NRC tapping tech for better analysis of nuclear accidents

Nuclear Regulatory Commission's SOARCA project highlighted as 'paucity of good data' said to be hampering efforts in Japan

Long before the nuclear disaster in Japan started to unfold, scientists in the U.S. began trying to gain a more precise and realistic picture of what would happen if a similar accident occurred in this country.

For the past few years, researchers from the Nuclear Regulatory Commission (NRC) have been engaged in a project called State-of-the-Art Reactor Consequence Analyses (SOARCA), to better understand how a nuclear reactor would behave in a severe accident, as well as what sort of radioactive release it would cause and how the plume would spread.

Similar research on hypothetical accidents at nuclear power plants have been conducted by the NRC and international nuclear safety groups for the past 25 years. What's different with SOARCA, says the NRC, is that it uses modern computing resources and modeling software to generate more accurate and realistic accident simulations. It also examines extremely rare, "one in a million"-type accidents that could have a significant impact.

Such modeling is designed to help develop better protections and responses to nuclear accidents. CNN reported Tuesday evening that an unnamed U.S administration official said that a "paucity of good data" was hampering efforts to construct a model of radioactive plumes in Japan.

SOARCA models also take into account some of the new accident mitigation technologies and strategies that are deployed in nuclear power plants these days. The models factor in updated emergency preparedness measures and plant improvements that were put in place after the 9/11 terrorist attacks.

Elmer Lewis, a professor of mechanical engineering at Northwestern University and an author of two books on nuclear power plant safety, said today that accident modeling information is most widely used to improve plant design.

However, information gleaned from simulations can be useful in dealing with developing situations such as the one going on in Japan, Lewis said. In an unfolding accident situation, though, modeling radioactive plume data can be a big challenge and typically requires information from a bunch of sensors on the ground and in the air, he said.

Engineers in Japan are currently trying to avert a full-scale meltdown of its Fukushima nuclear power plant. The plant was severely damaged in last week's earthquake and subsequent tsunami. Concerns about the safety of the plant have been escalating sharply over the past few days.

Those concerns were further heightened today after a third explosion rocked the facility, causing radiation to increase to potentially dangerous levels.

The NRC said on Monday that it has sent several nuclear experts to Tokyo to provide assistance to officials there.

Among other tasks, the team's mission is to better understand radioactive leaks' potential impact on people and the environment, the NRC said in a statement Monday.

As part of SOARCA, the NRC has run computer modeling and simulation tools to study at least two operating nuclear power plants in the U.S over the past couple of years.

One of the plants that participated in the initial phase of the SOARCA project is the Peach Bottom Atomic Power Station in Pennsylvania. The plant features a boiling water reactor similar to the most troubled reactors in Japan. Another plant involved is the Surry Power Station, a pressurized water reactor in Virginia.

The commission did not respond to requests for comment on the status of its SOARCA project. However, publicly available information states that the project's goal is to develop a better understanding of the consequences of a nuclear power plant accident involving a radioactive release. SOARCA will provide agencies and the public with the "latest basis" for assessing the consequences of severe accidents at nuclear power plants, the information notes.

The study is also designed to examine the value and the extent to which existing defense-in-depth measures at nuclear power plants will mitigate potential fallout in an accident.

According to a FAQ on the NRC's Web site, SOARCA is a research effort that seeks to "realistically estimate" the outcomes of the leak of a nuclear power plant's radioactive material.

A core component of SOARCA's tests is a software tool from Sandia National Laboratories called MELCOR (Methods for Estimation of Leakages and Consequences of Releases). The NRC describes MELCOR as software that can be used to model the "progression of severe accidents in light-water reactor nuclear power plants."

The NRC also uses a separate software tool called MACCS2 (MELCOR Accident Consequence Code Systems 2) to study the potential health implications of an accident involving radiation leaks.

"MELCOR is designed specifically for the purpose of predicting the response of nuclear power plants to severe accidents that might be initiated by low-frequency events involving multiple safety system failures," said Randall Gauntt, the manager of Sandia's severe accident and consequence assessment department.

One of the situations the software is designed to model is a so-called station blackout scenario initiated by seismic damage, similar to what is happening in Japan right now, he said.

"The MELCOR code analyzes severe accidents in nuclear power plants; their progression through core melting, should inadequate cooling be available; and the release to the environment, should containment systems fail," Gauntt said.

The potential public impact of radiation leaks are evaluated using the MACCS code, which was also developed at Sandia for the NRC, Gauntt said.

Jaikumar Vijayan covers data security and privacy issues, financial services security and e-voting for Computerworld. Follow Jaikumar on Twitter at @jaivijayan or subscribe to Jaikumar's RSS feed . His e-mail address is

Copyright © 2011 IDG Communications, Inc.

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