ML20245L644

Documents 890726 Conference Call Re Implementation Schedule for ATWS Mods.Proposed Schedule for Mods to Install ATWS Mitigation Sys Actuation Circuitry Based on Decision to Utilize Programmable Logic Controller

ML20245L644
Person / Time
Site:	Oconee
Issue date:	08/04/1989
From:	Tucker H DUKE POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 8908220222
Download: ML20245L644 (4)

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C DUKE POWER GOMPANY -

P.O. DOX 33189 CHARLOTTE, N.O. 28242 HAL B. TUCKER nus nou

" " " " " " (704) 373-4531' l August 4, 1989'

-U. S. Nuclear Regulatory Commission Document Control Desk-Washington, DC L20555-

Subject:

Oconee. Nuclear Station Document Nos. 50-269, -270, -287

'ATWS Implementation 10CFR50.62-By my letter. dated May 15,.1989, I had provided.to the NRC an implementation schedule for the ATWS modification at the Oconee Nuclear Station. -I had proposed in that letter the following schedule:

Unit 1: E0C-13 refueling outage - August 1991

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Unit 2: E0C-11 refueling outage - September 1990

-Unit 3: _EOC-12 refueling outage - March 1991  !

On July;26, 1989,;the. schedule for the implementation of the ATWS l . modification for Unit I was discussed with the NRC in regard to the potential for accelerating the above schedule for Unit 1 so -that installation would be completed during the Unit 1 E0C-12 refueling outage in April.-1990. ' The milestones and basis associated with ~ and the basis for the Unit 1 implementation schedule were discussed during the conference call.. The purpose of this letter is to document the July 26, 1989 conference' call.  !

1 A brief, description of the major milestones associated with the first i modification to install the Diverse Scram System (DSS) and the ATWS Mitigation System Activation Circuitry (AMSAC) planned for Oconee Unit 2 is provided by Figure 1. The basis for the proposed schedule is related  !

to our decision to utilize Programmable Logic Controller (PLC) Technology for our DSS /AMSAC logic. 1 The' utilization of PLC technology provides for greater flexibility and a better means of meeting the diversity design requirements. This technology offers a simplified means for the development and configuration l 1 :of'the control logic for the DSS /AMSAC Systems. Any changes and i

~ modifications to the logic are also simplified and more than likely will  !

not. require any hardware changes. In addition, performance data related l to the DSS /AMSAC logic can be collected and monitored without the need for j a Data Acquisition System. The power demands for this system is minimal, i thus the design requirements for the dedicated Uninterruptible j)oS5 i i 8908220222 890804 PDR ADOCK 05000269 P PDC

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Document Control' Desk August 4,'1989 Page 2 Power Supply (UPS).are simplified. Since the existing reactor protective system is based on analog modules and relay logic, the PLC technology provides a better means of satisfying the diversity design requirements of the ATWS rule than other options.

By-utilizing PLC technolot,y in this application, opportunity to integrate this. technology into other areas of the plant can be realized.

Furthermore, the design of the PLC is being done in-house, as opposed to-purchasing a black box from a vendor. This approach results in a greater amount of lead time for in-house engineering development; however, this will allow for improving our in-house engineering expertise for better maintenance and engineering support for the DSS /AMSAC equipment.

Other factors / issues affecting the proposed schedule are as follows:

o Modifications'to be implemented during a refueling outage are identified at least.a year in advance. As such, modifications to be implemented during the Unit i end of cycle 12 refueling outage have already been identified and scheduled.

o After final equipment specification, several months are necessary for procurement, delivery, and in-house programming.

o .The final design package needs to be provided to the field several months in advance of the outage. As the figure shows, this is possible for the Oconee Unit 2 EOC-11 but would not be possible for the Oconee Unit 1 EOC-12 refueling outage in April 1990.

o Some of the modification can be done while a unit is on-line. This work is scheduled to be done prior to the refueling outage in which the ATWS modification is to be implemented, with final tie-in and testing done during the refueling outage.

An attempt to accelerate the proposed schedule so that the ATWS modification could be completed for Unit I during the End-0f-Cycle 12 refueling outage would not necessarily result in closing out this issue for Oconee significantly earlier than proposed. At best we would close this issue for Oconee only five months earlier (based on outage schedule),

while significantly increasing the risk of implementing a modification that is inconsistent with NRC staff desires, and thus requiring a significant amount of time and resources to resolve.

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r,.s 4 Document Control Desk August 4,.1989 Page 3 1

I would also like to point out that the final' implementation of the ATWS modification in accordance with the proposed schedule,. for all three Oconee Units will be completed within two refueling outages from NRC approval of our conceptual design provided by the NRC letter dated March 22, 1989.

In closing, Duke will. continue to work aggressively, as we have in the past, to assure that the implementation of the ATWS modification at Oconee Nuclear Station" will be completed. as proposed. Accordingly, Duke strongly requests that the NRC review and approve the final design description, to be submitted by September 1, 1989, in a timely manner. This will go a l- long way in preventing the installation of a final design that is l inconsistent with the NRC staff desires, which would require additional l time and resources.to resolve. With the continued effort and cooperation of.the NRC staff, I am confident that NRC approval of the final design can be obtained to assure that this issue for Oconee Nuclear Station will be closed in a timely manner.

Very truly yours, l

C a. k ' q -

l l Hal B. Tucker PFG/55/td cc: Mr. L. A. Wiens Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, DC 20555 Mr. S. D. Ebneter Regional Administrator, Region II U. S. Nuclear Regulatory Commission 101 Marietta Street, NW, Suite 2900 Atlanta, GA 30323 l Mr. P. H. Skinner

. NRC Resident Inspector Oconee Nuc1N r Station l

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