CTR Technical Services, Inc.

2006 Newsletter

Advanced Core Monitoring Systems

Both the advanced pressurized water reactor (AP-1000) and the economic simplified boiling water reactor (ESBWR) will use fixed incore detectors to monitor the power distribution inside the reactor core. Most currently designed PWRs and BWRs use movable detector systems to obtain power distribution data once every 30 days or so. Movable systems provide a high resolution axial profile for each measured location but are difficult and expensive to maintain. Fixed systems remain in the core at all times and hence are much easier to maintain. They provide continuous monitoring of the power distribution though at less axial resolution than movable systems.

The type of detector used in fixed incore systems determines the replacement frequency (and hence, overall cost). The most common detector used today is rhodium, which provides an accurate measurement of the neutron flux at each detector location. A disadvantage of using rhodium, however, is that it depletes or "burns out" such that the detectors must be replaced every four to six years with fresh detectors. Consequently, neither of the advanced reactor types mentioned above will use rhodium for their fixed system.

The AP-1000 will use vanadium self powered detectors to continuously monitor the neutron flux at several hundred selected locations throughout the core. The vanadium detectors deplete much slower than rhodium and are expected to last ten or more years before having to be replaced.



The ESBWR will use gamma thermometers to continuously monitor the gamma flux at several hundred locations. The gamma thermometers measure the gamma heating at several axial locations within each string and this heating is proportional to the gamma flux. Since the thermometers do not "deplete" like neutron sensors, the lifetime is limited only by mechanical and electrical considerations and are expected to last ten or more years before having to be replaced.

By using fixed incore detectors that have a long lifetime, both advanced reactor designs will be less expensive to maintain and contribute to the overall goal of providing safe, reliable electricity at rates that are lower than electricity from fossil fuels.

Criticality Considerations for Uranium Enriched between 5 and 10%

CTR Technical Services was recently awarded a contract by the U.S. Nuclear Regulatory Commission (NRC) to study the criticality issues associated with handling uranium that has been enriched in U-235 between 5 and 10 weight percent. The study was completed in February of this year.

Regulators of the commercial nuclear industry have historically imposed an enrichment limit of 5 wt% U-235 for refining, processing, handling, manufacturing, and transporting uranium nuclear fuel for power reactors. Such a limit is not restrictive since today's power reactors are designed to operate efficiently with fuel enriched to less than 5 wt%. With advanced reactor concepts and designs, however, it may be desirable to use uranium enriched to higher than 5% to increase overall fuel utilization and reduce overall fuel costs. In the future, some processing plants may request a change in licensing to be able to process uranium that contains up to 10 wt% U-235. To this end, the NRC sought the advice of experts Tom McLaughlin, Francis Alcorn, Dale Lancaster, and Charles Rombough to identify the significant criticality issues that would be important for processing plants and their regulators to consider.



One issue is that 10 wt% uranium metal or uranium dioxide may become critical even when unmoderated (i.e., in a dry environment). How much material might become critical and is this a concern? Another question is whether a single fuel assembly enriched to greater than 5 wt% would become critical in water (for fuel enriched to 5 wt%, a single fuel assembly can not become critical in water). Is this an issue and, if so, how should regulations change for such assemblies? Another issue is that subcritical limits on mass and volume that had been based on a 5 wt% limit would not apply for fuel enriched to greater than 5 wt%. How should such limits be calculated?

Finally, are there sufficient critical experiments for fuel enriched in the 5 to 10 wt% range available for benchmarking? Are the analytical tools accurate? What are the sensitivity differences between 10 wt% fuel and 5 wt% fuel? How should overall safety margins change? The NRC will release their conclusions prior to the ANS annual meeting in Albuquerque this coming November.

Deep Observations on Life

When I die, I want to die like my grandfather--who died peacefully in his sleep. Not screaming like all the passengers in his car.

Author Unknown

Advice for the day: If you have a lot of tension and you get a headache, do what it says on the aspirin bottle: "Take two aspirin" and "Keep away from children."

Author Unknown

Relationships are hard. It's like a full time job, and we should treat it like one. If your boyfriend or girlfriend wants to leave you, they should give you two weeks' notice. There should be severance pay, and the day before they leave you, they should have to find you a temp.

Bob Ettinger

I think I know how Chicago got started. A bunch of people in New York said, "Gee, I'm enjoying the crime and the poverty all right, but it just isn't cold enough. Let's go west."

Richard Jeni

If life were fair, Elvis would be alive and all the impersonators would be dead.

Johnny Carson

Bigamy is having one wife/husband too many. Monogamy is the same.

Oscar Wilde

Suppose you were an idiot. And suppose you were a member of Congress... But I repeat myself.

Mark Twain

Do you know why they call it "PMS"? Because "Mad Cow Disease" was taken.

Unknown, presumed deceased

Don't find fault, find a remedy.

Henry Ford

Puzzles

1. How would you weigh a jet plane without using a scale? (Cutting the plane into pieces is not allowed)
   
   
   
   
2. Why are manhole covers round?
   
   
   
   
3. How do they make M&Ms so the hard candy shell is smooth all around, with no flat spots?

Rombough Completes 50 Mile Trail Run

Charles Rombough, President of CTR Technical Services, completed the Berryman 50 mile trail run in the Mark Twain National Forest. His time of 11 hours 56 min was good enough for 22nd overall out of 54 starters. Eric Grossman was first in 7:29:47 while Becky Leahy was the first female in 10:20:16. Times were slow because of the 93 degree temperature and high humidity.

Rombough was blessed with crew support from his fiancee, the lovely and gracious Karla (shown here), who provided him with a variety of drinks (coke, gatorade, slimfast, water), a variety of foods (Gu, power bars, potato chips), ice on the head, and a back rub upon request. Karla did a heroic job except toward the end when she was late getting to the last aid station.

After seeing Karla give all this support to Rombough, one of the runners told her "Whatever he's paying you, I'll double it."

Quotes

A good plan today is better than a great plan tomorrow.

General George S. Patton

Be thankful we're not getting all the government we're paying for.

Will Rogers

The less [government] the better. As far as [what] your personal goals are and what you actually want to do with your life, it should never have to do with the government. You should never depend on the government for your retirement, your financial security, for anything.

Drew Carey

A government that is big enough to give you all you want is big enough to take it all away.

Barry Goldwater

No endeavor that is worthwhile is simple in prospect; if it is right, it will be simple in retrospect.

Edward Teller (1908-2003) Physicist

Instead of loving your enemies, treat your friends a little better.

Edgar Watson Howe (1853-1937) Journalist

You have to be careful about being too careful.

Beryl Pfizer

It is a sign of strength, not of weakness, to admit that you don't know all the answers.

John P. Lougbrane

Horse sense is what keeps horses from betting on what people will do.

Raymond Nash

We need education in the obvious more than investigation of the obscure.

Justice Oliver Wendell Holmes

Who We Are

CTR Technical Services was incorporated on May 15, 1987 to provide technical support for the nuclear industry. Since then, we have done work for 33 worldwide organizations (located in 22 states and 4 foreign countries). We specialize in the fields of reactor physics calculations and measurements, reactor core monitoring, shielding evaluations, criticality evaluations, and custom software applications.

The President is Charles Rombough who has over 30 years experience in nuclear analysis and software development. Our associate is Steve Martonak who specializes in mathematical modeling of physical systems and computer programming. We have also teamed with Dale Lancaster of NuclearConsultants.com to expand our expertise into other areas.

CTR Technical Services, Inc.
950 Sugarloaf Road
Manitou Springs, CO 80829

Tele: 800 - 524-9328
Fax: 719 - 685-3579

Email: ctr@ctr-tech.com

Answers to Puzzles

1. Put the plane on a barge, mark the water line. Remove the plane and add 100 lb lead weights (for example) until the line is again at water level.
   
   
2. Round covers cannot accidentally fall through their holes, unlike a square or rectangular cover. Round covers can be rolled around to move them. Round covers always fit regardless of angle. Round holes are easier to dig.
   
   
3. Spray on the coating while the chocolates tumble around in a rotating drum.

List of Clients

ADTECHS Corporation
Alief Alamo Bank
Arizona Public Service Corporation
Arkansas Power & Light Company
Bechtel SAIC Corporation
Beijing Institute of Nuclear Engineering
CP&L Progress Energy
Consumers Power Company
Duke Power Company
E G & G
Environmental Measurements Lab
First Energy Corporation
Florida Power & Light Company
Florida Power Corporation
Fluor-Daniel Northwest
Framatome ANP
Galaxy Computer Services, Inc.
General Electric Nuclear Energy
Gesellschaft fur Nuklear-Behalter mbH
GPU Nuclear Corporation
Institute for Nuclear Energy Research
Korean Electric Power Research Institute
Los Alamos National Laboratory
Nuclear Management Company
U.S. Nuclear Regulatory Commission
Oak Ridge National Laboratory
Omaha Public Power District
Sacramento Municipal Utility District
Scientific Application International
TRW Environmental Safety Systems
Westinghouse Electric Company
Westinghouse Hanford Company
Yankee Atomic Electric Company