ML20236S030

Discusses Licensee Stating That Potential Ambiguities in SE Issued on 950609,approving Licensee TR NEDO-32368 Had Been Discovered

ML20236S030
Person / Time
Site:	Limerick
Issue date:	07/17/1998
From:	Thadani M NRC (Affiliation Not Assigned)
To:	Geoffrey Edwards PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
References
TAC-M91330, NUDOCS 9807240091
Download: ML20236S030 (6)

Text

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f"% k UNITED STATES g P; NUCLEAR REGULATORY COMMISSION l WASHINGTON, D.C. 30806 0001

%,..... July 17, 1998 Mr. Garrett D. Edwards Director-Licensing, MC 62A-1

, - PECO Energy Company Nuclear Group Headquarters Correspondence Control Desk PO Box No.195 Wayne, PA 19087-0195 l

SUBJECT:

PEACH BOTTOM ATOMIC POWER STATION, UNIT 3, Ct.ARIFICATION OF SAFETY EVALUATION SUPPORTING AMENDMENT NO. 224 INCORPORATING l

WIDE RANGE NEUTRON MONITORING SYSTEM (TAC NO. M91330)

Dear Mr. Edwards:

16. a letter dated January 23,1998, PECO Energy Company (the licensee) stated that it had discovered potential ambiguities in the safety evaluation (SE) issued on June 9,1995, approving the licensee's topical report NEDO-32368. The topical report, NEDO-32368, and the NRC SE of

, June 9,1995, supported the approval of Amendment No. 224, which allowed replacement of

! Source Range and Intermediate Range Neutron Monitoring (SRM and IRM) systems with a Wide Range Neutron Monitoring System (WRNMS). The licensee, in the January 23,1998, letter, j - further stated that a clarification of the potential ambiguities would be beneficial.

! ' The licensee stated that it discovered that there are three areas of potential ambiguity between the plant-specific WRNMS licensing topical report, NEDO-32368, prepared by PECO Energy and the SE dated June 9,1995, issued by the NRC approving NEDO-32368. The areas of ambiguity are:

1. Electrical separation and Regulatory Guide (RG) 1.75

2. Type of cable used under the vessel

3. Single failure in the self-test feature l

l We have reviewed these areas of ambiguity and have concluded the following:

l

! 1. Electrical Seoaration and Reaulatory Guide 1.75 The licensee recommends that the NRC's SE approving NEDO-32368 be revised to clearly state that electncel isolation and physical separation are provided to the extent necessary to comply with the independence requirement of (Institute of Electrical and Electronics Engineers)

. IEEE 279.

l The paragraphs in the SE that are in question are paragraph 5 of Section 3 and the only paragraph in Section 7. Paragraph 5 currently states -

The WRNMS is designed to meet the separation guidelines of RG 1.75, Rev. 2, with respect to the scope of the replacement system. Safety-related and nonsafety-related replacement gD equipment is separated physically and electrically. Where interfaces occur between safety and non-safety equipment, appropriate isolation devices (relays) are used per the existing design for channelindependence as required by lEEE 279. The eight WRNM channels are , o\

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G. Edwards electrically isolated ard physically separated from one another except immediately under the reactor vessel, where complete physical separation is not practical. The staff finds the above separation features to be consistent with IEEE 279 and RG 1.75, and therefore, acceptable.

Section 7.0 of the SER currently states, in part -

Based on the staff's review of PECO (Energy's) LCR 93-18 including NEDO-32368 and subsequent submittals, the staff concludes that the replacement of the SRM and IRM subsystems with the WRNMS in PBAPS Units 2 and 3 meets the requirements of IEEE-279, RGs 1.75,1.89,1.97 and 1.100 for safety-related instrumentation and control system design, i and is, therefore, acceptable.

When the staff reviewed PECO's submittal, it requested additionalinformation with regard to electrical separation and RG 1.75 (see the letter from G. A. Hunger to the NRC dated March 30, 1995). The NRC's question and PECO's response are as follows:

NRC Question 5 l

' ' In NEDO 32368, Section 3.5, the licensee states, "The WRNMS is not designed to meet the Regulatory Guide 1.75 (RG 1.75)." Identify where the PBAPS WRNMS does not conform to the guidance of RG 1.75, and the reasons for not conforming.

,PECO Energy Response to Question 5 The replacement WRNM system is designed to meet Reg. Guide 1.75, Rev. 2, with respect to the scope of the replacement system. Replacement equipment is separated physically and j electrically. Where interfaces occur between safety and non safety equipment, appropriate l isolation devices (relays) are used per the existing design for channel independence requirements of IEEE 279 (refer to Section 3.4, item 6 of NEDO-32368), though no attempt

l. was made to demonstrate compliance with RG 1.75 because it is not a requirement for l PBAPS.

4 Regarding the statement that, "the replacement WRNM system is designed to meet RG 1.75, j Revision 2, with respect to the scope of the replacement system," the staff concludes that the response to Question 5 is given to correct the earlier statement in NEDO-32368 that stated that the WRNMS is not designed to meet RG 1.75.

The staff accepts the licensee's statement that the WRNMS is designed to meet RG 1.75, Revision 2, with respect to the scope of the replacement system only (although compliance with RG 1.75 is not a requirement for PBAPS), the remainder of the plant may not meet RG 1.75, and it is committed only to the requirements of IEEE 279-1969, that is, the licensing basis for PBAPS.

The staff concludes that the SE reflects the information presented on the docket with regard to electrical separation, IEEE 279, and RG 1.75, and, therefore, the SE does not need to be revised.

I l

. . l G. Edwards ,

2. Tvoe of Cable Used Under the Vessel i

l The licensee points out that a triple-shielded, oiganic, coaxial cable qualified for the environment l was used for the detector signal cable run directly under the reactor vessel instead of the mineral-insulated cable indicated in Figure 2 2 of NEDO-32368. This difference first came to the attention of the staff during the inspection of the digital retrofit for the WRNMS at PBAPS Unit 3 l (Inspection Report No. 97008, January 12 through 16,1998). This difference is addressed in the NRC inspection report 98001, dated May 1,1998, where the NRC staff concluded that the difference does not affect the safe operation of WRNMS. Because this change was made to the design after the SE was issued, it is not discussed in the SE. The staff concludes that the SE does not need to be revised to include a discussion of the differences between the two types of cable.

3. Sinale Failure in the Self-test Feature NEDO-32368 discusses differences between the PBAPS plant-specific WRNMS and the previously approved WRNMS described in NEDO-31439-A.

NEDO-31439-A, Appendix C, Section C.6.4 states -

To guard against the loss of essential instrument functions, the primary NUMAC (The Nuclear Measurement Analysis and Control) microcomputer is isolated by serial data links. A single failure in self-test or front panel will not affect essential measurement function.

Section 4.0, paragraph 1 of the SE for NEDO-32368 states, in part -

The WRNMS software is also modularized such that a single failure in the self-test system or in the front display and keypad panel will not affect the essential measurement and trip functions.

The licensee requests that this paragraph of the June 9,1995, SE be modified to discuss how the reactor protection system trip logic responds to " fatal" and "non-fatal" failures of hardware modules that are detected by the properly funt tioning WRNMS self-test system. Such discussion was not the intent of this paragraph in the SE.

The intent of this paragraph in the June 9,1995, SE is to describe the immunity of the WRNM system from a single failure in one of the front display and keypad panel assemblies, or of the failure of the self test system to detect a failed hardware module in a WRNMS assembly. The staff has interpreted the information presented in NEDO-31439-A to indicate that the essential measurement and trip functions still would be expected to function after experiencing either of these two types of failures.

l I

I

. i

. 1 G. Edwards .

Th' e" staff concludes that the June 9,1995, SE reflects the information presented on the docket with regard to single failures of the self-test system or in the front display and keypad panel assembly.

Based on the above review, the NRC staff concludes that the June 9,1995, SE for the staff review of the topical report NEDO-32368 need not be revised.

Sincerely, original signed by B.Buckley for Mohan C. Thadani, Senior Project Manager Project Directorate 1-2 Division of Reactor Projects - 1/11 Office of Nuclear Reactor Regulation Docket No. 50-353 cc: See next page l

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DISTRIBUTION Docket File PUBLIC PDI-2 Reading JZwolinski

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WBeckner JWermiel NGilles WMortensen CAnderson, RGN-1 OFFICE PDI-2/PM d(h PDhkb HICB/BC PDI-2/D i NAME' MThadani:rb Mdbrien JWhel RCapra DATE' 7 /'7/98 ,

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The staff concludes that the June 9,1995, SE reflects the information presented on the docket with regard to single failures of the self test system orin the front display and keypad panel assembly.

Based on the above review, the NRC staff concludes that the June 9,1995 SE for the staff review of the topical report NEDO-32368 need not be revised.

Sincerely, 0:%h 0. \Y Mohan C. Thadani, Senior Project Manager Project Directorate 1-2 Division of Reactor Projects - 1/ll Office of Nuclear Reactor Regulation Docket No. 50-353 cc: See next page l

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Mr. Garrett D. Edwards Peach Bottom Atomic Power Station, PECO Energy Company Units 2 and 3 l cc:

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l J. W. Durham, Sr., Esquire . Chief-Division of Nuclear Safety E Sr. V.P. & General Counsel PA Dept. of PECO Energy Company 2301 Market Street, S26-1 Environmental Resources

' P.O. Box 8469 Philadelphia, PA 19101 Harrisburg, PA 17105-8469 PECO Energy Company ATTN: Mr. T. N. Mitchell, Vice President Board of Supervisors Peach Bottom Atomic Power Station Peach Bottom Township 1848 Lay Road R. D. #1 Delta, PA 17314 Delta, PA 17314 PECO Energy Company Public Service Commission of Maryland ATTN: Regulatory Engineer, A4-SS Engineering Division Peach Bottom Atomic Power Station Chief Engineer 1848 Lay Road 6 St. Paul Centre Delta, PA 17314 Baltimore, MD 21202-6806 Resident inspector Mr. Richard McLean U.S. Nuclear Regulatory Commission Power Plant and Environmental Peach Bottom Atomic Power Station Review Division -

[ P.O. Box 399 Department of Natural Resources Delta, PA 17314 _

B-3, Tawes State Office Building Annapolis, MD 21401 Regional Administrator, Region i U.S. Nuclear Regulatory Commission Dr. Judith Johnsrud 475 Allendale Road National Energy Committee King of Prussia, PA 19406 Sierra Club 433 Oriando Avenue Mr. Roland Fletcher State College, PA 16803 Department of Environment 201 West Preston Street Manager-Financial Control & Co-Owner Baltimore, MD 21201 Affairs Public Service Electric and Gas

! A. F. Kirby, til Company I~ - Extemal Operations - Nuclear P.O. Box 236 l Delmarva Power & Light Company Hancocks Bridge, NJ 08038-0236 l- P,0. Box 231 l' . Wilmington, DE 19899 Manager-Peach Bottom Licensing PECO Energy Company PECO Energy Company Nuclear Group Headquarters i

Plant Manager Correspondence Control Desk Peach Bottom Atomic Power Station P.O. Box No.195 1848 Lay Road Wayne, PA 19087-0195 Delta, PA 17314' l

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