ML11200A153
| ML11200A153 | |
| Person / Time | |
|---|---|
| Site: | Indian Point  |
| Issue date: | 07/11/2011 |
| From: | Dobson A, Sipos J State of NY, Office of the Attorney General |
| To: | Borchardt R NRC/EDO |
| References | |
| 2.206, G20110528, OEDO-2011-0503, EDATS: OEDO-2011-0512 | |
| Download: ML11200A153 (7) | |
Text
EDO Principal Correspondence Control FROM: DUE: 08/17/11 EDO CONTROL: G20110528 DOC DT: 07/11/11 FINAL REPLY:
Adam J. Dobson John J. Sipos Office of the Attorney General State of New York TO:
Borchardt, EDO FOR SIGNATURE OF : ** GRN ** CRC NO:
Leeds, NRR DESC: ROUTING:
Request to Lower the Licensing Basis Peak Cladding Borchardt Temperatures of Indian Point Units 2 and 3 Weber (EDATS: OEDO-2011-0512) Virgilio Ash Mamish OGC/GC DATE: 07/19/11 Dean, RI Bowman, OEDO ASSIGNED TO: CONTACT:
NRR Leeds SPECIAL INSTRUCTIONS OR REMARKS:
Ref. G20110218.
- . 3.
EDATS Number: OEDO-2011-0512 Source: OEDO I.Genra Inomto Assigned To: NRR OEDO Due Date: 8/17/2011 11:00 PM Other Assignees: SECY Due Date: NONE
Subject:
Request to Lower the Licensing Basis Peak Cladding Temperatures of Indian Point Units 2 and 3
Description:
CC Routing: Region I ADAMS Accession Numbers - Incoming: NONE Response/Package: NONE IOt Ifr er atio Cross Reference Number: G20110528 Staff Initiated: NO Related Task: Recurring Item: NO File Routing: EDATS Agency Lesson Learned: NO OEDO Monthly Report Item: NO IPoesIfr aioI Action Type: Letter Priority: Medium Sensitivity: None Signature Level: NRR Urgency: NO Approval Level: No Approval Required OEDO Concurrence: NO OCM Concurrence: NO OCA Concurrence: NO Special Instructions: Ref. G20110218.
Originator Name: Adam J. Dobson, et al. Date of Incoming: 7/1 1/20 11 Originating Organization: Office of the Attorney Document Received by OEDO Date: 7/18/2011 Geiieral,State of New York Addressee: R. W. Borchardt, EDO Date Response Requested by Originator: NONE Incoming Task Received: Letter Page 1 of I
STATE OF NEW YORK OFFICE OF THE ATTORNEY GENERAL ERC T. SCHNEIDERMAN DIVISION OF SOCIAL JUSTICE ATTORNEY GENERAL ENVIRONMENTAL PROTECTION BUREAU July 11, 2011 R. William Borchardt Executive Director for Operations U.S. Nuclear Regulatory Commission Washington D.C. 20555-0001 Re: 10 C.F.R. § 2.206 Request to Lower the Licensing Basis Peak Cladding Temperatures of Indian Point Units 2 and 3 in Order to Provide Necessary Margins of Safety - to Help Prevent Meltdowns - in the Event of Loss-of-Coolant Accidents, filed by Riverkeeper, Inc.
Dear Mr. Borchardt:
This Office respectfully submits these comments on the March 28, 2011 enforcement petition filed by Riverkeeper, Inc. requesting that the Nuclear Regulatory Commission ("NRC") lower the licensing basis peak cladding temperatures of Indian Point Units 2 and 3 in order to provide necessary margins of safety in the event of a loss of coolant accident. Riverkeeper, Inc. 10 C.F.R. § 2.206 Request to Lower the Licensing Basis Peak Cladding Temperatures of Indian Point Units 2 and 3 ("IP-2 and -3") in Order to Provide Necessary Margins of Safety - to Help Prevent Meltdowns- in the Event of Loss-of-Coolant Accidents ("LOCAS') and to have the Licensee of IP-2 and -3 Demonstratethat IP-2 and -3s Emergency Core Cooling Systems Would Effectively Quench the Fuel Cladding in the Event of LOCAS (March 28, 2011)(ML110890956) ("the Petition").
The well-documented Petition raises serious concerns that NRC has ignored significant test data suggesting that a self-sustaining, rapid, exothermic oxidation reaction can begin at much lower temperatures than NRC has set in 10 C.F.R. Part 50, Appendix K (ECCS Evaluation Models). These data call into question the validity of the safety margins derived from existing models. For this reason, NRC should reexamine whether the regulatory peak cladding temperature should be reduced in order to diminish the risk of a meltdown in the event of a design basis LOCA.
THE CAPITOL, ALBANY, N.Y. 12224-0341
- PHONE (518) 473-3105 e FAX (518) 473- 2534 0 WWW.AG.NY.GOV EDO -- G20110528
If, in fact, the peak cladding temperature of 2200'F provided for in 10 C.F.R.
§ 50.46(b)(1) and. the correlations relied upon in 10 C.F.R. Part 50, Appendix K are not conservative, the consequences in the event of a LOCA would. be severe, with the fuel assemblies unable to adequately dissipate heat through Emergency Core Cooling System (or "ECCS") cooling, eventually leading to runaway oxidation and the risk of a meltdown.1 Cladding oxidation .has played a significant role.in the recent Fukushima event, leading to a buildup of hydrogen and consequent explosions, which continue to ý"puzzle" the experts. See Yanmei Xie, Suspected Hydrogen Explosions in Japan Puzzle US Industry, Experts, Nucleonics Week 52:12 (Mar. 24, 2011). Given this clear example, the regulatory basis for the peak cladding temperatures should be reexamined, and specifically, NRC should address the licensing basis peak cladding temperatures of Indian Point, because that site's unique characteristics make an accident there particularly dangerous.
Figure 1: Fuel Assembly with Fuel Rod and Individual Pellet 2 In a light water _ .. ......
reactor, the uranium fuel is embedded in ceramic uranium dioxide pellets which are inserted into metal tubes that are bundled together in separate fuel assemblies. The cores of both IP2 and IP3 hold millions of pellets contained in nearly 40,000 fuel rods, which are*12 foot long tubes made of a.Zirconium alloy.(ZIRLO) 3. The fuel rods, in turn, are bundled into 193 separate fuel assemblies. So long as the zircaloy tubes remain intact, they can contain the uranium within the assemblies. Because of the importance of this barrier, the reactor's design basis sets a maximum temperature for the zircaloy tube or cladding to ensure that excessive core heat does not raise the temperature of the zircaloy tubes to the extent that they rupture.
To ensure that the core does not reach temperatures that will compromise the zircaloy tubes, NRC regulations.mandate that reactors be designed so that the temperature of the fuel cladding during.a LOC,,A not rise above the temperature at which the normal operation of the Emergency Core Cooling.System would be unable to prevent the temperature of the fuel cladding from rising further, and to prevent a 1 By way of comparison, 2200'F = 1093°C = 1366 K..
2 The image on this page was obtained from: GAO, NRC Needs to Do More to Ensure that Power PlantsAre Effectively Controlling Spent Nuclear Fuel, p. 2 GAO-05-339 (April 8,-2005).
3 For consistency, this comment uses the term "zircaloy," to refer to the family of zirconium alloys, Although each alloy possesses distinct properties, the metal zirconium, which reacts with hydrogen, is present in all of them.
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degree of oxidation caused embrittlement that makes the tubes more likely to fail.
This maximum temperature is the peak cladding temperature ("PCT"). If the cladding is maintained below this PCT, the ECCS is theoretically capable of preventing temperatures from.rising to the melting points of thefuel'and the cladding.
The Indian Point reactors are located 24 miles north of New York City., More than 17 million people live within 50 miles of Indian Point, 'a population' that is projected to grow to 20 million by 2035. According to the Atomic Energy Commission
("AEC"), the NRC, and the Federal Emergency Management Agency ("FEMA"),
more people live within 10 and 50 miles of the Indian Pointreactors than at any other operating power reactor in the nation. Indeed,: no other operating reactor- site in the. country comes close .to Indian Point in terms of surrounding population. 4 .
Moreover, the communities within the 50-mile radius 'around Indian Point also contain some of the most densely-developed and expensive real estate in the country, critical natural resources, centers of national and international commerce, transportation arteries and hub's, and. historic sites. Thus; a severe accident at Indian Point has the potential. to affect more people than an accident at any other reactor in the country- .
In the event of a severe ac cident at Indian Point, 'the safety of the surrounding population and communities depends on NRC 'safety regulations. In the: case of.:
peak..cladding temperature, the regulatory basis depends on models designed more than~five decades ago, and, as the Petition demonstrates, these models have been called into question by numerous experiments and studies, including:
- The CORA-2 and CORA-3 ex.perimIients, iiiitiated With a temperature ramp rate of 1 K/sec, had rapid.'tempera-ture increases of 15°C/sec, indicating-a 'runaway oxidationr'reaction-' that :commenced at approximately 1000 0 C- (1832 0 F),: ltading:"the CORA-2 and CORA-3 bundles to *maximum -temperatures '.bf '20000 C and: '2400'C, respectively; The National Research Universal Thermal-Hydraulic Experiment 1 revealed that the 'oxidation' of the*"zircalo6i dladding caused a 190 degree increase in temperature'- ven after all other heating sources were removed.*I This indicates th at in' an"' Iactual reactor," Where heat cannot be instalifly removed, the oxidationieaction' will 'significantly add to core teimnpeiature;-' ' "'
4 See, e.g., AEC, Population: DistributionAround Nuclear PowerýPlantSites., Figure 2: Typical Site PopulationDistribution(5-50 Miles) (April 17,A1973); FEMA, Nuclear Facilities& Population Density Within 10 Miles (June 2005).
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- SFD Experiment CORA-13 demonstratedthat a massive temperature escalation caused by runaway oxidation began at approximately 10000 C (1832°F);
- The CORA-16 and CORA-17 experiments showed that the oxidation of zircaloy was not accurately predicted by extant models, demonstrating the inapplicability of those models to the reactor environment;
- The LOFT LP-FP-2 Experiment showedz that a rapid temperature increase as a result of the autocatalytic oxidation reaction of Zircaloy cladding commenced at approximately 1400 K (2060'F) - well below the 10 C.F.R. § 50.46(b)(1) PCT limit of 2200'F;
" The BWR FLECHT Zr2K Test, showed an autocatalytic oxidation reaction occurring after -cladding temperatures reached between approximately 2100 and 2200'F;
- The NRU Reactor Full-Length High-Temperature I Test showed that autocatalytic oxidation began at approximately 2275°F or lower. The autocatalytic oxidation could not be prevented by increasing coolant flow to the fuel assemblies; and
- The PHEBUS B9R Test showed, that an autocatalytic oxidation reaction began when cladding temperatures were below 1477 K (2200OF).
Since IP2 was uprated in 2004 by 3.26% and IP3 was uprated in 2005 by 4.85%, the predicted maximum temperature the cladding would reach is 1937°F and 1961'F, respectively (the licensing basis maximum fuel rod temperatures), well over the temperature at which runaway oxidation has been demonstrated to occur in certain of the above studies.
The recent discovery of errors in the calculation of oxidation rates and peak cladding temperatures of two types of fuel produced by General Electric and in use at the Oyster Creek and Nine Mile Point, Unit I facilities. See Nuclear Regulatory Commission, Oyster Creek, Event Notification 46820 (May 4, 2011)5; Nuclear Regulatory Commission, Nine Mile Point, Unit 1, Event Notification 46827 (May 6, 2011).6 Although General Electric discovered several errors in its calculations, the net outcome of those errors was that the peak cladding 5 Available at: http://www.nrc. -ov/readint-rm/doc-collections/event-status/event/2011/20110505en.html#en46820.
6 Available at: http://www.nrc.g ov/reading-rm/doc-collections/event-
,t1 tus/event/20 11/20110509en.html#en46827.
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temperature of fuel actually in the reactors had been underestimated by about 145 and 60 degrees Fahrenheit, respectively. The Event Notification Reports indicate that prior to discovery and correction of the errors, both reactors had been operating at temperatures such that they did not satisfy the 2200'F criteria in 10 C.F.R. § 50.46. These errors demonstrate the fine margins under which reactors operate and the possibility that the existing models and the calculations upon which licensees rely to conform their reactor and fuel characteristics to those models.may not adequately protect the public.
The experiences of Three Mile Island Unit 2 and now Fukushima illustrate the danger of oxidation reactions. NRC must reexamine its regulations, and, in the meantime, it should immediately review and revise the licensing basis peak cladding temperatures of Indian Point Units 2 and 3. Additionally, while NRC undertakes that review and given the additional peak cladding temperature data identified above, it would be prudent for NRC to consider ordering Entergy - on an interim basis- to decrease the Indian Point reactors'. operating temperature in order to increase the margin of safety of the licensing basis peak cladding temperatures at the Indian Point. site, which has, by far, the largest surrounding population of any reactor site in the United States.,
If NRC determines that :§ 2.206 does not provide a forum to review these important issues, then NRC should transfer the record developed before the Petition Review Board to a rulemaking process and promptly and publicly review and respond to the data presented here.
Sincerely, Adam J. Dobson John J. Sipos Assistant Attorneys General
.(518) 402-2251 5