REGULATORY REQUIREMENTS AND PRACTICES IN STATES

2.3.1. Canada

In order to gain assurance that fuel performs safely, in other words, that it remains fit for service in normal operation and following events such as those discussed in Appendix II, the CNSC [9, 20–22] has implemented a set of regulatory checks which include a requirement for licensees to implement the following:

 A systematic fuel design and qualification process leading to the determination of the fuel acceptance criteria for normal operating conditions, DBAs and DECs without significant fuel degradation;

 A multidisciplinary programme for assessment of fuel performance;

 An annual reporting to the CNSC on fuel monitoring and inspection results which include, among other things, information regarding significant deviations from the fuel acceptance criteria for normal operating conditions and proposed corrective actions;

 Quarterly report on safety performance indicators [20];

 Event reports and notifications;

 A submission, for regulatory review, of fitness-for-service assessment after certain slow events (see Appendix II).

In Canada, fuel acceptance criteria for operational states and accident conditions are part of the licensees licensing basis. They are proposed by the designer or licensee, and subject to detailed regulatory review. Requirements and guidance regarding these criteria are provided in the CNSC regulatory documents REGDOC-2.4.1 [8] and REGDOC-2.5.2 [9].

2.3.2. China

In China, fuel design is required to comply with the safety legislation HAF 102 [23]. Section 4.2 of HAF 102 establishes requirements for fuel element design, which are described below:

“The design of fuel elements shall be such that they satisfactorily withstand the intended irradiation in the reactor core after deterioration processes.

Fuel element design shall consider following deterioration factors: external pressure of coolant, additional internal pressure due to fission product within fuel element, irradiation effect of fuel and other materials in fuel assembly, pressure and temperature change induced by power change, chemical effect, static load, dynamic load by flow induced vibration and mechanics vibration, heat transfer behaviour change induced by deformation and chemical effect. Margins shall be taken account for uncertain factors of data, calculation, and fabrication.

Fuel design limit including permitted fission product release rate shall not be exceeded in normal operation, AOO transient shall not lead to significant deterioration of fuel element, fission product release shall be kept to a minimum. Design of fuel assembly shall provide convenience for inspection of fuel structure and component. During accident condition, fuel element shall remain in position, the deformation shall not reach the extent that would prevent sufficient post-accident core cooling, and specified limits shall not be exceeded.”

2.3.3. India

In India, fuel acceptance criteria for normal operation, AOOs and accident conditions are part of the licensing basis. They are proposed by the licensee, and subject to detailed regulatory review. Requirements and guidance regarding these criteria are provided in the AERB regulatory documents, for example the AERB Safety Guide on Fuel Design for Pressurized Heavy Water Reactors, AERB/SG/NPP-PHWR/D-6 (under revision) [24].

The design of fuel elements and bundles is required to be such that they satisfactorily withstand the intended irradiation and environmental exposure in the reactor core despite all processes of deterioration that can occur under all operational states.

The design of fuel bundles needs to consider their post-irradiation handling and storage including those damaged during usage or handling.

Specified fuel design limits are not allowed to be exceeded in normal operation, and conditions that may be transiently imposed on fuel bundle during anticipated operational occurrences are not allowed to cause significant additional deterioration. Fission product leakage needs to be restricted by design limits and kept to a minimum.

Design is required to ensure for timely detection and removal of any failed fuel from the core during nuclear power plant operation. In design basis accidents, the fuel bundles need to remain in position and not to suffer distortion to an extent that would render post-accident core cooling ineffective; and specified fuel integrity limits are not allowed to be exceeded.

The aforementioned requirements for reactor and fuel element design shall also be maintained in the event of changes in fuel management strategy or operational conditions during the plant life.

2.3.4. Korea

Korean regulation requires that a quality assurance programme needs to be established to guarantee the performance of the fuel during normal operation, anticipated operational transients and accident conditions. This quality assurance programme needs to cover design, manufacturing, transportation and storage of the fuel.

The “Regulations on Technical Standards for Nuclear Reactor Facilities” also state that

“Specified Acceptable Fuel Design Limits (SAFDLs)” are defined, and they do not permit any failure of fuel rod during normal operation and AOOs.

There are no specific guidelines for the safety review of the CANDU fuel system in Korea.

Instead, the Korea Institute of Nuclear Safety (KINS) staff selectively utilize the safety review guidelines of LWR fuel system (KINS/GE-N001) and Canadian regulations.

Korean practice for CANDU fuel regulation is descriptive; the regulatory body reviews applicant’s methodologies using the relevant pressurized water reactor (PWR) fuel regulations and CANDU fuel experiences.

2.3.5. Romania

In Romania, the National Commission for Nuclear Activities Control (CNCAN) has licensed the nuclear fuel plant where the CANDU nuclear fuel bundles are manufactured, and also the research reactor where the nuclear fuel is tested to ensure that all the requirements for safe operation are met.

The regulatory framework for nuclear safety includes the nuclear safety regulations on the design and construction of nuclear power plants that established requirements for the nuclear fuel. These requirements aim to avoid failure of the fuel elements due to thermal or hydraulic causes during normal operation, during transients and in design basis accident conditions of moderate frequency.

In accordance with the regulations, nuclear fuel elements and assemblies are required to be designed to withstand satisfactorily the anticipated irradiation and environmental conditions in the reactor core in combination with all processes of deterioration that can occur in normal operation and in anticipated operational occurrences.

The fuel design analysis needs to account for all known degradation mechanisms of the fuel.

Allowance needs to be made for uncertainties in data, calculations and in manufacture.

Specified fuel design limits are not allowed to be exceeded in operational states so as to ensure that AOOs do not cause significant further deterioration.

Leakage of fission products is not allowed to exceed the design limits; furthermore, it needs to be kept to a minimum. Fuel assemblies are designed to permit inspection of their structure and component parts as appropriate after irradiation.

These design requirements need to be met even for changes in fuel management strategy or in operational states over the operating lifetime of the plant.

In Romania, nuclear fuel acceptance criteria for operational states and accident conditions are part of the licensing basis for nuclear power plants. The technical specifications and the acceptance criteria are proposed by the designer or licensee, and subject to detailed regulatory review and acceptance. CNCAN also approves the quality assurance plans and inspection and test plans for the manufacturing of the nuclear fuel.

3. REVIEW OF FUEL ACCEPTANCE CRITERIA FOR OPERATING