How operators are driving key safety reforms from nuclear plant accidents

What you need to know:

Nuclear safety became a major topic since the 2011 reactor meltdown at Japan’s Fukushima plant following an earthquake and tsunami accident that wreaked the facility.

In one of the backyards of the D.C. Cook nuclear power plant in Michigan, US, stands a special newly built thick-walled all-concrete structure officials say can withstand some of the most violent earthquakes and tornados.

Inside this structure that sits on an elevated section of the vast compound on the shores of Lake Michigan is a new high-capacity stand-by power generator. In a separate yard less than 150 metres away another set of about six new power generators mounted on wheels are parked side-by-side overlooking the main power house.

“These are part of ongoing safety reforms to ensure we don’t have a repeat of the type of incident that happened at the Fukushima nuclear plant in Japan,” Bill Schalk, the communication manager at of American Electric Power (AEP) that owns the D.C. Cook power plant, said in reference to the power back-up units.

Nuclear safety became a major topic since the 2011 reactor meltdown at Japan’s Fukushima plant following an earthquake and tsunami accident that wreaked the facility. The incident has triggered a scramble for heightened safety measures among operators and regulators across the US, Europe and Asia to avoid a repeat.

“In nuclear safety we have to continuously learn and improve,” said Jack Grobe, the executive director of Exelon Nuclear Partners, part of Exelon Generation, which operates the largest nuclear power fleet in the US.

Like the rest of the world, nuclear plant operators in the US are now putting emphasis on areas such as back-up power during outages caused by severe flooding or earthquakes and are upgrading their plants to ensure reactors and pools holding radioactive waste stay cool even when the main power supply is lost.

“The primary lesson from Fukushima is to have other external sources of power to keep the plant running even in the event of an accident because power is key in the life of the plant,” Shane Lies, a Vice President in-charge of engineering at D.C. Cook nuclear plant, said.

In response to the Fukushima accident, the US Nuclear Regulatory Commission (NRC) issued a three-pronged safety strategy for implementation by 2016. A key recommendation by the regulator was to have nuclear plant operators develop comprehensive strategies for dealing with emergencies that may interrupt off-site power and compromise the safety of nuclear reactors.

It also advised nuclear plant operators to install more reliable instruments to measure water levels at cooling pools, where spent nuclear fuel is stored, and install hardened venting systems to prevent explosions caused by rapid build-up of hydrogen gas.

The regulator, however, said the two orders relating to emergency equipment and spent fuel pools will apply to every nuclear reactor in the US even though the order to install hardened vents is only applicable to US boiling-water reactors that have “Mark I” or “Mark II” containment structures.

The order, the regulator said, will have the nuclear reactors improve their venting systems to prevent or mitigate core damage in the event of an accident such as Fukushima. The NRC further required that every operator in the US analyse and update its earthquake and flood risks, conduct “walkdowns” at each plant and assess the ability to communicate in, and deal with, an emergency.

Nuclear power operators in the US are implementing the NRC recommended safety reforms that are estimated to cost at total $2.5billion on completion. The operators of D.C. Cook Nuclear Power plant plan to invest about $50 million to stabilise alternative emergency power supplies through measures such as back-up batteries and generators.

Keen to learn

“We hope to be among the first to comply with the post-Fukushima reforms,” Mr Lies said.

Experts said these reforms such as those being implemented by the US nuclear power plant operators have been adopted globally as operators and regulators laid emphasis on learning from incidents and experiences among peers to enhance safety.

“Nuclear safety culture is taking precedent and industry players are now very keen to learn from one another to avoid repeating mistakes that may have been made by others,” Joseph Braun, a nuclear specialist at Argonne National Laboratory in Illinois said.

Prior to the Fukushima accident, nuclear operators world over were united in effecting corrective measures picked from the lessons earlier learnt from an accident at the Ukranian Chernobyl nuclear plant in 1986. Key lessons picked from the Chernobyl accident helped to avert catastrophe at the Fukushima plant despite the different circumstances under which the two accidents occurred.

While there was devastation in the Chernobyl incident due to radioactive leaks, thick containment walls at the Fukushima plant shielded the reactor cores such that a meltdown of the nuclear fuel would unlikely lead to a major escape of dangerous radioactive clouds into the atmosphere.

At Chernobyl, there was no containment structure and nuclear operators picked up a lesson and constructed containment walls.

Earlier in 1979, The Three Mile nuclear plant accident in the US — the most serious in the country’s commercial nuclear plant operating history— also handed operators worldwide some valuable lessons.

Peer review

The accident was caused by a valve malfunction compounded by human error, leading to partial meltdown of reactors and small off-site releases of radioactivity.

“Its aftermath brought about sweeping changes involving emergency response planning, reactor operator training, human factors engineering, radiation protection, and many other areas of nuclear power plant operations,” the US NRC said in a brief.

It also caused the NRC to tighten and heighten its regulatory oversight to enhance reactor safety. Apart from the quest to learn from such individual incidents, the urge to share experiences and expertise among rival operators has become so strong in Europe and Asia where authorities are even considering the creation of formal structures on peer review to bolster safety.

“Peer review has become a big concept in nuclear safety because parties want to assess each other to objectively bring out strengths and weaknesses in their respective programmes,” Jongile Majola, a nuclear energy consultant told Business Daily.

The European Union in June agreed a new law to strengthen safety standards and improve supervision of nuclear safety facilities based on lessons learned from the Fukushima incident.

“We need to put all our efforts into making sure that the highest safety standards are followed in every single nuclear power plant across the EU,” Energy Commissioner Guenther Oettinger said in a statement in June.

According to the new EU framework new nuclear power plants need to be designed in a way that reactor damage will not have any consequences outside the plant in order to prevent radioactive leakage.

Fukushima lessons

“The new directive builds on the lessons learned from Fukushima and the nuclear stress tests and is based on the latest international standards” the Commissioner said.

National regulators will be required to draft a strategy on how to communicate with the public if an accident happens and citizens must be given the opportunity to take part in decision-making to grant licences for new nuclear plants, the document further said.

The new legislation also introduces a system of European peer reviews to be carried out at least every six years.

“For the first time it sets out a clear nuclear safety objective to further reduce safety risks. It will introduce a system of European peer reviews to be carried out at least every six years. The revised directive also enhances transparency, in particular through better public information on the safety of nuclear installations,” Mr Oettinger said.

It strengthens the independence and the powers of national regulators. For the first time, it sets out a clear nuclear safety objective to further reduce safety risks, the Commission said.
The agreement is yet to be formally approved by heads of government to become law.

Asian nuclear nations are widely expected to walk in EU’s footsteps and even adopt peer review on safety matters. South Korean President Park Geun-hye last month urged the creation of a nuclear safety consultative group in Northeast Asia, given the high number of nuclear power plants in the region and public concerns over safety.

The Asian country operates 23 nuclear reactors supplying about a third of its power, but the Fukushima disaster, coupled with nuclear tests by its neighbour North Korea and a series of domestic nuclear scandals have hurt public confidence in the technology.

“Northeast Asia is a place where nuclear power plants are densely located,” Reuters quoted Park as having said in a televised speech for the National Liberation Day, noting safety has become a major issue for many people.

The President suggested China, Japan and South Korea should lead the formation of a nuclear safety consultation body nearly similar to the European Atomic Energy Community (Euratom) which helps to pool knowledge, infrastructure, and funding of nuclear energy besides ensuring the security of atomic energy supply within the framework of a centralised monitoring system.

The World Association of Nuclear Operators (WANO) has also greatly championed peer review in nuclear safety.

Accident mitigation

The association has, for several years, fostered a voluntary peer review programme in which commercial nuclear power plants host external reviews of their performances, mainly on how plants are operated.

The scope of peer reviews has, however, widened since 2011 after the Fukushima accident to include severe accident management or mitigation (SAM) guidelines as well as some design matters.

Peer reviews traditionally result in reports to the operator, and if these are not acted on, follow-up visits lead to special reports, and ultimately, if necessary, confrontation with the utility’s board.

In recent years WANO has even introduced pre-startup reviews as part of its peer review programme, particularly to address the situation of new plants in countries and organisations without previous nuclear power experience.

The reviews seek to evaluate how each operating organisation is prepared for start-up and make recommendations for improvements based on the collective experience of the world industry.

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