| United States Patent | 8,372,206 |
| Gross , et al. | February 12, 2013 |
High power density ultrasonic fuel cleaning with planar transducers
And here is a reference to a patent that issued during 2002:
| United States Patent | 6,396,892 |
| Frattini , et al. | May 28, 2002 |
Apparatus and method for ultrasonically cleaning irradiated nuclear fuel assemblies
| Inventors: | Frattini; Paul L. (Los Altos, CA), Varrin; Robert Douglas (Reston, VA), Hunt; Edwin Stephen (Arlington, VA) |
|---|---|
| Assignee: | Electric Power Research Institute, Inc. (Palo Alto, CA) |
| Family ID: | 22435141 |
| Appl. No.: | 09/545,354 |
| Filed: | April 7, 2000 |
Here is the link to Mark Leyse's PRM-50-84:
http://pbadupws.nrc.gov/docs/ML0708/ML070871368.pdf
Here is link to Summary of Public Comments on PRM-50-84:
http://pbadupws.nrc.gov/docs/ML0831/ML083110761.pdf
Here is a link to a significant inspection report;
http://www.nrc.gov/NRR/OVERSIGHT/ASSESS/REPORTS/rbs_2005008.pdf
Following is from the above inspection report:
Cycle 8 Fuel Failures: During Operating Cycle 8, the licensee experienced seven fuel
pin failures in high power regions of the core. All the fuel pin failures were located in
first burn fuel bundles. During Refueling Outage 8, the licensee found a significant layer
of crud on the fuel surface. Pictures of the crud indicated that it was primarily composed
of loose iron oxide deposits but the team observed some tenacious crud on the cladding
surface as well. The licensee did not perform a chemical analysis of the crud.
The crud increased the thermal resistance between the fuel cladding and the coolant
such that cladding surface temperatures were substantially higher than would normally
be expected. Normal cladding surface temperatures are about 560 EF (close to the bulk
coolant temperature). General Electric (the fuel vendor) calculated that the cladding
surface temperatures approached 1200 degrees F in localized areas. The higher temperatures
increased the cladding oxidation rate and, at approximately 1 year into the cycle, the
cladding oxidation layer extended the entire way through the cladding, creating a hole.
The team reviewed one technical study that discussed the behavior of crud on the
surface of boiler tubes (“Two-Phase Flow and Heat Transfer,” D. Butterworth and G.F.
Hewitt, Oxford University Press, 1977). The team noted that the thermal resistance of
crud is not normally sufficient to cause cladding temperature increases consistent with
those observed during Cycle 8. In most circumstances, “wick boiling” occurs within the
crud. That is, capillary coolant channels within the crud deliver coolant to the cladding
surface. Steam then escapes from the cladding surface in chimney type plumes. This
is a fairly effective method of heat transfer. However, in some instances the capillary
coolant channels can become clogged, creating a static steam blanket on the cladding
surface. Steam is an exceptionally good thermal insulator. This is the process that
caused the very high cladding surface temperatures and ultimately resulted in fuel
cladding failure.
Following is my blog entry from 2008:
Wednesday, September 3, 2008
Ultrasonic Fuel Cleaning: AREVA, EPRI, Westinghouse, Dominion and more
Go to GOOGLE and enter Ultrasonic Fuel Cleaning. Hunt a bit and you will find a lot: Areva, EPRI, 50.59 game,
Following is the text of Areva's advertisement, minus the photographs.
Ultrasonic Fuel Cleaning
Effective fuel cleaning technology to help assure performance and improve safety. AREVA NP offers patented Electric Power Research Institute (EPRI) Ultrasonic Fuel Cleaning (UFC) to prevent uneven crud deposits that can negatively affect fuel performance. With proven performance in applications at several domestic U.S. utilities, UFC can also reduce dose rates on primary components contaminated by the migration of activation products from core surfaces. Plus, we are an official EPRI licensee authorized to supply UFC equipment and services to nuclear stations worldwide. We can provide UFC for your next outage.
UFC was developed by EPRI to eliminate in-core flux depression by effectively removing deposits from fuel assemblies during refueling outages. Ultrasonic waves cause small particles of crud to release from the fuel assembly. Fuel pool water cools the fuel and transports particles to the filter banks where they are collected for final disposal. The system employs disposable filters to remove radioactive corrosion and activation products. Customers can store the filters in their fuel pool or process them for immediate shipping.
Cleaning Chamber Ensures Even Distribution A special cleaning chamber, similar to a fuel rack, holds ultrasonic transducers positioned on each face of the fuel assembly in an overlapping pattern. This configuration ensures even distribution of the ultrasonic energy into the fuel assembly. Reliable Console Controls the Process An operating console, located on the refuel floor near the edge of the spent fuel pool or reactor vessel, controls the process. The operator can easily observe the cleaning parameters and performance of the filtration unit. Underwater Filters Capture Removed Deposits. The underwater filters contain removed deposits while maintaining radiation to acceptable levels. A variety of filtration system designs are available to provide custom optimization.
BENEFITS
BWR or PWR application
Effectively removes crud
Improves fuel flux distribution
Improves fuel utilization
Reduces radiation source term
Reduces primary system dose rate
And here is the notice of EPRI's R&D award, also on GOOGLE:
October 05, 2005 09:00 AM Eastern Daylight Time
EPRI's Patented Nuclear Fuel Cleaning Technology Receives R&D 100 Award; Award Reception Slated for Oct. 20
PALO ALTO, Calif.--(BUSINESS WIRE)--Oct. 5, 2005--The Electric Power Research Institute (EPRI), three member companies, AmerenUE, Exelon Corp., and South Texas Project Nuclear Operating Co., and Dominion Engineering, Inc. (DEI) have earned a prestigious 2005 R&D 100 Award for ultrasonic cleaning of nuclear fuel, a promising new technology that safely removes deposits from irradiated fuel assemblies in nuclear power plants.
The annual awards are given by R&D Magazine for the most outstanding technology developments with commercial potential. The award reception will take place Thursday, Oct. 20 in Chicago; EPRI Senior Vice President and Chief Technology Officer Ted Marston is scheduled to attend.
"The future of the energy industry relies on pursuing innovative technologies that advance efficient, reliable and environmentally sensitive power generation and transmission," said EPRI CEO Steven R. Specker. "I applaud our team and member companies for their contribution towards this end."
The technology awarded delivers a patented process for removing corrosion products deposited on irradiated nuclear fuel pins using a unique form of ultrasonic technology. The technology was first applied at their nuclear power plants by the three EPRI member companies noted above, using equipment supplied by DEI.
"We were pleased to hear that our technology received an R&D Award," said Christopher J. Wood, a technical manager in EPRI's Nuclear Sector. "This breakthrough technology allows the full potential of current nuclear fuel designs to be achieved while maintaining excellent fuel reliability. Availability of a safe, reliable cleaning technology will also now allow utilities to further optimize fuel performance, core design, and reduce radiation fields and electricity generating costs."
This unique technology, developed in EPRI's Fuel Reliability Program, solves a significant emerging problem by removing deposits from nuclear fuel assemblies in nuclear power plants. Enhancing the performance of nuclear fuel is crucial to continue the improvement in electricity production from nuclear units. Over the past decade, nuclear power production has increased by over 20 percent, but this has placed additional demands on the fuel, as fuel temperatures have increased.
Some of the potential problems with fuel reliability result from the buildup of deposits on the surfaces of the fuel elements, which produces an insulating layer that could result in corrosion of the fuel cladding material at increased fuel pin temperatures. Until EPRI's developed technology, there was no effective way of removing these deposits during the working life of the fuel. Including early development demonstrations, this ultrasonic fuel cleaning technology has been used successfully eight times at nuclear power plants in the USA through 2004, and has been licensed worldwide. Seven additional commercial applications have taken place in 2005, including one in Spain. The technology used cleans all the fuel elements in every fuel assembly without any adverse effects. The cleaning process does not extend the schedule of routine refueling outages and is very cost-effective in pressurized water reactors. It is expected to result in a major reduction in radiation fields in boiling water reactors.
About the Electric Power Research Institute
The Electric Power Research Institute (EPRI), with major locations in Palo Alto, California, and Charlotte, North Carolina, was established in 1973 as an independent, nonprofit center for public interest energy and environmental research. EPRI brings together member organizations, the Institute's scientists and engineers, and other leading experts to work collaboratively on solutions to the challenges of electric power. These solutions span nearly every area of power generation, delivery, and use, including health, safety, and environment. EPRI's members represent over 90% of the electricity generated in the United States. International participation represents nearly 15% of EPRI's total R&D program.
And here is how NRC accepted Ultrasonic Fuel Cleaning under 50.59!
And here we have EPRI, way back in 1999, highlighting
its Ultrasonic Fuel Cleaning Process at Callaway as a 1999 payoff:
And, during September 2003, Westinghouse advertised its
ultrasonic fuel cleaning service. "As a result, the plant safety review
committee granted the application 10 CFR 50.59 approval."Ultrasonic cleaning means fast, safe removal of fuel-assembly crud buildup
Crud — corrosion products that accumulate on fuel surfaces — can break loose and spread to other parts of the system, causing radioactive buildup. Over time, crud that builds up on fuel surfaces becomes activated by neutrons to form radioactive nuclides, making crud cleanup a high priority.
Ultrasonic fuel cleaning can break up crud deposits during normal refueling, trapping particulates in filters for storage in the fuel pool. Designed by Dominion Engineering, Inc. (DEI), and patented by EPRI, the technique blasts crud with ultrasonic transducers.
Ultrasonic cleaning reduces the risk of fuel damage and takes a fraction of the time required by other methods. Controlling crud and other particulate inventory reduces out-of-core radiation fields and lowers radiation dosage levels.
Eliminating crud also mitigates local in-core flux supression and decreases the likelihood of axial offset anomaly (AOA) caused by lithium and boron concentrations. Ultrasonic cleaning also helps prevent crud-induced power shifts that can reduce output by as much as 20 percent.
Ultrasonic fuel cleaning was first used and verified at the Callaway plant in Missouri in 2001. After a year, no evidence of core-wide AOA was found, and early ex-core dosage was reduced significantly with no impact on critical path time. Measurements of assemblies before and after cleaning, and of particulate discharge at the filters, showed that ultrasound cuts crud deposits by about 80 percent. As a result, the plant safety review committee granted the application 10 CFR 50.59 approval.Ultrasonic cleaning is fast, too. During routine refueling, an assembly scheduled for reuse can be cleaned in as little as seven to ten minutes. Westinghouse is the first vendor to use this technique commercially. Our partnership with DEI gives utilities access to ultrasonic cleaning with minimal incremental costs.
Dominion (DEI), the inventors of Ultrasonic Fuel Cleaning, may have discussed this at a very recent meeting of PWR operators.
Sunday, July 20, 2008
PWR ALARA Association Board Meeting - Board Room
Wednesday, July 23, 2008
General PWR Session – Day 2
10:00 Ultrasonic Fuel Cleaning Process/Success – Dr. Robert Verrin (Dominion Engineering) Tentative
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