Text

NRR E-mail Capture - Second Draft RAI for RR I4R-20 (Quad Cities)
	ML14354A003
Person / Time
Site:	Quad Cities
Issue date:	12/18/2014
From:	Mozafari B; Plant Licensing Branch III
To:	Nicely K; Exelon Corp
References
	Download: ML14354A003 (3)
	v • d • e

1 NRR-PMDAPEm Resource From:

Mozafari, Brenda Sent:

Thursday, December 18, 2014 4:49 PM To:

Nicely, Ken M.:(GenCo-Nuc) (ken.nicely@exeloncorp.com); Simpson, Patrick R.:(GenCo-Nuc) (patrick.simpson@exeloncorp.com)

Cc:

Purnell, Blake; Tate, Travis

Subject:

Second DRAFT RAI for RR I4R-20 (Quad Cities)

Hi Ken, Below is the 2nd Draft RAI needed to guide any discussion regarding RR 14R-20 pertaining to Quad Cities. The RAI will provide discussion points to help us focus on where clarification can make our issues understood by all.

SECOND REQUEST FOR ADDITIONAL INFORMATION ON THE FOURTH TEN YEAR 10-YEAR INSERVICE INSPECTION INTERVAL REQUEST FOR RELIEF I4R-20 FOR EXELON GENERATION COMPANY, LLC.

QUAD CITIES NUCLEAR POWER STATION, UNITS 1 AND 2 DOCKET NUMBERS: 50-254 AND 50-265

1. SCOPE By letter dated January 23, 2014, (Agencywide Documents Access & Management System (ADAMS)

Accession Number ML14023A865), the licensee, Exelon Generation Company, LLC (EGC), submitted Request for Relief (RR) I4R-20 from the requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components for Quad Cities Nuclear Power Station, Units 1 and 2 (QCNPS 1 and 2). The request for relief applies to the fourth 10-year inservice inspection (ISI) interval, in which the licensee adopted the 1995 Edition through the 1996 Addenda of ASME Code Section XI as the code of record. The U. S. Nuclear Regulatory Commission (NRC) requested that the licensee provide further information, and the licensee provided a response to the Request for Additional Information (RAI) in a letter dated October 16, 2014, (ADAMS Accession Number ML14293A450).

However, certain requested information was not provided and/or requires clarification in order for the staff to complete the evaluation of the licensees request. Please submit answers to the following questions.

2. REQUEST FOR ADDITIONAL INFORMATION

1) The licensee provided only cross-sectional sketches showing idealized beam projections that were part of the ISI examination reports, but did not include volumetric coverage maps obtained on all of the subject components, as requested by NRC in general question 1.d of the original RAI:

Show cross-sectional or surface coverage plots to describe the ASME Code volumes and surfaces examined.

Because this material has been omitted, it is unclear whether specific volumetric coverage(s) included areas near the inner surface using the appropriate ultrasonic wave angles and modalities. These are typically the most highly stressed regions, exposed to operating environments where service degradation would be expected to occur, should it be manifested. One would have to make assumptions on coverage in these regions, if the beam projection sketches are employed during the Staffs evaluations. Please submit the requested cross-sectional plots showing volumetric coverage obtained.

2

2) The licensees RAI response states that all ASME Category B-A, Items 1.12 (longitudinal welds) were conducted using ASME Section XI, Appendix VIII, performance-demonstrated techniques. However, it was noted that for QCNPS 2, an ASME Appendix VIII procedure was used for the Item B.140 (top head-to-flange) weld. Mandatory Appendix I of ASME Section XI states that the RPV top head-to-flange weld is excluded from Appendix VIII rules and is required to meet the requirements of ASME Section V, Article 4.

State whether QCNPS 2 has an NRC-approved alternative in place to use PDI-qualified methods on the RPV top head-to-flange weld instead of those required by ASME V, Article 4. Reference the NRC SER that approves this deviation, and the PDI-certification document.

3) ASME V, Article 4 does not require specific angles or modes of propagation; only prescriptive requirements for calibration and scanning are listed. The licensee elected to use 60-degree refracted longitudinal (RL) beam probes. On fine-grained carbon steel components such as this, it would seem that shear waves provide the best opportunity for detection of planar flaws. Please discuss the use of the 60-degree RL probe on the top head-to-flange welds in lieu of shear wave methods.

4) In addition, during the 2008 course of examinations on QCNPS 2, nine (9) previously detected indications (found acceptable per ASME) on the RPV top head-to-shell weld were again observed with the 60-degree RL probe examination. Apparently, a 45-shear technique operating at reference amplitude was subsequently employed, and the indications could not be discerned from the clad-to-base metal interface noise. The licensee used this 45-degree examination to support a conclusion that these indications had not grown since the last examination. Please discuss:

a. If the ASME Appendix VIII-approved (via PDI) procedure allows the use of a 45-degree shear wave (operating at reference level) method to determine whether a reflector is recordable, based on amplitude alone.

b. Whether the 60-degree RL technique could have been used to size the existing indications as was done with previous examinations.

5) The licensee requested relief for limited examinations of dissimilar metal welds included in their risk-informed piping program. These welds are designated as R1.20, which indicates that no known degradation mechanism has been identified. The licensee obtained significant volumetric coverage on these welds (approximately 86 per cent), however, it is unclear whether the correct RI-ISI designation has been assigned. Please discuss the following:

a. The welds are at carbon steel nozzles to stainless steel piping safe ends. Are the dissimilar metal welds (DMWs) constructed of Alloy 82/182 materials?

b. While not as prevalent as in PWRs, instances of stress corrosion cracking have been observed at DMWs in BWRs. Justify why the R1.20 designation remains valid, given this fact.

Brenda L. Mozafari Senior Project Manager, NRR/DORL U.S. Nuclear Regulatory Commission Dresden 2/3 and Quad Cities 1/2 301-415-2020 email: brenda.mozafari@nrc.gov

Hearing Identifier:

NRR_PMDA Email Number:

1788 Mail Envelope Properties (Brenda.Mozafari@nrc.gov20141218164900)

Subject:

Second DRAFT RAI for RR I4R-20 (Quad Cities)

Sent Date:

12/18/2014 4:49:01 PM Received Date:

12/18/2014 4:49:00 PM From:

Mozafari, Brenda Created By:

Brenda.Mozafari@nrc.gov Recipients:

"Purnell, Blake" <Blake.Purnell@nrc.gov>

Tracking Status: None "Tate, Travis" <Travis.Tate@nrc.gov>

Tracking Status: None "Nicely, Ken M.:(GenCo-Nuc) (ken.nicely@exeloncorp.com)" <ken.nicely@exeloncorp.com>

Tracking Status: None "Simpson, Patrick R.:(GenCo-Nuc) (patrick.simpson@exeloncorp.com)"

<patrick.simpson@exeloncorp.com>

Tracking Status: None Post Office:

Files Size Date & Time MESSAGE 6065 12/18/2014 4:49:00 PM Options Priority:

Standard Return Notification:

No Reply Requested:

Yes Sensitivity:

Normal Expiration Date:

Recipients Received: