Sunday, April 22, 2012

Solar Flares and Nuclear Safety

Solar flares

Photo by Fernando Reyes Palencia

Power grid failure presents a serious risk to the operation of nuclear reactors, which require electricity to maintain cooling water circulation even when shut down. As demonstrated by the reactor meltdowns at the Fukushima reactor complex, if you lose power lines and suffer backup generators failures at he same time, the loss of cooling capabilities rapidly causes the situation to spiral out of control.

Besides the natural disaster impacts of earthquake and tsunamis, another natural phenomenon—solar flares—poses dangers unlikely to be factored into the accident trees that assess plant operational risks. Coronal Mass Ejections (CMEs), which peak during regular cycles of the sun, can potentially disrupt the energy grid and render nuclear plants unable to maintain coolant circulation far beyond the week that diesel backup generators are required to function. In Flare-up: How the Sun Could Put an End to Nuclear Power, Gar Smith writes:

A 2011 Oak Ridge National Laboratory report warned of a 33 percent likelihood that a solar flare could lead to “long-term power loss” over a nuclear reactor’s life. With 440 nuclear power plants in 30 countries, and 250 research reactors, there are nearly 700 potential Fukushimas waiting to be unleashed.

Faced with a grid collapse, nuclear plants must rely on backup power to cool reactor cores and spent-fuel ponds. But the Nuclear Regulatory Commission requires only eight hours of battery power and enough fuel to run emergency generators for a week. Restoring outside power to Fukushima’s damaged reactors was a daunting task even when Japan had a functioning grid to fall back on. If the Sun sends a geomagnetic tsunami sweeping across Earth, it could become impossible to provide any form of traditional power.

The failure of the Solar Shield Bill (H.R.668), which included provisions that could protect the grid against the threat of geomagnetic storms, illustrates how woefully unprepared we are to deal with the very likely possibilities of large-scale power blackouts. As Gar points out in his article:

The US could protect its grid by spending around $1 billion to “harden” 350 key EHV transformers and stock blast-proof warehouses with replacement parts. Transformers could be protected with ground resistors. Costing about $40,000 each, they could be installed on 5,000 critical transformers for less than $200 million – about one-tenth the cost of a B-2 bomber.