ML18038B245

Forwards Response to NRC 941208 RAI Re BFN Plant Surveys & Tests Completed on Digital Components of Reactor Bldg Ventilation Radiation Monitoring Equipment

ML18038B245
Person / Time
Site:	Browns Ferry
Issue date:	04/14/1995
From:	Salas P TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
TAC-M84161, TAC-M84162, TAC-M84163, NUDOCS 9504190122
Download: ML18038B245 (9)

Text

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REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR-9504190122 DOC. DATE: 95/04/14 NOTARIZED: NO FACIL:50-259 Browns Ferry Nuclear Power Station, Unit 1, Tennessee 50-260 Browns Ferry Nuclear Power Station, Unit 2, Tennessee 50-296 Browns Ferry Nuclear Power Station, Unit 3, Tennessee AUTH.NAME AUTHOR AFFILIATION SALAS,P.

Tennessee Valley Authority RECIP.NAME 'ECIPIENT AFFILIATION Document Control Branch (Document Control Desk)

SUBJECT:

Forwards response to NRC 941208 RAI re BFN plant surveys tests completed on digital components of reactor bldg ventilation radiation monitoring equipment.

DISTRIBUTION CODE D030D COPIES RECEIVED:LTRj ENCL g SIZE: 5 TITLE: TVA Facilities Routine Correspondence NOTES:

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0 RECIPIENT ID CODE/NAME PD2-3 WILLIAMS,J.

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Tennessee Valley Authority. Post Office Box 2000, Decatur, Alabama 35609 April 14, 1995 U.S. Nuclear Regulatory Commission ATTN:

Document Control Desk Washington, D.C.

20555 Gentlemen:

In the Matter Of Tennessee Valley Authority Docket Nos.

50-259 50-260 50-296 BROWNS FERRY NUCLEAR PLANT (BFN)

RESPONSE

TO NRC REQUEST FOR ADDITZONAL INFORMATZON (RAZ) REGARDING UPGRADED REACTOR BUILDING VENTZLATION RADIATZON MONITORING (RBVRM) EQU1PMENT (TAC NOS.

M84161I M84162~

AND M84163)

The purpose of this letter is to provide TVA's reply to NRC's RAI, dated December 8,

1994, regarding the upgraded RBVRM equipment installed at BFN.

The questions in the RAI concerned the BFN plant surveys and tests completed on the digital components of the reactor building ventilation radiation monitoring equipment.

The surveys and testing were conducted to demonstrate the capability of the upgraded RBVRM equipment to withstand the expected spectrum of electromagnetic and radio frequency interference.

The enclosure provides the information requested in the NRC letter.

TVA provided the references listed in the response during previous submittals concerning the BFN RBVRM equipment.

There are no commitments contained in this letter. If you have any questions, please telephone me at (205) 729-2636.

Sincerely, o Salas Manager of Site Licensing Enclosure cc:

See page 2

i 86164

'sr5041sr0122 tst50414 PDR ADOCK 05000259 P

PDR

U.S. Nuclear Regulatory Commission Page 2

April.14, 1995 Enclosure cc (Enclosure):

Mr. Mark S. Lesser, Acting Branch Chief U.S. Nuclear Regulatory Commission Region II 101 Marietta Stre'et, NW, Suite 2900 Atlanta, Georgia 30323 NRC Resident Inspector Browns Ferry Nuclear Plant Route 12, Box 637

Athens, Alabama 35611 Mr. Z. F. Williams, Project Manager U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852

ENCLOSURE TENNESSEE VALLEY AUTHORZTY BROWNS FERRY NUCLEAR PLANT (BFN)

UNITS 1p 2~

AND 3

RESPONSE

TO NRC REQUEST FOR ADDZTZONAL INFORMATION (RAI)

REGARDING UPGRADED REACTOR BUILDING VENTILATIONRADIATION MONITORING EQUIPMENT (TAC NOS M84161g M84162~

AND M84163)

PURPOSE P

The purpose of this enclosure is to provide TVA's response to NRC's RAI dated December 8,

1994.

The following is a restatement of the requested information followed by TVA's response.

NRC Question Number 1

Explain why margins found in the tests are sufficient to assure that the system would not be affected by electromagnetic interference.

Include why measured margins are large enough to include measuring instrumentation accuracy and the short data measurement period.

'U TVA's Response Question Number 1

National Technical Systems (NTS) verified the margins specified in NTS test 31370-94M (Reference

1) between the Reactor Building Ventilation Radiation Monitoring (RBVRM) equipment susceptibility testing and the measured environment.

The. difference was a

minimum of 21 decibels (dB), which was a factor of approximately 11 (i.e., test levels are approximately ll times greater than the measured environment) for Conducted Emissions/

Conducted Susceptibility.

Further, NTS verified a minimum of 10 dB of margin between plant environment and test levels (a factor of approximately

3) for Radiated Emissions/Radiated Susceptibility.

These margins exceed the 6 dB safety margin that is specified in Reference 2.

Susceptibility testing on the Nuclear Measurement Analysis and Control (NUMAC) RBVRM was performed in accordance with Military Standard (Mil-Std.) 461D/462D and International Electrotechnical Commission (IEC) 801-series requirements.

The test equipment accuracy requirements specified in Reference 3 are in accordance with those specified in Mil-Std. 462D, and are as follows:

Distance+5

%Frequency

+2 Amplitude, Receiver+2 dBAmplitude, System+3 dB Time+5 4

C

J The on-site Electromagnetic Interference (EMI) mapping performed by NTS at BFN (Reference 4) was performed in accordance with Mil-Std.

461C/462, and utilized test equipment with accuracies similar to those given above.

Assuming that these test equipment inaccuracies are both random and independent, the combined inaccuracy would be 4.24 dB using the square root-sum-of-the-squares method as stated below:

~3dB~+3 dB~~4

~ 24 dB This measurement is 5.76 dB less than the minimum measured margin of 10 dB (a factor of approximately 2).

The BFN mapping data was obtained over a period of four weeks, with several days of mapping performed on the refuel floor during refueling operations (as requested by NRC).

Additionally, BFN completed several days of mapping in the main control room during reactor startup from the Unit 2, Cycle 7 outage.

The data obtained at these different locations during different plant conditions (Unit 2 refueling and startup) are similar.

Based on accepted industry and military practices, the extended data gathering period, and the preceding discussion, the test level versus mapped level margins are adequate.

NRC Question Number 2

Explain why the Browns Ferry Nuclear Plant configuration was tested only to the International Electrotechnical Commission (IEC) standard 801-5, Level 2, justifying why Level 2 testing is sufficient for Browns Ferry.

TVA's Response Question Number 2

BFN cabling and raceways are segregated according to voltage and/or current levels, which reduces the potential for and severity of induced voltages due to cable interactions.

A comparison of the BFN mapping data and the IEC 801-5, Level 2, testing (Reference 1) shows there is a minimum of 51 dB margin between the susceptibility laboratory test data and the BFN mapping data.

Additionally, the NUMAC RBVRMs installed at BFN have over 18 months operating experience without having experienced any surge related failures.

Further, the NUMAC RBVRM was tested for Surge Withstand Capability by the application of a 2500V peak-peak 1.25 Mhz signal to the power leads'NEDE-32026).

Based on the identified margin, lack of surge related failures, and additional diverse testing, TVA considers that the NUMAC surge withstand testing is adequate.

E-2

NRC Question Number 3

Explain why IEC 801-4 susceptibility signal spectra (Level 4),

which is a fast transients/bursts test, is compared with Mil-Std.

461D CE101 (a low frequency noise emission test) and Mil-Std.

CE103 (testing for emission noise between 10 Khz and 10 Mhz).

TVA's Response Question Number 3

The IEC 801-4 Electrical Fast Transient test is run in the time domain; which references all numbers as a function of time.

This time domain susceptibility signal was converted to the frequency domain by means of an inverse Fourier transform.

This converted

data, which begins at 10 Hz and extends beyond 100 Mhz, is directly comparable to the frequency domain CE101 and CE103 mapping data.

NRC Question Number 4

Explain why IEC 801-4 and Mil-Std. CS114 bulk cable injection test (which injects noise signals between 10 Khz and 400 Mhz) are compared.

TVA's Response Question Number 4

TVA compared the IEC 801-4 and CS114 tests to determine if the testing performed by General Electric (GE)

(IEC 801-4) sufficiently bound the requirements of Mil-Std. 4613D, and CS114 Curve 5.

TVA determined that the GE testing sufficiently bounds the requirements of Mil Std.

461D and CS114 Curve 5.

Accordingly, TVA concluded that performance of CS114 testing was unnecessary.

REFERENCES 1 ~

2 ~

3

~

4 ~

National Technical Systems (NTS) Test Report Number 31370-94M, Test Report for Analysis of Min Control Room Mapping Data and GE/C&C NUMAC Laboratory EMI Test Data for Tennessee Valley Authority Browns Ferry Nuclear Plant.

Electric Power Research Institute (EPRI) Guidelines for Electromagnetic Interference Testing in Power Plants, EPRI TR-102323, Final Report dated September 1994.

C&C Laboratory, Electromagnetic Compatibility Test Report (MS3I-001F.TR) on RBVRM, Part Number:

304A37148G001; Serial Number:

093091-EP-1 for GE Nuclear Energy, General Electric Company dated September 1993.

National Technical System (NTS) Test Report Number 60254.04-94N-1, Test Report for Point of Installation Electromagnetic interference (EMI) Mapping of Control Room and Refuel Floor, Browns Ferry Station, Units 1, 2, and 3 for Tennessee Valley Authority, Browns Ferry Nuclear Plant.

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