CP-201400144, Clarification to Response to Request for Additional Information for Relief Request No. C-3 for Unit 2 Reactor Pressure Vessel Leak-Off Flange (Second ISI Interval Start Date: August 3, 2004; Second ISI Interval End.

Clarification to Response to Request for Additional Information for Relief Request No. C-3 for Unit 2 Reactor Pressure Vessel Leak-Off Flange (Second ISI Interval Start Date: August 3, 2004; Second ISI Interval End.

ML14055A318
Person / Time
Site:	Comanche Peak
Issue date:	02/11/2014
From:	Flores R, Madden F Luminant Generation Co, Luminant Power
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
CP-201400144, TAC MF2997, TXX-14020
Download: ML14055A318 (4)

Text

Rafael Flores Luminant Power Senior Vice President P 0 Box 1002

& Chief Nuclear Officer 6322 North FM 56 rafael.flores@Luminant.com Glen Rose, TX 76043 Lum inant 2548975590 C 817 559 0403 F 254 897 6652 CP-201400144 Ref. # 10CFR50.55a(a)(3)(ii)

TXX-14020 February 11, 2014 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555

SUBJECT:

COMANCHE PEAK NUCLEAR POWER PLANT DOCKET NO. 50-446 CLARIFICATION TO RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION FOR RELIEF REQUEST NO. C-3 FOR THE UNIT 2 REACTOR PRESSURE VESSEL LEAK-OFF FLANGE (SECOND ISI INTERVAL START DATE: AUGUST 3,2004; SECOND ISI INTERVAL END DATE: AUGUST 2,2014)(TAC NO. MF2997)

REFERENCES:

1. Letter logged TXX-13145 dated October 31, 2013, from Rafael Flores to the NRC submitting Relief Request No. C-3 for the Unit 2 Reactor Pressure Vessel Leak-Off Flange (Second ISI Interval Start Date: August 3, 2004; Second ISI Interval End Date:

August 2, 2014)

2. Letter logged TXX-14004 dated January 23, 2014, from Rafael Flores to the NRC responding to Requests for Additional Information for Unit 2 Relief Request C-3

3. Phone conversation dated January 28, 2014, between the NRC and Luminant Power discussing response to Requests for Additional Information for Unit 2 Relief Request C-3 (TAC No. MF2997)

4. Email dated January 30, 2014, from Balwant Singal of NRR to Tim Hope of Luminant Power providing Follow-up Requests for Additional Information for Unit 2 Relief Request C-3 (TAC No. MF2997)

Dear Sir or Madam:

Pursuant to 10 CFR 50.55a(a)(3)(ii), Luminant Generation Company LLC (Luminant Power) submitted Relief Request C-3 for Comanche Peak Nuclear Power Plant (CPNPP) Unit 2 for the second ten year inservice inspection interval via Reference 1. Per Reference 2, Lunminant Power provided the NRC with a response to a request for additional information (RAI) regarding the subject relief request. During a phone conversation between Luminant Power and the NRC, Reference 3, Luminant Power discussed clarifications to the response to RAIs. Per Reference 4, the NRC provided follow-up questions regarding the CPNPP Unit 2 relief request C-3. Luminant Power's clarifications and follow-up responses are provided in the attachment to this letter.

A member of the STARS Alliance YkLA"l Callaway

• Comanche Peak

• Diablo Canyon

• Palo Verde

• Wolf Creek

U. S. Nuclear Regulatory Commission TXX-14020 Page 2 of 2 02/11/2014 This communication contains no new commitments regarding CPNPP Unit 2.

Should you have any questions, please contact Mr. Jack Hicks at (254) 897-6725.

Sincerely, Luminant Generation Company LLC Rafael Flores By: A14. 242d r*W*. Madden Director, External Affairs

Attachment:

Comanche Peak Nuclear Power Plant Unit 2 Clarifications to the Response to Request for Information Regarding Relief C-3 for the Reactor Pressure Vessel Leak-Off Flange (Second 10-Year ISI Interval Start Date: August 3, 2004) c- Marc L. Dapas, Region IV Balwant K. Singal, NRR Resident Inspectors, Comanche Peak Jack Ballard, ANII, Comanche Peak Robert Free Environmental Monitoring & Emergency Response Manager Texas Department of State Health Services Mail Code 1986 P.O. Box 149347 Austin, TX 78714-9347

Attachment to TXX-14020 Page I of 2 COMANCHE PEAK NUCLEAR POWER PLANT UNIT 2 Clarifications to the Response to Request for Information Regarding Relief C-3 for the Reactor Pressure Vessel Leak-Off Flange (Second 10-Year ISI Interval Start Date: August 3, 2004)

NRC's Request 1 For Follow-Up Information:

1. Section 5 "Burden Caused by Compliance" and Section 6 "Proposed Alternative and Basis for Use" of Attachment 1 of RR C-3 stated, in part, Therefore, compliance with the IWC-5220 system leakage test requirements results in an unnecessary hardship without a sufficient compensating increase in the level of quality and safety.

In lieu of the requirements of IWC-5220, a VT-2 visual examination of the accessible areas will be performed each period on the piping subjected to the static pressure head when the reactor cavity is filled. This test will be part of the reactor coolant Class 2 leakage test.

The NRC staff notes that the ASME Code,Section XI, IWC-5220 "System Leakage Testing" includes two sub-articles, IWC-5221 "Pressure" and IWC-5222 "Boundaries." (a) Please clarify whether the proposed system leakage test was submitted as an alternative to address only the pressure requirement as specified in IWC-5221. (b) IWC-5222(a) and (b) require specific pressure boundaries for the system pressure tests. The NRC staff notes that the licensee's submittal did not address the requirements of IWC-5222(a) and (b). If IWC-5222(a) and IWC-5222 (b) are also the subject of this RR, please discuss the hardship caused by compliance with IWC-5222(a) and 1WC-5222(b), and provide corresponding alternatives.

Luminant Power's Response to Follow-Up Request 1:

Luminant Power did not seek relief from Subsubarticle IWC-5220, which includes Paragraphs IWC-5221 and IWC-5222. The relief request was for Paragraph IWC-5221, which requires that the system leakage test be performed with lines pressurized to the system pressure prior to performing a VT-2 visual examination.

To provide clarification that the relief was sought for Paragraph IWC-5221, Section 5 "Burden Caused by Compliance" and Section 6 "Proposed Alternative and Basis for Use" of Attachment 1 of RR C-3 are repeated below with corrections:

5. Burden Caused by Compliance:

Purposely failing or not installing the inner O-ring in order to perform a pressure test would require purchasing a new O-ring set and the time and radiation exposure associated with removing and reinstalling the RPV head to replace the O-rings would be an undue hardship.

Therefore, compliance with the IWC-5221 system leakage test requirements results in an unnecessary hardship without a sufficient compensating increase in the level of quality and safety.

6. Proposed Alternative and Basis for Use:

In lieu of the requirements of IWC-5221, a VT-2 visual examination of the accessible areas will be performed each period on the piping subjected to the static pressure head when the reactor cavity is filled. This test will be part of the reactor coolant Class 2 leakage test.

Attachment to TXX-14020 Page 2 of 2 COMANCHE PEAK NUCLEAR POWER PLANT UNIT 2 Clarifications to the Response to Request for Information Regarding Relief C-3 for the Reactor Pressure Vessel Leak-Off Flange (Second 10-Year ISI Interval Start Date: August 3, 2004)

If the inner O-ring should leak during the operating cycle it will be identified by an increase in temperature of the leak-off line above ambient temperature. This high temperature would actuate an alarm in the Control Room, which would be closely monitored by procedurally controlled operator actions allowing identification of any further compensatory actions required.

This leakage would be collected in the Reactor Coolant Drain Tank.

Additionally, the flange seal leak-off line is essentially a leakage collection/detection system and the line would only function as a Class 2 pressure boundary if the inner O-ring fails, thereby pressurizing the line. If any significant leakage does occur in the leak-off line piping itself during this time of pressurization then it would clearly exhibit boric acid accumulation and be discernable during the proposed VT-2 visual examination that will be performed unpressurized as proposed in this request. The elevation of the Reactor Vessel flange is 834' 1/2". The elevation for the water level when the cavity is flooded is 858" 6". Therefore, the minimum pressure at the opening of the flange leak-off line when the exam is performed is 24' 5 1/2" of static pressure head or 10.6 psi.

There has been no known evidence of corrosion, stress corrosion cracking, or fatigue in the subject flange leak-off piping at CPNPP.

NRC's request 2 for follow-up Information:

2, Please discuss leakage detection capabilities at the plant, and or any measure(s) taken, to monitor and identify leakage in an unlikely event of a through wall leak in the RPV flange seal leak-off line piping concurrent with leak or failure of the RPV flange inner seal during normal operation.

Luminant Power's Response to Follow-Up Request 2:

During normal operation, the inner O-ring isolation valve is open. Should the inner O-ring leak, a high temperature alarm actuates at 140'F in the control room, informing the operator of the leak. The operator monitors reactor vessel flange leak-off temperature in accordance with CPNPP alarm procedures (ALM-053A for Unit 1 and ALM-053B for Unit 2) and closes the valve, isolating the leak. The procedure directs shutting the manual isolation valve and opening another valve, transferring RCS pressure boundary maintenance to the outer O-ring. Opening the valve then transfers leak detection to the outer O-ring. All drainage/leakage is piped to the reactor coolant drain tank. The procedure also addresses notifying chemistry department to increase monitoring of containment atmosphere to detect possible outer O-ring failure; perform an operations test to determine leakage rate as applicable; and initiating corrective action documents to identify the condition and correct the condition as applicable.