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Consultants, Clients and Contractors: How Effective Communication Can Improve the Seismic Qualification of Nuclear Facilities

Extreme Loads and structural risk

Consultants, Clients and Contractors: The Communication Triangle of Seismic Qualification of Nuclear Facilities

Principal Engineer, Russell Powell, and his team, have been performing Seismic Walkdowns at Nuclear facilities throughout the UK for over 20 years; and are widely renowned as experts in their field. The following article discusses some of their key findings, highlighting common and reoccurring issues that consultants, clients and contractors should remain mindful of. 

"For years, I have been performing seismic walkdowns at every nuclear power station across the UK, as well as several other nuclear facilities around the globe. This has given me extensive exposure to a wide variety of circumstances, including the top problems that should be addressed industry-wide. My advice begins with addressing the communication between consultants, clients and contractors."

Russell Powell
Russell Powell,
Principal Engineer

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The Primary Problem: Installation Deficiencies 

When addressing the seismic qualification of plants and equipment, the problem I've found to be the most common is installation deficiencies. This is not to say that the installers (contractors) are not doing a good job; they are just not always installing exactly as per the design. Changes in the position of a bracket or bolt, or the orientation of support, however small, can negate the design qualification status.

When consultants are performing a technical assessment of a design, we perform calculations and, in some cases, run Finite Element Analysis (FEA) models to ensure that the design meets the requirements set out by the client. These designs are then passed to the client and installer. Unfortunately, this is where the communication triangle between consultants, clients and contractors can begin breakdown.

If there is a lack of knowledge from installers as to why something has been designed a particular way, it can make it difficult to not only install but source and manufacture as well. This leads to small changes being made that installers assume may not have any impact, but ultimately can completely change the seismic response of an item or make surrounding equipment an interaction concern when it previously was not. 

However, not all installation deficiencies emerge because of changes in design; some are the result of human error. I have previously worked on jobs where contractors new to the nuclear industry were qualified to complete "regular" installations but did not have the proper experience to work in nuclear facilities, leading to cut corners. Although the jobs are not done incorrectly per se, they were not completed to the expected standards, causing problems for our clients. 

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The Ultimate Cost: Time and Money

When the contractor’s installation team has not followed the design exactly or has cut corners, this generally comes to light during the interim or post-installation walkdown, when the works are nearing completion and the commissioning phase has or is about to start.

During the post-installation walkdown, a seismic review team is on-site to review the works from a seismic safety perspective. However, when items have not been correctly installed (or as per the design intent), problems occur; these problems often provide a cost and time implication to the client. Incorrectly installed items may need moving or replacing, and additional justifications and calculations may be required. In some cases, a further walkdown to confirm that any modifications or repairs have been made and satisfy the design intent may be necessary.

All this will cost the client time money. Certain deviations could add significant costs due to fixing or addressing the problem and delays in commissioning.

Our Recommendation: Ask Questions Now to Avoid Fixing the Design Later

My advice to contractors working in the nuclear industry is to ask questions or raise technical queries (TQs) promptly. If contractors cannot follow the design for any reason, they should contact the designer before completing the installation; it will save the client time and money and avoid embarrassing incidents.

One of the best features of ABS Group walkdowns is that we can go to the site on short notice and use our experience to review projects as they are happening. When our clients (or their contractors) come across a problem, it does not take days of calculations to resolve; once on-site, we can evaluate almost instantly. If we then need to perform calculations, we have all the necessary information to do so.

The Design and Installation Process in an Ideal World

The key to the ideal scenario is transparency on all parts. If the client brings us in at concept, we can discuss seismic requirements with the designer before they start. Then, we can perform an early design review and assess whether the design is suitable (from a seismic perspective). Following this, we can go to the site for a pre-installation walkdown, where the team (designers/client/operators) can walk and talk the route, looking for any potential concerns, ultimately dealing with any necessary design changes before installation begins.

Then, depending upon the size of the project, ABS Group can perform interim walkdowns. These would identify and resolve any site-led changes or unforeseen installation difficulties, such as heavy rebar preventing anchorage or scaffolding that has been put up in such a manner that prevents the drill from being used. When it comes to the post-installation walkdown, it’s more of a confirmatory sign-off.

This process can often prevent costly measures for the client. Although it may seem like an unnecessary cost at the beginning of a job, in the long run, it can prevent issues that may lead to delays in the start-up of a facility and save organizations large-scale costs at the end of a job.

ABS Group: Your Seismic Walkdown Experts

For the past 25 years, ABS Group has assisted a variety of clients and sites across a wide range of industries in both the U.S. and UK in completing successful reviews of safe shutdown systems and components utilizing the seismic walkdown methodology. Our engineers have significant experience and are widely recognized as subject matter experts. ABS Group has been instrumental in the compilation of earthquake experience databases, with access to all original records, allowing us to provide our clients with unique, cost-effective and practical solutions to resolving their pressing needs. 

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