Energi- och värmeöverföring

This document provides guidance for performing and validating the sequence of steady-state calculations leading to prediction in all types of operating commercial nuclear reactors, of the following: — reaction-rate spatial distributions; — reactivity; — change of nuclide compositions with time. The document provides the following: a) guidance for the selection of computational methods; b) criteria for verification and validation of calculation methods used by reactor core analysts; c) criteria for evaluation of accuracy and range of applicability of data and methods; d) requirements for documentation of the preceding.

The present test method uses radioactive methyl iodide (CH3131I) as a tracer to determine the in-situ decontamination factor of an iodine trap. An in-situ test allows to reach the global efficiency of the trap characterized by the sorbent efficiency but also by the implementation of the trap within the ventilation duct) while the intrinsic efficiency of a charcoal is characterized in a laboratory by ISO 18417[4] (or other national standards as ASTM D3803[6]). This document provides general and common requirements for this method to assess the efficiency of an iodine trap, but also, the tools requirements, accuracy and the provisions needed to ensure safety of the workers, public and the environment during the test. This reproductible method can support nuclear facility operators as a reference method to compare the decontamination factor evaluated by this method to reference values (e.g. safety criteria, national legislation, etc.). Because of the use of a radioactive tracer, some cautions apply. First, this method is usually used for ventilation systems with monitoring of gaseous iodine releases in environment in accordance with the national regulations. Second, this method is not used to determine the decontamination factor of iodine traps used in ventilation systems with air release in rooms with potential presence of workers (e.g. control room). A non-radioactive method is preferred. This document can apply to installations with low inventory of radioiodine equipped with iodine traps (e.g. small laboratories). In this case, some provisions can be adapted but always in accordance with the national regulations. Finally, this document mainly deals with iodine traps using impregnated activated carbon. However, this method can be used with some adaptations to other solid sorbent as inorganic sorbent (e.g. zeolite  – aluminum and silica base usually doped with silver nitrate - or impregnated catalytic supports.

ISO 16659 series provide different test methods aiming at assessing the performances of radioactive iodine traps in ventilation systems of nuclear facilities. This series deals with iodine traps with solid sorbent, mainly activated and impregnated charcoal, the most common solid sorbents used in ventilation systems of nuclear facilities, as well as other sorbents for special conditions (e.g. high temperature zeolites). ISO 16659-1 provides the general requirements to be applied for all methods of the series. The scope of this document is to provide general and generic requirements for the test method using cyclohexane (C6H12) as a tracer to determine the mechanical leakage rate of iodine trap. This reproducible method can support nuclear operators to compare the result with reference values given in safety reports. Unlike the method of radioactive methyl iodide described in ISO/DIS 16659-2, the cyclohexane field test method covered in this document does not directly give a decontamination factor for the iodine trap, but only the iodine trap performance information of an integrity test, and the interpretation of whether the performance of the iodine trap meets the requirements needs to be combined with the results of the radioiodine efficiency test of the adsorbent in the iodine trap. Due to the use of the environmentally friendly test reagent of low-toxicity in the field tests, the method is mainly suitable for ventilation systems of those habitable spaces (e.g. main control rooms of nuclear power plants), and performance test of a single iodine adsorber before its delivery and acceptance. In addition, the method can also be used for iodine traps with activated carbon sampling canister (e.g. Deep Bed Iodine Adsorber Type III and Drawer Iodine Adsorber Type II).

This document specifies the general principles and requirements for the design and performance evaluation of emergency core cooling system (ECCS) strainer of the pressurized water reactor (PWR) nuclear power plant, including the debris source walkdown, upstream analysis, the design of the sump strainer equipment, and the debris head loss test and analysis, Chemical effect test and analysis, downstream effects (in- vessel) test and analysis, and downstream effects (ex-vessel) analysis. This document is applicable to design and performance evaluation of ECCS strainer of PWR nuclear power plant. Other reactor types can be implemented by reference.