Study claims nuclear plants still safe

The growing concern for nuclear power plants and terrorists attacks was alleviated last week by a report from the Nuclear Energy Institute (NEI), which stated that such events would not pose a significant threat to public health.

The study was jointly undertaken by the Electric Power Research Institute (EPRI) and the NEI.

With the aid of engineering experts, the report surveyed issues such as the probability that terrorist threats could cause damage on reactor fuel, the extensity of radiation emissions from a power plant's containment building (which stores the reactor) and the probability of public health consequences due to potential radiation exposures.

The overall security of nuclear plants stem from two sources: the robust engineering design which include thick walls surrounding sensitive equipment, and security personnel who constantly monitoring the plant for any abnormal activity.

According to EPRI, nuclear reactors are designed with a defensive safety strategy that requires failure of three specific barriers before a release of radioactivity would occur: fuel rods, the reactor cooling system/pressure vessel which has steel walls about nine inches thick and the housing building with concrete three to five feet thick.

Furthermore, the organization found the structures that house nuclear reactor fuel, including dry storage containers, would protect against a release of radiation even if struck by a large commercial jetliner.

The NEI also asserts that since 9/11, all government-owned nuclear plants have instituted more than 28 security measures mandated by the Nuclear Regulatory Commission (NRC).

Several of these measures include security forces, increased patrols, additional security posts and physical barriers, moving vehicle-checkpoints, greater law enforcement and stricter control of site access.

Much of these security approaches were not only designed in response to external agents.

Seismic activity, such as earthquakes, was a large factor when determining the structure and security of nuclear power plants. Earthquakes are able to shatter large buildings because of seismic waves, or large-scale vibrations in three perpendicular directions.

The structure"s response of these events is a function of the architecture, the nature of foundation, the soil, and moisture levels, and the duration/intensity of such vibrations.

Historical analysis of such natural catastrophes have shown that simple construction techniques, such as placing the heavier material at the ground level, or symmetry in a structure's design, prove to be important factors when determining if a building will survive a seismic event.

When addressing the radionuclide release from these structures, the NEI concluded that such an occurrence was highly unlikely and the likelihood of one fatality is less than one chance in 6,000 years, a statistic 80 times lower than the NRC"s safety standard for nuclear plant operation.

The main question at hand, however, centered around whether the spent nuclear fuel and/or the main reactor would be at risk. According to several scientists and engineers overseeing the plants, the containment building, which holds these two entities, is able to retain a large percentage of the radiation so that it is not released to the environment and atmosphere. Additionally, damage to the reactor fuel to a point where a substantial release of radiation might occur is a process that takes several hours -- which will allow a significant emergency response.

When reporting their results, the NEI calculated the estimated public health risks accompanying a low-probability terrorist attacks, and compared them to previously calculated risks common to the general public. They concluded that there was a 0.004 percent chance that both a terrorist attack could occur and the public would consequently be significantly threatened.