Pre-operational tests

Considerable experimental and theoretical knowledge on various aspects of LMFR design construction, pre-operation testing and operation has been collected by several Member States with fast reactor programmes over the past decades. 

After the installation of the system, the whole system was tested to prove the installation integrity. This covered test items as same as the factory tests. In the pre-operation test, the system experienced more than 10 initiation against the transients such as load rejection at 20%, 50%, 75% and 100% power, LOPA at 20% power, plant trip at 50% power and Main Steam Isolation Valve Closure at 100% etc.. 

During the pre-operational tests of the reactor no vibration measurements were performed on the reactor internals as, at that time, the problem of the internal fatigue failures inside the vessel had not yet become the serious safety problem which in subsequent years it was to become. 

In the pre-operational tests, components and systems are tested. Integrated tests of several interacting systems are performed too. Therefore, the functional consistency of the systems to the design is verified, as well as the absence of vibrations, normal operation in general and the normal expansion and contraction of systems while they heat up and cool down, etc. 

It is very desirable that operating personnel directly take part in the pre-operational tests, together with the representatives of the contractors, in order to get used to the plant components. 

It is not usually considered necessary that the pre-operational tests programme is explicitly approved by the safety control body, but its contents, time schedule and results are, however, timely communicated to it. On the other hand, the nuclear tests programme must have prior approval because it must fully demonstration the safety characteristics of the plant and because, whilst it is being carried out, the risk of accidents involving radioactive products starts. 

On the basis of practical experience, at least nine months are necessary for the pre-operational tests and at least three months for the nuclear tests. Causes, sometimes trivial, of delay may always intervene, thus extending the time required. Often a great deal of time is lost because of defective pipe support anchorages, pipe vibrations and fluid leakages from systems and from buildings. 

Initial startup testing procedures have been prepared and implemented to demonstrate that structures, systems, and components (SSCs) and processes will perform as intended. Initial testing includes, as appropriate, bench tests and proof tests prior to installation, mockup tests, pre-operational tests, post-maintenance tests, post-modification tests, and operational startup tests. Safety-related items are subject to the quality-assurance requirements of SNL/NM Research Reactor and Experimental Programs (RREP) Quality Assurance Program Plan (SNL 1998a), as implemented by the facility Project/Experiment Quality Plan (PEQP). Testing inciudes those initial tests mandated by applicable Technical Safety Requirement (TSR) surveiilance requirements (see Chapter 5.0, "Derivation of Technical Safety Requirements") and Operational Readiness Review (ORR) requirements (see DOE O 425.1 and DOE-STD-3006-93). 

During pre-operational testing of the Reactor Coolant System, the support displacements will be monitored for concurrence with calculated displacements and/or clearances. Subsequent inspections of supports which are integral with Reactor Coolant System components will be in accordance with Section XI of the ASME Code. 

Component Cooling, and Service Water fluid systems shall, in order to assure that the system safety functions can be accomplished, be designed to withstand the adverse dynamic loads imposed by condensation-induced and other water hammer events, and include features to minimize the probability of water hammer occurrences. BTP ASB 10-2 requires pre-operational tests to be performed on the feedwater system to demonstrate the effectiveness of the design and operating procedures to inhibit steam generator water hammer. 

In summary, the design, manufacture, pre-operational testing, and in-service testing of the boundary valves used in the interface between safety-related HP and LP systems is controlled in accordance with the ASME Code and, thus, satisfies the intent of SRP Section 3.9.6, Revision 2. Therefore, this issue is resolved for the System 80+ Standard Design. 

Pre-operational testing for operability is performed on the CSS and is described in CESSAR-DC Section 14.2.12.1.40. In addition, limiting conditions for operation (LCOs) for the CSS are... 

The prototype reactor MONJU of 280 MW(e) power was stopped temporarily due to a leak in the non-radioactive secondary heat transport system, that occurred in December 1995 during the 40% power pre-operational testing phase. 

In April 1996 the first part of the next license (safe enclosure establishment and pre operational tests) was granted (see also TAB. I) concerning mainly the erection of the new ventilation and the exhaust air measuring system. That work was finished on schedule in September 1996. 

In Japan, valves are manufactured under a strict quality control system to minimize the manufacturing errors. In case of manufacturing error exists, steam tests and nitrogen gas tests are conducted in a pre-operational test to confirm the set pressure. Nitrogen gas test is conducted in a periodical inspection to confirm that the shift of the set pressure is within the allowable limit. 

IEEE 415, 1976, "Planning of pre-operational testing programs for class IE power systems for nuclear power generating stations. ... 

The conditions which are not able to be tested during operation are tested during the pre-operational test. Under the safety rule by the individual utilities, maintenance standards of ESF, RPS and Emergency Cooling System have been established. In case that any non-conformity to the standard is recognized by a surveillance, the plant will be forced to shut down depending on its significance. 

Following construction and installation testing, pre-operational commissioning is performed to demonstrate that equipment and systems perform in accordance with design criteria so that initial fuel loading, initial criticality and subsequent power operation can be safely undertaken. Pre-operational tests at elevated pressure and temperature are referred to as hot functional tests. 

The general objectives of the pre-operational test programme are the following ... 

Plant equipment used in the performance of pre-operational tests is operated in accordance with appropriate operating procedures. This gives the plant operating staff an opportunity to gain experience in using these procedures and to demonstrate tiiat the operator has Suitably Qualified and Experienced Persons (SQEPs) to opoate the fedlity prior to the initial aiticality. 

The start-up commissioning begins with iititial fuel loading after the pre-operational testing has been successfully completed. 

Pre-operational testing is performed as system and equipment availability allows. The interdependence of systems is also considered. Sequencing of the start-up tests depends on specified power and flow conditions and intersystem prerequisites. The start-up test schedule establishes that, prior to core load, the test requirements are met for those plant stmctures, systems and components that are relied upon to prevent, limit or mitigate the consequences of postulated accidents. Commissioning is sequenced so that the safety of the plant is not dependent on untested systems, components or features. 

Test abstracts for the pre-operational testing are described in detail in Section 14.2.9 of the EDCD (Reference lO.S.These are test summaries, some of which only apply to the first APIOOO tests, which describe the purpose of the test, the prerequisites, methodology and aceeptanee eriteria. 

EXPERIENCE IN CONSTRUCTION AND PRE-OPERATIONAL TESTING OF THE PROTOTYPE LMFRs... 

---