Acceptance methods are the ways utilized to verify acceptance criteria. Depending on item importance and procurement requirements, the methods may involve any or all of reviews of supplier documentation, item receipt inspection upon delivery, source inspection (factory inspections and tests), and post-installation site acceptance testing. Testing activities may involve chemical, physical, or performance tests.
3.4.2.1 Supplier documentation reviews
Supplier documentation reviews involve confirmation that the supplier has effectively implemented a management system containing elements required for the item(s) being procured.
Supplier audits with engineering involvement are typically performed to evaluate supplier processes (see Section 3.3.3). Such audits should be supplemented with other
acceptance methods where audits have not verified implementation of all areas of the supplier management system, where the supplier has had findings in certain areas that have been agreed to be corrected; or where the operating organization has information indicating that the supplier may have deficiencies in supplied items.
3.4.2.2 Source inspection
Source inspection is typical when a procured item is vital to plant safety, complex in design or manufacture, difficult or complicated to test, difficult to verify acceptance criteria upon receipt (after delivery), or when a supplier management system has not been directly observed and audited.
Source and post-installation inspections should be planned in writing, and typically involve establishment of witness and hold points for associated factory or site acceptance testing. All findings and test results should be documented.
For critical equipment being assembled far from the operating organization’s location, consideration should be given to establishing resident oversight personnel at the factory location during component fabrication.
(a) Witness and hold points
Suppliers follow a process of self-inspection where they verify quality of their work progressively under requirements of their own management system - often with the aid of checklists.
Hold points and witness points are production stages at which the customer (NPP operating organization) may need additional inspection, verification or documentation to ensure that the product meets their quality or other requirements prior to proceeding. Once these requirements have been satisfied, the next stage of production can be completed. Suppliers typically make agreements with customer organizations to provide advance notice of the timing of such points so that arrangements can be made for availability of required inspectors. Typically, such agreements also allow for access to and regular surveillance of a manufacturing facility. This allows for intermittent monitoring of any stage of the work in progress by the customer and in some cases the NPP regulator.
Verification measures will vary with the product specification method. For performance specifications, verification involves testing. For specifying by reference, verification is to a standard, or through third-party certification to that standard. Verification procedures are documented in the procurement requirements or ITP as hold points and witness points.
A hold point is a mandatory verification point beyond which a work process cannot proceed without authorization by a designated person. Hold points are usually assigned to critical aspects of the work that cannot be inspected or corrected at a later stage because they will no longer be accessible or would cost significant rework. Work cannot proceed until the designated person is able to verify quality of the completed work and releases the hold.
Hold points should be used sparingly as each potentially introduces production delays that can be caused by delays in scheduling of the required inspections.
A witness point is an identified point in the process where the designated person may review, witness, inspect or undertake tests on any component, method or process. The manufacturer is required to notify the designated person who may or may not take the opportunity to witness the specific test. If the designated person declines the opportunity to attend, the testing and any further manufacturing steps can proceed.
Where the physical presence of the designated person may not be required as part of an ITP, a review point may be established whereby a responsible entity such as a designer
should review results of a test/inspection prior to the manufacturer proceeding to the next stage of manufacturing.
(b) Factory acceptance testing (FAT)
Factory acceptance tests (FATs) are done at the factory to make sure that requirements are met. Tests are normally done in the presence of a customer designated representative, and in some cases with a third party inspection agency. FATs should be specified for products if it is possible to physically test the product at the production facility prior to shipment. Tests should be comprehensive, test both hardware and software components as an integrated unit, and should use equipment that is identical to that at the plant where practical.
It is good practice that individuals involved in future commissioning or site testing of the equipment attend FATs. This allows them to learn about the equipment at a detailed level and provide any feedback on it prior to its shipment.
FATs are typically a sub-part of the product’s ITP and thus follow a pre-approved procedure. Typical content of a FAT procedure is [67]:
• Statement of location and dates of the FAT. • Description of general approach.
• Description of method of logging errors or concerns raised during the FAT; • Specification of revision levels of hardware and software to be tested. • Specification of exact configuration of equipment being tested. • Personnel safety issues that may apply during testing;
• Specific steps and sequence of testing.
Some items typically checked during a comprehensive FAT are:
• Equipment hardware and software versions are per documented requirements; • Fabrication and installation is per approved drawings;
• Inputs and outputs are connected as per approved drawings; • Equipment calibration is correct;
• Trips, bypasses, manual shutdowns, alarms, and diagnostic functions operate per design;
• Equipment outputs, computations, timing, and operator functions behave as per design;
• Equipment response to failures (loss of air or electrical power supply etc.) is as per design.
Following the FAT test results are documented. If failures were encountered then the reasons for failure should be recorded and corrective actions taken. Applicable parts of the FAT that were affected by the failure or could have been affected by equipment changes or other remedial measures made to address the failure will then need to be repeated as necessary.
3.4.2.3 Receipt inspection
Receipt inspection is the review of received material when it is delivered into the operating organization’s care and control at its warehouse. This is an important point at which procured items can be stopped from entering the plant for use if they do not have necessary assurances that quality and technical requirements have been met.
A key aspect of receipt inspection is verifying identity of the incoming item. This ensures any assumptions made surrounding like-for-like versus equivalent or alternate item replacements are correct, links the item to corresponding procurement documents and enterprise part tracking systems (which may use part number, serial number, and/or a receiver
applied unique identification system), provides some assurance that changes or errors have not occurred with the shipment, and confirms identify of the item prior to proceeding with acceptance testing.
Standard inspections involve simple checks for shipping damage and that the received item is the item ordered and matches the delivery paperwork (item identification and quantities shipped). Such inspections are suitable for situations where the act of inspection would not adversely affect integrity, function, or cleanliness of the item, where its design is simple, and acceptance criteria are readily verified by other means. Individuals performing inspections should be aware of (and trained in identifying) possible signs of counterfeit or fraudulent items (see Section 7).
For some items more advanced receipt inspection is necessary. This may include use of special test and inspection equipment such as metal alloy analysers, hardness testers, etc. These can verify material properties that would be expensive to correct if discovered following installation. From the supplier’s perspective the process of site acceptance testing (see next section 3.4.2.4) is often considered a form of advanced receipt inspection, in that it is required to be successfully completed prior to final acceptance of the item by the operating organization.
Items that fail receipt inspection or arrive with incomplete documentation are required to be segregated from normal stock and quarantined so that they are not utilized by accident in the NPP.
3.4.2.4 Post installation testing / site acceptance testing (SAT)
Post installation or site acceptance tests (SATs) are used when it is difficult to verify acceptance criteria without the item being installed and in use. They are done at the NPP following installation, often as part of the commissioning process. The tests confirm acceptance criteria that cannot be confirmed in the factory, and can be used to validate that no damage has occurred to the items during shipping or storage.
Commissioning tests usually envelop SATs as they often are required to confirm the integrated (entire) system meets its design requirements, not just to confirm that a particular component or set of components from a supplier meet their procurement requirements. Commissioning guidance
is provided in IAEA Safety Requirements document SSR-2/2 [3], Safety Guide NS-G-2.9 [68],
and NE series guide NP-T-2.10 [69].
Some items that cannot be factory confirmed might include interfaces between the new equipment with other already installed or new plant equipment, suitability of maintenance tooling (access availability or usability), or responses to in plant disturbances.
Like FAT testing, SATs are typically a sub-part of a product’s ITP and thus should
follow a pre-approved procedure.