SVPLTR 09-0045, Revised License Renewal Commitment for the Testing of Drywell to Suppression Chamber Vent Lines Expansion Bellows

Revised License Renewal Commitment for the Testing of Drywell to Suppression Chamber Vent Lines Expansion Bellows

ML092870472
Person / Time
Site:	Dresden
Issue date:	10/02/2009
From:	Hanley T Exelon Generation Co, Exelon Nuclear
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
SVPLTR 09-0045
Download: ML092870472 (5)

Text

Exekln Exelon Generation Company, LLC www.exeloncorp.com Nuclear Dresden Nuclear Power Station 6500 North Dresden Road Morris, IL 60450-9765 SVPLTR: #09-0045 1 OCFR.54 October 2, 2009 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington D.C. 20555-0001 Dresden Nuclear Power Station, Unit 2 Renewed Facility Operating License No. DPR-19 NRC Docket No. 50-237 Dresden Nuclear Power Station, Unit 3 Renewed Facility Operating License No. DPR-25 NRC Docket No. 50-249

Subject:

Revised License Renewal Commitment for the Testing of Drywell to Suppression Chamber Vent Lines Expansion Bellows

Reference:

(1) Letter (RS-03-180) from Mr. Patrick R. Simpson (Exelon Generation Company, LLC), to the NRC, "Additional Information for the Review of the License Renewal applications for Quad Cities Nuclear Power Station, Units 1 and 2 and Dresden Nuclear Power Station, Units 2 and 3", dated October 3, 2003 (2) NUREG 1796, "Safety Evaluation Report Related to the License Renewal of the Dresden Nuclear Power Station, Units 2 and 3 and Quad Cities Nuclear Power Station, Units 1 and 2" (3) NUREG 1856, "Safety Evaluation Report Related to the License Renewal of the Brunswick Steam Electric Plant, Units 1 and 2' The purpose of this letter is to inform the NRC that Exelon Generation Company, LLC (EGC) is revising a commitment identified in References (1) and (2) for Dresden Nuclear Power Station (DNPS).

In Reference (1), as a part of EGC's license renewal application for DNPS, EGC identified that the primary containment Drywell to Suppression Chamber Vent Lines expansion bellows (vent line bellows) were constructed of two plies of Type 304 stainless steel and as two-ply expansion bellows, their testing required the use of a plant unique methodology. Based on that information, the NRC in Reference (2), Section 3.5.2.2.1, "Containments," credited that specific testing as the basis for a safety decision in the safety evaluation.

It has been subsequently determined that the vent line bellows at DNPS are constructed of only a single-ply of Type 304 stainless steel, which prevents them from being tested as described in Reference (1).

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October 2, 2009 U.S. Nuclear Regulatory Commission Page 2 of 2 The vent line bellows (quantity 8 per unit) penetrate the torus shell and connect to the vent header within the torus. The vent line bellows attach between the exterior of the vent line and the exterior of the torus shell, providing the required differential movement between these items without developing significant interaction loads. One end of each bellows is welded to the outside of each vent line. The other end is welded to the torus shell. Based on this arrangement, the interior air space between the bellows and the vent line is open to the torus air space.

The interior of the bellows is not accessible due to the small gap between it and the vent pipe. The exterior of the bellows is covered by protective plates to prevent accidental mechanical damage during operation. Two drawings showing the construction details of the bellows are attached to this letter. These single-ply expansion bellows can only be properly pressure tested by a 10 CFR Part 50, Appendix J, Type A test.

The remainder of the information regarding the vent line bellows as described in Reference (1) is unaffected. Therefore, the conclusions reached in Reference (2) for both susceptibility to stress corrison cracking (Section 3.5.2.2.1) and fatigue analyses (Section 4.6.2.3) remain accurate. The vent line bellows remain within the scope of License Renewal but are not part of the scope of the pressurized testing being performed for two-ply mechanical penetrations expansion bellows.

EGC's review of the matter concludes that the use of the combination of the ASME Section Xl, Subsection IWE Program and 10 CFR Part 50, Appendix J Program, Type A testing will adequately assure the detection of cracking should it occur for the vent line bellows. The NRC has previously accepted the use of Appendix J Type A testing for single-ply vent line bellows, (as documented in Reference (3), Section 3.5.2.2.1).

Therefore, EGC is revising the commitment to test the vent line bellows for DNPS Units 2 and 3 to credit its Appendix J Type A testing.

Should you have any questions concerning this letter, please contact Ms. Marri Marchionda at 815-416-2800.

Respectfully, Tim Hanley Site Vice President Dresden Nuclear Power Station Attachement: Construction Details of Drywell to Suppression Chamber Vent Lines Bellows cc: Regional Administrator- NRC Region III NRC Senior Resident Inspector - Dresden Nuclear Power Station

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