ASME briefing informs Capitol Hill staffers about U.S. nuclear plants

Francis Dietz
ASME Government Relations

WASHINGTON — Tests conducted by Sandia National Laboratories indicate that America's 103 nuclear power plants provide a significant level of protection against terrorist attacks, experts said last month during an ASME-sponsored briefing on Capitol Hill.

The briefing, "The Nation's Nuclear Infrastructure," was part of a series of briefings on vulnerability and security that ASME organized after Sept. 11. The series is sponsored by ASME and several other engineering and scientific societies.

The purpose of the briefing last month was to give congressional staff an overview of the integrity of nuclear power plant containment structures and safety requirements for the transportation of radioactive waste material.

About 80 congressional staffers and members of federal agencies and the engineering and science community attended. The event was hosted by Rep. Doug Ose, R-Calif., who is chairman of the House Subcommittee on Energy Policy, Natural Resources and Regulatory Affairs, which has jurisdiction over the Nuclear Regulatory Commission.

Ose delivered welcoming remarks, and Rep. Heather Wilson, R-N.M., a member of the House Energy and Commerce Committee, briefed the audience on several nuclear security provisions that passed the House during the past session. Several other members of Congress also attended the briefing.

ASME Past President Robert E. Nickell explains the design of U.S. nuclear power plants.

 

 

Federal design requirements help to ensure that "Nuclear power plant structures, such as the containment, the spent fuel pool, and dry storage systems, are quite rugged and robust," said ASME Past President Robert E. Nickell, who is an expert on nuclear power.

Although there are many variables when designing against disaster, Nickell explained that the federal design requirements to provide a margin of safety for nuclear power plant structures also provide some level of protection against sabotage or terrorist attacks.

Nickell and Ken Sorenson, manager of the Transportation Risk and Packaging Department at Sandia National Laboratories, educated the audience about the strict standards, including ASME standards, that govern construction of nuclear power plant containment structures and the casks that are used to transport spent nuclear fuel.

Nickell said that design requirements to protect public health and safety from internal pressure brought on by a loss-of-coolant accident and that protect the containment structure from tornado-borne projectiles and seismic events also serve to provide a measure of protection against sabotage.

The reason is redundancy, known as defense-in-depth design principles, which provides four layers of protection from both internal and external threats.

Without actually saying that a nuclear containment structure could withstand the impact of a fuel-laden aircraft, Nickell explained the four layers of protection — the cladding around the nuclear fuel itself, the concrete shield walls surrounding the fuel containment area, the reactor pressure vessel and the containment structure — and the results of half-scale tests conducted in Japan and jet aircraft impact tests conducted in the United States.

Nickell said that tests conducted by the Central Research Institute for the Electric Power
Industry of Japan in the late 1980s found that a hard-nosed projectile traveling at a high rate of speed can penetrate the thickest concrete wall.

During the Sandia tests in 1997, a 4,000-pound jet engine slammed into a 24-inch-thick concrete wall at 240 mph, resulting in extensive cracking and spallation — concrete pieces on the inside of the wall become dislodged and airborne — but no penetration.

The same engine impacting a 63-inch-thick, reinforced concrete wall, similar to the exterior of a nuclear containment structure, at 480 mph resulted in less damage and no penetration.

Comparing the two tests, Nickell noted that the test in Japan used a hard-nosed projectile, similar to an armor-piercing shell, while the Sandia test used an actual jet engine, which is much more collapsible while still being the most dense part of an aircraft.

In his presentation, Sorenson entertained the audience with several video clips of actual tests performed on the casks used to transport spent nuclear fuel to storage sites.

In the clips, casks were subjected to a full-scale drop from nine meters onto an unyielding target, a one-meter puncture test onto a steel pin welded to an unyielding surface, a thermal test in which the cask was totally engulfed in a 1,475-degree fire for 30 minutes, and a full-scale rail test in which the cask was smashed into a concrete block at 81 mph.
In all cases, the casks held their cargo with no leakage.

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