Commissioning organization approaches

Detailed organization charts, job descriptions and responsibilities of the groups involved depend on the industrial make-up of the project and on the contractual models for the project’s construction, commissioning and operational phases. The most common contract models are the following:

FIG. 16. Project activities during various project phases.

— Turnkey contract for the whole plant, with owner supervision. These can include build–own–operate or build–

operate–transfer approaches where the NPP vendor operates the plant for an extended period (i.e. several years or the entire NPP life) following commissioning.

— Engineering, procurement and construction (EPC) contracts, with the owner providing overall coordination.

— Engineering and procurement contracts, with construction and commissioning performed by the owner (with technical assistance from contractors).

Whatever the contract model, the owner/operator holds the final responsibility for all nuclear safety aspects of a nuclear installation. The owner/operator is responsible for production and sets the cost of electric power to the electric power distribution company. Therefore, it is essential for the owner/operator to check construction and installation of SSCs before they are turned over at the end of commissioning to make sure they adhere to requirements defined in nuclear legislation, regulations, applicable codes and standards, contract specifications, and in any other pertinent document.

Ideally, the owner/operator would have resources to confirm that all requirements contained in these documents have been met. In reality it is not practical for the owner to check for compliance by inspecting and testing every single SSC in the plant. Therefore, to expedite the execution of a commissioning programme, some confirmation activities are usually entrusted to suppliers/constructors or outsourced to qualified organizations.

There are many possible combinations of construction management and commissioning implementation plans. Table 2 describes five typical examples of project implementation approaches and how they impact commissioning.

As shown in Table 2, the division of responsibilities for commissioning varies depending on the construction contract approach adopted and the owner/operator’s strategy. Commissioning is the last quality management activity administered by the owner/operator. While planning commissioning, the owner/operator will do an analysis and balance the resources to be deployed against the benefits likely to be accrued.

There are several possible models concerning the owner/operator’s involvement in commissioning. The most common approaches are listed below:

— Owner/operator checks, inspects and tests SSCs in the field, as construction proceeds.

— An entrusted architecture–engineering firm checks, inspects and tests SSCs in the field and compiles confirmation records. The owner/operator reviews the records.

— Owner/operator or an entrusted architecture–engineering firm checks the records which vendors have prepared for commissioning. The owner/operator or an entrusted architecture–engineering does a walk down check in the field before turnover, but does not participate in the commissioning tests.

— Owner/operator receives the commissioning records of tests and inspections, conducts random checks on a graded basis and archives the records without a complete review of all items in the records.

— Owner/operator performs an owner’s review mainly focused on safety, quality and performance.

The owner/operator will develop a test confirmation strategy for the commissioning turnover. There are several factors to be considered when developing the strategy from the viewpoint of nuclear safety and operations reliability. Some of these to be considered for an overall plan are:

— The owner’s human and financial resources available for commissioning;

— Regulations regarding SSCs significant to nuclear safety;

— Experience and qualifications of the equipment suppliers regarding installation and preoperational testing;

— Experience and qualifications of the construction/installation contractors;

— Construction methodologies such as field designs, pre-fabrication, packaged SSCs and large modular construction;

— Degree of quality assurance and quality control for each SSC during fabrication and installation;

— Differences in practices between the owner/operator and the vendors;

— Availability of qualified architecture–engineering firms acting on behalf of the licensee in implementing the commissioning plan.

TABLE 2. PROJECT IMPLEMENTATION APPROACHES AND THEIR IMPACT ON COMMISSIONING

Case Responsibility for

overall project

Division of responsibility for commissioning Organization/group Main responsibilities

Case A Owner/operator Construction Verifications and prerequisites for

preoperational tests Commissioning management Preoperational tests

(system functional tests) Operations (preparation) Initial fuel loading and startup

tests

Case B Owner/operator Construction Verifications and prerequisites for

preoperational tests

Operations (preparation) Commissioning management group I: preoperational tests (system functional tests) Commissioning management group II: initial fuel loading and startup tests

Case C EPC contractor or main contractor Construction Verifications

Commissioning management Prerequisites for preoperational tests

Preoperational tests (system functional tests) Operating organization

(licensee) Initial fuel loading and startup tests

Case D EPC contractor or main contractor Construction Verifications and prerequisites for preoperational tests

Commissioning management Preoperational tests (system functional tests) Operating organization

(licensee) Initial fuel loading and startup tests

Case E EPC contractor or main contractor Construction Verifications and prerequisites for  preoperational tests

Commissioning organization

(main commissioning contractor) Preoperational tests (system functional tests) Initial fuel loading and startup tests

Operations Operations carries out selected sets of commissioning tests, including preparations and confirmation of  plant configurations, as per work  requests from commissioning and in accordance with operating manuals and test procedures as approved by a commissioning management group

Note: In all cases, the organization responsible for construction (either owner/operator or EPC contractor/main contractor) takes ownership of commissioning. The various cases listed in the table reflect different owners’ interests and cater to various local capabilities. The implementation model adopted should be the one best suited for the plant construction in the specific local environment.

Table 3 provides an example of how to develop a commissioning test strategy that considers system significance from the viewpoints of nuclear safety and operational reliability. In the table, ‘safety class’ refers to a classification of SSCs in an NPP (in this case into classes 1, 2, 3 and other) based on their nuclear safety significance (refer to IAEA Safety Standards Series No. SSG-30, Safety Classification of Structures, Systems and Components in Nuclear Power Plants [135] for further details on safety classification). Safety class is combined with an evaluation of potential impacts on reliable operation to determine overall significance. Once significance is defined, each item to be commissioned is evaluated (assigned a grade) from the viewpoint of its contribution to the entire system to determine the relevant commissioning items to target. Namely, a grading strategy concerning the commissioning items for each system should be developed. For example, systems related to reactor trip systems would receive more thorough commissioning attention (e.g. reviews, oversight) than those associated with a warehouse or administrative building.

TABLE 3. COMMISSIONING GRADING STRATEGY

Nuclear safety — reliable operation Safety class 1 Safety class 2 Safety class 3 Other classes Failure may lead to a loss of power generation in

the long term A A B B

Failure may affect stable power production A B B B

Others A B C D

Note: A — Very significant; B — Significant; C — Somewhat significant; D — Insignificant.

Today, NPPs are constructed using a global supply chain. Practices may vary between countries; therefore, if practices are not explicitly described in contracts or other documentation, they may not be implemented. Ideally, careful attention is given to writing contract terms and defining agreements on the scope of delivery, developing the list and sequence of commissioning activities, and detailing the documentation and records to be provided.

All requirements and expectations need to be spelled out and agreed upon by both the owner and the vendors or contractors.