ML20217B915

Provides Clarifying Info to Enable NRC to Complete Review of License Change Request ECR 98-01802,re Changes Necessary to Support Installation of Digital Pr Neutron Monitoring & Incorporate long-term T/H Stability Solution Hardware

ML20217B915
Person / Time
Site:	Peach Bottom
Issue date:	10/06/1999
From:	Hutton J PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9910130112
Download: ML20217B915 (3)

Text

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g PECO NUCi_ EAR 71M=Tra A Unit of PECO Energy **#' ""

October 6,1999

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Docket Nos. 50-277 50-278 License Nos. DPR-44 DPR-56 i

U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555

Subject:

Peach Bottom Atomic Power Station, Units 2 and 3

' Supplemental Information Regarding Facility Operat:ng License Change Request ECR 98-01802

Reference:

Letter from Garrett D. Edwards, PECO Energy Company, to USNRC, dated March 1,1999

Dear Sir:

In the reference letter, PECO Energy Company submitted License Change Request (LCR) ECR 98-01802 requesting changes to the Peach Bottom Atomic Power Station

'(PBAPS), Units 2 and 3, Facility Operating Licenses.

The proposed changes are necessary to support installation of a digital Power Range Neutron Monitoring (PRNM) system and incorporate long-term thermal-hydraulic stability solution hardware.

The purpose of this letter is to povide clarifying information to enable the NRC to

. complete the review of the LCR.'

Technical Specification Table 3.3.1.1-1 establishes the Allowable Value of the -

Average Power Range Monitors (APRM) Neutron Flux-High Function as 119.7%. This Allowable Value was calculated using an NRC approved setpoint methodology based on the PRNM equipment specifications and the Analytical Limit of 122.0% previously established for the APRM scram clamp function. - Prior to implementation of the PRNM system, the APRM scram clamp Analytical Limit had been increased from 120.0% to

- 122.0% based on analysis performed by GE. However, no increase of the Allowable Value of the APRM scram clamp function had previously been sought based on the I increased Analytical Limit so the APRM scram clamp Allowable Value established in I the current Table 3.3.1.1-1 is based on an Analytical Limit of 120.0%.

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October 61999 Page 2 Deletion of the Rod Block Monitor (RBM) Downscale Function from the Technical

Specifications is permitted because it fails to meet any of the four criteria of 10CFR50.36 (c)(2)(ii). In the original analog RBM, the 'aciusion in the Technical Specifications of a Downscale Function in addition to the Inop Function had some merit because the analog equipment had some failure modes that cr@d result in a i

reduction of signal, but not a full failure. Unlike other neutron monitw ig system '

Downscale Functions, there are no normal operating conditions which are intended to be detected by the downscale function. Therefore, the RBM Downscale Function is, in fact, part of the overall RBM Inop Function.

The replacement of the original analog RBM equipment with the NUMAC digital RBM results in all of the original analog processing being replaced by digital processing.

One effect of this change is to eliminate the types of failures that can reasonably be detected by the downscale trip function. In addition, the Inop function is enhanced in the NUMAC RBM by the use of automatic self-test and other intamal logic to increase the detectability of failures and abnormal conditions that can occur in the digital i equipment and to directly include these in the RBM inop function.

The FsBM downscale trip function will detect substantial reductions in the RBM local flux after a " null"is completed (a " null" occurs after a new rod selection). This function, in combination with the RBM Inop function, was intended in the original system to detect problems with or abnormal conditions in the RBM equipment and system.

However, no credit is taken for the RBM downscale trip function in the establishment of the RBM upscale trip analytical limits or setpoint values.

Therefore, in the NUMAC ARTS RBM, there is no incremental value or benefit provided by the RBM downscale trip function. However, this function is physically retained in the NUMAC RBM equipment installed at PBAPS.

If you have any questions, please contact us. )

Very truly yours, mes A. Hutton, Jr.

irector- Licensing

Enclosure:

Affidavit 1

cc H. J. Miller, Administrator, Region I, USNRC I A. C. McMurtray, USNRC Senior Resident Inspector, PBAPS

- R. R. Janati, Commonwealth of Pennsylvania

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COMMONWEALTH OF PENNSYLVANIA :

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ss.

COUNTY OF CHESTER  :

1 J. J. Hagan, being first duly swom, deposes and says:

That he is Senior Vice President of PECO Energy Company; the Applicant herein; that he has read the foregoing letter conceming License Change Request ECR 98-01802 and knows the contents thereof; and that the statements and matters set forth therein are true and correct to the best of his knowledge, information and belief.

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ce residant Subscribed and swom to before me this d day of 1999.

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/ Not ry Public carol ANNO .7 PubHc uL"Mahis:'tleub v

Member, PennsyNane Assocaton of Notados