How an Indian Point Meltdown Could Cause a Large Radiological Release
Since the devastating accident at the Fukushima nuclear power plant one year ago, Entergy spokespeople have been quick to make unsubstantiated claims about how “it can’t happen here.” Such public distortions include misleading statements about whether Entergy could avoid large-scale radiological releases from Indian Point during an accident. As described below in an article written by Mark Leyse, there is much cause for concern about whether the build-up of hydrogen during an accident could be managed at Indian Point in order to avoid harmful explosions that could expose the public to unsafe levels of radiation.
Don’t Let It Happen Here! Know and spread the truth!
How an Indian Point Meltdown Could Cause a Large Radiological Release
By Mark Leyse
When a meltdown occurs in a nuclear reactor, the final barrier to protect the public from a radiological release is the reactor’s containment. The Fukushima Dai-ichi accident demonstrated that containments can be breached by hydrogen explosions. In a meltdown large quantities of hydrogen are produced when reactor core materials, such as the fuel cladding, chemically react with steam.
If a meltdown were to occur at Indian Point, it would be possible for one of the containments to be breached by a hydrogen explosion; however, there is no assurance that the plant’s owner, Entergy, could control the total quantity of hydrogen generated in such an accident, which could exceed 1000 kilograms.1 Indian Point has two pressurized water reactors with large dry containments, large cylinders with domes, comprised of reinforced concrete with a steel liner, a different design than Fukushima Dai-ichi’s containments.
The Nuclear Regulatory Commission does not require owners of pressurized water reactors with large dry containments to control the hydrogen that would be generated in a meltdown.2 And an N.R.C. task force report on insights from the Fukushima Dai-ichi accident claims that the pressure spike of potential hydrogen explosions would remain within the design pressure of large dry containments.3 However, according to the N.R.C.’s own safety analyses, conducted a decade ago, hydrogen explosions inside large dry containments could cause pressure spikes exceeding 110 pounds per square inch,4 which is about twice the design pressure of Indian Point’s containments.5
Three Mile Island Unit 2 was a pressurized water reactor with a large dry containment. In the Three Mile Island accident, a hydrogen explosion occurred in the containment, initiated most likely by an electric spark. 6 The explosion did not breach the containment. Yet that does not preclude the possibility that if a meltdown were to occur at Indian Point, a hydrogen explosion could breach one of the containments, exposing the public to a large radiological release.
Indian Point is located in Buchanan, New York on the Hudson River, 34 miles north of Central Park. According to a recent Natural Resources Defense Council report, if winds were blowing south, a release of radiation from Indian Point on the scale of the Fukushima Dai-ichi accident could contaminate a swath of land between Buchanan and the George Washington Bridge, rendering it uninhabitable for generations. An accident releasing radiation on the scale of the Chernobyl accident could render Manhattan uninhabitable. 7
Last year, a few weeks after the Fukushima Dai-ichi accident, Indian Point spokesman, James Steets, was quoted in a New York Times blog article as saying that Indian Point’s containments each have two hydrogen recombiners and that one alone could eliminate all the hydrogen produced in a major accident.8 Hydrogen recombiners are safety devices located in containments; in a meltdown accident, these devices would recombine hydrogen and oxygen molecules, yielding steam and heat. Hydrogen recombiners are intended to reduce hydrogen concentrations in the containment in order to prevent hydrogen explosions.
The problem with what Mr. Steets said is that he is incorrect. One or two hydrogen recombiners would not have prevented the hydrogen explosions that occurred at Fukushima and one or two would not prevent a hydrogen explosion at Indian Point if a meltdown were to occur. European pressurized water reactor containments have up to 60 hydrogen recombiners yet even 60 would not be capable of eliminating all of the hydrogen produced in a meltdown within a time frame that would prevent an explosion. At certain points in a meltdown accident, more than five kilograms of hydrogen could be produced per second; 9 each hydrogen recombiner can only eliminate several grams of hydrogen per second.10
Hydrogen recombiners can also malfunction by having unintended ignitions when exposed to elevated hydrogen concentrations. In a meltdown accident, a hydrogen recombiner’s ignition could cause a hydrogen detonation (an explosion with a combustion wave traveling faster than the speed of sound, relative to the unburned gas)¹¹. Hydrogen detonations occurred in the Fukushima Dai-ichi accident.
In summary: the N.R.C. does not require Entergy to control the hydrogen that would be generated in a meltdown; there is no assurance that Entergy would be able to control the hydrogen; and a hydrogen explosion could breach one of Indian Point’s containments, exposing the public to a large radiological release.
1. International Atomic Energy Agency, “Mitigation of Hydrogen Hazards in Severe Accidents in Nuclear Power Plants,” IAEA-TECDOC-1661, July 2011, pp. 9, 10 ( http://www-pub.iaea.org/MTCD/Publications/PDF/TE_1661_Web.pdf).
2. 10 C.F.R. § 50.44 Combustible gas control for nuclear power reactors (http://www.nrc.gov/reading-rm/doc-collections/cfr/part050/part050-0044.html ).
3. The N.R.C. task force report states: “PWR facilities with large dry containments do not control hydrogen buildup inside the containment structure because the containment volume is sufficient to keep the pressure spike of potential hydrogen deflagrations within the design pressure of the structure.” See Charles Miller, et al., NRC, “Recommendations for Enhancing Reactor Safety in the 21st Century: The Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident,” SECY-11-0093, July 12, 2011, available at: www.nrc.gov, NRC Library, ADAMS Documents, Accession Number: ML111861807, p. 42 (http://pbadupws.nrc.gov/docs/ML1118/ML111861807.pdf).
4. According to the N.R.C.’s calculations, the pressure resulting from an adiabatic and complete hydrogen burn involving up to a 100 percent core metal-water reaction could be 114 psig for Three Mile Island Unit 1, 129 psig for Oconee Units 1, 2, and 3, and 135 psig for Turkey Point Units 3 and 4, which are all pressurized water reactors with large dry containments. See NRC letters regarding exemptions from hydrogen control requirements for Three Mile Island, Oconee, and Turkey Point (all written before 10 C.F.R. § 50.44 was revised in 2003 to no longer require hydrogen control for pressurized water reactors with large dry containments); available at: www.nrc.gov, NRC Library, ADAMS Documents, Accession Numbers: ML020100578, ML011710267, and ML013390647, respectively (http://pbadupws.nrc.gov/docs/ML0201/ML020100578.pdf), (http://pbadupws.nrc.gov/docs/ML0117/ML011710267.pdf), and (http://pbadupws.nrc.gov/docs/ML0133/ML013390647.pdf).
5. The design pressure of Indian Point Units 2 and 3’s containments is 47 psig. See Entergy, “Technical Facts: Indian Point Unit 2, Plant Specific Information,” (http://www.entergy-nuclear.com/content/resource_library/IPEC_EP/TechnicalFacts2.pdf) and Entergy, “Technical Facts: Indian Point Unit 3, Plant Specific Information,” (http://www.entergy-nuclear.com/content/resource_library/IPEC_EP/TechnicalFacts3.pdf).
6. E. Studer, et al., Kurchatov Institute, “Assessment of Hydrogen Risk in PWR,” Eurosafe, November 1999, p. 1 (http://www.eurosafe-forum.org/files/b4.pdf).
7. Natural Resources Defense Council , “Nuclear Accident at Indian Point: Consequences and Costs,” October 2011, p. 1 (http://www.nrdc.org/nuclear/indianpoint/files/NRDC-1336_Indian_Point_FSr8medium.pdf).
8. Matthew L. Wald, “U.S. Dropped Nuclear Rule Meant to Avert Hydrogen Explosions,” March 31, 2011, New York Times, Green, A Blog about Energy and the Environment, (http://green.blogs.nytimes.com/2011/03/31/u-s-dropped-nuclear-rule-meant-to-avert-hydrogen-explosions/).
9. In a severe accident, during the reflooding of an overheated core up to 300 kilograms of hydrogen could be produced in one minute. See E. Bachellerie, et al., “Generic Approach for Designing and Implementing a Passive Autocatalytic Recombiner PAR-System in Nuclear Power Plant Containments,” Nuclear Engineering and Design, 221, 2003, p. 158 (http://www.sciencedirect.com/science/article/pii/S0029549302003308).
One report states that between 5 and 10 kilograms of hydrogen could be produced per second, during the reflooding of an overheated core. See J. Starflinger, “Assessment of In-Vessel Hydrogen Sources,” in “Projekt Nukleare Sicherheitsforschung: Jahresbericht 1999,” Forschungszentrum Karlsruhe, FZKA-6480, 2000.
10. OECD Nuclear Energy Agency, “State-of-the-Art Report on Flame Acceleration and Deflagration-to-Detonation Transition in Nuclear Safety,” NEA/CSNI/R(2000)7, August 2000, available at: www.nrc.gov, NRC Library, ADAMS Documents, Accession Number: ML031340619, p. 1.6 ( http://pbadupws.nrc.gov/docs/ML0313/ML031340619.pdf).
11. In the event of a severe accident, “[i]n a situation when the hydrogen concentration rises, a delayed ignition [by a hydrogen recombiner] enhances the risk because it may start a detonation.” See K. Fischer, et al., “Hydrogen Removal from LWR Containments by Catalytic-Coated Thermal Insulation Elements (THINCAT),” Nuclear Engineering and Design, 221, 2003, p. 146 (http://www.sciencedirect.com/science/article/pii/S0029549302003485).
