Taking good care of your Nuclear Power Plant

Have you ever thought of your nuclear power plant like a living body?

For example,

  • Control computers & protection system are like the brain / central nervous system
  • Reactor Core – heart
  • Primary Heat Transport piping – blood vessels
  • Steam Generators, Turbine and Electrical Generator – muscular system
  • Electrical, Instrumentation and Control Systems – peripheral nervous system
  • Ventilation and Air Conditioning Systems – respiratory system
  • Fuel Handling – digestive system
  • Auxiliary cooling circuits – lymphatic system
  • Structures – skeletal system
  • Radioactive waste management systems – excretory system
  • Plant safety parameters – pulse, blood pressure, hematological parameters, glucose levels, etc.
  • Event diagnosis – like the medical diagnosis process for determining which disease or condition causes a person’s symptoms and signs.

Of course, no analogy between two complex organisms can be perfect, but you get the idea.

The soul is represented by the people who run the nuclear power plant and their nuclear safety culture is the personality of the operating organization.

In principle, taking good care of a nuclear power plant is a lot like looking after yourself to keep healthy and stay out of trouble. And if you work in a nuclear power plant, the connection is even stronger for you.

Taking care of your nuclear power plant requires comprehensive safety assessments, a robust design, reliable operation and maintenance, effective surveillance, testing and in-service inspections, large numbers of nuclear professionals, proper training and qualification programs and facilities, sound financial resources, careful decision-making, effective regulation and continuous learning. A strong nuclear safety culture supports and links together all these elements that are essential for the healthy, successful and long life of your nuclear power plant.

We, as nuclear professionals, are personally responsible and accountable for taking proper care of our nuclear installations and materials, thus protecting ourselves, our colleagues, the population and the environment. Each of us has a role in ensuring nuclear safety.

How are you taking care of your Nuclear Power Plant?

Taking good care of equipment

I would like now to be more specific and discuss about taking care of the NPP systems, structures, components and equipment. In the following, I will refer to these collectively using the abbreviation SSCE. Although the specific requirements differ for the particular SSCEs, there are many common applicable requirements and principles that, if implemented, will ensure the performance of the SSCEs in accordance with the design intent.

First, in order to take good care of the SSCEs, you have to know them as well as practicable. They are important because they can be safety-related, their failure may cause a transient, an accident or / and hazard to the personnel or simply because they are important to production, they may be expensive and difficult to replace.

To really know your SSCEs, you need to understand their design bases and operation. These include the conditions for which they have been designed to operate or to continue to function or to maintain their integrity. You have to know if the SSCE is credited in design basis accident analysis and / or in severe accident management, and to understand its role and expected performance.

Also, you need to know many other things about the SSCEs, as applicable, such as: the operating ranges; operating and design margins; the relevant requirements from the applicable codes, standards and regulations; materials requirements; need for electrical supply, cooling water, instrument air, technical gases, lubricating oil, fuel oil, etc.; qualifications and protections (environmental, seismic, fire protection, flood protection,  etc.); safety class; code class where applicable; reliability, service life (and whether the SSCE is replaceable or not), ageing mechanisms; requirements for redundancy, independence, diversity and preferred mode of failure (or “fail-safe”); failure modes and effects; parameters to be monitored; predictive maintenance techniques; preventive maintenance activities and recommended frequency; necessary in-service inspections and related techniques, surveillance routines, different types of tests (functional performance tests, surveillance tests, etc.); ageing management plan / condition assessments and any Time Limited Ageing Analyses (TLAA). It is also essential to know the SSCE’s physical location in the installation and its interactions with other equipment.

Depending on the importance of the SSCE, you need to ensure alarms are available in the main control rooms and on local panels for the relevant parameters.

You have to know the operational limits and conditions (OLCs) / technical specifications for safe operation associated with the SSCE (safety limits, safety systems settings, limiting conditions for operation, surveillance requirements, design features and administrative controls) and the actions required in case of deviations from the limiting conditions for operation. Also, it is good to know also any importance measures / values coming out of the PRA (Probabilistic Risk Assessment) / PSA (Probabilistic Safety Assessment) studies (e.g. FV (Fussel-Vessely), RRW (risk reduction worth), RAW (risk achievement worth or risk increase), Bi (Birnbaum), etc.), but be aware of the quality and limitations of the PRA/PSA studies.

It is useful to know also the human factors engineering (HFE) considerations for the SSCE.

Taking care of the SSCEs includes ensuring that their associated documentation is complete and accurate: design bases are complete; standards and requirements are clear; as-built flowcharts, drawings and details are verified and validated in the field; operating manuals, alarm response procedures, including diagnosis of failures and degradation, are available; operating experience records are maintained; the testing and inspection procedures include the acceptance criteria; identification information is complete (tag number, manufacturer, supplier(s), model no., serial no., stock code numbers for the components); other information that would be necessary in the procurement process is available, like the lead time for procuring a new similar equipment if needed.

Looking after your equipment includes operation and maintenance. You need toensure the operating manuals, alarm response procedures and maintenance procedures are complete, technically correct, validated as far as practicable and available for use. Ensure the equipment is in the right configuration and correctly identified / labelled, in accordance with the validated as-built documentation for the plant. You also need to keep temporary modifications at minimum and limit their duration. You have to ensure monitoring / surveillance, testing, maintenance, in-service inspections (including NDE (non-destructive examinations) and you need to plan these activities carefully. As part of the work planning, you have to assess the risk from taking the equipment out of service (use Equipment Out of Service applications if available). You have to record, diagnose and analyze failures and indications of degradation; perform root causes for failures of important equipment; take corrective and preventive actions and monitor their effectiveness; record and retain records of equipment performance, to be able to monitor trends.

You also need to perform walk-downs, look at your equipment and listen to it, as applicable, whenever possible. Observe good house-keeping and material condition.

Monitor the health of SSCEs, using relevant performance indicators. Ensure environmental qualification is maintained, seismic qualification is maintained and take measures so that protection against other external hazards is ensured (fire protection, flooding protection, lightning protection, protection against electromagnetic interference, protection against missiles, etc.); also remember to ensure protection against inadvertent manipulation (e.g. bumping, etc.) where this may be of concern. Ensure FME (foreign material exclusion) for your equipment.

Have the necessary authorizations for work. Use only approved procedures. Do PJB (Pre-Job Briefing) as required. Before working on equipment, make sure the configuration and conditions are the correct ones, for the current mode of operation of the plant. Additional care must be taken if the conditions are different than those you worked in on another occasions, than those considered during work planning and preparation or than those for which you have been trained. Have contingency plans for cases where something may go wrong.

Make sure you have the right tools for maintenance. Don’t step or climb on equipment. It’s not good for it and it’s not good for you. Don’t take shortcuts. Take care of yourself and your colleagues, make sure you work safely, have the right PPE (Personal Protective Equipment) and radiation work permit and radiological protection equipment.

Assess potential problems due to obsolescence. Ensure sufficient inventory of spare parts. Observe the quality assurance requirements. Take all necessary measures to prevent the use of counterfeit, fraudulent or suspect items. Make sure you can replace equipment when its service life has expired.

When important SSCEs do no perform as expected, complex assessments should be taken to assess their acceptability for continued operation. For this you need to have in place TOE (Technical Operability Evaluation) and ODM (Operational Decision-Making) processes.

Training and qualification of personnel is very important for taking good care of your plant’s SSCEs. Ensure personnel qualified for monitoring the SSCE, for designing modifications when necessary, for configuration management, for ageing management, for diagnosing failures and degradations. Ensure clear responsibilities and accountabilities.

Use simulators and mock-ups, whenever possible, for the training and qualification of operators and maintainers. Use the adequate human performance tools / error prevention techniques.

Ensure technical assistance is available for cases where in-house resources are not sufficient.

Use operating experience, both internal and external, to make sure you are up to date with information that may be important to the performance of the SSCEs; use significant operating experience reports (SOERs) and other types of reports issued by international organizations documenting experience with equipment; use relevant results from research and development programs to be informed of state-of-the-art techniques in predictive maintenance and in-service inspections.

Ensure availability of resources for taking good care of your SSCEs: budget for maintenance, spare parts and technical assistance.

It’s been a long article (I appreciate you interest if you’ve read it all) and although it covers the essentials of taking care of equipment, the above lists of things to know and do are not exhaustive. Nor are they supposed to be known and done by a single person in an organization. System engineers, operators, maintainers, safety analysts, instructors, managers and even the regulators contribute to taking care of a nuclear power plant SSCEs. We have different, specific responsibilities but a shared interest in keeping nuclear power plants safe. Our knowledge, as well as our attitudes and behaviors, are important elements of nuclear safety culture.

How well do you know the equipment you have to look after and what do you do to take good care of it? The more you know, the more you care. Make your own checklist of things to know and do and see who else can help you in ensuring you look after your nuclear power plant SSCEs in the best possible way.  

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