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Monthly Archives: January 2014

NRC Grants Ft. Calhoun License Amendment Request

Lara Uselding
Public Affairs Officer
Region IV

When someone sees the words Fort Calhoun and flooding in the same document, it gets attention. So we thought we’d provide some insight into a document — issued this week — with that very word combination.

Ft. Calhoun Senior Resident Inspector John Kirkland provides "boots on the ground" oversight at the plant.

Ft. Calhoun Senior Resident Inspector John Kirkland provides “boots on the ground” oversight at the plant.

The Fort Calhoun Station, located north of Omaha, Neb., and operated by the Omaha Public Power District (OPPD), recently restarted after a long hiatus. But months before that happened, in April 2012, OPPD asked permission to implement a license change involving actions to protect the plant at high and low river levels.

On Jan. 28, 2014, the NRC granted the request and issued a license amendment officially changing when the plant should be powered down during a flood scenario. Simply put, the change involves powering down at 1004 feet mean sea level versus the previously set level of 1009 feet. In addition to setting the river rising to a lower level, the NRC document also specifies that the plant must shutdown within six hours of river levels dropping below 976 feet 9 inches mean sea level.

This all started back in 2010 when NRC inspectors identified concerns with the plant’s flood protection strategy. So this is not a newly identified item and it does not change the plant’s design basis flood. It is an official change to the plant’s license during flood conditions and provides a more conservative level of action.

It is important to note that prior to restart, the licensee made modifications to the plant and had plans in place to protect the plant from rising river levels.

There is still ongoing and important work being done by OPPD, NRC and the U.S. Army Corps of Engineers to evaluate flood risks at the site in accordance with the post-Fukushima actions. The current target date for OPPD providing this information to the NRC is March 12, 2014. In the meantime, the plant is safe and has measures in place to respond to flooding events.

The Wonderful World of Radiography: How Radioactive Sealed Sources Check Welds

Betsy Ullrich
Sr. Health Physicist
Region I

During construction of pipelines and fabrication of large metal structures, welding is used to join the parts. It is very important to know the welds are structurally sound and the whole piece will be strong enough for its job. For example, the pipes used to transport natural gas must be properly welded together so that the gas does not leak from the pipes.

constructionAnd metal I-beams used in constructing a parking garage must be properly welded so that the structure can hold the weight of the vehicles in the garage. How can this be done? Often, workers perform “radiography” using sealed sources to inspect the weld to see if it is correct.

What is radiography? It is term used to describe using gamma rays or x-rays to inspect the structure of some large dense material. Although x-ray machines may be used for this, they are limited by their need for an electrical source, and because x-rays can only penetrate certain materials. A radiography device (sometimes referred to as a radiography camera) uses sealed sources that emit gamma radiation that can penetrate very dense materials such as metal. Radiography devices can be used without electricity and are portable, making them handy to use at work sites.

Because a radiography source, while small in size, emits gamma radiation that can penetrate several inches of metal, it must be stored in its shielded container. When a weld needs to be inspected, a long guide tube is connected to the device that allows the source to travel to the location that needs to be inspected. A long drive cable also is attached to the other end of the device. This allows the radiographer performing the inspection to stand far away from the radiation source during the inspection. Typically, the source is in the guide tube only a few seconds to a few minutes, depending on what is being inspected.

Radiography is used to inspect welds on pipes for oil rigs; large tanks that hold gasoline; airplane engines; and other large metal structures. So the next time you use natural gas, or park your car in a multi-story garage, you might remember the important role a radioactive source plays in keeping you safe.

NRC Science 101 – Quantities and Units of Measure

Suzanne Schroer
Reliability and Risk Analyst

science_101_squeakychalkIn the last Science 101 blog post, we discussed measurements made in various units of measure, particularly meters, grams and liters. You might be wondering where these units of measure come from and how they relate to one another. If so, you’re in luck, as that is the topic for today’s post.

Quantities are characteristics or properties we are trying to measure, such as the length of an object. Units of measure are how we express measurements of quantities. For length, the unit we would use in science is meters. A unit is really only a particular amount of some quantity used as a reference point for measurements of that quantity. Put differently, units of measure are chosen and accepted by the people who use them.

Often, units of measure were agreed upon many years ago. One meter is as long as it is because that’s what scientists agreed to use as a base unit for length. A meter could have been some other length. For the sake of establishing well-defined and easily-accessible units of measure, the General Conference of Weights and Measures (a collection of scientists from multiple countries) created in 1960 the Sytème International d’Unités (otherwise known as the SI¬). This system relies upon the base units of measure listed in the following table.

Table 1

Often times, however, the base unit of measure can be either too large or too small to be useful in describing a particular measurement. For example, while we could talk about the distances between cities in meters, we would be using very large (and, as such, cumbersome) numbers. For example, from Portland, Maine, to St. Louis, Missouri, is 2,060,000 m or 2,060 km. Similarly, if we are talking about the size of atoms, the basic building blocks of matter, speaking in terms of meters would be difficult as the diameter of a hydrogen atom is only 0.000000000120m. So, instead, for the sake of convenience, we often use prefixes to modify the size of the base unit. The following table lists a number of such prefixes using meter for the base.

Table2 Update again

The above table lays out conversion factors, ratios that can be used to convert one unit to another. For example, one such ratio, expressing the relationship between kilometers and meters, would be 1 km / 1000m. Using this ratio, we can convert 12348m into 12.348km (12348m x 1km / 1000m).

The NRC uses these same ideas when measuring radiation. These measurements will be discussed in an upcoming Science 101 post. As always, thank you for reading the NRC’s Science 101 blog series.


Keeping Knowledge “In the Family” at the NRC

Tom Boyce
Branch Chief, Regulatory Guide Development Branch

The NRC’s Office of Nuclear Regulatory Research (RES) produces regulatory guides to provide guidance that nuclear utilities can follow to meet NRC rules for the design and operation of their nuclear plants. The NRC staff also use regulatory guides to review applications from the utilities for plant permits and licenses. New guides are developed when needed – and existing ones are regularly reviewed and updated.

The Regulatory Guide Development Branch (part of RES) is very concerned with promoting “knowledge management” within the agency. We have an obligation to preserve key technical information especially as people leave the agency. Therefore, we have taken steps to make sure we capture, preserve, and transfer important technical knowledge.

communicationwordcloudNRC knowledge management especially is focused on two major ideas. First of all, it is focused on capturing and preserving agency knowledge (technical information) while the information is fresh and available. Second, and equally as important, knowledge management also means ensuring the collected information is transferred to the next generation of NRC staff.

To do this, we encourage NRC staff members to write their knowledge into regulatory guides as they identify technical and regulatory issues. This helps keep the knowledge in a permanent and long-lasting record. This also helps prevent technical information from becoming difficult to find over time. This is a very important responsibility, especially because of staff retirements or reassignments.

 In addition, the NRC staff teams up its junior staff with senior staff to perform the reviews and updates of the regulatory guides. This approach effectively helps pass on regulatory information to the junior staff. It also ensures that this important guidance continues to be available to the NRC staff, its stakeholders, and the public.

Critical knowledge can’t be lost if the NRC is to continue to meet its important mission. We make sure it isn’t.

Moving Forward on Updating Cost vs. Benefit Analysis

Alysia Bone
Rulemaking Project Manager

 What are the costs and benefits of the NRCs’ safety regulations? It’s a question we regularly ask as one way to make sure our regulations make sense.

We’re in the process of updating two cost-benefit guidance documents — NUREG/BR 0058 and NUREG/BR 0184 – at the direction of the Commission and after receiving public input. Our update plan is now available online. Our goal is to make sure we are using the right tools to compare costs and benefits so we implement changes that reduce risks and enhance safety in a responsible way.

The updated guidance will do a number of new things. It will include the cost for replacing the energy generated by nuclear power plants. It will also improve the method for putting a dollar amount on health impacts from radiation. We’ll revise terms and definitions for consistency across the agency, and we’ll look at how we use more subjective factors in cost-benefit assessments. We expect these changes will bring our cost-benefit process up to date and help us make more consistent decisions for reactors as well as other licensed activities.

NRC staff experts have been working on this in response to the Commission’s direction for a paper on our approach to considering the economic consequences of a potential nuclear accident. The Commission was responding to the staff’s August 2012 paper and recommendations, which were based on a review of the agency’s economic consequences process in place at the time of the 2011 Fukushima accident. The 2012 staff paper described where considerations of economic consequences fit in the NRC’s review of new reactor licenses, renewal of existing licenses, or major changes to our safety regulations. That earlier paper recommended updating the cost-benefit guidance used to perform these analyses.

In the plan to update cost-benefit guidance, we’ve committed to presenting any identified potential policy issues to the Commission for its consideration. As the staff further develops these potential policy issues, staff will hold public meetings to receive feedback from industry and members of the public, before advising the Commission.

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