL SPECIFICATIONS.
The higher heat load caused by improperly loading fuel into dry casks can cause higher temperatures inside the cask that could in turn warp the lid because of uneven temperature distribution inside the cask. If the lid warps, then it can cause exacerbation of cracking around the bolt holes in the stainless steel cask. If the bolt holes crack, the stainless steel cask (5/8” thick) can crack, the lid can become dislodged, and radiation can escape. If there is sufficient cracking, oxygen can permeate the cask, which has been vacuum-sealed with helium. If oxygen hits the zircaloy cladding on the fuel rods, they can spontaneously ignite, causing an uncontrolled release of radiation. If that happens, it would be a catastrophe of unprecedented proportion.
What has PG&E done about this? They’ve sharpened up their pencils and shown us that it’s all just “fine.” They report that the “total thermal load has not been exceeded.” No problem!
Never before in the history of US nuclear power has an operator so failed to follow technical specifications for spent fuel loading. Technical specifications are the nuclear industry’s bible, and they are to be followed precisely. PG&E has CONSISTENTLY VIOLATED the clear instructions that they are ordered to adhere to.
San Luis Obispo Mothers for Peace calls for immediate additional NRC oversight in the form of two additional inspectors at Diablo Canyon nuclear power plant for at least the next two years.
We call for a public NRC investigation into the root cause of the problem.
We call for the immediate inspection of all 34 dry casks to look for cracking, warping and escape of radiation into the environment.
And we call for the immediate shutdown of the plant until the problem has been fully and completely corrected.