Review of Regulatory Requirements for Implementing an Aging Management System for the IPR-R1 Triga Reactor of CDTN

CDTN ( Centro de Desenvolvimento da Tecnologia Nuclear ) owns an IPR-R1 Triga research reactor (Training, Research, Isotopes, General Atomics) that has been in operation for over 60 years. One of the issues that comes up by this operating time is aging management. Aging management includes the functions and issues involved with management, maintenance, operation, inspections, operational testing, design changes, structural calculations, and others. Management of aging of structure, system and equipment must be implemented proactively throughout the life of a research reactor. According to the CNEN standard NE 1.04, in the absence of national standards, the documents of the International Atomic Energy Agency (IAEA) or the country that is the designer must be used. The use of the IAEA standards is beneficial for many reasons, including the global base and years of experience and the variety of documents related to the aging management of nuclear research reactors. However, this reactor is an American project, so the requirements of Nuclear Regulatory Commission (NRC) are also applicable. This article will discuss the IAEA and NRC requirements to implement an aging management system for the CDTN


INTRODUCTION
CDTN owns the Triga IPR-R1 research reactor (Training, Research, Isotopes, Atomics), which was acquired from General Atomics of San Diego -General by the government of the State of Minas Gerais in 1960.Its first criticality occurred in 1960 with a maximum thermal power of 30 kW.In the 7 years, chemical elements were complemented to the core increasing the power to 100 kW.In 2004 the configuration of the core and instrument was changed; more abundant elements were added and a power of 250 kW was reached.The new configuration was maintained, but the reactor only operates at a maximum power of 100 kW.Therefore, this reactor has been operating for more than 30 years.One of the issues that comes to the fore at the time of the operation is the management of aging.This includes functions and issues related to, operation, inspections, operational management, design changes, testing, and others.[1] According to the CNEN NE 1.04 [2] standard, in the absence of national standards, documents from the International Atomic Energy Agency or the country that is the designer must be used.The use of IAEA standards is beneficial for many reasons, including a global base and years of experience and a variety of related to nuclear reactor aging management.[3] The aging management must be proactively implemented throughout the life of a research reactor.[4] This applies to renovation and modernization projects.Practice, the aging program carried out by program programming, constant and integrated, such as the application of good operational practices and the maintenance of maintenance management with an operational experience.
Refurbishment and modernization projects should not limit a simple replacement of equipment, systems or structures.They must also seek security improvements to comply with security updates.[1] To define an aging management is important to understand the national and international regulatory requirements.Following the CNEN standards, this article will discuss the regulatory requirements of IAEA and NRC.

MATERIALS AND METHODS
This work is theoretical; therefore, it is based on a review of the normative basis regarding the aging management of research reactors in the world.This work will be according the standard CNEN NE 1.04 (Licensing of Nuclear Facilities) Section 6.5 -Codes and Technical Standards" [2]: 6.5.1 Items must be designed, manufactured, assembled, constructed, tested, tested and inspected according to technical standards compatible with the importance of the safety function to be performed.6.5.2In applying the provisions of item 6.5.1, updated Brazilian codes and standards must be adopted.In the absence of adequate Brazilian standards, Codes, Guides and Recommendations of the International Atomic Energy Agency (IAEA) should preferably be used and, in their absence, international standards or those of technically developed countries, provided that these standards and regulations are accepted by Cnen.6.5.3In exceptional cases, requirements contained in codes and standards may not be met, provided that the applicant fully demonstrates that there are design conditions that allow, without prejudice to safety, the adoption of other proposed criteria, and that this demonstration is accepted by Cnen.8.7.6 -The Permit for Permanent Operation of an installation will be granted for the term requested by the applicant or for a set term.In the case of a nuclear power plant, the term will not exceed the limit of 40 (forty) years from the date of granting of the Permit for Permanent Operation." Based on these requirements, it is possible to develop the following considerations: 1) Brazil does not have a standard for an aging management program for research reactors, so the options for the normative basis for the Triga IPR-R1 are: -International Atomic Energy Agency norms and American standards considering that the reactor is an American designer.
2) The Brazilian standard does not establish a deadline for Permit for Permanent Operation of research reactors.

RESULTS AND DISCUSSION
3.1.Based on the requirements 6.5 and 8.7.6

of CNEN NE 1.04 [2]
It is possible to develop the following considerations: (i) Brazil does not have a standard for an aging management program for research reactors, so the options for the normative basis for the IPR-R1 Triga are: -International Atomic Energy Agency norms and American standards considering that the reactor is an American designer.
(ii) The Brazilian standard does not establish a deadline for Permit for Permanent Operation of research reactors.The hierarchy of documents applicable to aging management according to the IAEA:
-IAEA Specific Safety Guide No. SSG-24, Safety in the Utilization and Modification of Research Reactors [9].

Normative basis for Aging Management according to American regulations
According to Part 50 of Title 10 of the U.S. Code of Federal Regulations [11], the following standards are applicable: -10CFR 50.34 "Applications: Technical Information" [12] It is necessary to conduct a preliminary analysis and evaluation of the design and performance of structures, systems and components of the facility in order to assess the risk to public health and safety resulting from the operation of installation and including the determination of safety margins during normal operations and anticipated transient conditions during life of the installation, and the adequacy of structures, systems and components foreseen for the prevention of accidents and the mitigation of the consequences of accidents.
-10CFR 50.36 "Technical Specifications" [13] Operational Limit Conditions (OLC) are the lowest functional capabilities or performance levels of equipment necessary for the safe operation of the facility.
Inspection requirements relate to tests, calibrations or inspections to ensure that what is necessary for the quality of systems and components is maintained, that the operation of the facility will be within safe limits, and that LOCs are met.
-10CFR 50.59, "Changes, Tests, and Experiments" [14] Change means a modification, addition or removal of facility or procedures that affect a design function, method of performing or controlling the function, or an assessment that demonstrates that the intended functions will be maintained.
A licensed nuclear facility may make changes as described in the final safety review report, procedures, and conduct tests or experiments without having to obtain a license change.
However, if it is considered a technical change, the installation must request a license change.10CFR 50.59 explains which conditions of changes are treated as a technical change and requires that all changes must be recorded and records must be maintained so that they are traceable and auditable.
-10CFR 50.90, "Application for Amendment of License, Construction Permit, or Early Site Permit" [15] Whenever the holder of a license, including a construction license and operating license under this part, wishes to change the license or license, the change request must be submitted to the NRC, fully describing the desired changes, and following to the extent that it complies.applicable, the prescribed form for original orders.
In addition to these documents, the NRC has released a document that is a guide for managing research reactor aging: -NUREG-1537, "Guidelines for Preparing and Reviewing Applications for the Licensing of Non-Power Reactors" [16]: -This document describes how to present, for the regulatory body, a License Renewal Application for Research reactor.
-The applicant must take into account the various deterioration mechanisms for the components and systems under consideration and note which mechanisms are applicable for those components and systems.
-The candidate must determine and justify acceptable levels of deterioration of the components and systems under consideration.
-The analysis must show that unacceptable levels of deterioration can not be reached during the leave period.If the analysis cannot show this, tests and measures to measure deterioration should be discussed.For components and systems that are to be tested or measured, the applicant must propose technical specifications that indicate the frequency of testing or measurement and provide performance standards for the component or system under consideration.
-The facilities maintenance program must be organized, and systematic approach considering the issue of prior use of components and systems and must be based on analysis, tests, measurements or recommendations of the manufacturer to carry out maintenance.
-The applicant must show that the components significant to the safety of the de-energized reactor will function satisfactorily during the period of the license.

CONCLUSION
Brazil does not have a standard for an aging management program for research reactors, so the options for the normative basis for the IPR-R1 Triga are international standards and documents.This work describes a review of the normative basis regarding the aging management of research reactors according to IAEA and American standards.This normative basis can be followed by CDTN for implement an aging management for IPR-R1 Triga reactor.
It will be necessary to prepare the License Renewal Application according to the document U.S.NRC [16] (NUREG-1537), and U.S.NRC [17] (10 CFR 50).CDTN needs to send this document to the regulatory body.
Management according to the IAEAAccording to IAEA (2010)SSG 10 [5], the purpose of the aging management system is to ensure that the facility meets the safety requirements derived from: -Regulatory agency requirements; -Project requirements and assumptions; -Security Analysis Report; -Operational Limit Conditions (OLC); -Administrative requirements.The aging mechanisms as defined in SSG 10 [5] are: -Radiation -changing properties; -Temperature -change of properties; -Drag due to stress / pressure; -Mechanical displacement / fatigue / vibration wear and cyclic loads; -Material deposition (eg, raw material); -Flow-induced erosion; -Corrosion; -Flood -deposition and chemical contamination; -Fire -effects of heat, smoke and reactive gases; -Obsolescence and technology change; -Change in Acceptable Requirements or Standards; -Others (time dependent phenomena).