ML20211P396

Forwards RAI Re Licensee 970131 & 0902 Requests for Approval to Incorporate Lower Values of Reactor Coolant Dose Equivalent Iodine Levels in TS for Byron,Unit 1 & Braidwood, Unit 1

ML20211P396
Person / Time
Site:	Byron, Braidwood
Issue date:	10/07/1997
From:	Lynch M NRC (Affiliation Not Assigned)
To:	Johnson I COMMONWEALTH EDISON CO.
References
TAC-M97894, TAC-M97895, TAC-M99535, TAC-M99536, NUDOCS 9710200182
Download: ML20211P396 (8)

Text

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

Octcher 7, 1997

.- Ms. Irene M. Johnson, Acting Manager Nuclear Regulatory Services Commonwealth Edison Company -

Executive Towers West III 1400 Opus Place, Suite 500 Downers Grove IL 60515-

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION REGARDING REDUCTIONS IN THE REACTOR COOLANT DOSE EQUIVALENT IODINE LEVELS - BYRON AND l BRAIDWOOD STATIONS (TAC NOS. M97894, M97895, M99535 AND M99536)

Dear Ms. Johnson:

By letters dated January 31, 1997, and September 2,1997, Commonwealth Edison Company (Comed) submitted requests for license amendments for Byron, Units 1 and 2, and Braidwood, Units 1 and 2, respectively. The submittals requested approval to' incorporate lower values of the reactor coolant dose equivalent iodi::e lavels in the technical specifications for Byron Unit 1, and Braidwood, Unit 1. Several additional submittals have been made, each

providing clarifying information or responding to NRC requests for additional information (RAI). -

In reviewing the Comed submittal of August 14, 1997, we have determined that additional information is needed. Please provide the information requested in the enclosed RAI so that we may complete our review.

Sincerely, OnginalSi9ned By:

f M. D. Lynch, Senior Project Manager

?roject Directorate III-2 Division of Reactor Projects - III/IV Office of Nuclear Reactor Regulation Docket Nos. STN 50-454, STN 50-455, STN 50-456, STN 50-457

Enclosure:

RAI cc w/ encl: See next page Qistribution:

Docket File -PUBLIC PDIII-2 R/F E. Adensam EGAl \

R. Capra l C. Moore M.D. Lynch OGC 015B18 ACRS T2E26 G. Dick S. Bailey R. Lanksbury, RIII S. Coffin 0704- C. Beardslee 0704 E. Sullivan 0704 P. Rush 0704 R. Emch 010D4 C. Hinson 010D4 DOCUMENT NAME: G:\CMNTJR\ BRAID-BY\BB97894.RAI Te recive a copy of thi&Acument, ir6hynte in the boas "C" = Copy without enc,losures "E" = Copy with enclosures *N" a No co.y 0FFICE #1QDG-h h 1.A:TMI II-2 lUD:PDIII-2 lE NAME- . h '

t! Wore ( RCapra Rw DATE 10kPJ/97 - 10 ( /97 10/ l /97 9710200182 971007 FICIAL RECORD COPY DR ADOCK 0500 4 g {g

Octtber 7, 1997

, Ms. Irene M. Johnson, Acting Manager

Nuclear Regulatory Services commonwealth Edison Company Executive Towers West III 1400 Opus Place, Suite 500 Downers Grove, IL 60515

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION REGARDING REDUCTIONS IN THE REACTOR C00LANI DOSE EQUIVALENT IODINE LEVELS - BYRON AND BRAIDWOOD STATIONS (TAC N05. M97894, M97895, M99535 AND M99536)

Dear Ms. Johnson:

, By letters dated January 31, 1997, and September 2, 1997, Commonwealth Edison Company (Comed) submitted requests for license amendments for Byron, Units 1 and 2, and Braidwood, Units 1 and 2, respectively. The submittals requested approval to incorporate lower values of the reactor coolant dose equivalent tod'ie levels in the technical specifications for Byron, Unit 1, and Braidwood, Unit 1. Several additional submittals have been made, each providing clarifying information or responding to NRC requests for additional information (RAI).

In reviewing the Comed suomittal of August 14, 1997, we have determined that additional information is needed. Please provide the information requested in the enclosed RAI so that we may complete our review.

Sincercly, onginalSigned Br.

M. D. Lynch, Senior Project Manager Project Directorate III-2 Division of Reactor Projects - III/IV Office of Nuclear Reactor Regulation Docket Nos. STN 50-454, STN 50-455, STN 50-456, STN 50-457

Enclosure:

RAI cc w/ enc 1: See next page Distribution:

Docket File PUBLIC PDIII-2 R/F E. Adensam EGA1 R. Capra C. Moore M.D. Lynch OGC 015B18 ACRS T2E26 G. Dick S. Bailey R. Lanksbury, RIII S. Coffin 0704 C. Beardslee 07D4 E. Sullivan 0704 P. Rush 0704 R. Emch 010D4 C. Hinson 01004 i DOCUMENT NAME: G:\CHNTJR\ BRAID-BY\BB97894.RAI 13 reiv. . copy of this document, toShy,te in the box: =c= = Copy without enclosures *E' s Copy with enclosures "We a No copy l0FFICE #@DgG-) h J.A:WI.II-2 l69:PDIII-2 lE lNAME ACH7r6h

BMe' ore ( RCapra &

lDATE 10h>J/97 ' 10 ( /97 10/7 /97 0FFICIAL RECORD COPY

jo urg

'g .

\* UNITED STATES NUCLEAR REGULATORY COMMISSION k WASHINGTON, D.C. 3066A001

% . . . . ,.!}

J

\

I October 7, 1997 Ms. Irene M. Johnson, Acting Manager Nuclear Regulatory Services Commonwealth Edison Company Executive Towers West III 1400 Opus Place, Suite 500 ,

Downers Grove, IL 60515

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION REGARDING REDUCTIONS IN THE REACTOR COOLANT DOSE EQUIVALENT IODINE LEVELS - BYRON AND BRAIDWOOD STATIONS (TAC NOS. M97894, M97895, M99535 AND M99536)

Dear Ms. Johnson:

By letters dated January 31, 1997, and September 2, 1997, Commonwealth Edison Company (Comed) submitted requests for license amendments for Byron, Units 1 and 2, and Braidwood, Uaits 1 and 2, respective 1v. The submittals requested approval to incorporate lower values of the reactor coolant dose equivalent l iodine levels in the technical specifications for Byron, Unit 1, and t

Braidwood, Unit 1. Several additional submittals have been made, each providing clarifying information or responding to NRC requests for additional information (RAI).

In reviewing the Comed submittal of August 14, 1997, we have determined that additional information is needed. Please provide the information requested in the enclosed RAI so that we may complete our review.

l Sincerely,

( '

M. D. Lynch, Senior Project Manager Project Directorate III-2 Division of Reactor Projects - III/IV Office of Nuclear Reactor Regulation Docket Nos. STN 50-454, STN 50-455, STN 50-456, STN 50-457

Enclosure:

RAI cc w/ encl: See next page

, I. Johnson Byron /Braidwood Power Stations Comonwealth- Edison Company cc:

Mr. William P. Poirier, Director George L. Edgar Westinghouse Electric Corporation Morgan, Lewis and Bochius Energy Systems Business Unit 1800 M Screet, N.W.

Post Office Box 355, Bay 236 West Washington, DC 20036 Pittsburgh, Pennsylvania 15230 Attorney General Joseph Gallo 500 South Second Street Gallo & Ross Springfield, Illinois 62701 1250 Eye St., N.W.

Suite 302 EIS Review Coordinator Washington, DC 20005 U.S. Environmental Protection Agency 77 W. Jackson Blvd.

Michael I. Miller, Esquire Chicago, Illinois 60604-3590 Sidley and Austin One First National Plaza Illinois Department of Chicago, Illinois 60603 Nuclear Safety Office of Nuclear Facility Safety Howard A. Learner 1035 Outer Park Drive Environmental law and Policy Springfield, Illinois 62704 Center of the Midwest 203 North LaSalle Street Commonwealth Edison Company Suite 1390 Byron Station Manager Chicago, Illinois 60601 4450 North German Church Road Byron, Illinois 61010 U.S. Nuclear Regulatory Commission Byron Resident Inspectors Office Kenneth Graesser, Site Vice President 4448 North German Church Road Byroi. Station Byron, Illinois 61010-9750 Commonwealth Edison Station 4450 N. German Church Road Regional Administrator, Region III Byron, Illinois 61010 U.S. Nuclear Regulatory Commission 801 Warrenville Road U.S. Nuclear Regulatory Commission Lisle, Illinois 60532-4351 Braidwood Resident Inspectors Office Rural Route #1, Box 79 Ms. Lorraine Creek Braceville, Illinois 60407 Rt. 1, Box 182 Manteno, Illinois 60950 Mr. Ron Stephens Illinois Emergency Services Chairman, Ogle County Board and Disaster Agency Post Office Box 357 110 East Adams Street Oregon, Illinois 61051 Springfield, Illinois 62706 Mrs. Phillip B. Johnson Chairman 1907 Stratford Lane Will County Board of Supervisors Rockford, Illinois 61107 Will County Board Courthouse Joliet, Illinois 60434

J

. Commonwealth Edison Company Braidwood Station Manager Rt. 1,-Box 84 Braceville, Illinois 60407 Ms. Bridget Little Rorem Appleseed Coordinator 117 North Linden Street Essex, Illissois 60935 i

Document Control Desk-Licensing Commonwealth Edison Company l 1400 Opus Place, Suite 400 Downers Grove, Illinois 60515 Mr. H. G. Stanley Site Vice President Braidwood Station Commonwealth Edison Company RR 1, Box 84 Braceville, IL 60407

, REQUEST FOR ADDITIONAL INFORMATION REDUCTION IN PRIMARY COOLANT IDDINE CONCENTRATION I

-BYRON STATION. UNIT 1. AND BRAIDWOOD STATION. UNIl 1 DOCKET NOS. STN 50-454 AND STN 50-456

Background

The Byron and Braidwood Nuclear Power Plants, Units 1 (Byron, Unit 1, and

-Braidwood, Unit 1) both have plant-specific steam generator (SG) tube repair criteria with a higher voltage limit (a 1.0 volt Interim Plugging Criteria

-(IPC)) discussed in Generic Letter (GL) 95-05. The highet voltage repair j limit was based on stabilization of the tube support plates (TSPs) by >

-expansit.,n of selected tut <es at the support plate intersections so that the TSPs could be credited as staying .in place under postulated main steamline break (MSLB) conditit,ns. Braidwood, Unit 1, implemented the 3.0 volt IPC at l

the end-of-cycle (EOC). 5 in November 1995. In the spring 1997 outage at the EOC-6, the-licensee compared the actual bobbin coil eddy current voltage distribution of its outside diameter stress corrosion cracking (00 SCC) TSP indications with the arojected voltage distribution obtained during the previous outage per tie 3.0 volt IPC methodology. The licensee found that the predicted voltage distribution was nonconservative with respect to the actual voltage distribution. As a result, the predicted leakage during a postulated MSLB event significantly underestimated the leakage calculated based on actual EOC eddy current indications (i.e., 6.99 gpm versus 11.5 gpm). However, the latter value was still well wnthin the site allowable leakage limit (19.0gpe). The licensee attributed the nonconservative prediction of the E0C voltage distribution to a voltage-dependent growth rate that appears to have occurred, in part, as a result of the higher voltage repair criteria in effect at Braidwood, Unit 1. For the current operating cycle (Cycle 7), the licensee revised its prediction methodology and ap;, lied voltage-dependent growth rates to predict the E00-7 conditions. The licensee also revised the EOC-8 predictions for Byron, Unit 1, since similar voltage-dependent growth rates may exist. Based on E0C predictions that incorporated voltage-dependent growth rates, both stations concluded that reactor coolant system dose-equivalent iodine-(DEI) levels should be reduced.

The-current site allowable leakage limit at (room temperature conditions at Braidwood, Unit 1, is 19.0 gpm and at Byron, Unit 1, is 26.0 gpm. These-limits are each associated with a DEI level of 0.35 mic.rocuries/ gram. The EOC predictions for conditional MSLB leakage from ODSCC TSP indications is 57.1 gpm and 21.9 gpm at Braidwood, Unit 1, and Byron,-Unit 1, respectively. .

When leakage from intact SGs and top-of-the-tubesheet-(TTS) indications are also included in the leakage projections, the total EOC leakage for each plant increases to 62.4 and 44.8 gpm. Thus,- to maintain the dose consequences of a MSLB event within acceptable limits, -Braidwood, Unit 1, proposed to reduce its DEI to~ 0.10 microcuries/ gram which will result in a site allowable leakage ENCLOSURE

o limit of 66.3 gpm, and Byron, Unit 1, proposed to reduce its DEI to 0.20 microcuries/ gram which will result in a site allowable leakage limit of 45.5 gpm.

As part of the review and approval of the DEI level reduction license amendment requests, the staff reviewed the voltage-dependent growth rate methodology Commonwealth Edison Company (Comed) used to revise the E0C predictions for the ODSCC TSP indications. The methodology was submitted to the staff August ~ 14, 1997, in the licensee's report discussing the results of the analyses of the SG inspection data obtained after Braidwood, Unit 1, Cycle 6. The following questions were generated durIng staff review of this cubmittal.

Additional infortnation Reauested The following questions apply to both Byron, Unit 1, and Braidwood, Unit 1:

l. For the predictions of the EOC conditions at Braidwood, Unit 1, Comed used a lower voltage value of 1.1 volt for the highest voltage bin.

Since the behavior of voltages between 1.1 and 1.5 volt appears to be different from the behavior of voltages above 1.5 volt (reference Figure 5-3 of the August 14, 1997, submittal), discuss the appropriateness of l- the lower voltage value of 1.1 volt other than that the 1.1 volt limit provides 200+ indications as mentioned in GL 95-05. Assess the change in the calculated EOC conditions (i.e., voltage distributions and MSLB leakage) for Braidwood, Unit 1, as the lower voltage value of the highest voltage bin changes from 1.1 volt to higher voltages, such as 1.45 and 2.0 volt, using NRC approved methodology (i.e., probability of detection (P00) = 0.6).

2. For the predictions of the EOC conditions at Byron, Unit 1, Comed used a lower voltage value of 0.9 volt for the highest voltage bin. Since the behavior of voltages between 0.9 and 1.5 volt appears to be different from the behavior of voltages above 1.5 volt (reference Figure A-4 of the August 14, 1997, submittal), discuss the appropriateness of the lower voltage value of 0.9 volt other than that the 0.9 volt limit provides 200+ indications as mentioned in GL 95-05. Assess the change in the calculated EOC conditions (i.e., voltage distributions and MSLB leakage) for Byron, Unit 1, as the lower voltage value of the highest voltage bin changes from 0.9 volt to higher voltages, such as 1.45 and 2.0 volt, using NRC approved methodology (i.e., P00 - 0.6).

3. Discuss why an independent assessment of the voltage-dependent methodology is not needed. Provide the basis for Comed's conclusion that "benciimarking" the methodology using the same data used to develop l the methodology provides an adequate demonstration of the ability of the voltage-dependent methodology to conservatively predict the EOC conditions at Braidwood, Unit 1, and Byron, Unit 1.

=s

. l The following questions apply to Braidwood, Vait 1, only.

4. In the August 14, 1997, submittal, Table 6-2 and Figure 6-5 presented a i comparison of predicted and actus.1 bobbin voltage distributions for SG

'C' at EOC-6, using the voltage dependent Cycle 6 growth and a POD of 0.6. Discuss how well the voltage-dependent methodology works for each ,

SG and at all voltage levels (i.e., both above and below 3.0 volt),

a) Provide similar tables and figures for all four SGs, for all voltages levels.

b) Discuss how well the voltage-dependent growth rates conservatively predict the actual voltages for all SGs and for all voltage ranges. Discuss how well the voltage-dependent growth rates conservatively predict EOC-6 MSLB leakage for each SG.

5. Figure 5-3 of the August 14 submittal depicts the voltage growth during Cycle 6 as a function of the beginning of cycle (BOC)-6 voltage.

Provide similar figures for the remaining SGs as well as a com)osite figure. Discuss the voltage-dependency of growth for each SG 3ased on the data in the figures.

6. Discuss other characteristics that could possibly explain the apparent dependency of growth rates on initial bobbin coil voltage. What other factors has Comed evaluated in an effort to understand the high growth behavior of these indications? Include, as a minimum, in the response:

(1) the location of the indications; and (2) the age of the indications.

7. Provide a comparison between the projected EOC leakage obtained fo' lowing the approved methodology using the Cycle 6 hybrid growth distribution and the proposed voltage-dependent growth rate methodology discussed in the August 14, 1997, submittal. Discuss how the difference between the two values justifies the application of a voltage-dependent growth rate methodology.

8. Discuss the basis for limiting the hybrid growth distribution to include the largest three growth values found in any of the SGs. Assess the expected effect of including the top 5 or 10 growth values on the projected EOC leakage.

_ . _ _ ____