CTR Technical Services Newsletter

2008

Startup Physics Testing

After every fuel cycle of a pressurized water reactor (PWR), about a third of the fuel assemblies are discharged. New fuel assemblies replace the discharged assemblies, and all of the fuel assemblies are moved around to form a new reactor core. Design calculations are performed to ensure that the new core can be operated safely for the next year or two. Prior to escalating to full power, however, the new core is tested to ensure that the reconstructed core matches the design calculations. This is called "Startup Physics Testing." The purpose of startup physics testing is to measure certain neutronic characteristics of the reconstructed core and compare those measurements to predictions. If the measurements agree with the predictions within a predetermined tolerance, then there is assurance that the reconstructed core and the designed core are the same.

The five basic characteristics that must be confirmed for the new core are (1) reactivity balance, (2) reactivity control, (3) power distribution, (4) capability to shutdown, and (5) requirement to shutdown. The reactivity balance is confirmed by measuring the all-rods-out (ARO) soluble boron concentration at critical, hot zero power (HZP) conditions and comparing it to the predicted value. Agreement means that the total amount of fissile material and absorbing material in the core is consistent with the design. Reactivity control is confirmed by measuring the reactivity response of the core to temperature changes (called the isothermal temperature coefficient or ITC) and comparing it to the predicted value. Agreement means that the behavior of the core to temperature changes is consistent with the design. Power distribution is confirmed by measuring the distribution of neutron flux throughout the reactor core at low, intermediate, and high power levels and comparing them to the design predictions. The power distribution must be confirmed at lower power levels prior to escalating to higher powers. Capability to shutdown is confirmed by measuring the worth of all, or a selected subset, of the control rod banks and comparing these worths to the design predictions. Agreement means that the core is behaving as expected and there is sufficient shutdown margin. Requirement to shutdown is confirmed by measuring the total reactivity difference between zero power and full power. This represents the reactivity elements that the control rods have to overcome in a reactor trip.

The ANS Standard, ANSI/ANS-19.6.1 Reload Startup Physics Tests for Pressurized Water Reactors, specifies the minimum startup test program that must be performed after each refueling of a PWR. To confirm the five basic characteristics described above, the minimum program consists of the HZP ARO boron concentration measurement, the HZP ITC measurement, the control rod worth measurements, the low, intermediate, and full power distribution measurements, and the total power defect measurement. If the results of these measurements compare favorably with the design predictions, then there is assurance that the as-built core and the designed core are the same and that the reactor can be operated as designed until the next refueling.

The Temelin Nuclear Power Station

The Temelin Nuclear Power Station is located near the town of Temelin, a village in South Bohemia in the Czech Republic. It is operated by the state-owned company CEZ and employs around 1000 full time workers.

The first plans for the power station were drafted in the late 1980s, the final project was submitted in 1985, and construction of the operating units began in 1987. After the non- violent overthrow of the Communist government in 1989, a decision was made to build only two reactors instead of the previously planned four. However, plans for four reactors were reopened in 2005.

In the 1990s, several alterations to the original Russian design were made to raise the power station's reliability and safety to West-European standards. The reactor core consists of 163 hexagonal fuel assemblies, each with 312 fuel rods and 19 guide tubes in a hexagonal lattice. Control rods are positioned above 61 of the 163 fuel assemblies. Each unit generates 3000 MW of thermal energy at full power. Unit 1 was connected to the grid in June, 2002 while Unit 2 was online in April, 2003. They undergo annual refueling.

Charles Rombough of CTR Technical Services has been contracted by the fuel supplier, Westinghouse, to help perform nuclear design calculations for the Temelin nuclear station. The plant has four cooling towers, each with a height of 150 meters. The diameter at the base amounts to 130 meters. The external wall has a surface area of 44,000 square meters.

Gamma Thermometers Undergoing Testing

A new type of core monitoring instrument, the gamma thermometer (GT), is currently undergoing extensive testing in an operating boiling water reactor. A gamma thermometer is a rugged, solid-state device that responds to the gamma flux inside the reactor core. The instrument is stationery during plant operation and does not deteriorate with long term radiation exposure.

There are several strings of gamma thermometers being tested. Preliminary results to date look encouraging in showing that the instrument can provide an accurate measurement of the power distribution when compared to the traversing incore probe (TIP) system. Data is being collected during steady- state, normal operating maneuvers, and transients. CTR Technical Services is assisting in a full evaluation of the results, which has not yet been completed.

Replacing the TIP system with a complete GT system saves costs because the GT system has no moving parts and requires little or no maintenance.

Deep Observations on Life

If a woman has to choose between catching a fly ball and saving an infant's life, she will choose to save the infant's life without even considering if there's a man on base.

Dave Barry

Sometimes I think war is God's way of teaching us geography.

Paul Rodriguez

The problem with the designated driver program: it's not a desirable job, but if you ever get sucked into doing it, have fun with it. At the end of the night, drop them off at the wrong house.

Jeff Foxworthy

Puzzles

1. There are two envelopes containing money. One envelope contains twice as much money as the other. You are allowed to choose any envelope and open it. You are then allowed to trade your envelope for the other one. For example, suppose you choose an envelope and it contains $100. If you trade, you will either get $200 or $50. Do you trade? (Answer this question before reading the next puzzle)
   
   
2. If you assume that the probability of the second envelope containing $200 is 50% (and similarly for $50), then your average "expectation" is .50 x 200 + 0.50 x 50 = 125 while your risk is only 100. This implies that you should trade. But you can see that this expectation/risk ratio would always be true even before looking inside the first envelope! And so you would always trade no matter what the envelope contained. Clearly, something is wrong since you would keep trading forever as long as you did not look inside. What is wrong?

Quotes

Never let the fear of striking out get in your way.

Babe Ruth

If we desire to secure peace, one of the most powerful instruments of our rising prosperity, it must be known that we are at all times ready for war.

George Washington, Dec 13, 1793

The accumulation of all powers, legislative, executive, and judiciary, in the same hands ... may justly be pronounced as the very definition of tyranny.

James Madison, Jan 30, 1788

Freedom is the right to tell people what they do not want to hear.

George Orwell

As long as you're going to be thinking anyway, think big.

Donald Trump

It is dangerous to become overconfident in the infallibility of purely theoretical analysis and so to neglect experimental science. Many other predictions made during the past ten years have been proven wrong. No theory, no matter how beautiful its equations, has any more value than Democritus' original speculation until its predictions have been verified by the hard-boiled experimenters.

Philip M. Morse, 1939

Only two things are infinite, the universe and human stupidity - and I'm not sure about the former.

Albert Einstein

Never was good work done without much trouble.

Chinese proverb

Call it a clan, call it a network, call it a tribe, call it a family. Whatever you call it, whoever you are, you need one.

Jane Howard (1935-1996) Writer

Technology is just a tool. In terms of getting the kids working together and motivating them, the teacher is the most important.

Bill Gates

The recipe for well-being, then, requires neither positive nor negative thinking alone, but a mix of ample optimism to provide hope, a dash of pessimism to prevent complacency, and enough realism to discriminate those things we can control from those we cannot.

David G. Myers Psychologist and educator

Being a friend means mastering the art of timing. There is a time for silence. And a time to let go and allow people to hurl themselves into their own history. And a time to pick up the pieces when it's all over.

Gloria Naylor Novelist

The best way to have a good idea is to have a lot of ideas.

Linus Pauling

Today, because America has acted, and because America has led, the forces of terror and tyranny have suffered defeat after defeat, and America and the world are safer.

President George W. Bush

Losing an illusion makes you wiser than finding a truth.

Ludwig Borne (1786-1837) Journalist

When you talk, you repeat what you already know; when you listen, you often learn something.

Jared Sparks

Answer to Puzzle

The statement "If you trade, you will either get $200 or $50" implies that the likelihood of either one is equal. This is true only if the content of the second envelope is independent of the first. But this is not the case. If you have chosen the envelope that contains twice as much money as the other one, then the probability is 0% that the other envelope contains $200. Conversely, if you have chosen the envelope that contains 1/2 the money of the other one, then the probability is 0% that the other one contains $50. The correct question is "What is the likelihood that you have chosen the envelope that contains twice as much money?" Clearly, it is 50-50 and so trading must be 50-50 as well. Another way of looking at it is "what is the likelihood that the two amounts are 100/200 versus 100/50?". Without any other information to guide you, it is 50-50. Now suppose that you had to pay an entry fee of $75 to choose one of the two envelopes. Suppose that it contains $50. Do you trade?

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 34 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

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
Korea Nuclear Engineering Services Company
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

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