ML13091A055

Summary of Meeting on March 20, 2013, with Calvert Cliffs Nuclear Power Plant, LLC, to Discuss the Proposed Risk-Informed Approach to the Resolution of Generic Letter 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation D

ML13091A055
Person / Time
Site:	Calvert Cliffs
Issue date:	04/10/2013
From:	Bhalchandra Vaidya Plant Licensing Branch 1
To:
Vaidya B K, NRR/DORL/LPL1-1, 415-3308
Shared Package
ML13092A198	List: ML13091A055
References
TAC MC4672, TAC MC4673
Download: ML13091A055 (8)

Text

REGuZq>-0;;,. UNITED STATES NUCLEAR REGULATORY COMMISSION /!! <I: C"> 0 WASHINGTON, D.C. 20555-0001 t;; April 10, 2013 i'J') ****.. LICENSEE: Calvert Cliffs Nuclear Power Plant, LLC Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2 SUMMARY OF ADDITIONAL CATEGORY 1, PUBLIC MEETING ON MARCH 20,2013, WITH CALVERT CLIFFS NUCLEAR POWER PLANT, LLC, TO DISCUSS THE PROPOSED RISK-INFORMED APPROACH TO THE RESOLUTION OF GENERIC LETTER 2004-02, "POTENTIAL IMPACT OF DEBRIS BLOCKAGE ON EMERGENCY RECIRCULATION DURING DESIGN BASIS ACCIDENTS AT PRESSURIZED-WATER REACTORS" (TAC NO. MC4672 AND MC4673) On March 20,2013, a Category 1 public meeting was held between the U.S. Nuclear Regulatory Commission (NRC) and representatives of Calvert Cliffs Nuclear Power Plant (CCNPP), LLC, the licensee, at NRC Headquarters, Rockville, Maryland. The purpose of the meeting was to continue the discussion of the licensee's proposed risk-informed approach to the resolution of Generic Letter (GL) 2004-02, "Potential Impact of Debris Blockage on Emergency Recirculation during DeSign Basis Accidents at Pressurized-Water Reactors (PWRs)" for Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2 (Calvert Cliffs). This meeting was a continuation of the discussion that took place in the Category 1, Public Tele-conference on January 8,2013. The licensee's presentation material is provided in Enclosure 2 to this meeting summary. The licensee (1) presented an overview of Calvert Cliffs' risk-informed approach and forecasted schedule to the resolution of GL 2004-02; (2) discussed the licensee's risk-informed approach versus previous NRC accepted methodologies for deterministic calculations and compared its approach to how South Texas Project (STP) is proceeding forward; and (3) continued the discussion of the Calvert Cliffs chemical effects head loss considerations. The CCNPP expressed its deSires to have monthly discussions from this point moving forward in order to adhere to the proposed testing schedule. The NRC staff responded that they would like to talk when there is a "step-change" in the test plans, and the deterministic vs. Risk Informed (RI) considerations are included in the documentation. NRC will review the document CHLE-005 (which will be publicly available as part of the meeting summary), and determine the most appropriate way to provide feedback. Tim Sande, a public attendee, asked for clarification on how a deterministic margin is quantified vs. how a risk-informed approach test is quantified. The NRC responded by stating that there are a number of different ways to build in margin, and the NRC is more than willing to entertain different approaches. However they would need additional details in order to properly comment on them.

2 A list of attendees is provided as Enclosure 1, but may not be all inclusive. The licensee's presentation slides are provided in ADAMS Accession No. ML 13086A549 and the summary discussions is provided in Enclosure Members of the public were in attendance. Public Meeting Feedback forms were not Please direct any inquiries to me at 301-415-3308, or Bhalchandra K. Project Manager Plant Licensing Branch 1-1 Division of Operating Reactor licensing Office of Nuclear Reactor Regulation Docket Nos. 50-317 and 50-318

Enclosure:

1. List of Attendees 2. Summary of Discussions cc w/encl: Distribution via Listserv Bailey . -_..LIST OF MARCH ADDITIONAL MEETING WITH CALVERT CLIFFS NUCLEAR POWER PLANT, RISK-INFORMED APPROACH TO THE RESOLUTION OF GL CALVERT CLIFFS NUCLAR POWER PLANT. UNIT NOS. 1 AND : ORGANIZATION ......_..........NRCNRRIDE I NRC/NRR/DE,-::----.----,---.-------.-.--........--.-.-...----........--.-..'--'---"jNR I Gloria Kulesa j MPR Associates, Inc. ..*--------....-**..*--r*--------*--****-**-*-* --------...i Enercon Services. Inc. (Public Participant) Zigler(*) Services, Inc. (Public Participant) 1"""'"[T-o-m-K-on-e-rt-h----------**..*--------rCalvert Cliffs .*.-...--. Andrew Henni I Bob Peterson I Peter Wi Ikens(*y-*---------**u-.... Amanda Harrison(*) IAndrew E. Kauffman(*) Calvert Cliffs ..... -------.--......., .._..._-_.-........... Sargent & Lundy LLC -.....--.. ---..... . (*) by Toll-Free line Enclosure 1 SUMMARY OF DISCUSSIONS CATEGORY 1, PUBLIC MEETING ON MARCH 20, 2013 G12004-02, GSI 191 1) The licensee indicated that a number of steps were being taken to support resolution of GSI-191 at Calvert Cliffs including replacement of some fibrous insulation (roughly 80 percent of the mineral wool) with reflective metallic insulation, enlarging refueling pool cavity drains, removal of aluminum sources from containment, installation of instrumentation to monitor emergency core cooling system suction temperature and operational changes to control post-LOCA sump temperatures. In addition, the plant is performing the engineering for removal of additional fibrous insulation, if needed to resolve the issue. 2) The licensee indicated additional strainer testing was performed in 2010 that was not submitted to the NRC. The additional tests with the proposed post-2018 plant configuration had a total head loss, including chemical effects, approximately 7 times lower than the earlier strainer tests. In addition to a change in the test debris amounts, the licensee indicated that the 2010 strainer tests were performed with a slower addition of WCAP-16530 precipitates compared to the earlier tests. 3) The staff stated that the licensee's path forward is not clear, such as whether a deterministic or risk-informed solution was being pursued. The licensee stated that they hoped to show deterministically that strainer head loss and in-vessel effects would be acceptable based on decreased chemical effects. The licensee, however, is going to begin their evaluation using a risk-informed approach. 4) The staff indicated that it would be difficult to review and provide feedback on the licensee's methods without knowing more details concerning the licensee's approach. For example, the staff would have different expectations for a risk-informed approach as compared to a deterministic approach. 5) The licensee and staff discussed a number of items related to chemical effects testing. Since the test plan is still under development, the staff and licensee will continue the discussion when details become available. a. The licensee agreed that they would ensure the sensitivity and reproducibility of any "detector bed" used in long-term testing. b. Test details such as quantities of materials, pH profile, temperature profile, flow past test materials, cooling during the final part of the test, interpretation of test results, and repeatability are important features that the NRC staff will consider in the overall evaluation. c. The licensee stated that they are currently contracting to build a chemical test facility in which to perform the testing. Enclosure 2

-The licensee stated that they were currently working on getting some preliminary dissolution tests performed using autoclaves to evaluate the highest temperature portion of the test. The licensee stated that they would like to have staff feedback on the procedure being used. The licensee provided the procedure (CHLE-005) to the NRC staff during the meeting. Licensee document CCNPP-CHLE 002, "Chemical Effects Head Loss Experiment (CHLE) Protocol for Calvert Cliffs Nuclear Power Plant," discussed a proposed method for applying chemical effects head loss from a long term vertical head loss loop test with a "detector bed" to reduce the conservatism of chemical effects head loss measured during strainer tests with WCAP-16530 precipitate addition. The NRC staff indicated that it may consider such an approach but more details would need to be available before the staff could perform an evaluation. Some guiding principles that the staff would use to evaluate this type of approach would include: (i) confidence exists that the limiting precipitate formed during representative testing results in less chemical head loss impact than the limiting chemical head loss impact from testing with WCAP precipitate; (ii) confidence exists that the detector bed head loss is similar or conservative with respect to chemical effects impact over the range of potentially limiting plant-specific debris beds; (iii) phenomenological (e.g., chemistry) and other uncertainties are adequately accounted in the overall assessment. For example, the NRC staff expects the following information would be provided to help the staff better understand the proposed approach: Results from all strainer tests with WCAP precipitate such that the baseline head loss and head loss due to chemical precipitate addition during strainer tests is well understood. Results from detector bed shakedown testing that show the baseline head loss is stable and reproducible. Test results demonstrating the detector bed is at least as sensitive to chemical precipitates as the debris beds that formed during plant-specific strainer tests. Details concerning how the chemical head loss from the proposed long-term tests with plant materials would be applied to the strainer tests with WCAP precipitate. A discussion of how the uncertainties related to post-LOCA chemical effects are accounted for, as applicable, in either a deterministic or risk-informed approach. In response to a statement in licensee document CHLE-002, the NRC staff stated that it would not be appropriate to ignore a chemical effects head loss increase less than 10 percent of the long-term test baseline head loss. The licensee discussed how piping less than 2 inches in diameter would be addressed. Currently, it is not planned to include piping below 2 inches in the evaluation. However, for larger piping, all size breaks will be considered from a 'Y2 inch

-3 hole size up to and including a double-ended guillotine break. The staff stated that the licensee approach will be discussed with cognizant NRC staff that were not at the meeting to determine if the licensee's methodology is adequate. The licensee and staff discussed the assumptions used for the transport evaluation. The licensee noted that some of the assumptions used by STP for their risk-informed pilot were not yet reviewed and accepted by the staff. The licensee stated that they intended to use transport methods that had been approved by the NRC staff. The staff and licensee discussed how outstanding chemical effects PIRT issues could be addressed in their testing and evaluation. The NRC staff noted, in general, that chemical effects evaluations that contain greater margin will need to address fewer PIRT issues. The staff and licensee agreed on the path forward for most of the PIRT issues. The staff clarified that an agreement that "testing can address a PIRT item" does not necessarily mean the issue is resolved since the test details become important to addressing the issue. The NRC staff stated that they need further internal discussions on Items 5.1 Inorganic Agglomeration and 6.2 Organic Agglomeration. The NRC staff also stated that they consider a number of the PIRT Items related to the presence of a radiological source term to be linked, with the general issue being whether the presence of a radiological source term could affect the head loss across a debris bed. The staff stated that they were unsure how additional chemical effects test results would be applied by the licensee to their plant-specific in-vessel effects, but noted that if the licensee can show the amount of fibrous debris reaching the reactor vessel core following a LOCA was within the limit specified in the NRC staff's Safety Evaluation Report for WCAP-16793, this should not be an issue. The licensee stated that they were planning on performing bypass testing to determine inputs for downstream evaluations. This is acceptable to the NRC staff. The staff also stated that the licensee may consider contacting the Salem Plant because the staff had agreed with Salem representatives that it was possible for them to use previous bypass test results. The staff questioned whether the licensee's debris preparation procedures for fibrous and particulate debris would result in realistic surrogates. The licensee is considering the appropriate methods to prepare the debris.

-4 REFERENCE DOCUMENTS: CCNPP-CHLE-001, Revision Oc, "Chemical Effects Head Loss Experiment (CHLE) Test Plan for Calvert Cliffs Nuclear Power Plant." ML13038A487 -Endorsement of NEI 10-07. (ML 13035A453) CCNPP-CHLE-002, Revision Oe, "Chemical Effects Head Loss Experiment (CHLE) Test Protocol for Calvert Cliffs Nuclear Power Plant." (ML 13086A550). CCNPP-CHLE-003, Revision Oc "Chemical Effects PIRT Considerations for Calvert Cliffs Nuclear Power Plant." (ML 13086A551) CCNPP-CHLE-005, Revision 1, "Chemical Effects Autoclave Experimental Plan for Calvert Cliffs Nuclear Power Plant." (ML 13088A220) Calvert Cliffs Nuclear Power Plant, Units 1 and 2 -PIRT Item Summary. (ML 13038A604)

A list of attendees is provided as Enclosure 1, but may not be all inclusive. The licensee's presentation slides are provided in ADAMS Accession No. ML 13086A549 and the summary of discussions is provided in Enclosure 2. Members of the public were in attendance. Public Meeting Feedback forms were not received. Please direct any inquiries to me at 301-415-3308, or Bhalchandra.Vaidya@nrc.gov. Ira! Bhalchandra K. Project Manager Plant Licensing Branch 1-1 Division of Operating Reactor licensing Office of Nuclear Reactor Regulation Docket Nos. 50-317 and 50-318

Enclosure:

1. List of Attendees 2. Summary of Discussions cc w/encl: Distribution via Listserv DISTRIBUTION: PUBLIC RidsOgcMailCenter lWertz, NRR LPLI-1 RlF RidsRgn1 MailCenter JCassidy, EDO Region I RidsAcrsAcnw_MailCTR SBailey, NRR RidsNrrDeEsgb RidsNrrDorl PKlein, NRR N. Morgan, NRR/DORL RidsNrrDorlLpli-1 MYoder, NRR RidsNrrPMCalvertCliffs SSmith, NRR RidsNrrLAKGoldstein RidsNrrDssSsib ADAMS Accession Nos.: Package: ML 13092A198 Meeting Summary: ML 13091A055 ee mg N f LM f 0 Ice: ML 13050A511 Presentatlon S'd 6A549lies: M 1308 OFFICE DORULPU-1/PM DORULPU-1/LA DE/ESGB/BC DSS/SSIB/BC DORULPLI-1/BC NAME BVaidya KGoldstein GKulesa SBailey SMeighan DATE 04/04/13 04/04/13 04/09/13 04/10/13 04/10/13 OFFICIAL RECORD COpy