May 01, 2011

Carnival of Nuclear Energy 50

1. Idaho Samizdat - Initial look at lessons learned from Fukushima Below are the first 10 of 14 lessons learned listed at Idaho Samizdat.

This paper outlines the initial list of lessons learned from the multiple sequence of events, some interpretations of the news releases and the aspects of safety culture that contrast Japan and the U.S. during crisis management.

It is based largely on events of the first three weeks and professional interpretation of publically accessible information. It is being released without peer review and in this summary form. Only the provisionally conclusive lessons learned are noted below.

1) Nuclear R&D institutions must consider alternatives to zirconium-based and zircaloy cladding so that chemical reactions that generate hydrogen is prevented. We (as an industry) need to accelerate development and deployment of non-hydrogren producing cladding materials; that is, assuming that the coolant/ moderator/ reflector remains (light) water.

2) Having multiple (reactor) units at one site, having more than two units on site needs critical review in terms of post-accident response and management. We must consider the energetic events at one unit exacerbating the situation (safe shutdown) at the other.

3) Further, there is a definite need for a backup (shielded) reactor plant control center that is offsite (remote) so that the accidents can be managed with partial to full extent of reactor plant status (P, T, flowrates, valve status, tank fluid levels, radiation levels).

4) There is a need for standby back-up power, via diesel generator and battery power, at a minimal elevation (100feet/31m) above and some distance from the plant (thus remotely located). This is needed to offset loss of off-site power for plants subject to environmental water ingress (foremost tsunami). Spare battery power should also be kept off-site and in a confirmed ‘charged’ state.

5) It is clear that the spent fuel pool (SFP) cannot be in proximity of the reactor core, reactor pressure vessel or containment itself. The SFP, in current form, is essentially an open volume subcritical assembly that is not subject to design requirements generally defining a reactor core.

Yet, unless thermohydraulic cooling is maintained, it is subject to the similar consequences as a reactor core without adequate cooling. Therefore, we need new passive designs of the SFP, away from the actual plant’s reactor core.

6) Thus needs to be a re-definition of the spent fuel pool. A new standard and design requirement is needed for the spent fuel pool. It should be ‘reclassified’ as a subcritical assembly with a potential to go critical with no active or passive control (rod or soluble ‘poison’) mechanism. Further it needs to be some distance from the reactor plant.

7) We need to identify key valves for emergency core cooling and require them to be non-electrically activated. Otherwise these valves need a secondary means of open and closed status that is remotely located.

8) If an ‘in-containment’ SFP is maintained, then the fuel transfer crane system must be designed so that it is available to remove the fuel during a post-accident phase. OR a second means such as a robotic arm needs to be available.

9) There needs to be a volumetric guidance analysis for ultimate (decay heat) cooling contingency plans so that not only limitations on volume are understood but also transfer of liquids from one volume to another.

Spare tanks and water-filled tanks need to be kept on site as uptake tanks for ‘runoff’ in case of addition of cooling during accident management phases. Spare means to produce boric acid needs to be available off-site. Earthquake-proof diesel generator housing also need to be water-proof. Remote diesel generators are also needed with access to equally remote diesel fuel tanks (also see 4).

10) For nuclear power plants located in or near earthquake zones, we cannot expect structural volumes and ‘channels’ to maintain structural integrity. We should also expect the immediate ground underneath these structures to be porous (earth). Thus design of these volumes and channels should be such that they minimize connections to other (adjacent) volumes from which contaminated (liquid) effluents can flow.

2. Atomic Insights challenges the New York Academy of Sciences to more fully repudiate the "Chernobyl Consequences"

Why are the conclusions of the NYAS report versus the consensus reports so dramatically different? There are several facts that contribute to the difference:

a. Fear of radiation was rampant and deep-seated. Government actions were confusing and contradictory. Several of the medical specialists who investigated the after-effects of Chernobyl noted that fear of radiation could by itself explain the spread of depression, alcoholism, absenteeism, abuse of drugs, sleeplessness, and the symptoms that such ills create and sustain. One example: Prior to 1986, the rate of abortions downwind of Chernobyl was fairly constant. The year following showed an additional 50,000 to 100,000 abortions, and abortion rates for following years returned to nearly the previous level. This is presumably because physicians advising pregnant women were ill-informed about the effects of low-dose radiation, and added to the problem, rather than alleviating it. It was repeatedly reported that fear of radiation was much more destructive than the radiation itself.

b. The Ukrainian government offered extensive incentives to declare oneself a “Chernobyl victim.” The original contract with the Soviet government promised that any person injured by the reactor would be fully taken care of, at the expense of the Russian government. This provision came to include housing, hospitalization and other medical care, and cash. The program became so lavish and extensive that resentment grew up against the “victims” who were judged by many to be parasites. There were fund-raising tours through USA and elsewhere, of malformed “Chernobyl victims” who didn’t even all live in or near Chernobyl.

c. A collection of anecdotes is not data. Correlation does not prove cause. The data cited in this report were accumulated by stumbling across correlations of various illnesses or symptoms, regardless of whether such symptoms have ever been known to result from irradiation. Most have not. Recognizing that such post-hoc pattern-building is generally disparaged by scientists, the authors argue that in the Chernobyl situation, it is required. There is no attempt to replicate or peer-review the data. The need for statistical significance is specifically denied.

d. “Exposed to radiation” does not mean “injured,” though the report implies otherwise. All life-forms have been exposed to radiation, since the dawn of time. Table 1.9 of the report’s Chapter 2 shows the number of people “Suffering from Chernobyl Radioactive Contamination.” Heavily contaminated areas is 270,000; Outside Europe is 4,000,000,000. These four billion people are said to be suffering from a Chernobyl radiation dose of 0.025mSv. This is about 1% of the global average radiation background from all sources, and many people will casually take actions that increase their radiation dose a hundred times the Chernobyl dose, just from the everyday activities of living.

Marshall Brucer, “the father of nuclear medicine,” in his canonical “Chronology of Nuclear Medicine,” indicates how extensive this variation can be. On page 323, he lists various radiation background levels (with cosmic ray contribution removed) from New York City at 0.62mSv/year to SW France up to 87.6; to the potash fertilizer area in Florida up to 1,750. He notes, “If you live in one place on earth, your background may vary from day to day by a factor of ten, or even 100…The inside exposure rate can change by a factor of 10 within hours, just by opening windows.” He notes that building with brick, rather than wood, can nearly double your daily radiation dose, but that the radioactivity of bricks and concrete is also highly variable: from 0.05 to 4.93 mSv/hr for bricks, and from 0.29 to 2.54 for concretes. “A factor of 10 daily variation [in radioactivity] marks the diets of most people.” As to the specific isotopes unique to nuclear fission: despite statements to the contrary in the report, over 99% of those were put into the air by nuclear weapons tests, not the reactor.

The authors’ theory of radiation damage is bizarre. “One physical analogy can illustrate the importance of even the smallest load of radioactivity: only a few drops of water added to a glass filled to the brim are needed to initiate a flow. The same few drops can initiate the same overflow when it is a barrel.” [TR note: No, it doesn’t. Just try it. The water will not run up and over the sides of a glass or a barrel.]
“…we simply do not know when only a small amount of additional Chernobyl radiation will cause an overflow of damage and irreversible change in the health of humans and in nature” No evidence is offered to support this unorthodox theory of radiation damage.

One other factor makes the tiny Chernobyl dose appear to be so significant–the statistical magic of small numbers. Cluster analysis has been made notorious by Sternglass, Wing, et al. They look at the cancer rate in counties surrounding, say, a nuclear facility. They are shocked to find that about half the counties are above average. (This is not Lake Woebegone, where all the children are above average.) Asked about the other half, they say these are not of interest; those people are just lucky. If the average annual rate of cancer deaths in the counties of this study is, for example, 10, then suppose one of that 10 moves to an adjacent county. That raises the death rate for the new county to 11, and lowers the old county to 9 – a 20% difference! If, instead of 10, the average is hundreds, or thousands; do they then lose the magic of small numbers? Not at all. They can then break the data down into particular types of cancers, and/or age groups or other categories of individuals. The possibilities are endless. And it’s all bad science.

3. NEI Nuclear notes - NEI Weekly Update on Fukushima Daiichi
Plant Status from April 29, 2011

* Priorities this week at Fukushima continued to be cooling the reactors and fuel pools, draining water from the turbine buildings and concrete structures that house piping to reduce radiation levels, and containing the spread of radioactive materials. Tokyo Electric Power Co. is increasing the amount of cooling water injected into reactor 1 at the Fukushima Daiichi plant as part of a plan to cover the fuel.

* TEPCO plans to build a storage and processing facility that can hold 70,000 tons of highly radioactive water at the plant.

* Overall, site radiation dose rates are stabilizing or decreasing. The most recent radiation readings reported at the plant site gates ranged from 4.8 millirem per hour to 2.2 millirem per hour. TEPCO has released a map showing radiation levels around the site, based on readings taken on different days since the incident began.

* TEPCO said this week that it will build a wall of sandbags along the shoreline at the Fukushima Daiichi site as a temporary measure against another possible tsunami. The company also moved emergency power generators to higher ground to prevent the reactors' cooling systems from failing in case a major tsunami hits the plant again. The utility will sandbag the shoreline at the plant to a height of several meters. Priority will be put on the area near the waste processing facility, where highly radioactive water is being moved from around the reactor buildings. TEPCO is also planning to build a breakwater on the shoreline, as the sandbags cannot remain the long-term solution for a possible tsunami.

4. World Nuclear News - Consolidation for US nuclear generators

Exelon and Constellation Energy have announced a $7.9 billion merger. Under the name Exelon, the resulting firm will be America's largest generator of nuclear power by an even greater margin.

The firm will retain the name Exelon and its current headquarters location in Chicago, although retail and wholesale operations currently under Constellation will be based in Baltimore. Renewables businesses for both firms will be placed in Baltimore and the overall firm will keep its three utility brands, BGE, ComED and PECO. It will count a generation portfolio of over 34,000 MWe, of which about 19,000 is nuclear from 22 reactors. About 55% of delivered electricity would come from this.

5. Idaho Samizdat - Will Fukushima increase interest in small modular reactors?

What if industrialized countries began to mitigate the risk of similar future events by building resilient networks of small modular reactors? What if instead of building a single 1,000 MW nuclear reactor, a utility laid plans to build six-to-eight small modular reactors (SMRs) in locations near major demand centers for electricity?

A resilient grid of SMRs built in a distributed network would be much less susceptible to damage from natural disasters or man-made disruptions. If one SMR goes out of service, it doesn't create a regional blackout for everyone else in the utility's service area.

Another issue that comes to mind is whether continued reliance on traditional light water reactor (LWR) designs is the only feasible path forward for SMRs? A lot of emphasis, perhaps too much, has been made on the production of hydrogen when fuel assemblies with their zirconium cladding are uncovered from cooling water. At Fukushima three of the six reactors suffered significant damage to their secondary containment structures from hydrogen explosions.

The ARC-100 reactor design concepts contain intriguing safety measures which might benefit highly industrialized countries seeking a more resilient power grid. Similar benefits might come from other SMR designs including those that use conventional LWR designs. It depends in part on the pace of advancement in fuel cladding materials science.

The key idea is to find ways to avoid future consequences of having too much electrical generation capacity invested in a single site. This is especially important in areas where there is a potential for earthquakes, tsunami, and other natural disasters or man-made disruption. SMRs buried underground add the natural containment of that design paradigm to their protective envelope.

Changes will also be needed in the way rate structures are set for resilient networks of SMRs compared to rates for single large plants. Perhaps the lure of lower costs for T&D architectures will be an incentive for utilities to speed up their assessments of SMRs in the wake of Fukushima?

6. ANS Nuclear Cafe - Chernobyl: 25 Years Later

Almost 50 people died in the Chernobyl disaster. But even as we mourn those who lost their lives that fateful day 25 years ago, we must also acknowledge the important changes the industry has made around the world that ensure the safety of this energy source. We also know, even at this early stage, that no one died as a result of the incident at Fukushima, and we’ll continue to study the events there in order to improve safety and reliability.

Source: "Life-Cycle Assessment of Electricity Generation Systems and Applications for Climate Change Policy Analysis," Paul J. Meier, Univ. of Wisconsin-Madison, Aug. 2002

7. ANS Nuclear cafe - was Fukushima correctly rated on the international nuclear events scale ?

In the weeks and months ahead, we will have an even greater opportunity to analyze this accident and place it into proper historical context. Given the information currently available, it seems that the Japanese government’s INES ranking for Fukushima may be too high and the IAEA may need to consider revisiting the criteria used to classify nuclear events on the INES.

8. Yes Vermont Yankee - Entergy and Vermont Part 2: Shumlin Fights Entergy

Vermont Yankee paid all costs of its application for a Certificate of Public Good, including consulting fees for Gundersen and others hired by the Vermont legislature to evaluate the plant and advise the legislature. Now that Entergy is suing Vermont, Shumlin must reach into the taxpayers' pockets to get the "resources" of lawyers and expert witnesses that he wants for the legal battle. The "Bank of Entergy" is closed to him now.

9. Nuclear Green - The Molten Salt Reactor Family: Uranium Fuel

There are many different possible Molten Salt Reactor designs. Nuclear fuel is one possible source of reactor design variations. Two potential nuclear fuel cycles can be used in Molten Salt Reactors. Choice of fuel cycles can make a difference in reactor designs. One of the two fuel cycle options uses uranium. There are in fact several different types of uranium fueled Molten Salt Reactors.

10. Nextbigfuture - Applying the Union of Concerned Scientist (UCS) analysis of Chernobyl to Commercial Aviation

UCS all things nuclear has an analysis of how many deaths occurred at Chernobyl based on linear no threshold view of radiation. So 0.01 milliSieverts (1 milliRem) for each of 6 billion people in the world is calculated to add 4000 deaths from cancer. 0.3 milliSieverts (30 milliRem) for 500 million people in europe is calculated to add 9000 more deaths from cancer.

Using the same analysis, 79,000 and 40,000 are reasonable estimates of the number of excess cancers and cancer deaths attributable to the flying in the past decade. The numbers increase even more over the 25 years since Chernobyl and would be 200,000 excess cancers and 100,000 excess deaths from commercial aviation over the last 25 years.

11. Nextbigfuture - A visual inspection by remote controlled camera has shown no significant damage to the used fuel pond of Fukushima Daiichi unit 4 and a Fukushima update from Brave New Climate.

There had been fears of serious damage to nuclear fuel stored in the pond after a series of fires and explosions in the vicinity. Highly radioactive and heat-emitting used nuclear fuel is stored for a few years in the ponds before transfer to a larger storage pond shared by all six reactors at the site. However, the reactor was in a period of maintenance with the full core temporarily stored, requiring very much more cooling than the years-old fuel. This contributed to problems at the pond as water heated up and evaporated after the tsunami of 11 March disabled cooling and water top-up systems.

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