ML19326C783

Forwards Responses to Questions Concerning re-evaluation of ECCS Performance Requested by R Snaider & J Burdoin

ML19326C783
Person / Time
Site:	Arkansas Nuclear
Issue date:	11/23/1977
From:	David Williams ARKANSAS POWER & LIGHT CO.
To:	Desiree Davis Office of Nuclear Reactor Regulation
References
NUDOCS 8004280718
Download: ML19326C783 (6)

Text

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NRCPor.M 195 U.S. NUCLE 4R F.EGULATO AY CC" 'ISSION ET NUMYEP m.7.,

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nsteses' se ce oEsCn'"' " Ltr trans the f ollov '.ng: iP ENCLOSURE Respective responses to questions con-cerning Re-evaluation of ECCS performance. . .

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Director of Nuclear Rea [G mrron-p4dal4 -

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ATTN: Mr. D. K. Davis , Acting Chief A 4/

Operating Reactors Branch #2 Q, N U. S. Nuclear Regulatory Commission Washington, D. C. 20555 pff gi\\g

Subject:

Arkansas Nuclear One-Unit 1 Docket No. 50-313 License No. DPR-51 Re-Evaluation of ECCS Performance (File: 1510, 0930)

Gentlemen:

Per requests posed by your Messrs. R. Snaider and J. Burdoin, enclosed find those respective responses to their questions concerning the captioned subject.

If you have any further questions and/or comments, please advise.

Very truly yours, 0

ey Daniel H. Williams l

Manager, Licensing DHW:RMC:dr Attachment

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TAM P AYING, INVE STO A CWNE O 3 MEMGE A MICOLE SOUTH UTILITIES S YSTEM

ITEM 1 In your singic failure analysis of CV-3824, service water discharge to flume valve, you stated that the breaker to this valve will be

-locked open and tagged during normal operations. Describe in more detail the status of a locked open breaker. Describe the positive action required to restore the breaker to operating condition.

RESPONSE

Motor operated valves are locked open by removing the breaker from the circuit, thereby creating an open circuit. The motor can then not actuate the valve. The breaker is tagged administrative 1y and cannot be placed back into the circuit without proper administrative approval. The handwheel to the valve is also tagged so that manual operation will not be effected without proper administrative approval.

ITEM 2 Is either or both of the service water valves, CV-3823 or CV-3824 required to operate (open or close) in any of the various safety system sequences?

If so, describe the operation (s).

RESPONSE

CV-3823 or CV-3824 perform no automatic safety function.

ITEM 3 Are the two core flood tank vent valves (CF-3A and CF-3B) referred to in attachment 2 of your letter dated 7/9/75, those same valves (CV-2417 and CV-2420) as listed in your response to Question 5, in your letter of 8/3/76? If not, identify these vent valves by number and identify the P6ID drawing which shows the location of these vent valves. Do these vent valves have redundant position indication in the main control room?

RESPONSE

Valves CF-3A and CF-3B are CV-2417 and CV-2420, respectively. There is no redundant position indication.

ITEM 4 In your justification, attachment 2 of the letter dated 7/9/75, for not locking out core flood tank vent valves, you take credit for the orifice and section of pipe between the vent valve and orifice. Is this equipment and installation of this section of piping and orifice classified as safety grade?

RESPONSE

The piping and orifice between the core flood tank and vent valve, as well as the vent valve are classified as Class I.

ITEM 5 In your submerged valve analysis (Attachment 3 to your letter dated 7/9/75) you addressed only one core flood tank block valve, CV-2415.

Describe status of block valve CV-2419 which you identified in your response to question 5 in your letter of 8/3/76. Describe in more detail the status of the power to valves CV-2415 and CV-2419 when in the open and close positions. Do these valves have redundant position indication in the main control room?

RESPONSE

CV-2419 is located at elevation 358'-6" and was therefore not considered to be. subj ect to submergence.

Power to these valves is removed by opening the circuit breaker to the operator and " hold" tagging the breaker when at power. During plant cooldown, the " hold" tag is removed and the breaker is put back into the circuit. The valve is then stroked closed and verified closed.

After verification, the breaker is again opened and " hold" tagged.

There is no redundant position provided.

ITEM 6 Identify from which bus / buses CV-1213, CV-1215, CV-2216, CV-2217, and CV-1053 (Attachment 3 of your letter dated 7/9/75) are energized and are these safety class buses? Do these valves have redundant position indication in the main control room?

RESPONSE

CV-1213 and CV-2216 are powered from Motor Control Center (MCC) B71 which is fed from 4.16kV bus Al and CV-1215 and CV-2217 are powered from MCC B24 which is fed from 4.16kV bus A1. CV-1053 is powered from MCC B5 which is fed from 4.16kV bus A3.~ Bus Al is not a safety class bus. Bus-A3 is a safety class bus.

There is no redundant position indication provided.

ITEM 7 You have indicated in your respnse to Question 4' (single failure review) in your letter dated 8/3/76 that valves CV-1054 and CV-4400 are located below containment building flood elevation 357'-0" and that these two valves do receive as ESAS signal. You did not address these two valves in either of your letters of 7/9/76 or 8/3/76.

a) Describe the safety function they perform.

b) Identify from which bus / buses valves CV-1054 and CV-4400 are energi:ed.

i c) Do these valves have redundant position indication in the Main Control Room?

R$5PONSE a) CV-4400 is not located inside the Reactor Building but rather is located in the Reactor Auxiliary Building. Its function, as well as CV-1054 (3/4" sample line), are to effect containment isolation, b) CV-1054 is energized from MCC B51 (4.16kV bus A3). CV-4400 is solenoid operated from the Green 125V DC panel.

c) No ITEM 8 Valves CV-1053 and CV-4446 which are normally closed valves receive isolation signals during ECCS operation and are located below containment building flood elevation of 357'-0". What protective measures have been or will be taken to insure that these valves will not cause a vital motor control center to be lost to an electrical fault at the valve drive motor following submergence?

RESPONSE

The 480 V MCC Combination motor starters are provided with an instantaneou::-

trip element and an overload relay for each phase. This provides motor and cable protection, and the isolation of individual motor circuit faults so as not to effect other MCC loads.

ITEM 9 Similar to the above question, what protective measures have been taken or will be taken to insure valves CV-1214 and CV-1216 (normally open) which receive isolation signals will not fault a vital motor control center following submergence.

RESPONSE

See Response to Item 8.

ITEM 10 What is the present status of the fully qualified submersible valve operators for valves CV-1051 and CV-1410 as first reported in your response to question 4 in your letter dated 8/3/76.  ;

RESPONSE

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Modifications were 1:rst reported in our letter of July 9,1975 and again in our August 22, 1975 letter to you. These new operators were installed during our refueling shutdown of Januatr-March 1977. i l

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ITEM 11

- Reference FSAR Figure No. 8-1 station single line diagram: What loads

are supplied from 120; volt as instrument panels Y-1 and Y-27

RESPONSE

The loads supplied from the panels are those which are used during normal operation. No vital loads are supplied from these panels.

ITEM 12

' How are these loads different from those 120 volt ac loads energi:ed from RS-1/3.and RS-2/47 .

RESPONSE

Inverters RS-1 and 3 (Red) and RS-2 and 4 (Green) supply power for nuclear instrumentation, reactor protection systems, engineered safeguard systems, and other vital loads.

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