ML19309E781

Advises That 800416 Commitment to Perform Tests to Show Various Single Power Failures for NNI-X & NNI-Y Cabinets Have Been Changed.Per Conversations W/G Vissing,Test Will Be Performed Involving 120 Vac Transfer Switch Power Loss

ML19309E781
Person / Time
Site:	Arkansas Nuclear
Issue date:	04/18/1980
From:	Rueter D ARKANSAS POWER & LIGHT CO.
To:	Reid R Office of Nuclear Reactor Regulation
References
1-040-13, 1-40-13, NUDOCS 8004240380
Download: ML19309E781 (4)

Text

i H EL PIN G BUILO ARKANSAS A RK ANS AS POWER & LIGHT COMPANY P O BOX 551 UTTLE ROCK. ARKANSAS 72203 *[501'371-4191 J

April 18,1980 DONALO A. RUETER DIRECTOR TECHNICAL AND ENV RCNMENTAL SERVICES 1-040-13 Director of Nuclear Reactor Regulation ATTN: Mr. R. W. Reid, Chief Division of Operating Reactors Branch #4 U. S. Nuclear Regulatory Commission '

Washington, D. C. 20555

Subject:

Arkansas Nuclear One - Unit 1 Docket No. 50-313 License No. DPR-51 Followup Action As A Result of The Crystal River-Unit 3 Event on February 26, 1980 (File: 1510)

Gentlemen:

Our letter of April 16, 1980 to Mr. R. W. Reid of your staff provided you with our commitment to perform a test which would show the effects of various single power supply failures for the NNI-X and NNI-Y cabinets.

This test was being performed in order to verify the design of our NNI system as described in our letter of March 12, 1980, and to verify the performance of the A.C. power supply upgrade as described in our March 24, 1980 letter.

Through conversations with your Mr. Guy Vissing, AP&L has learned that the proposed test is unacceptable to the NRC staff. Our understanding is that the staff feels the test must consist of a loss of power output from the 120 V.A.C. transfer switch which AP&L is installing. Our position is that the addition of the transfer switch eliminates the possibility that the single failure of the inverter power supply could result in a loss of power to the NNI system. The transfer switch greatly enhances power supply reliability and makes it very difficult, if not impossible, to postulate any single failure which would result in loss of A.C. power to the distribution and fuse panels.

Mr. Vissing informed us that the staff was very persistent that a test be performed to determine what instrumentation is lost on loss of A.C.

power from the proposed 120 V.A.C. transfer switch. We expressed our T A X P AYING, INVESTOR OWNE D MEMBE A MIDDLE SOUTH UTILITIES SYSTEM

, 3o94240 M D

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i Mr. R. W. Reid April 18,1980 s

. 1-040-13 i

concern that performance of the test might possibly result in a reduction in the degree of protection provided to public health and safety because it requires that the unit be forced into a degraded operating condition for the period of the test.

We have not seen or heard any quantitative evidence to support the test described above. However, since it appears that we have no alternative, AP&L hereby commits to a test involving a loss of A.C.

power output from the 120 V.A.C. transfer switch. This test will be performed in addition to the test described in our April 16, 1980 letter.

As a result of the modification which will be made to provide a back-up source of A.C. power, several indications will be available following various NNI/ICS power upset events, in addition to those given in Attachment 1 of our March 12, 1980 letter. Attached to this letter is a revised listing of the indications.

Very truly yours, 9

fo Donald A. Rueter DAR/ MAS /lp Attachment l

s

ATTACHMENT 1 Power Loss Power Loss Power Loss Power Loss Parameter 24VDC-X 24VDC-Y 118VAC-X 118VAC-Y Pressurizer Level C C C C Pressurizer Level Temp Comp -

SRX -

SRX Pressurizer L.'ater l eir.p SIY C,SIXl SCY 1 C,SIXl RC Outlet Temp (Th )

Loop A WR C C C C RC Outlet Temp (Th )

Loop B WR C C C C RC Inlet Temp (Tc )

Loop A WR SIY C,SIXl SCY.1 -

C,SIX 1 RC Inlet Temp (Tc )

Loop B WR SIY C,SIX l SCY1 C.SIXl 0TSG A Startup Level - C,SIX1 ,3 SCY1 C,SIXl OTSG B Startup Level SCY1 SIX3 SCY1 SIX OTSG A Operating Level SRY C,SRX2 SCYI C,SRX 2 OTSG B Operating Level C,SRY 2 SRX SCY1 SRX 1

OTSG A Pressure SIY C,SIX 1 SCY C,SIX 1

OTSG B Pressure C,SIY 1 SIX SCY SIX DH Removal Flow A -

I -

I DH Removal Flow B I -

I -

Makeup Tank Level - C,SRX 2 SCYI C.SRX2

]

BWST Level SIY SIX -

SIX RCS Wide Range Press. R4 R4 -

R4 DH Cooler Temp Loop A DSCHG I,C -

I,C -

DH Cooler Temp i

Loop B DSCHG -

I,C - I,C Saturation Meters Ch 2 R Ch 1 R Ch 2 R Ch 1 R I

s

. ATTACHMENT 1 l (continued) t Symbols:

(-) -

Indicates none available I

I C - Computer

! I -

Indicator R -

Recorder Prefix S -

Selectable between X or Y

?

l Suffix X or Y - Denotes signal origin or dependency u o i

110tes:

1. Either indication to operator and input to other function cy; computer input, but not both. ,

2. Either recorded and input to other functions cg computer input, but not both.

1

3. Either X or Y transmitter can be selected for indication.

4. Transmittar is from Engineered Safeguards.

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