2200 degrees Fahrenheit is Too High

PRESENTATON BY BOB LEYSE TO ACRS SUBCOMMITTEE ON POWER UPRATE, NOVEMBER 17, 2010

2200 FAHRENHEIT IS TOO HIGH

I’m Bob Leyse and I have been in this business since 1950. I’ll race through the slide in 10 minutes. The slide covers two PRMs by Mark Leyse. The Committee is urged to digest those after this meeting, and that will take longer than 10 minutes, however, the members can certainly justify applying that time in their billing to ACRS. The slide has the ML numbers.

There are two items: the 2200 degree Fahrenheit PCT limit is too high and crud has a substantial impact on the PCT during a LOCA. Moving for a moment to today’s meeting, most of the AREVA presentation is reasonably not available to the public, however, I think it is likely that none of the KATHY games include the impact of a range of crud deposits.

OK, back to the slide. This is called the POWER UPRATE COMMITTEE, which presupposes that Power Uprates are in order. What we really need is a Power Level Review Committee.

The 2200 degree Fahrenheit PCT limit is too high. The 2200 PCT limit is based on embitterment criteria. The Baker-Just equation was placed into 50.46 and it has been convenient in licensing. According to analyses funded by NRC, when the Baker-Just correlation is applied, the predicted thermal runaway starts at 2600 degrees Fahrenheit, while the alternative Cathcart-Pawel correlation of Reg. Guide 1.157 yields runaway at 2700. However, an array of experiments having multirod assembles of rods with zirconium alloy cladding reveal that thermal runaway begins well below the 2600 to 2700 range. Perhaps the most impressive is LOFT LP-FP-2 where thermal runaway of the fuel bundle was initiated in the 2060 to 2240 degree Fahrenheit range. The series of CORA experiments at Karlsruhe with Zirconium alloy cladding of bundled electrically heated rods yielded thermal runaway over a range from about 1800 to 2200 degrees Fahrenheit.

The NRC staff is taking PRM-50-93 very seriously, and so should the ACRS.
The current User Need Request from NRR to RES is High Priority.
The requested deliverable for this user need is a technical letter report and the initial due date for a thoroughly researched final report was September 30, 2010.

However: On October 27, 2010, the NRC published for public comment a notice of consolidation of petitions for rulemaking. The PRMs to be consolidated are PRM-50-93filed by Mark Edward Leyse on November 17, 2009, and PRM-50-95 filed on June 7,
2010, by Mark Edward Leyse and Raymond Shadis, on behalf of the New England Coalition. What Mark Leyse filed on June 7, 2010 was not a
PRM, it was a 2.206 petition. It appears that by consolidating these actions by Mark Leyse, the NRC has extended the deadline for producing a Technical Letter Report regarding PRM-50-93. Nevertheless, the priority is established by the technical facts that are in the record and diligent and timely attention by the ACRS is most certainly called for under its mandate “to initiate reviews of specific generic matters or nuclear facility safety-related items.”

Moving to the impact of crud; PRM-50-84 details the impact of crud on the steady-state temperature distribution and stored energy in the fuel at the onset of a postulated LOCA.

Crud increases the operating fuel rod surface temperature and fuel rod stored energy. Crud decreases the overall heat transfer coefficient at the fuel rod. Crud adversely impacts the coolant flow distribution throughout the reactor core (fuel rod locations with heavier crud layers have less flow). Thus crud leads to substantial increases in the PCT during a LOCA.

In its Advance Notice of Proposed Rulemaking: Performance-Based ECCS Acceptance Criteria, July 29, 2009, NRC addresses PRM-84 as follows: In summary, to address the technical concerns related to crud in the PRM-50-84 petitioner’s request for rulemaking, the NRC is considering amending § 50.46 to specifically identify crud as a parameter to be considered in best-estimate and Appendix K to Part 50 ECCS evaluation models.

PRM-50-84 reports that EPRI will complete a program during 2008 that will “… determine the effect of tenacious crud on fuel surface heat transfer.” So far, I have found no open reporting of this.

AREVA and Westinghouse have brochures that describe ultrasonic fuel cleaning services. The recent Westinghouse brochure lists more than 12 LWRs that have used Ultrasonic Fuel Cleaning for crud removal from fuel elements. And from the AREVA brochure I quote, “AREVA NP offers patented Electric Power Research Institute (EPRI) Ultrasonic Fuel Cleaning (UFC) to prevent uneven crud deposits that can negatively affect fuel performance.”
Also interesting is a patent application: Chemical Enhancement of Ultrasonic Fuel Cleaning. Here are a few sentences (Only read the three sentences that are in bold.)
A method for cleaning an irradiated nuclear fuel assembly includes chemically enhancing a technique utilizing an apparatus including a housing adapted to engage a nuclear fuel assembly. A set of ultrasonic transducers is positioned on the housing to supply radially emanating omnidirectional ultrasonic energy to remove deposits from the nuclear fuel assembly. Any corrosion products remaining after ultrasonic fuel cleaning will have exposed surfaces that are susceptible to chemical dissolution.

The mechanical cleaning is effective, but it is not 100% efficient because corrosion products remain on the fuel assemblies. It is estimated that ultrasonic cleaning removes up to 80% of the total corrosion product inventory on the fuel

According to the subject method, chemical addition is localized to the water in the ultrasonic cleaning chamber rather than throughout the primary system, which minimizes the total liquid waste generated by orders of magnitude. Less aggressive chemistries can be selected that take advantage of the ultrasonic fuel cleaning environment. Only the fuel assemblies are exposed to the chemicals, so there is less chemical cleanup required for the vessel or ex-core piping. In certain embodiments, the chemical addition steps could be applied to selected high flux assemblies that have high corrosion deposition, while other fuel assemblies could be cleaned only ultrasonically.


The references by Mark Leyse and J. S. Lee that are listed at the end of the handout each disclose that crud significantly increases the local surface temperature of the cladding and the stored energy within the fuel.

NRR and RES are continuing their preparation of the Technical Letter Report that is to be the basis for a timely recommendation to the NRC Commissioners regarding the disposition of PRM-50-93. In the meantime, ACRS should not concur with any Power Uprate proposal until PRM-50-93 is resolved.

I have about two minutes left. I have worked at GE, Hanford and San Jose; Westinghouse, Monroeville; DuPont, Savannah River; Argonne, and the Nuclear Safety Analysis Center at EPRI. Elsewhere, during the 1970s, I invented, branded and marketed the RADCAL GAMMA THERMOMTER. GE Hitachi references my IEEE paper that describes the gamma thermometer that is central to their current licensing report, "Gamma Thermometer System for LPRM Calibration and Power Shape Monitoring." October 6, 2010. Accession Number ML102810320.

For emphasis, I repeat, you may tell the Full Committee to not concur with any Power Uprate proposal until PRM-50-93 is resolved.

Thank you.

SLIDE: PRESENTATION TO SUBCOMMITTEE ON POWER UPRATE

2200°F is nonconservative. PRM-50-93(ML093290250)

Petitioner (Mark Leyse) requests that NRC revise 10 C.F.R. § 50.46(b)(1) to require that the calculated maximum fuel element cladding temperature not exceed a limit based on data from multi-rod (assembly) severe fuel damage experiments.

Mark Leyse also authored and submitted on behalf of New England Coalition a 2.206 petition requesting that NRC order the lowering of LBPCT of VYNPS (ML101610121). NRC recently converted this to PRM-50-95; the public comment period is now open.

The User Need Request for PRM-50-93, NRR to RES, is High Priority. (ML100770117)

Multirod severe fuel damage experiments reveal that 2200°F is too high.

LOFT LP-FP-2 experiment at INL Runaway began at 2060°F – 2240°F
CORA experiments at Karlsruhe Runaway began at 1832°F - 2192°F
PHEBUS B9R-2 Runaway began at <2200°f>Impact of crud PRM-50-84 (ML070871368)

Petitioner (Mark Leyse) requests that NRC amend Appendix K to Part 50—ECCS Evaluation Models I(A)(1), The Initial Stored Energy in the Fuel, to require that the steady-state temperature distribution and stored energy in the fuel at the onset of a postulated LOCA be calculated by factoring in the role that the thermal resistance of crud and/or oxide layers on fuel cladding plays in increasing the stored energy in the fuel. This requirement also needs to apply to any NRC approved best-estimate ECCS evaluation models used in lieu of Appendix K calculations.

To address the technical concerns related to crud ... in PRM-50-84 ... the NRC is considering amending § 50.46 to specifically identify crud as a parameter to be considered in best-estimate and Appendix K to Part 50 ECCS evaluation models.
ANPR: Performance-Based ECCS Acceptance Criteria, 07/29/2009, ML091250132.

Ultrasonic Fuel Cleaning under 10 C.F.R. § 50.59: An Areva brochure, Ultrasonic Fuel Cleaning, was recently updated, 11/05/2010. The Westinghouse brochure, NS-FS-0085, April 2009, reports, Ultrasonic Fuel Cleaning has been used at the following plants: ANO, Callaway, Catawba, Ft. Calhoun, McGuire, Millstone, Quad Cities, Seabrook, South Texas 1 & 2, Vogtle 1 & 2, Vandellos, and Watts Bar.

Mark Leyse coauthored, “Considering the Thermal Resistance of Crud in LOCA Analysis,” ANS 2009 Winter Meeting, November 15-19, 2009, Washington, D. C.

J. S. Lee, et al., “Effects of Crud on the Fuel Rod Integrity in Steady-State and LB-LOCA Condition,” 2008 Water Reactor Fuel Performance Meeting, Seoul, Korea.