ML061160445

RAI Related to Unit 2 Steam Dryer Inspection

ML061160445
Person / Time
Site:	Quad Cities
Issue date:	04/28/2006
From:	Banerjee M Plant Licensing Branch III-2
To:	Crane C Exelon Generation Co
Banerjee M, NRR/ADPT, 415-2277
References
TAC MC0878
Download: ML061160445 (5)

Text

April 28, 2006 Mr. Christopher M. Crane, President and Chief Nuclear Officer Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

QUAD CITIES NUCLEAR POWER STATION, UNIT 2 - REQUEST FOR ADDITIONAL INFORMATION RELATED TO THE UNIT 2 STEAM DRYER INSPECTION (TAC NO. MC0878)

Dear Mr. Crane:

The Nuclear Regulatory Commission (NRC) staff is reviewing the results of the recent steam dryer inspection at Quad Cities Nuclear Power Station (QCNPS), Unit 2. One aspect of this review is to ensure implementation of the commitments documented in your letter to the NRC dated January 26, 2006, Commitments and Plans Related to Extended Power Uprate Operation. This review has determined that additional information is needed. The specific information being requested is formally addressed in the enclosure to this letter. The request was initially transmitted via e-mail to you on April 12, 2006. We received responses to some of the questions via e-mail. However, we request that the responses be formally submitted to the NRC on the docket.

The NRC staff considers that timely responses to requests for additional information help ensure sufficient time is available for staff review and contribute toward the NRCs goal of efficient and effective use of staff resources. If you have a question or need further information, please contact me at (301) 415-2277.

Sincerely,

/RA by D.Collins for/

Maitri Banerjee, Senior Project Manager /RA/

Plant Licensing Branch III-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-265

Enclosure:

Request for Additional Information cc w/encl: See next page

Mr. Christopher M. Crane, President April 28, 2006 and Chief Nuclear Officer Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

QUAD CITIES NUCLEAR POWER STATION, UNIT 2 - REQUEST FOR ADDITIONAL INFORMATION RELATED TO THE UNIT 2 STEAM DRYER INSPECTION (TAC NO. MC0878)

Dear Mr. Crane:

The Nuclear Regulatory Commission (NRC) staff is reviewing the results of the recent steam dryer inspection at Quad Cities Nuclear Power Station (QCNPS), Unit 2. One aspect of this review is to ensure implementation of the commitments documented in your letter to the NRC dated January 26, 2006, Commitments and Plans Related to Extended Power Uprate Operation. This review has determined that additional information is needed. The specific information being requested is formally addressed in the enclosure to this letter. The request was initially transmitted via e-mail to you on April 12, 2006. We received responses to some of the questions via e-mail. However, we request that the responses be formally submitted to the NRC on the docket.

The NRC staff considers that timely responses to requests for additional information help ensure sufficient time is available for staff review and contribute toward the NRCs goal of efficient and effective use of staff resources. If you have a question or need further information, please contact me at (301) 415-2277.

Sincerely,

/RA by D.Collins for/

Maitri Banerjee, Senior Project Manager Plant Licensing Branch III-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-265

Enclosure:

Request for Additional Information cc w/encl: See next page DISTRIBUTION:

PUBLIC LPLF R/F RidsNrrDorlLplf RidsNRRPMMBanerjee RidsNrrLADClarke RidsAcrsAcnwMailCenter RidsOGCRp RidsRgn3MailCenter RidsNrrDorlDpr TScarbrough CWu RidsNrrDeEemb RidsNrrDciCptb RidsNrrDciEmcbA ADAMS Accession Number: ML061160445 *concurred via email OFFICE LPL3-2/BC LPL3-2/LA DE/EEMB/BC DCI/EMCB-A/BC LPL3-1/BC NAME D.Collins DClarke* KManoly KGruss LRaghavan DATE 4/28/06 4/27/06 4/27/06 4/27/06 4/28/06 OFFICIAL RECORD COPY

Quad Cities Nuclear Power Station Units 1 and 2 cc:

Site Vice President - Quad Cities Nuclear Power Illinois Emergency Management Station Agency Exelon Generation Company, LLC Division of Disaster Assistance &

22710 206th Avenue N. Preparedness Cordova, IL 61242-9740 110 East Adams Street Springfield, IL 62701-1109 Quad Cities Nuclear Power Station Plant Manager Exelon Generation Company, LLC Document Control Desk - Licensing 22710 206th Avenue N. Exelon Generation Company, LLC Cordova, IL 61242-9740 4300 Winfield Road Warrenville, IL 60555 Regulatory Assurance Manager - Quad Cities Exelon Generation Company, LLC Senior Vice President of Operations 22710 206th Avenue N. Exelon Generation Company, LLC Cordova, IL 61242-9740 4300 Winfield Road Warrenville, IL 60555 Quad Cities Resident Inspectors Office U.S. Nuclear Regulatory Commission Vice President - Licensing and Regulatory 22712 206th Avenue N. Affairs Cordova, IL 61242 Exelon Generation Company, LLC 4300 Winfield Road David C. Tubbs Warrenville, IL 60555 MidAmerican Energy Company One River Center Place Director - Licensing and Regulatory 106 E. Second, P.O. Box 4350 Affairs Davenport, IA 52808-4350 Exelon Generation Company, LLC 4300 Winfield Road Vice President - Law and Regulatory Affairs Warrenville, IL 60555 MidAmerican Energy Company One River Center Place Assistant General Counsel 106 E. Second Street Exelon Generation Company, LLC P.O. Box 4350 200 Exelon Way Davenport, IA 52808 Kennett Square, PA 19348 Chairman Manager Licensing - Dresden, Quad Cities Rock Island County Board of Supervisors and Clinton 1504 3rd Avenue Exelon Generation Company, LLC Rock Island County Office Bldg. 4300 Winfield Road Rock Island, IL 61201 Warrenville, IL 60555 Regional Administrator U.S. NRC, Region III 801 Warrenville Road Lisle, IL 60532-4351

REQUEST FOR ADDITIONAL INFORMATION QUAD CITIES NUCLEAR POWER STATION, UNIT 2 DOCKET NO. 50-265 In reviewing Exelon Generation Company, LLCs (Exelons) results of the steam dryer inspection at Quad Cities Nuclear Power Station (Quad Cities), Unit 2, the NRC staff has determined that the following information is needed in order to complete its review:

1. Please provide the following information to the NRC staff:

(a) steam dryer inspection results and analysis, including metallurgical reports; (b) steam dryer failure root cause report; (c) steam dryer stress analysis report; (d) justification for the steam dryer repair, including the extent of the repair, impact of the repair on steam dryer structural characteristics, and evaluation of remaining steam dryer; and (e) description, analysis, and justification for the electro-magnetic relief valve (ERV) modification in support of extended power uprate (EPU) operation, including evaluation of the shaker table test failure?

2. Provide the main steam line (MSL) strain gage and accelerometer data, and walkdown information, during the power ascension.

3. For the QCNPS, Unit 2 power ascension test procedure, TIC-1402, please provide the power ascension intervals for test condition (TC) steps and hold times above original licensed thermal power (TC 12 to 18).

4. Provide the basis for the vibration acceptance criteria for Levels 1 and 2 in Attachment 9.2 of TIC-1402.

5. Provide the basis for the MSL strain gage data acceptance criteria for Levels 1 and 2 in Attachment 9.3 of TIC-1402.

6. Provide the scope and objectives of the walkdowns that are planned at specific test condition steps.

7. Provide the extent of and the justification for leaving the small cracks in service during operation, especially at EPU.

8. For the large dryer crack in the skirt base metal at the 135-degree location, provide the following information and documentation supporting your responses.

(a) What may be the magnitude of plastic strains and residual stresses introduced by the reported installation difficulty?

(b) What may be the corresponding reduction in the fatigue stress limits?

(c) What may be the stresses acting at the crack location?

(d) What is the stress intensity at the crack tip?

9. In the stress analysis submitted by Exelon in August 2005 (Report GENE-0000-0043-5391-01-P), the maximum stress intensity in the skirt was high (24,285 psi) when 2 percent damping was assumed. Then damping in the skirt was increased to 4 percent and the corresponding maximum stress intensity was reduced to about 9,000 psi. Explain the basis for assuming that 4 percent damping is a reasonable estimate of the actual structural damping.

10. Explain why some small fatigue cracks in several vane assemblies are not repaired. Did initial installation introduce any residual stress at the crack locations? What may be the magnitude of this stress? What may be the driving force for these cracks? How does this driving force compare with the one acting on the large crack at the 135-degree location? How much these small cracks may grow during the next fuel cycle?

11. Are the MSL strain gage data at 2957 MegaWatts thermal (MWt) available? How does this data compare with the corresponding data at 2885 MWt and at pre-EPU condition?

Provide similar comparison for reactor pressure vessel level sensor data.

12. What may be the magnitude of the weld residual stresses at the repaired crack location? What may be the effect of these residual stresses on the fatigue stress limits?

Explain why the repaired crack location may not be susceptible to fatigue cracking.

13. Address how the magnitude of residual stresses created as a result of highly constrained weld repair is determined. How do these residual stresses affect the fatigue life for the material?

14. Discuss the potential for loose parts resulting from the failure of the backing bar.