Q & A: With a Nebraska Nuclear Plant Operator

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PostThu Jun 23, 2011 6:50 pm » by domdabears


Q: People see photos of Fort Calhoun Nuclear Station surrounded by water and dikes near Cooper Nuclear Station being overtopped near Brownville. Are these plants at risk from the Missouri River floods?

OPPD: If you look closely in the photos, our plant, our substation and other buildings are dry behind berms, sandbag walls and AquaDams. The plant is secure from water to the 1,014 feet above sea level elevation (the river is now at 1,006). It also has diesel generators and additional fuel staged to provide power from on site.

NPPD: There have been at least five situations of flooding around the Brownville area since 1952, and Cooper Nuclear Station, which has experienced several floods since it began commercial operation in 1974, was built to withstand various natural disasters, including tornadoes and earthquakes. The site was elevated 13 feet above the natural grade to 903 feet sea level elevation to accommodate the maximum, probable flooding event. (Earlier this week floodwaters came within 18 inches of 902 feet -- the mark at which Cooper would be shut down.)

Q: What steps have you taken to protect the power plants?

OPPD: In addition to the sandbagging, the berms and the AquaDams, more power lines were run to the training center and administration building. Concrete barriers were moved into place in some locations.

NPPD: Cooper initiated its flood procedure plan May 30. Plant staff have been filling sandbags and constructing physical barriers to protect the site's equipment in and outside of buildings, substations and electrical switch yards. Also, operations and security staff essential for 24-hour coverage are staying on site.

Q: Comparisons have been made between what happened to Japanese nuclear power plants and those in Nebraska because of their proximity to the Missouri River. Some people say Cooper Nuclear Station is particularly vulnerable because it has the same basic design as the Japanese reactors. (Note: This question does not apply to OPPD because its reactor is of a different design.)

NPPD: Extremely unlikely. The Midwest is not susceptible to a tsunami. ... Cooper is designed against flooding from the Missouri River, and NPPD is confident the safety systems are in place to respond to a major, natural disaster or crisis event. The accident at Fukushima Daiichi was initiated by two severe natural disasters ... an earthquake measuring 9.0 on the Richter scale (and) ... a tsunami.

It is true that both Cooper and the Fukushima Daiichi units are boiling-water reactors. However, it is misleading to make a direct comparison. The plant's General Electric BWR-4 design has been enhanced or modified to include steam-driven coolant pumps that operate independently from AC power. Station batteries are used for automatic operation, and procedures are in place to manually operate without DC power.

Cooper Nuclear Station also houses two permanent redundant safety-related automatic emergency diesel generators capable of powering all safety-related equipment. These diesel units would be the first to go online during an emergency loss of power. They would automatically start and load without operator action. Only one is needed, so the second is additional protection. We also installed a third emergency diesel generator during this past spring's refueling outage.

Cooper has enough fuel to run one diesel generator at least 40 days. A reserve fuel oil supply resides in underground bunkers to protect it from environmental conditions. These bunkers are anchored so as not to "float" if the river table were to rise. The bunkers collectively contain a minimum of 49,500 gallons. Cooper also has two fuel tankers on site, each of which holds 7,000 gallons.

Other equipment, such as fuel pool cooling pumps, four independent sets of batteries that provide DC power to safety-related equipment, a portable diesel generator to charge these batteries and a diesel-driven, portable fire pump, are also on site to provide additional generation and support.

Finally, Cooper has a "beyond-design-basis" strategy to mitigate against events like those that took place in Japan. To our knowledge, the Japanese do not plan for "beyond-the-design" basis.

Q: What happens if the Missouri River floods the reactor building?

OPPD: Fort Calhoun Station is protected to the 1,014-foot line, far above the current sea level elevation. With the containment building sealed, river water cannot enter it. ... The fuel in the spent fuel pool is underwater for a purpose, to stay cool. The top of the spent-fuel pool is at elevation 1,038 feet. The fuel in the containment building also is underwater by design.

NPPD: It is unlikely the Missouri River water will reach the reactor building. Our operational procedures and "beyond-the-design" strategies serve as protection, but we also have physically protected the reactor building from water. Four-foot-high barricades are in place both outside and inside the building. ... The water would have to be above 907 feet sea level elevation before it would intrude the building. That is an approximate 7-foot rise to the river's current water level. Even if water did intrude the building, it would be directed to floor drains.

Q: What is the likelihood that radioactive particles could enter the water or atmosphere from an accident caused by floodwaters?

OPPD: The fuel is safe and secure.

NPPD: Again, extremely unlikely. Cooper has physical and equipment barriers in place that would prevent any radioactivity from entering the water, the first of which is preventing the water from entering the building.

Q: If floodwaters do inundate Fort Calhoun, what is the risk to people living in the surrounding area?

OPPD: We feel that the plant is secure. The risk to the surrounding area will be provided by the flood, not our plant.

NPPD: We are taking the proactive and precautionary steps to minimize any risk.

Q: Have OPPD and NPPD received phone calls and emails from people concerned about the safety of both plants? What is your response?

OPPD: We have responded with facts on what we are doing to stay on top of the situation. We held a news conference last Friday to address concerns and questions from the news media.

NPPD: We have received a handful of emails. ... Nuclear power is a safe technology. Federal regulations, the industry's nuclear safety culture and history reinforce this. We have repeatedly withstood adverse conditions.

Q: What is the risk if both plants are shut down for months?

OPPD: Obviously, there is a financial impact, depending upon the price of replacement power and the amount needed. OPPD has other generating stations that are still providing power.

NPPD: There may be financial risks whenever a power plant is taken offline for a significant period of time, but NPPD has other generation resources it can call upon. ... It can also buy power on the market from other utilities.

Read more: http://journalstar.com/news/local/artic ... z1Q7Q2Uusp
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