ML20137R067

Rev to 851223 Application for Amend to License NPF-43, Revising Tech Spec 3/4.9.2 Refueling Operations/ Instrumentation & Clarifying Control Rod Withdrawal Process

ML20137R067
Person / Time
Site:	Fermi
Issue date:	02/04/1986
From:	Agosti F DETROIT EDISON CO.
To:	Adensam E Office of Nuclear Reactor Regulation
Shared Package
ML20137R071	List: ML20137R067 ML20137R131
References
VP-86-0007, VP-86-7, NUDOCS 8602070183
Download: ML20137R067 (4)

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Newport M cngan 4a:% Nuclear ISOn omss4mo operauons February 4, 1986 VP-86-0007 Director of Nuclear Reactor Regulation Ms. Elinor G. Adensam, Director Project Directorate No. 3 Division of BWR Licensing U. S. Nuclear Regulatory Commission Washington, D.C. 20555

Reference:

1) Fermi 2 NRC Docket No. 50-341 NRC License No. NPF-43

2) Detroit Edison to NRC Letter, " Request for Amendment to Fermi 2 Technical S pec if ic a-tions Regarding the Source Range Monitor Downscale Rod Block Setpoint". VP-85-0236, dated December 23, 1985

Subject:

Supplemental Information for Requested SRM Setooint Technical Soecification Amendment Detroit Edison submitted a request for an amendment to Fermi 2 Technical Specifications 3/4.3.6, 3/4.3.7.6 and 3/4.9.2 via Reference 2. Subsequent conversations with NRC-NRR staff have identified four items requiring clarification or revision. The following provides the requested information.

1. Revision to 3/4.9.2 Detroit Edison has agreed to modify the wording of Technical Specification 3/4.9.2, " Refueling Operations / Instrumentation", to clarify the intent of the revision provided in Reference 2. Attachment 1 provides the modified wording of the footnote which supersedes the Reference 2 revision to Technical Specifications page 3/4 9-4.

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Ms. Elinor G. Adensan February.4, 1986 VP-86-0007 Page 2

2. Verificati_on of S i g n a l-t o-IkingAtis Detroit Edison confirms that operational procedures require that within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> prior to reactor startup, ,

each SRM is determined to be operable by either: 1) verifying the SRM reads >3 cps and < 10 # cps; or 2) with 4 reading between 3 cps and 0.7 cps, the signal to noise J ratio is known t o b e j> 2 : 1. (Subsequent to the approval of the requested Technical Specification revision, this procedure will be modified, as ~ necessary, to reflect a low setpoint of 0.3 cps.)

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3. Control Rod Withdrawal Process A concern was identified relative to the potential for j challenging the Reactor Protection System (RPS) as a

, -result of initiating reactor startup from the revised downscale setpoint of 0.3 cps.

The Fermi 2 reactor startup program provides assurance that this will be unlikely, and that criticality will be attained in a controlled manner. The procedure governing control rod withdrawals during the approach to critical requires a minimum of three seconds wait between rod withdrawal steps (after the settle light 4 extinguishes). Whenever the SRM readings are less than 3 cps an additional one minute wait will be required if i a period alarm is encountered. Large reactivity

additions in any step are prevented by a combination of the hardwired Rod Sequence Control System (RSCS) for all rod withdrawals up to the low power setpoint and the Reduced Notch Worth Procedure (RNWP) incorporated

, in the rod pull sheets for rod groups 3 and 4 where i initial criticality has been demonstrated to occur, and on up to the low power setpoint.

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The.SRMs are verified to be providing a c c'u r a t e readings

prior to startup (as reflected in Item 2 above) and l procedures require the operator to both add reactivity slowly and observe the SRM readings.

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i Ms. Elinor G. Adensam February 4, 1986 VP-86-0007 Page 3 i

4. Summary of Signal-to-Nqits_ Ratio Teal Reference 2 indicated that an in-situ test had been performed with the Fermi 2 SRMs to verify both the ability to read 0.1 cps and the presence of a signal-to-noise r a t i o j> 2 at 0.3 cps. A brief description of this test follows.

The channel B SRM was chosen for this test since it was judged to have reflected the most " noise" during its operating history. SRM B was fully withdrawn from the core, after which a voltage meter was connected to it at local output plugs. Approximately two minutes after SRM B had reached the " full-out" position, the Log Count Rate Meter indicated 0.1 cps, and the voltage meter read 0.5 VDC. After an additional five minutes the Log Count Rate Meter stabilized at below 0.1 cps, while the voltage meter in d ic a t ed a -1.0 VDC. Because the Log Count Rate Meter had been previously calibrated at +10 VDC full scale (7 decades), the bottom reading was 1.5 VDC below the 0.1 cps reading (corresponding to 1 about a full decade in cps)

Therefore, it was verified that noise within the SRM

. system provides feedback much less than the equivalent of 0.1 cps and that a count rate of 0.1 cps can be read clearly. In addition, as the downscale setpoint may be

. reduced to 0.3 cps, the signal-to-noise ratio at this lower setpoint will be 22:1.

Reference 2 above had a typographical error on Page 4 of 4 in Attachnent 1. The first sentence in the first paragraph should read, " Reduction in SRM rod block -

setpoints to 0.3 cps has been reviewed and found acceptable by the NRC in a prior case"...instea'd of

" Reduction in SRM rod block setpoints to 0.7 cps has been' reviewed and found acceptable by the NRC.in a prior case".

Detroit Edison appreciates the prompt review provided on Reference 2. Based on the current SRM count rate, we i estimate that the antimony-berry 11ium source strength may be insufficient to maintain 0.7 cps beyond March 1, 1986.

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If Ms. Elinor G. Adensam 4 February 4, 1986 VP-86-0007 Page 4

Please contact Mr. R. L. Woolley at (313) 586-4211 if you j have any further questions concerning this matter.

Sincerely.

- D JC

.:r- si [

F. E. Agosti

' Vice President

Nuclear Operations With attachment cc

Mr. P. M. Byron

! Mr. M. D. Lynch Mr. L. E. Phillips

! Mr. H. J. Richings j

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