ML20141J503

From kanterella
Jump to navigation Jump to search
Forwards Addl Info on Spds,In Response to NRC 860211 Request.Measures Taken to Protect Safety Sys from Electrical Interference Include Cable Separation & Signal Isolation
ML20141J503
Person / Time
Site: Maine Yankee
Issue date: 04/18/1986
From: Whittier G
Maine Yankee
To: Thadani A
Office of Nuclear Reactor Regulation
References
7468L-SDE, GDW-86-98, MN-86-57, NUDOCS 8604280156
Download: ML20141J503 (11)
v • d • e


Text

. _.

MAIRE HARHEE ATOMMPOWER00MPARUe ,uavgr,Q: gy,'s h (207) 623-3521 ve April 18, 1986 HN-86-57 GDH-86-98 Director of Nuclear Reactor Regulation United States Nuclear Regulatory Commission Washington, D. C. 20555 Attention: Mr. Ashok C. Thadani, Director PHR Project Directorate #8 Division of Licensing

References:

(a) License No. DPR-36 (Docket No. 50-309)

(b) USNRC Letter to MYAPCo dated February 11, 1986

Subject:

Additional Information on 5PDS Gentlemen:

Attachment A provides our response to the requests for additional information contained in your letter, Reference (b).

For completeness, we have duplicated your specific requests for information concerning isolation devices used in our SPDS design and have provided our response after each one.

Please contact us if you have any additional questions.

Very truly yours, MAINE YANKEE ATOMIC POWER COMPANY 0}b AV G. D. Whittier, Manager Nuclear Engineering and Licensing GDH/bjp

Enclosure:

Attachment A (10 Pages) cc: Dr. Thomas E. Murley Mr. Pat Sears Mr. Cornelius F. Holden 7468L-SDE 8604280156 860418 bb Ii PDR ADOCK 05000309 p PDR r

,(

MAINE YANKEE ATOMIC POWER COMPANY l

Attachment A l MN-86-57 ,

1(a) MRC Reauest For the type of device used to accomplish electrical isolation, describe the specific testing performed to demonstrate that the device is acceptable for its application (s). This description should include elementary diagrams when necessary to indicate the test configuration and how the maximum credible faults were applied to the devices.

1(b) Response Determination of acceptability for use of the Energy, Inc., isolation devices in the Maine Yankee SPDS was performed by. test and analysis.

Aging qualification was done by analysis. Seismic qualification and Surge Withstand Capability (SNC) qualification were performed by actual testing. Item 5 below discusses seismic and environmental qualifications.

Testing for S'HC involved three test configurations:

(1) Transverse mode SHC test, (2) Common mode SHC test, and (3) SHC functional test.

Enclosed Figures 1, 2, and 3 of Attachment A show the actual test configurations for the digital isolation devices. The test signal characteristics are noted below:

Peak Voltage: 2.5 kV.

Frequency: 1.0 to 1.5 MHz (no adjustment)

Haveshape: First half of cycle to be full peak voltage, then -

envelope decays to 501 of the crest value of the first peak in not less than six seconds from tne start of the wave (no adjustment).

Repetition: The test wave shall be applied to the test specimen 60 times per second for two seconds.

Source Impedance: 150 ohms.

The tested digital isolation devices passed the SHC testing.

Pass / fail criteria are defined in Item 4 below.

The enclosed Figures 4, 5, and 6 of Attachment A show the actual test configurations for the analog isolation devices. Test signal characteristics were identical to those used for testing the digital isolation devices.

The tested analog isolation devices passed the SHC testing.

Pass / fail criteria are defined in Item 4 below.

7468L-SDE

..- . MAINE YANKEE ATOMIC POWER COMPANY 2(a) NRC Reauest

[ Provide] data to verify that the maximum credible faults applied -

during the test were the maximum voltage / current to which the device could be exposed, and define how the maximum voltage / current was ..

determined, 2(b) Resoonse The maximum credible fault to which the isolation devices could be exposed was determined by reviewing the signal input portion of the plant computer (MODCOMP Model M0DACS III). Based on that review, it was determined that the maximum credible fault was 20 volts. Item 1, above, notes the actual test signal characteristics.

3(a) NRC Reauest

[ Provide] data to verify that the maximum credible fruit was applied to the output of the device in the transverse mode (between signal and return) and other faults were considered (i.e., open and short circuits).

3(b) Resoonse As shown in the Figures 1 and 4 test configurations, the maximum voltage of 2,500 volts was applied to the output of the isolation card in the transverse mode. In addition, a " failure modes and effects" analysis was performed by the vendor which included faults such as open circuits, short circuits, loss of voltage, loss of filter, and grounds. For an input-to-output short of the isolation device (and the resultant loss of IE function), the MTBF was calculated by the vendor to be 3.06 x 106 hours0.00123 days <br />0.0294 hours <br />1.752645e-4 weeks <br />4.0333e-5 months <br /> for analog isolation devices and 7.30 x 105 hours0.00122 days <br />0.0292 hours <br />1.736111e-4 weeks <br />3.99525e-5 months <br /> for digital isolation devices.

4(a) NRC Reauest Define the pass / fail acceptance criteria for each type of device.

4(b) Resoonse A functional test was performed on each isolation card after the SHC qualification test was performed.

For the analog isolation cards, failure of the functional test was defined as:

(i) "Zero" and/or " Gain" adjustments cannot be made to bring the amplifier output within tolerances, and (ii) After application of SHC voltage, the amplifier output fails to return to within 1% of pre-SHC voltage application values.

7468L-SDE

, , MAINE YANKEC ATOMIC POWER COMPANY For the digital isolation cards, failure of the functional test was defined as:

(iii) Test power supply output voltage less than six volts.

.(iv) Test power supply output voltage greater than 45 volts.

(v) Output voltmeter reading less than 3.9 volts.

5(a) NRC Reauest Provide a commitment that the isolation devices comply with the environment qualifications (10CFR50.49) and with the seismic qualifications which were the basis for plant licensing.

5(b) Response The isolation devices installed at Maine Yankee for the SPDS are located in the mild environment of the Main Control Room. Testing or analysis for environmental effects was performed by the vendor in the areas of effects due to aging and effects due to seismic events. The isolation devices will not be exposed to radiation, chemical effects, submergence, high temperature, high pressure, or high humidity under anticipated operational occurrences. An evaluation of possible synergistic effects was made by the vendor and none were identified as having a significant affect on equipment performance. Margins accounting for unquantified uncertainties were addressed by the ..

vendor as part of the pass / fail criteria for final test acceptance.

Actual testing was performed with identical equipment under similar conditions. An analysis by Maine Yankee showed that the equipment ,

qualification complies with the EQ requirements of 10CFR50.49 for this installation.

The Energy Incorporated Isolation System has been seismically qualified in accordance with the requirements of IEEE Standard 344-1975. The required response spectra used in the qualification effort greatly exceeds Maine Yankee's FSAR requirements as well as the higher 0.2g Regulatory Guide 1.60 accelerations. The cabinets were anchored, in accordance with the qualification testing requirements, to the 0.29 Regulatory Guide 1.60 accelerations, which envelope FSAR requirements.

6(a) NRC Reauest Provide a description of the measures taken to protect the safety i systems from electrical interference (i.e., electrostatic coupling,  !

EMI, common mode and crosstalk) that may be generated by the SPDS. I 7468L-SDE

. . MQIME VANKEE ATOMIC POWER COMPANY 6(b) Response Several measures were taken to protect the safety systems from electrical interference:

(i) Cable seoaration - New cable trays were installed for routing safety system cables to the isolation devices. The new - cable trays provided physical separation between .

channels, and instrument and power cables were placed in separate trays. Separation outside the trays was maintained via conduit or physical separation. This minimizes any contact between instrument cables and power cables.

(ii) Cables - Each safety system analog signal is carried via a twisted-shielded pair cable. Cable shields were connected to the insulated instrument ground bus.

(iii) Isolation - The signal isolation between Class 1E and non--Class 1E circuits also isolates safety systems from any electrical interference generated on the non-C1. ass lE portion of the systems.

7(a) NRC Reauest Provide information to verify that the Class lE isolator is powered from a Class lE power source.

7(b) Response The isolation devices for the MY SPDS are powered from non-Class IE power sources.

The isolation cards are powered on the non-Class IE side of the isolation interface. Cabinet No.1 is powered from DP/IAC and Cabinet No. 2 is powered from DP/ PAC. Each of these power sources is an interruptible, diesel generator-backed power supply. Interruption of the power to the isolation device does not affect the performance of the associated Class IE instrument loop. Use of a diesel generator backed power supply ensures that information for the SPDS will be available post-accident. ..

7468L-SDE

w

. .. . m 9

O LON MON.C SWC. T ESTEE.

O filGH SY N C.O ,

i 1

g- _ _ _ _ _ _ _ _ _ _ _ _ q g 1%OLATOR CAR D +15 ,

>> t 15V I I T POWER I - SUffLT 6 1 >>

,, I + a l "l TEST l SCOPE SYNCC llNPUT OUTPUT l >

C HA NNEL I I n Ql_ ,l-l :s e OCH.T C H.I C L____________J l i l DIGITAL ISOLATION DEVICE 

                     *lTPICAL CIIANNEL TEST CONFIGURATION                    MYP 86-252 FOR TRANSVERSE HODE SWC TEST Enclosure A Figure 1 of 6            .

i d 

                                                                                                 ,    .. , e 4

O HIGH Ff0N.O , SWC TESTER 

                      -O LOW                  SYNCC r-----------

l MLATOR CARD cz;; ;; ci l 15v g POWER l 

                                                      +15       ,     + s u r e t. Y I                               -

1 >>0 . g l+ l y I I TEST SCOPE 3YNC G llNPUT OUTPUT l , CHANNEL ' 

             %l_

i + i >> oIi o cn z cou o L____________J I l DIGITAL ISOLATION DEVICE TYPICAL CllANNEL TEST CONFIGURATION FOR C0tMON HODE SWC TEST MYP 86-252 Enclosure A Figure 2 of 6

1 1 i p___________q , g i SOL ATOR CAED 4l5 }} 4 ISV POWEC T f _ suppty 6i, TE3 T Y TEST >> POWER l lN PUT OUTruT l CHANNEL VOLTMETEK SUPPLY al w I s g- - , L___________J - 1 I 

           -                          DIGITAL ISOLATION DEVICE MYP 86-252 TYPICAI. TEST CIIANNEL C0NFICURATION             Enclosure A igure 3 of 6
 ;                                     FOR SWC FUNCTIONAI. TEST 5

O LOW MON.C 1 SWC. TESTEE O HIGH SY N C.C 1 1 

      ---__________q j

i' l lSOLATOR CAR D +15 . i >> + 15V

1 I T POWEE
                                                            - SurrLT I

6 I >> I+ i gl TEST " I l >>- l ' llNPUT OUTPUT l SCOPE S1NCC C H A NNEL ') Cl_ g .g_ l rs 

                                                 , >> :,;    OCH7-     CH.I C

. L _ _. _ _ _ _ _ _ _ _ _ _ _i j l i j l i ANALOG .o0LATION DEVICE I TYPICAL CHANNEL TEST CONFIGURATION E A , FOR TRANSVERSE HODE SWC TEST Figure 4 of 6 .

d 

                                                                                                                          .. t O HIGH            MON.C                                                      .

SWC TESTER 

                                       -O LOW             SYNCC i

r----------- , psy C2;; ;; Cl l I 3OLATOR CAED >/ - g POWER l 

                                                                   +15                  + s u r et. Y g

I >>s 

                          -3+

n 

                                                                      -   I I,>

s , I TEST SCDP OYNC O l INPUT O lsT P U Tl , I CHANNEL l n 

                          /s
                                                                      + , >> \ j         O cis.2        CILI C "g-l                             L____________J i

ANALOG ISOLATION DEVICE TYPICAL CilANNEL TEST CONFIGURATION MYP 86-252 Enclosure A FOR COtHON HODE SWC TEST Figure 5 of 6 1

g___________q , g I SOL ATOR CARD -l85 }} 4 ISV POWEC . l T 6i,f _ gyppty l TE3 T S TEST >> ' POWER llNpus T OUTVUT l ' cesANNE L VOLTMETEK SUPPLY a I lw w, _ _ g- - l_ _. _ _ _ _ __ _. _ _ _ _ _J - I ANALOG ISOLATION DEVICE TYPICAL TEST CIIANNEL CONFICURATION 8 22 j FOR SWC FUNCTIONAI. TEST Figure 6 of 6 

                                                                                  .}}
Retrieved from "https://kanterella.com/w/index.php?title=ML20141J503&oldid=2855505"