ML14206B144

May 21, 2014 Summary of Meeting with Exelon Generation Company, LLC, to Continue Discussions on the Proposed Risk-Informed Approach to the Resolution of Generic Letter 2004-02 (TAC Nos. MC4672 and MC4673)

ML14206B144
Person / Time
Site:	Calvert Cliffs
Issue date:	11/06/2014
From:	Morgan N S Plant Licensing Branch 1
To:
Morgan N S
References
GL-04-002, TAC MC4672, TAC MC4673
Download: ML14206B144 (6)

Text

LICENSEE: Exelon Generation Company, LLC FACILITY: Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2 SUBJECT: SUMMARY OF MAY 21,2014, MEETING WITH EXELON GENERATION COMPANY, LLC, TO CONTINUE DISCUSSIONS ON 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" WITH A FOCUS ON ONGOING CHEMICAL EFFECTS TESTING AND EARLY RESULTS (TAC NOS. MC4672 AND MC4673) On May 21, 2014, a Category 1 public meeting was held between the U.S. Nuclear Regulatory Commission (NRC) and representatives of Exelon Generation Company, LLC, the licensee, at NRC Headquarters, Two White Flint North, 11545 Rockville Pike, Rockville, Maryland. The purpose of the meeting was to discuss 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" with a focus on ongoing chemical effects testing and early results for Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2. The meeting notice and agenda, dated May 8, 2014, is available in the Agencywide Documents Access and Management System (ADAMS) at Accession No. ML 14128A233. A list of attendees is provided in the Enclosure, but may not be all inclusive. The licensee discussed: (1) Autoclave test results; -CCNPP-CHLE [chemical effects head loss experiment]-005 High Temperature Tests (ADAMS Accession No. ML 13149A399) -CCNPP-CHLE-006 Metals Tests (ADAMS Accession No. ML 13149A405) -CCNPP-CHLE-01 0 Concrete & Insulation Tests (ADAMS Accession No. ML 14206A993) -CCNPP-CHLE-011 Long Term Integrated Simulation Tests (ADAMS Accession No. ML 14206B001) (2) Integrated CHLE test plans; (3) Small scale penetration test plans; and (4) Future periodic meetings. (See ADAMS Accession No. ML 14142A323).

-2-Plant Modifications 1. The licensee indicated that it is continuing to work on modifications to regulate sump fluid temperature at the site and plans to complete installation of temperature instrumentation during the 2015-2016 outages. The licensee is performing this modification to provide the operators with additional options to ensure adequate emergency core cooling system flow in the event of a loss-of-coolant accident (LOCA). 2. The licensee stated that during the 2014 refueling outage, some fibrous insulation located near potential large-break LOCA (LBLOCA) locations was replaced. The replacement activities focused primarily on removing mineral wool. 3. The licensee removed some calcium silicate located near potential LBLOCA locations. The remaining calcium silicate insulation in this location was double-jacketed and double-banded to prevent it from being a source of debris. The calcium silicate insulation that was removed was replaced with reflective metal insulation. Downstream Effects-lnvessel 4. The licensee stated that strainer "bypass" tests performed in 2007 resulted in approximately 8 grams of fiber per fuel bundle passing through the strainer. This test did not meet NRC guidance and more testing is planned. Strong Acid Generation 5. The licensee stated that strong acid generation was determined using published information on radiolysis and release of ionizing radiation for post-accident conditions. This information will be used in upcoming testing and evaluation of the postulated LOCA environment. CHLE Test Program 6. The licensee stated that it is developing a baseline test for the double-ended guillotine break LBLOCA. This test will only include boron and no other chemical elements. The licensee indicated that it is still developing the design basis of the chemical effects tests. Autoclave Testing Preliminary Results-CHLE-005 7. The purpose of the high temperature test is to determine if operating a large scale test at less the 200 degrees Fahrenheit would result in representative dissolved species concentrations compared to the highest projected post LOCA temperatures. The licensee stated that the high temperature test was conducted at two temperature regimes. The results of the testing conducted at 195 degrees Fahrenheit for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> were compared to tests conducted at 280 degrees Fahrenheit for 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br />. The licensee indicated that the concentrations of calcium, zinc, and copper in tests conducted at 195 degrees Fahrenheit were equivalent to tests conducted at 280 degrees Fahrenheit. The licensee stated that the concentrations of aluminum at 195 and at 280 degrees Fahrenheit do not converge. However, the licensee stated that the concentration levels are lower than the levels observed in WCAP-16530. The licensee

-3 -is proposing to add metal salts to make up the difference in chemical elements. The NRC found the approach of adding salts to achieve expected dissolved specie concentrations acceptable, but did not provide feedback on the merits of the individual chemicals proposed by the licensee. Autoclave Testing Preliminary Results 8. At the time of the meeting, the licensee stated that it had performed 60 autoclave tests. 9. The licensee stated that it will use coated coupons to model inorganic zinc. The licensee also indicated that it will include galvanized steel in the testing. 10. The licensee stated that it will obtain concrete from the same batch of concrete found in containment. Integrated CHLE 11. The licensee stated that it is working on shake-down testing at the Alden lab facility. At the time of the meeting, the licensee stated that the alkyds autoclave testing is still in progress. 12. The licensee stated that the integrated test will include galvanized steel and inorganic zinc coated steel coupons. The velocity in the test will be comparable to the approach velocity of the debris bed for the strainer. The sodium tetraborate used in the experiment will be in the form of small granules. The licensee stated that the ratio of the spray phase to the injection phase is approximately 8:1. The licensee stated that the best estimate for pH for the integrated test is 7.3. Similarly, the pH for the autoclave test was determined to be 7.3. The licensee indicated that it will not make efforts to maintain the pH of the integrated test; rather it will add the representative amount of buffer and allow the system pH to evolve during the test. Previous tests have shown that the buffered system maintains a stable pH during testing. 13. The licensee stated that it will send test plans for CHLE-01 0 and -011 and papers on Marinate and zinc to the NRC staff. 14. The licensee stated that it will confirm the debris bed sensitivity by adding WCAP-16530-NP-A precipitate to the test tank. This will also provide information relative to the lag time between precipitation in the test tank and head loss response in the vertical loop containing a debris bed. Members of the public were in attendance. A Public Meeting Feedback form was received. The NRC staff reviewed the form and entered the information into the Public Meeting Feedback System.

-4-Please direct any inquiries to me at 301-415-1016, or Nadiyah.Morgan@nrc.gov. Docket Nos. 50-317 and 50-318 Enclosure: List of Attendees cc w/encl: Distribution via Listserv Nadiyah S. Morgan, Project Manager Plant Licensing Branch 1-1 Division of Operating Reactor licensing Office of Nuclear Reactor Regulation LIST OF ATTENDEES MAY 21, 2014, MEETING WITH EXELON GENERATION GL 2004-02 RISK-INFORMED RESOLUTION CALVERT CLIFFS NUCLEAR POWER PLANT, UNIT NOS. 1 AND 2 !NAME , Nadiyah Morgan Paul Klein , Matt Yoder I Stephen Smith ' Aloysius Obodoako : Steve Kinsey I Eric Federline I ORGANIZATION , Exelon MPR Associates, Inc. 1 MPR Associates, Inc. i Exelon Exelon Enclosure

-4-Please direct any inquiries to me at 301-415-1016, or Nadiyah.Morgan@nrc.gov. IRA/ Nadiyah S. Morgan, 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: List of Attendees cc w/encl: Distribution via Listserv DISTRIBUTION: PUBLIC LPLI-1 R/F RidsAcrsAcnw_MaiiCTR RidsNrrDorl RidsNrrDorllpli-1 RidsNrrPMCalvertCiiffs RidsNrrLAKGoldstein RidsRgn1 MaiiCenter A. Obodoako, NRR P. Klein, NRR M. Yoder, NRR S. Smith, NRR ADAMS Accession No.: ML 142068144 T. Wertz, NRR T. Bowers, EDO Region I RidsNrrDeEsgb M. Diaz-Colon, NRR RidsNrrDssSsib OFFICE DORL/LPLI-1/PM DORL/LPLI-1/LA DE/ESGB/BC DSS/SSIB/BC DORL/LPLI-1/BC NAME NMorgan KGoldstein GKulesa VCusumano BBeasley DATE 8/12/2014 08/07/2014 10/15/2014 10/16/2014 11/06/2014 OFFICIAL RECORD COPY