IEEE SC-2 International Standard Review KTA 3500 versus IEEE 323-2003

Historical Use of Standard The history of the KTA standards development begins in 1973. At this time (end of 2003), the program of the KTA contains 102 defined safety standards, 91 of them are issued standards, 2 draft standards and 9 draft standards are in preparation; 22 standards are in the revision process, for 6 of them a revision draft standard is already published. KTA standards are primarily considered to set the requirements and to prescribe the procedures/instructions how to achieve a certain level of nuclear safety with respect to the ALARA principle from a „systemic“ point of view . Practically, KTA standards shall be understood as a code for formal as well as for technical activities how to reach the prescribed level of safety. In this respect a similarity can be found between NRC Regulatory Guides and KTA standards, which go however more deep. KTA safety standards are organized to a nineteen (19) topical group. KTA Standard Group 3500 is devoted to „Instrumentations and Reactor Protection“. KTA 3503 and 3505 address mater of the equipment verification of adequacy for using in NPP that licensed in Germany.

Historical Use of Standard (contd.) Program KTA 2000 - In 1998, the KTA initiated the program KTA 2000. The KTA-regulations shall be supplemented to a regulation pyramid, to get a hierarchical structure for the requirements of the nuclear safety standards. After the KTA comments trial, the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety issued a statement that is considered the project failed. Due to that the presidency of the KTA decided to suspend the project as of November 2003. At this time, part standards of KTA Standard Group 3500 are issued in next revision, especially KTA 3505 in August and KTA 3503 in October.

Comparison to IEEE 323 Scope of Standard Principles of Qualification Qualification Methods Qualification Program Documentation

Scope of Standard The term Environmental Qualification, virtually Equipment Qualification, in KTA standards is not explicitly used. The qualification process, as known in U.S. practice, is implemented via KTA standards using a large variety of procedures for design, construction, installation, maintenance, testing, etc. In this respect, it is difficult to select one appropriate clear and equivalent KTA standard because IEEE 323 is the generic standard for electrical safety-related equipment covering generally e.g. sensors, transmitters, cabinets, and other specific electrical equipment as electric motors, actuators, etc. (having their own specific IEEE Stds). As the most appropriate KTA standards of the group 3500 standard for comparison can be selected, especially 3501, 3503 and 3505. This triplet is reasonable consider for comparison as one complex. The KTA 3501 standard is the superior to the daughter standards 3503 and 3505. KTA Standard 3501 - Reactor Protection System and Monitoring Equipment of the Safety System KTA Standard 3503 - Type Testing of Electrical Modules for the Reactor Protection System KTA Standard 3505 - Type Testing of Measuring Transmitters and Transducers of the Reactor Protection System

Scope of Standard (contd.) This triplet of KTA standards describes the nuclear safety technology concept of the reactor protection system and monitoring equipment of the safety system. The concept is based on requirements for design, manufacturing, installation, operating, testing, etc., and, on the proper documentation of these activities. The daughter KTA standards – 3503 and 3505 – deal with type testing of the I&C equipment and comprise the requirements including the principles, procedures and methods of tests and equipment performance verification. KTA 3503 standard is intended for equipment installed in mild environment service conditions, while KTA 3505 standard is intended for equipment installed in harsh environment service conditions.

Principles of Qualification KTA 3501 standard discerns between two approaches: equipment operated for some time with certain operational experience newly developed or modified equipment In first, the verification based on the equipment’s operational experience is allowed and, for special cases this verification can be complemented with type tests or analyses. In second, the verification of equipment for service can be realized only by means of type proving theoretically and practically.

Qualification Methods As methods of qualification (verification for operation) KTA standards allow type testing, operating experience, analyses, and combined methods (analogically like IEEE 323). However, these methods are strictly prescribed in KTA 3503 and 3505.

Qualification Program The qualification program is comprised in KTA standards 3503 and 3505. These standards discern two parts – the part theoretical and the part practical. For KTA 3503 the theoretical part encompasses the reliability assessment, the maximum loads analysis, the preparation of the test procedure, and the assessment of input data. The reliability assessment is to determine the reliability factor of the equipment for 10+E7 in-service hours – for operational feedback, and the character and the rate of failure by analysis. The maximum loads analysis is to determine the limit parameters (static and dynamic) for equipment and its electrical interfaces. As for preparation of the test procedure, it must be prescribed the sort of type tests, the testing device, and the mode of execution (the steps and their sequence). The assessment of input data serves to verify the data completeness and applicability.

Qualification Program (cont’d) The practical part encompasses the functional tests, the mild-environment tests, the mechanical resistance tests, the electrical characteristics tests. The functional tests consist of e.g. the signal response, adjustable range, hysteresis, performance characteristic of the logical function etc. The mild-environment tests simulate the conditions during transport, storage and operation. These tests include cyclic changes of temperature and of humidity, long-term constant temperature and humidity, and the test with rapid change of temperature. Mechanical resistance tests include vibration resistance within the frequency ranges from 5 to 35 Hz and from 5 to 100 Hz, and the shock test. The electrical characteristics tests include basic electrical tests.

Qualification Program (cont’d) KTA 3505 prescribes the same tests as the KTA 3503 and add the radiation test (for normal operation conditions) and the accidental conditions test. The accidental conditions test include temperature ageing, radiation ageing, the test according to thermodynamic curves (temperature, pressure and humidity), the accidental radiation dose test, the spray medium test (boric acid solution). Both KTA standards, 3503 and 3505, prescribe the test sequence.

Documentation For each test a report must be performed containing following information: number of the test report equipment type and description including condition changes equipment identification tested equipment manufacturer identification of the test specification steps of the test with the test parameters, e.g. test room temperature, power supply, humidity test assembly, measuring instrument, testing device certain number of test output data test results place and date test laboratory, names and signatures of examiners

Documentation (cont’d) The fails, obvious failures and damages met during the test must be mentioned within the test report. The data measured during the test are presented in the form of tables and these tables shall also contain required values including allowable deviations. The test results are summarized in test certificates. The test certificate must contain following information: number of the test certificate equipment type and description including condition changes list of the test documents including basic data tested equipment manufacturer test program including steps of the test with the test parameters test results place and date test laboratory, names and signatures of examiners and experts It is allowed to summarize several test certificates into one main test certificate

EMI/RFI KTA standards 3503 and 3505 contain in their practical part the section concerning the functional tests. Within this section there are listed requirements to verify the behavior of the equipment when subjected to external interferences. Among these interferences are: short-circuit strength electrical fluctuations signal noise ratio high-frequency interferences over-voltage stability backward disturbances The behavior of the equipment subjected to mentioned interferences is checked by monitoring of functional tests parameters like the signal response (etc. as mentioned above).

Microprocessor Based Review KTA standards do not include this subject but generally the approach according to KTA 3503 is applicable.

Conclusions and Recommendations IEEE 323 and KTA 3500 have a similar philosophy KTA 3500 are more detailed and suited to purpose of the German designed NPP KTA Standards 3503 a 3505 for EQ is less versatile as IEEE 323 and some approaches can be considered as a more conservative (e.g. seismic testing)