Relating Safety Issues to the MSR

This white paper is the result of our analysis of the safety issues addressed by the molten salt LFTR power generator design based on ORNL/TM-7207.

Safety WP on Molten Salt LFTR Power Generator

RELATING ADDITIONAL SAFETY ANALYSIS ISSUES AND CONCERNS TO THE MSR…

ORNL/TM-7207 – 3.5 — SAFETY CONSIDERATIONS
The main feature of the Denatured Molten Salt Reactor which sets it apart from solid-fuel reactor types is that the nuclear fuel is in fluid form (molten fluoride salt) and is circulated throughout the primary coolant system, becoming critical only in the graphite-moderated core.  Possible problems and engineered safety features associated with this type of reactor will be quite different from those of the present light water reactor and liquid-metal fast breeder reactor designs.  …In the Denatured Molten Salt Reactor, the primary system fluid serves the dual role of being the medium in which heat is generated within the reactor core and the medium that transfers heat from the core to the primary heat exchangers.  Thus, the entire primary system will be subject to both high temperatures (700 degrees Celsius at the core exit) and high levels of radiation by a fluid containing most of the daughter products of the fission process.
Because of the low-fuel-salt vapor pressure, however, the primary system design pressure will be low.  In terms of level of confinement, the entire reactor primary system is analogous to the fuel cladding in a solid-fuel reactor.  Although much larger, it will not be subject to the rapid thermal transients (with melting) associated with the Light Water Reactor and the Liquid Metal Fast Breeder Reactor accident scenarios.
Two additional levels of confinement will be provided in the Denatured Molten Salt Reactor, in accord with present practice.  Note that the once-through Denatured Molten Salt Reactor has safety advantages because a large and complex part of the primary containment of a breeder MSR — the chemical reprocessing plant — is substantially reduced and because less radioactive material is routinely removed from containment.
The breach of the reactor primary system boundary, resulting in a spill of highly radioactive salt into the primary containment, will probably provide the design-basis accident.  The analogous event in a solid-fuel reactor would be major cladding failure.  Possible initiators of this accident include pipe failure, missiles, and pressure of temperature transients in the primary salt system.
Failure of the boundary between the primary and secondary salt in the primary heat exchangers could be especially damaging.  In the event of salt spill, a possibly redundant system of drains would be activated to channel the salt to the continuously cooled drain tank.  The system primary containment, which is defined as the set of hermetically sealed concrete-shielded equipment cells, would probably no be threatened by such a spill, but cleanup operations would be difficult.
A unique safety feature of the Denatured Molten Salt Reactor is that, under accident shutdown conditions, the fuel salt would be led to the emergency core cooling system represented by drain tank cooling rather than vice versa.  The reactor and containment must be designed so that the decay-heated fuel salt reaches the drain tank under any credible accident conditions.  In any case, the decay heat is associated with a very large mass of fuel salt so that melt-through (or “China Syndrome”) is apparently not a problem.
The safety philosophy for accidents involving the reactor core is very different for fluid-fueled than for solid-fueled reactors because the heat source is mainly in the liquid-fuel salt and not in a solid, which requires continuous cooling to avoid melting.  A liquid metal fast breeder reactor, for example, has a large amount of stored energy (which must be removed under any accident conditions) in the fuel pins.  Dryout, which means immediate meltdown in a liquid metal faster breeder reactor, would not be nearly as severe in the Denatured Molten Salt Reactor because the heat source is removed along with the coolin capability.
First-order analysis has shown that a flow blockage of a central coolant channel of the reference Denatured Molten Salt Reactor which reduces the flow to less than 20% of nominal will probably result in local voiding of that channel.  ..Under any of-normal conditions, the fuel salt will be channeled to the drain tank, which must have reliable systems for decay heat removal.
No credible means exists for achieving recriticality once the fuel salt has left the graphite-moderated core.

“Fukushima Daiichi Site: Cesium-137 is 85 times greater than at Chernobyl Accident” by Akio Matsumura

 ‘Spend fuel at Fukushima Daiichi safer than asserted‘, Posted by Will Davis, 16 May 2012, http://ansnuclearcafe.org/012/05/16/spent-fuel-at-fukushima-not-dangerous/
In recent days, a number of articles have been printed that assert that a grave danger exists at the Fukushima Daiichi nuclear genrating station.  These articles claim that this danger exists due to the condition of the spent nuclear fuel at the site and th supposedly shaky condition of its storage and care.
Assertion 1:  The spent fuel pools, particularly at Fukushima Daiichi No. 4 plant 91F-4), are liable to collapse
Since shortly after the Tohoku quake and tsunami, TEPCO has continually inspected the buildings at the site for physical integrity.  More importantly, TEPCO has conducted seismic safety studies of all the reactor buildings; the results of these studies are linked below, which show that the reactor buildings are safe in the event of further (even severe) earthquakes.
Assertion 2:  The spent fuel pool at 1F-4 is in particularly dire structural condition
TEPCO has continuously monitored the 1F-4 building for damaging (having no damaged reactor in the building, it is the most widely accessible among 1F-1 through 1F-4, and thus most easily examined).  TEPCO has also constructed, as a result of structural studies performed on the building, a steel-reinforced concrete support beneath the spent fuel pool at this plant.  Photos are available at TEPCO  “Completion of Installation of Supporting Structure…”
Assertion 3:  The spent fuel in these plants’ spent fuel pools could ignite, leading to a massive radiological release
This assertion is patently false.  First, it is important to understand that in order for fuel to ignite, it has to get hot — and in its present condition, submerged in spent fuel pools with redundant cooling systems and filtration systems, constant remote temperature monitoring, backup generating and pumping systems in mobile units in place (on standby), and high reach concrete pump trucks on site (if necessary), there is no chance of the fuel heating up in any significant way while it is in the pools in the buildings.
We have seen already that it’s unlikely that the buildings would be damaged in a quake — and we can surmise, given the manpower and equipment on site, that even if any sort of equipment leak or malfunction temporarily suspended cooling for the spent fuel, that malfunction would be quickly detected and fixed.  So, it’s just not likely at all that the fuel would even begin to get noticeably hot n the spent fuel pools as-is now.  Temperatures of the water in the spent fuel pools is current in the 30 degrees Celsius and under range.
In order for apocalyptic assertions of a “fuel clad ignition and fire” to occur, moreover, the clad itself would need to be heated to incredible temperatures, which just isn’t possible.  Ignition of the cladding (Zircalloy-w) on those fuel elements can occur roughly at 900 degrees Celsius in the proper conditions, but it’s important to note that, depending on the surrounding conditions (presence or absence of water vapor and oxygen content of the surrounds), the material may not ignite at that temperature anyway.  From NUREG/CR-4982:  “The cladding on such fuel will not ignite until 900 degrees Celsius (1652 degrees F.), while the fuel melting point for U0-2 fuel is 2880 degrees Celsius (5216 degrees, F.).“
PLEASE NOTE THAT THE MOLTEN SALT LFTR POWER GENERATOR DOES NOT GENERATE SPENT NUCLEAR FUEL THAT MUST BE COOLED UNDER WATER FOR 60 MONTHS BEFORE IT CAN BE CUT UP AND STORED IN STEEL CASKS UNDERGROUND.
16 May 2012 – Small Power Reactors:
” Mining development in the North will require reliable sources of electricity and one alternative being talked about is small nuclear reactors. The CNSC is ready to review a design if a proponent brings us an application; and we will license it if we are convinced that it will be safe.”
— www.nuclearsafety.gc.caTHE MOLTEN SALT LFTR POWER GENERATOR WE ARE BUILDING HAS UNIQUE SAFETY ADVANTAGES OVER EVERY SOLID FUEL CYCLE REACTOR DESIGN.  NO WATER IS USED IN COOLING THE REACTOR CORE.  THE MOLTEN SALT REACTOR OPERATES WITHOUT HIGH, EXPLOSIVE PRESSURES, PUMPING THE FUEL SALT THROUGH THE PRIMARY LOOP ABOUT ONCE PER MINUTE.  THE ACIDIC FUEL IS WELL-MIXED THROUGHOUT AND ALSO CHEMICALLY BOUND IN THE ALKALINE SALT — AN INCREASE IN TEMPERATURE OF THE FUEL SALT DIMINISHES THE CRITICALITY, MELTS THE FREEZE PLUG THAT RELEASES THE FUEL SALT DOWN INTO THE NON-CRITICAL FUEL TANKS WHERE CONVENTIONAL COOLING FREEZES THE FUEL SALT.  A LOSS OF POWER STOPS THE COOLING FAN THAT KEEPS THE FREEZE PLUG FROZEN — THIS MELTS THE FREEZE PLUG THAT RELEASES THE FUEL SALT DOWN INTO THE NON-CRITICAL FUEL TANKS WHERE CONVENTIONAL COOLING FREEZES THE FUEL SALT.

NRC staff criticizes official’s handling of Fort Calhoun…

The letter alleges that Pruett was unconvinced of the need for a red finding and directed NRC staff to do additional, allegedly wasteful studies that took “several man-weeks of effort.”

The letter then says Pruett missrepresented the regional staff’s concerns when he traveled to NRC headquarters to discuss Fort Calhoun’s problems. He allegedly told headquarters’ personnel that his staff agreed with his determination that the fire at Fort Calhoun was not a significant safety issue.

“The willingness of Mr. Pruett to intentionally distort the fact to achieve his personal goals is irrefutable and they constitute an irreconcilable breach of integrity,” according to the letter.

Last month, the commission found that a red finding was merited.

The fire occurred in the electrical panel that guarantees electricity to the plant’s spent fuel pools. As a result of the fire, the pool was without electricity for about 90 minutes. According to federal regulators and OPPD, the pool had more than 80 hours of residual cooling ability, so public safety was not at risk.

Several things about the fire disturbed inspectors, including: faulty design and maintenance of the panel contributed to the fire; OPPD workers were unable to quickly get into the electrical room; and OPPD was tardy in notifying emergency officials.

Nuclear reactors are clumped into regions for oversight. Both OPPD’s Fort Calhoun and the Nebraska Public Power District’s Cooper Nuclear Station are overseen by Region IV of the NRC, which is based in Arlington, Texas.

Reactors have two federal inspectors who work on-site, and the rest, such as Pruett, work at regional offices.

John Kirkland, the senior resident inspector at Fort Calhoun, said that he has had no problems with Pruett and that at “absolutely” no time did Pruett push him to soft-pedal an inspection.

“I’ll be honest with you, Troy and I got along very well,” Kirkland said.

If the problems occurred as the letter characterizes, they came during meetings Kirkland didn’t attend, he said.

“The thing you need to realize, is that if Troy did disagree on the character of a finding — that’s why we have an open collaborative work environment — it still came out red,” he said.

 THE THING TO NOTE HERE IS “AS A RESULT OF THE FIRE, THE POOL WAS WITHOUT ELECTRICITY FOR ABOUT 90 MINUTES.  ACCORDING TO FEDERAL REGULATORS AND OPPD, THE POOL HAD MORE THAN 80 HOURS OF  RESIDUAL COOLING ABILITY, SO PUBLIC SAFETY WAS NOT AT RISK…. ‘ …IT STILL CAME OUT RED,’ HE SAID…”
The NRC regional director somehow concluded that the objective should be to fix the problem rather than raise a hue and cry nationally over what ‘they’ had done.
At the same time, it is necessary to note that the molten salt LFTR power generator that we are building will have no cooling pool on its premises, since there is no spent nuclear fuel generated every couple of years that must be cooled down for 60 months before it can be cut up and stored in casks.
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Edition: U.S.

Without fanfare, the nation’s nuclear power regulators have overhauled community emergency planning for the first time in more than three decades, requiring fewer exercises for major accidents and recommending that fewer people be evacuated right away.

The revamp, the first since the program began after Three Mile Island in 1979, also eliminates a requirement that local responders always practice for a release of radiation.

At least four years in the works, the changes appear to clash with more recent lessons of last year’s reactor crisis in Japan.

Under the new rules, the Nuclear Regulatory Commission and the Federal Emergency Management Agency, which run the program together, have added one new exercise: More than a decade after the 9/11 terrorist attacks, state and community police will now take part in exercises that prepare for a possible assault on their local plant.

Still, some emergency officials say this new exercise doesn’t go far enough.

And some view as downright bizarre the idea that communities will now periodically run emergency scenarios without practicing for any significant release of radiation.

These changes, while documented in obscure federal publications, went into effect in December with hardly any notice by the general public.

An Associated Press investigative series in June exposed weaknesses in the U.S. emergency planning program. The stories detailed how many nuclear reactors are now operating beyond their design life under rules that have been relaxed to account for deteriorating safety margins. The series also documented considerable population growth around nuclear power plants and limitations in the scope of exercises. For example, local authorities assemble at command centers where they test communications, but they do not deploy around the community, reroute traffic or evacuate anyone as in a real emergency.

The latest changes, especially relaxed exercise plans for 50-mile emergency zones, are being flayed by some local planners and activists who say the widespread contamination in Japan from last year’s Fukushima nuclear accident screams out for stronger planning in the United States, not weaker rules.”…..

OF COURSE, THIS ALARMISM OF HUFF POST GREEN SHOULD BE TEMPERED BY THIS HEADLINED STORY:

Numbers prove how safe nuclear power is

MAY 11, 2012 4:00 AM  •  EDWARD GREISCH, MOLINE

After last year’s nuclear leak, 573 certified deaths were caused by evacuation-related stress at Fukushima, Japan. Zero deaths were because of radiation as of Feb 4.

Fukushima’s natural background radiation still is higher than the radiation from the reactor leak. Its background radiation plus the radiation from the reactor leak still is less than the natural background radiation in the Quad-Cities. Natural background radiation varies greatly from place to place. Our background radiation is about 350 millirems per year. That’s 0.350 rem per year.

People living in Ramsar, Iran, have a background radiation of 10 to 20 rems per year and report no ill effects.

Members of StopCoal of Canada were arrested last week for blocking some coal trains headed for a seaport near Vancouver, Canada. StopCoal’s purpose is to stop global warming.

Coal-fired power plants put 100 to 400 times as much radiation into your environment as nuclear accidents, including Chernobyl. Coal contains uranium and all of uranium’s radioactive decay products. Only 52 people died at Chernobyl, mostly firefighters.

Edward Greisch

Moline

Safety It always helps to stop and take a close look for yourself.  This Vermonter does exactly that:

Regular Citizen on Vermont Yankee Nuke Dangers …22 Oct 10

Hey — What About That China Syndrome at 3 Mile Island !?

Do Not Forget Chernobyl !

T H E   S A F E T Y   C O N T E X T   O F   T H E   L F T R

We can substantiate that the LFTR represents the safest of all nuclear power generation alternatives.  These resources illustrate the context of this finding:

Three documents illuminate the Basics of Nuclear Energy, published by the New Mexico Bureau of Geology and Mineral Resources:

Nuclear power uses the energy created by controlled nuclear reactions to produce electricity.

The most commonly used nuclear reaction for power generation is nuclear fission.  Nuclear fission is the splitting of an atom’s nucleus into parts by capturing a neutron.  Nuclear fission produces heat – if you add all the masses together of the production of a reaction you do not get the starting mass.  This loss of mass is the heat and electromagnetic radiation produced during fission.

How Nuclear Energy Works

Currently about 17% of electricity worldwide is produced by nuclear power plans, but in some countries, like France, over 70% of their electricity is produced by nuclear power.

Here’s how it works in currently operational nuclear power technology.

The Basics

Nuclear energy has become much more attractive recently because it can decrease dependence on fossil fuels (oil, gas, and coal).

Why Nuclear Power?

…the latest generation of reactors feature improvements over older technologies.  But even as attention focuses on nuclear as an alternative to fossil fuels, questions remain about whether the newer reactors are sufficiently foolproof to be adopted on a large scale.

How Safe Are the Current Generation of Nuke Reactors?

Modern nuclear power plants are safer in all respects than fossil-fuel plants, their track record proves it.  Future nuclear plants can take steps now to ensure public safety and success of their nuclear facilities.

Will Nuclear Energy help or hurt our environment

Small Modular Reactors, of which the LFTR is the best possible example, present special safety factors that are quite different from every existing reactor today.  To understand why these SMR designs are game-changers, this MP3 provides an accurate overview.

Overview — Safety and the SMR

Nuclear power is portrayed by the major media and by environmental activists as dangerous and perhaps even sinister.  Wind power, on the other hand, is considered benign.  But the tracks records of nuclear power and wind power present a different picture.

Wind vs. Nuclear Power — Which Is Safer?

One of the three technologies that underpin the proposed global revolution is that of the Integral Fast Reactor (IFR), a type of nuclear energy system that nullifies most of the arguments against nuclear power that have been voiced for decades.  This response to a GREENPEACE argument is made by Tom Blees, author of Prescription For The Planet.

Rebuttal to Greenpeace on Nuclear

This compendium by “Next BIG Future” presents statistics that substantiate the claim of its headline that “Rooftop Solar Power Is Actually More Dangerous Than Chernobyl!”

Deaths per TeraWatt hour for all energy sources

From the outset, there has been a strong awareness of the potential hazard of both nuclear criticality and release of radioactive materials.  There have been two major reactor accidents in the history of civil nuclear power – Three Mile Island and Chernobyl.  One was contained without harm to anyone and the other involved an intense fire without provision for containment.  These are the only major accidents to have occurred in some 14,000 cumulative reactor-years of commercial operation in 32 countries.

World Nuclear Society — on Safety

The Most Serious U.S. Reactor Accident– Prompt Criticality-SL-1