----- Original Message -----
Sent: Saturday, March 27, 2004 3:23 PM
Subject: [MbrExchange] EnLG 2004mar25 In Native Alaska, Nuclear Industry Pitches New 'Micro-Nuke' (+ DOE Assessment)
In Native Alaska, Nuclear Industry Pitches New 'Micro-Nuke'Pacific News Service, Mar 25, 2004
Editor's Note: Far north in a mostly Native Alaskan town along the Yukon River, the Toshiba Corp. seeks to build a "super-safe" nuclear power plant.
Residents, eager to lower costly power bills, are interested, but wary.
Health Physics Society April 2004 describes this "Pint Sized Powerhouse" in 2 page article.
GALENA, Alaska--The Nuclear Regulatory Commission hasn't issued a permit for a new commercial nuclear power plant in the United States since the late 1980s, when the technology topped the list of energy industry taboos following the infamous meltdown of the Chernobyl reactor in the U.S.S.R. But if Japan's Toshiba Corp. has its way, the prototype for a new generation of "micronuclear" power plants will be constructed on a remote stretch of the Yukon River in Alaska before the end of the decade.
Last summer, representatives from Toshiba made the journey from Tokyo to Galena, a predominately Alaska Native village with a population of about 700. They met with community leaders to present their "4S" system, which stands for Super-Safe, Small and Simple.
According to Toshiba, the 4S could cut electricity costs for the village by more than 75 percent for at least 30 years. The plant would also use water from the Yukon River to create hydrogen gas to be stored in fuel cells, one of the most talked-about forms of renewable energy in recent years.
Galena serves as a hub for a handful of smaller villages along the Yukon and its tributaries. The region is made up of thousands of square miles of largely untouched boreal forest encompassing three National Wildlife Refuges, and includes some of the world's most renowned moose habitat. Like most communities in Western Alaska, Galena is a fly-in village; there are no highways, roads, or power lines linking it to the state's larger population centers. Large diesel generators must produce all electricity locally, using fuel delivered by a river barge during the summer months when the Yukon is ice-free.
The resulting electricity costs for local residents per kilowatt-hour is nearly three times the national average, even with assistance from a state-funded subsidy program.
Toshiba has pledged that the 4S prototype would be constructed at no cost to the village. Galena would have a cheap, clean-burning solution to all its energy needs for three decades, in exchange for becoming an international nuclear guinea pig.
Community member Rand Rosecrans cautioned Toshiba representatives at the presentation that many residents would have strong opinions: "You say the word 'nuclear' and lots of people are going to have an automatic negative reaction." So far, tribal and city leaders have expressed a cautious interest and desire to learn more about the idea.
"Like anything new, it's going to have to be studied pretty closely before we agree to bring it in," Louden Village Council Chief Peter Captain told the Anchorage Daily News.
In 2001, the Baker Institute for Public Policy at Rice University released working papers that examined the 4S system and three other similar reactors. The report was co-authored by Neil Brown, a Nuclear Engineer at the Lawrence Livermore National Laboratory. In a phone interview, Brown explained that besides being smaller than most reactors, the 4S is a liquid sodium-cooled reactor, not a water-cooled one.
According to Brown, there are 21 sodium-cooled reactors around the world -- including Japan's MONJU reactor, which Toshiba helped construct with three other companies in the 1985.
After construction delays, MONJU first went critical in 1994, but was shut down after an accidental sodium leak and fire occurred in late 1995 while operating on low power. No radiation leaked out, but community concerns have kept MONJU shut down.
"MONJU has definitely not been a success," says Paul Gunter, a reactor specialist with the Nuclear Information and Resource Service in Washington, D.C. Gunter said that experience with sodium-cooled reactors in the United States has not been much better. "The main concern (with this type of reactor) is that sodium and water have a tremendous explosive reaction. There was another near accident in Detroit at Fermi Unit One in 1966, resulting from loose parts."
But attorney Douglas Rosinski, of the Washington, D.C., firm Shaw Pittman, which represents Toshiba, says the 4S system is nothing like the infamous nuclear power plants of the past. He compares the 4S to a completely self-contained, automated "nuclear battery" with no moving parts. At the heart of the 4S system is a log-sized uranium core, which would generate power for 30 years before needing to be disposed of and replaced.
Brown said the reactor is similar to the first submarine reactors, and that Toshiba's design includes inherent safety characteristics, making it "a low-pressure, self-cooling reactor."
Toshiba hopes to have a 4S system operational by the end of the decade, but the cost of testing and licensing the prototype to the satisfaction of the Nuclear Regulatory Commission could keep it from getting off the ground. Which is why a rural Alaska Native village with remarkably high-energy costs was chosen as an ideal site for a prototype.
Rosinski and others seek to gather enough political support to secure significant funding for the project. Alaska's senior Senator, Republican Ted Stevens, the Senate pro tempore and chair of the powerful appropriations committee, has said that he supports Toshiba's proposal, but that it will have to first clear the hurdle of public opinion.
The Department of Energy plans to send staff to the region to evaluate energy production capabilities, including the 4S. They plan to complete a report by the summer.
USDOE Assessment of 4s in REPORT TO CONGRESS ON SMALL MODULAR REACTORS May 2001
3.9 4S (Japan)
The 4S is a LMR, using sodium as the coolant. The 4S design is based on the principles of simplified
operation and maintenance, improved safety and economics, and proliferation resistance. The 4S
design combines infrequent refueling, about every ten years, with a short construction period based on
factory fabrication. The designer is Central Research Institute of Electric Power Industry (CRIEPI),
The primary coolant system includes an electromagnetic pump to pressurize the liquid sodium coolant
and an intermediate heat exchanger, both placed inside the reactor vessel and above the core. The
secondary system consists of another electromagnetic pump, a helical-tube type steam generator, and a
sodium-water reaction product release system. The balance-of-plant systems include the nuclear steam
supply system, a turbine generator, and heating and ventilation systems. There is a containment vessel
that envelops the reactor vessel and the top dome.
The reactor fuel uses a metallic alloy (either U-Zr or U-Pu-Zr) which has been developed in the United
States, and later in Japan. In the 4S reactor core, the steady-state power level is maintained throughout
the core life primarily by slow vertical movement of a graphite reflector surrounding the core, rather
than by using neutron-absorbing control rods. Thus, the reactor power is controlled by allowing more
neutrons to leak out of the core (i.e., to not be reflected back into the core), rather than by absorbing
more neutrons in the core using control rods. Even though the method of using a movable reflector is
unconventional, the ability to control the reactor power is the same as using control rods.
The 4S design is a small reactor designed to have totally passive safety systems that do not require
power and may not require valve movements to initiate them. Unlike helium-cooled reactors, where the
helium gas has no effect on the reactor power, and water-cooled designs, where the presence of water
is required for the reactor to function, a sodium-cooled reactor can be more reactive without the
coolant in the core unless the “sodium void coefficient” is negative. A negative sodium void reactivity
coefficient is achieved in the 4S design by keeping the core diameter small, thus enhancing the radial
neutron leakage. The fuel temperature coefficient is also negative, so that reactor power inherently
decreases with increasing temperature. Load following is achieved in an innovative way by controlling
the water flow to the steam generator, thus manipulating the core inlet temperature. That is, as the
generator output matches the load, changes in the coolant temperature introduce a positive or negative
reactivity effect in the core, causing the reactor power to follow. This feature greatly simplifies
operation of the 4S power plant.
The use of a movable reflector to control neutron leakage and thus the reactor power is perhaps the
most unique feature of this concept. Liquid sodium is a coolant with excellent heat capacity, very high
thermal conductivity, low-operating pressure, and superb natural convection capability. Decay heat is
removed from the core by natural circulation of the primary coolant, and discharged by a coil system
placed above the intermediate heat exchanger. If the main pump fails, however, a passive cooling is
also provisioned using natural circulation of air from outside the guard vessel.
While the presence of plutonium in the fuel may be considered a proliferation and diversion risk, the fuel
is always in a highly-irradiated form, providing a level of self-protection. The fuel is also handled
remotely, so that there is never any direct physical contact between the fuel and plant personnel. This
physical separation enhances diversion resistance.
Overall Assessment and Potential Issues
In summary, although the 4S concept is at the basic design stage, sodium cooled reactor technology is
well developed. The 4S design is an evolutionary use of proven concepts, and as such, there would not
appear to be any technical barriers to this design and its deployment. With 10 years continuous
operation without refueling, greatly simplified operation with autonomous control, and a short
construction period based on factory fabrication, it is especially suited for remote sites. The design is in
the early stages of development and may not be ready for deployment in this decade.