ML20247C406

Initiates Discussion Over Need to Reconsider Installation Date for Unit 1 Re Atws.Due to New Design,Implementation for Unit 1 Scheduled for Spring 1991 & Unit 2 for Spring 1990

ML20247C406
Person / Time
Site:	Zion  File:ZionSolutions icon.png
Issue date:	09/08/1989
From:	Trzyna G COMMONWEALTH EDISON CO.
To:	Office of Nuclear Reactor Regulation
References
0276T, 276T, NUDOCS 8909130351
Download: ML20247C406 (3)

Text

-

-r -

, ' ,. g

/ 's Comm:nwrith Edison

! / 72 West Adams Street, Chicago, Illinois

~

5 2 Address Reply to: Post DfficT6P6T kj Chicago, Illinois 60690 0767 L September 8, 1989 Director of Nuclear Reactor Regulation US Nuclear Regulatory Commission' Mail Station P1-137 Hashington, DC 20555 l

1

Subject:

Zion Nuclear Power Station, Units 1 & 2 License Nos. DPR-39 and DPR-48 ATHS Implement 6 tion Schedule 4

EBC Docket Nos. 50-295 and 50-304

Reference:

May 22, 1989, Letter from CP Pate1 to TJ Kovach Gentlemen:

The above referenced letter transmitted the Safety Evaluation Report (SER) for the Anticipated Transients Without Scram (ATHS) and informed us that the ,

proposed design of the ATHS system is in compliance with 10 CFR 50.62 paragraph (c)  !

(1). The letter also indicated that the expected installation dates were -l understood to be Fall 1989, for Unit 1; and Spring 1990, for Unit 2. The Unit 2 i installation date is consistent with the implementation time as stated in our previous correspondence. However, the Unit 1 installation date leaves significantly less time than we previously indicated that would be necessary to implement the ATHS modifications. This means that Unit 1 could be shutdown for an extended period to meet the proposed deadline. Therefore, the purpose of this letter is to initiate a discussion over the need to reconsider the installation l date for Unit 1.

Such a discussion of the installation date is contemplated by the Implementation paragraph of the ATHS rule, 10 CFR 50.62(d), which states that a negotiation process would be employed to determine implementation schedules that i exceed the two refueling outage guidance contained in the rule. All of our previous correspondence indicated that compliance with the schedular guidance of the ATHS rule was contingent upon receipt of NRC approval of the proposed ATHS design by a calendar date that provided us the lead-time that is required to process a modification. The intention of such correspondence was to initiate the schedular negotiation process. Unfortunately, the absence of the negotiation process resulted in the date indicated in the SER as it relates to Unit 1, that is  ;

inconsistent with our previous correspondence and is not achievable because of the j insufficient amount of lead time that is required to process a modification.

However, we feel that entry into that negotiation process now can result in a mutually agreeable implementation date in the near future, foSI is t c91 f;k90900

.00r 9 P

. __ e

~. . ,h. .

Dir. of. Nuclear Reactor Reg. -

2' .

September 8, 1989 Commonwealth Edison, understands that a new implementation schedule for Unit I which extends the ATHS installation date involves safety considerations.

Those considerations in this case show that a change-in the Unit 1 Implementation date'does not adversely affect the margin of safety because'the Station will continue to use the ATHS Mitigation procedures which have provided acceptable compensatory measures in-lieu of an installed ATHS system. Moreover, the safety leprovement after installation of the ATHS will be greater than currently contemplated because.an extended schedule provides us the opportunity to install a more current ATHS design. Otherwise, if the schedule is not extended, Zion would install the older, original design which would not provide the same high level of safety.

The original proposed design that was described in the SER was premised on the use of equipment and technology available at the time of the first submittals. .

These submittals began in 1986 and continued through 1988. Subsequent to the j submittal of these documents, Zion Station has reviewed the ATHS design that was '

recently approved for our Byron /Braidwood facilities. This design utilizes current l technology equipment,.and would be an improvement to the Zion design. In addition,  !

replacement parts for the H-7300 series of equipment, which was intended for use in l the original Zion proposal, are becoming obsolete and difficult to procure. The (

new proposed Zion design would incorporate the best features of the Byron /Braidwood i and Zion designs._.It is important'to note that tne newly proposed changes will not affect the logic design of the. system (ie, there are no changes to parameters such j as'use of Steam Generator level circuitry; selection of high auctioneered nuclear i power signal; 401. power level for arming ATHS, etc.). In summary, the same signals I from the old design will be conditioned by better hardware as proposed in the new design. A formal submittal of the new design will be forwarded to your office within 30. days.

Because the new design has been developed from previously approved designs, Zion is moving ahead to procure equipment, issue design drawings etc.

prior to issuance of a new SER. The Station is also intending to divide the

. modification into outage /nonoutage segments to expedite the installation. This .

means that the Station will use its best efforts to install those elements of the j modifications during the nonoutage period prior to the next scheduled refueling. ,

The implementation schedule for Unit 1 is the Spring, 1991, Refueling Outage. The '

schedule for Unit 2 is unaffected by the change to the new design because the existing schedule provides sufficient time to accomplish the change, and therefore, '

remains as the Spring 1990, Refueling Outage.

1 l

scl/0276T:2 I ,

t

l Q kY

' ' D'r.

I of Nuclear Reactor' Reg.:

3' - September 8, 1939

.y

-Commonwealth Edison feels.that Under these circumstances, public safety-will best be' served by negotiating an extended installation schedule for Unit.'l.

Not only.will such.a new schedule leave in place the existing,' effective o compensatory measures, it-is prudent because it will permit us to install.a contemporary. design.that can be maintained for the. life.of the plant. Therefore, it.is our belief that our schedular inconsistencies can best be resolved by a meeting of our technical personnel, rather than by. invoking the more formal

, ' exemption process outlined in 10 CFR 50.12.

Please direct any questions that you may have regarding this matter to this office.

Very truly yours,

-if ,

o G.E. Trzyna Nuclear Licensing Administrator

/scl:0276T:1-3 cc: C. Patel-NRR Senior Resident Inspector-Zion

)

- _ _ _ - _ _ _ _ - _ _ _ -