Choosing the right fluid system component supplier is vital for a nuclear utility. The lengthy life span of nuclear power plants means that the utility is selecting a supplier with which it will work for several decades. Not only does the reliability and quality of the product need to be right, so too do the related services provided.
Mark Orlando, Swagelok, USA
With renewed interest in nuclear power generation resulting in significant new construction activity in many regions of the world, there is an immediate and projected shortage of qualified component suppliers. Declining activity in the nuclear power industry over the last three decades of the 20th century led to attrition among suppliers.
Quality suppliers employ state-of-the-art equipment to minimize variables in manufacturing.
Some component companies went out of business, while others abandoned their nuclear certification programs, which can be costly to maintain. In addition, due to approaching retirements, the nuclear industry is in danger of losing a large and important body of knowledge. Nuclear engineers and other experts who grew up with the industry in the 1960s and 1970s are preparing to leave the field, and their nuclear construction expertise will, unfortunately, be leaving with them.
Given these challenges, this article is intended to provide some guidance as to how to select a fluid system component supplier with the appropriate certifications. It should be useful to any company involved in the construction of a nuclear power plant, as well as companies handling waste transportation, fuel manufacturing, and waste processing. For ease of reference, all such interested parties will be referred to as utilities.
In addition to certifications, there are other criteria to consider when selecting a component supplier, including the supplier’s service offerings, quality programs, and auditing process. A utility should consider these aspects if it is to promote safety and ensure efficient and economic operation over the full operating life (60+ years) of today’s nuclear power plants.
When a utility selects a fluid system component supplier, it is selecting a supplier with which it will do business for many decades. This supplier can have a significant effect on the utility’s bottom line, not only through the quality and reliability of the product, but also through related services and solutions provided.
Even before the product is quoted or purchased, the supplier’s services may be drawn upon. As the reactor or power plant is being designed, engineers may employ the supplier’s CAD drawings of component parts which, in the best case scenario, are readily available online and downloadable into any number of different CAD applications.
Following good manufacturing practices ensures consistent production from component to component.
Working with the supplier during the early stages of a project should be encouraged because the supplier, as an expert in fluid system components, may be able to help identify potential solutions. In some cases, a custom-engineered product may be viable.
For example, a bellows valve could be engineered to order with tubing extensions of certain lengths, special end connections, air actuators, limit switches, or packing material options. Such accommodations could eliminate steps during construction or improve functionality, resulting in considerable savings to the utility.
As the time for construction or maintenance approaches, the supplier’s local sales and service representative should be available to develop a plan to ensure that the product will be available at the required times. The representative should also be available to provide on-site product support and technical service, including training for the utility’s technicians and installers. Two of the main reasons for failure in fluid system components are incorrect product selection and incorrect installation.
The best suppliers will show breadth, not only in their product line but also in the range of industries serviced. When the supplier offers a broad range of fluid system products, the utility stands to benefit, as it will not have to qualify and maintain multiple fluid system suppliers at unnecessary expense. The utility also stands to benefit when the supplier services other industries, such as chemical, oil and gas, or alternative fuels. Such a supplier is able to bring products to the nuclear market that have been proved in many diverse applications.
As part of the selection process for choosing a qualified fluid system component supplier, utilities should look for suppliers that implement comprehensive quality controls over materials, component designs, manufacturing processes, safety recall reporting, and their own sub-tier suppliers.
• Material controls. A quality supplier will ensure that the materials used in its components meet or exceed industry accepted quality standards. Such suppliers have controls in place to trace materials from their origin to final sale to customers. Suppliers will check materials upon receipt at the facility, at various stages in the manufacturing process, and before delivery. Sound material controls allow a supplier to review test reports for specific materials and show that important requirements have been met for required characteristics and tests such as chemical composition, corrosion resistance and mechanical properties have been performed.
• Design controls. Suppliers that employ sound engineering practices can produce components that consistently meet the design inputs provided by a utility. For example, suppliers set tracking mechanisms to confirm that components are designed to the appropriate pressure and temperature ratings, as well as flow requirements. Suppliers may utilize qualified third-parties to provide independent validation that design inputs will yield the desired outputs. Suppliers may even employ software controls on design tools to ensure the tools operate as intended. Finally, they incorporate testing mechanisms to verify that the design outputs will produce a component that meets specifications.
• Manufacturing controls. On the manufacturing end, quality component suppliers employ qualified personnel and utilize good manufacturing practices to ensure components are consistently produced. A competent supplier will have standard training procedures in place to make sure personnel performing critical operations, such as welders, inspectors, examiners and auditors, are up-to-date on proficiency requirements and are supervised by qualified individuals. Good suppliers will carefully plan manufacturing procedures to minimize variables and limit room for error.
• Safety recall reporting. A component supplier’s commitment to quality does not end when parts leave the manufacturing facility. Should defects be discovered in components that have been shipped to the marketplace, a quality supplier will have systems in place to immediately notify customers and recall the parts. Safety recall systems require precise traceability of materials and actions throughout the manufacturing process. Therefore, suppliers with accurate reporting mechanisms excel in marketplace notification in the unlikely event of product recalls.
• Supplier controls. Finally, a sound component supplier will impose the same level of quality controls described above on its own suppliers. As part of a component supplier’s robust quality programme, monitoring of its suppliers may involve conducting routine audits, qualification checks, and surveillance.
SAFETY-RELATED AND CODE REQUIREMENTS
Beyond service and quality, fluid system component suppliers must provide parts that meet appropriate certifications. Fluid system components for the nuclear industry may be either commercial grade or safety-related grade. The former are employed in non-critical areas, such as general support equipment and compressed air systems. Components for these systems are off-the-shelf and typically do not require special certifications.
By contrast, safety-related products must conform to a nuclear code or standard that is enforced by the appropriate jurisdictional authority and/or by a government bureau or government-assigned agency.
Component assembly is a critical process in product manufacturing.
The term safety-related applies to structures, systems, components, procedures, and controls of a facility or a process relied upon to remain functional during and following design basis events to ensure: firstly, integrity of the reactor coolant pressure boundary; secondly, capability to shut down the reactor and maintain it in a safe shutdown condition; and thirdly, capability to prevent or mitigate off-site exposure1.
To date, there is no single international code or standard for safety-related nuclear power components. Each country adopts its own code, although some countries may choose to employ the same code as another country or one closely modelled on it.
The nuclear standard developed by the American Society of Mechanical Engineers (ASME) was the world’s first nuclear code, and it remains today the most widely accepted, with many countries following it in North America, Latin American, Europe, and Asia.
China is a burgeoning nuclear nation and plans to increase its nuclear installed power generating capacity from a current 9 GW output to 50-60 GW by 2020 and to 120 GW to 160 GW by 2030. The common practice in China is to build nuclear power plants to the codes specified by the construction company.
Therefore, China’s nuclear plants adhere individually to a variety of codes, including the US ASME code and the French RCC-M code, as well as codes from Canada, Russia, and other countries. Further, China is working toward developing its own code, which currently appears to be based on best practices found in other countries’ standards.
Various codes are followed depending on the country in which the plant is being built and the type of plant. We cannot discuss all codes in this article, so we will focus on the ASME and RCC-M codes.
QUALIFYING AND PROCURING SAFETY-RELATED COMPONENTS
The process for qualifying and procuring safety-related components is dictated, in large part, by the code. Adhering to codes helps suppliers prove that manufacturing processes will consistently generate quality components with minimal risk of defects. For peace of mind, utilities should consider auditing a supplier’s manufacturing operations (see “Supplier Audits Give Utilities Peace of Mind” sidebar). Both the ASME and RCC-M codes define design and construction rules for mechanical components in nuclear power plants and primarily apply to safety-related components.
The RCC-M code was originally derived from the ASME code, but has diverged from it over the years. The RCC-M code contains several supplementary requirements for procurement of components, including design verification; document and data control; purchasing data; product identification and traceability; inspection, testing, and examination; and control of nonconforming products.
A fundamental difference between the ASME and RCC-M codes is whether deviations are allowed. A great number of influential parameters are fixed under the ASME code, and no deviation from the code is permissible. However, the RCC-M code offers some latitude. The RCC-M code defines reference practices that are to be followed for specific components.
A supplier may propose alternative practices. Suppliers must request prior approval and submit test results demonstrating that an alternative practice is equivalent, or superior to, the reference practice. To ensure effectiveness of these alternatives, the RCC-M code defines the extent of each manufacturing inspection technique, the areas subjected to examination, the appropriate surface preparation, and the associated acceptance criteria.
Other unique differences between the ASME and RCC-M codes include:
- Material specifications. The majority of the world has adopted consistent material standards for metal grades. Therefore, subtle yet important differences exist between the codes. Qualified component suppliers recognize these nuances and will utilize appropriate materials to accommodate the standards. If material differences are minor, a supplier may request an alternative practice when following the RCC-M code.
- In-house versus third-party protocols. The ASME code allows component suppliers to follow procedures from design through delivery in-house. For example, fully trained personnel are able to train other individuals within an organization, and testing may be completed by the supplier. The RCC-M code, however, requires that external third-parties complete training, testing, and other activities.
- Component validation. Under the ASME code, suppliers may validate component designs through testing to
determine if a part will perform as intended. Following proper quality procedures, the component may be designed, manufactured, and finally tested. The RCC-M code, however, places emphasis on design analysis as part of the validation process. Instead of testing after manufacturing, a component undergoes further design analysis to review characteristics like stress allowances and wall thickness.
Despite the differences between the two codes, most organizations agree that components produced for either code are more or less equivalent in quality and performance. Once the supplier has been qualified for adherence to an appropriate code, a request for quote may be issued to that supplier, part of which will consist of technical documents that dictate design, processing, reporting, document formatting, nonconformance handling, and other parameters.
In response to the request for quote, the supplier issues a quote, including a detailed response to all document requirements, indicating how each specification will be fulfilled.
When the utility issues the purchase order, it has the option of requesting witness or hold points. These enable the utility to observe a particular step in the manufacturing process.
In the case of a hold point, the utility requests that the manufacturer stop at a particular point in the manufacturing process and not proceed until the utility can be present to observe.
In the case of a witness point, the utility requests that it be informed in advance of certain manufacturing processes so it may exercise the option of observing that process; however, the process is not held up if the utility does not show up at the designated time.
Before delivering the product, the supplier must issue an appropriate report as detailed in the purchasing documents. This is typically called an End of Manufacturing Report (EOMR). The EOMR is commonly reviewed by the utility, or its representative, during the releasing inspection. The process of selecting a code-certified fluid system component supplier is complex. It requires a thorough understanding of the code requirements, as well as a thorough review of all prospective suppliers willing to follow the code.
The supplier’s process should be transparent and open to review. Beyond code certification, the utility must consider the supplier’s service offering, technical and design assistance, training, testing documentation, breadth of product line, and the proximity of the sales and service representative. Utilities should also consider taking part in an audit of the supplier’s manufacturing operations.
To repeat, the utility is not just purchasing a product; it is entering into a relationship with a supplier whose level of service can profoundly affect the bottom line for many years to come. The supplier should exhibit a culture in which quality, service, research, and innovation are held in high esteem.
1. Nuclear Energy Institute, Nuclear Power Quality Assurance fact sheet, https://nei.org
Supplier audits give utilities peace of mind
Conducting an audit of a fluid system component supplier’s manufacturing operations offers a utility the opportunity to gain confidence in the supplier and perhaps enhance efficiency in its own operations.
While documentation can prove that a component supplier has a quality manufacturing operation, seeing it in action gives utilities a first-hand view of the competency of the supplier and its employees. Utilities can observe the maturity of the supplier’s quality systems and get a look at the people behind the components.
During an audit, utilities may observe the strict controls in place throughout a manufacturing operation, such as those applied to interface points. Interfaces are points at which any sort of change occurs, such as changes in materials, processes, or even personnel.
For example, a critical interface point is the handoff of responsibility from one person to another, whether between steps in a process or a change in shift. Transfer of paperwork and knowledge must occur at these interfaces to ensure materials and parts continue on their way toward a quality end component that meets design specifications.
An audit may also involve reviewing a supplier’s material and traceability controls, including the positive material identification (PMI) process. During PMI, a supplier cross-checks that a material is what it is supposed to be. Many utilities conduct PMI as part of their quality control program. However, this step may be redundant if the component supplier has a solid program in place. A utility may, therefore, choose to eliminate PMI in its own operations, adding efficiency as a result.