ML15187A274
| ML15187A274 | |
| Person / Time | |
|---|---|
| Site: | Boiling Water Reactor Owners Group |
| Issue date: | 08/31/2015 |
| From: | James Drake Licensing Processes Branch (DPR) |
| To: | Anthony Mendiola Licensing Processes Branch (DPR) |
| Drake J | |
| Shared Package | |
| ML15187A267 | List: |
| References | |
| Download: ML15187A274 (5) | |
Text
August 31, 2015 MEMORANDUM TO: Anthony J. Mendiola, Chief Licensing Processes Branch Division of Policy and Rulemaking Office of Nuclear Reactor Regulation FROM:
Jason J. Drake, Project Manager
/RA/
Licensing Processes Branch Division of Policy and Rulemaking Office of Nuclear Reactor Regulation
SUBJECT:
TRIP REPORT FOR U.S. NUCLEAR REGULATORY COMMISSION (NRC) STAFF VISIT TO NWT CORPORATION ON MAY 27-28, 2015, TO OBSERVE BOILING WATER REACTOR (BWR) OWNERS GROUP (BWROG) CHEMICAL EFFECTS TESTING RELATED TO THE EMERGENCY CORE COOLING SYSTEM, SUCTION STRAINER PROJECT On May 27-28, 2015, the NRC staff visited NWT Corporation in San Jose, California and met with representatives of the BWROG, emergency core cooling system (ECCS), suction strainer (SS) Project Committee. This meeting followed an agreement established in the December 4, 2014, public meeting (Agencywide Documents Access and Management System (ADAMS)
Accession No. ML14356A148) with the BWROG, to conduct an on-site visit with NWT Corporation to witness and discuss chemical effects testing. The NRC staff participating in the visit included Vic Cusumano (NRR/DSS/SSIB), Jason Drake (NRR/DPR/PLPB), Matthew Yoder (NRR/DE/ESGB), and Paul Klein (NRR/DE/ESGB). The enclosure provides a list of all participants. The following provides a description of testing and key discussions.
Discussion Dr. Steve Sawochka of NWT provided the opening remarks for the meeting along with NWT corporate background and scope of services provided. Updates and reposes to previous NRC staff comments from the January 8, 2015, teleconference meeting (ADAMS Accession No. ML15133A359) were discussed at the onset of the meeting.
During the visit, the NRC staff received an update of the chemical effects testing program.
Potential post-accident chemical effects in BWRs are being evaluated by benchtop testing and vertical loop head loss testing. NWT representatives provided a tour of the laboratory, allowed the NRC staff to observe testing samples and provided a detailed overview of both the benchtop testing equipment and high temperature loop facility.
CONTACT: Jason Drake, NRR/DPR 301-415-8378 Jason.Drake@nrc.gov
The primary goal of the benchtop tests is to assess the tendency for precipitates to form in simulated BWR post-LOCA conditions. Three sets of benchtop tests (18 total tests), had been completed prior to the NRC staff visit. Test Sets 1 and 2 contained aluminum with or without fiberglass insulation in sodium pentaborate and demineralized water solutions, respectively.
Test Set 3 contained galvanized carbon steel and demineralized water. Two of the galvanized carbon steel tests contained some fiberglass, two other galvanized carbon steel tests added sodium pentaborate after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. All bench tests were performed in 2 liter polycarbonate containers at 2000F for 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />, followed by 1400F for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, and 1100F for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. In general, material release rates from these tests were in reasonable agreement with earlier bench testing performed by Alion Science and Technology. No precipitate formation was visually observed in any of the benchtop tests. A limited decrease in solution concentrations in some cases, however, suggests precipitates may have formed.
A small scale vertical loop piping system was constructed to evaluate how chemical precipitates, if formed, affect the head loss of across a fiber bed. The vertical loop contains a pump, a heater to raise the temperature, a feed tank for mixing chemicals, an exposure column that permits control of flow past test specimens, and a 4-inch diameter column with a perforated test screen. A data logger records flow, conductivity, differential pressure, feed tank level, and temperature. Figures 1 and 2 show the overall NWT piping loop and the test screen, respectively. The NRC staff observed the building a fiber bed on the test screen in the vertical loop. NWT personnel used a commercial beater to prepare 5 gram batches of fiberglass in test solution. These batches were subsequently added to the loop to establish a test bed on the perforated screen.
Three vertical loop head loss tests were completed prior to the NRC staff visit. Two tests were performed with demineralized water and the third test used a sodium pentaborate solution to represent the chemistry with standby liquid control (SLC) System injection. The head loss in the third test was significantly greater than the first two tests. Analysis of the results is in progress.
The following items highlight key observations provided by the NRC staff to the representatives from the nuclear industry during our visit:
- 1. The NRC staff expressed appreciation for the opportunity to visit and observe chemical effects related testing. The NRC staff thinks on-site observation of testing combined with discussion with subject matter experts significantly improves our ability to understand the BWROG program.
- 2. The NRC staff reiterated the importance of an accurate, fleet-wide response to the plant materials survey since the chemical effects testing parameters are based on the survey response. Incomplete survey responses could result in plant material combinations not being evaluated in the current program. The BWROG indicated that plant materials surveys validation will be completed in the 3rd Quarter of 2015.
- 3. Given the uncertainty related to post-accident SLC injection timing, tests should evaluate a range of conditions related to sodium pentaborate addition times to determine which times and materials may be the most limiting with respect to precipitate formation and head loss.
- 4. An evaluation should be performed that considers if post-LOCA acid generation would affect suppression pool pH in the absence of sodium pentaborate.
- 5. Estimates of uncoated steel should include areas of coating removed within the pipe break zone of influence (ZOI).
- 6. The NRC staff considers the formation of a repeatable, stable, debris bed that will detect chemical precipitates to be a critical step in the vertical test loop evaluations. Beds should be demonstrated to be capable of detecting precipitates at the start of the test.
Note that the NRC staff does not mean to imply that precipitates be added to each test to demonstrate sensitivity since that may confound post-test bed analysis.
- 7. Incremental addition of precipitate to determine the amount of precipitate (mass per area) that results in significant head loss is a good way to benchmark these tests to previously performed testing. For example, following the visit, NRC staff compared the aluminum based chemical precipitate addition in the NWT loop to earlier bed sensitivity testing performed at the Argonne National Laboratory (ANL). The total quantity of precipitate (on a grams of aluminum per test screen area) added in the NWT sensitivity test was approximately double that of the ANL test. It is not clear to the NRC staff if the difference was from more efficient filtering by the ANL bed (fiber prepared in a blender) or a result of differences in timing of precipitate addition.
- 8. The NRC staff questioned if different flow conditions could increase the release rate of some materials (e.g., carbon steel, galvanized steel) relative to the bench top testing.
For example, the NRC staff asked if higher flow or water cascading from a higher elevation could remove corrosion products from plant materials in a way that would not be reflected in the bench tests.
- 9. The NRC staff suggested leveraging of PWR data and experimental baselines from PWROG/BWROG counterparts that have performed elevated temperature vertical loop tests.
Project No. 691
Enclosure:
List of Participants
ML15187A274; *concurred via e-mail NRR-106 OFFICE DPR/PLPB/PM DPR/PLPB/LA*
DE/ESGB/BC DSS/SSIB/BC DPR/PLPB/BC DPR/PLPB/PM NAME JDrake DHarrison GKulesa VCusumano AMendiola JDrake DATE 08/24/2015 08/18/2015 08/25/2015 08/26/2015 08/28/2015 08/31/2015 ENCLOSURE List of Participants NRC Staff Visit to NWT Corporation to Observe Chemical Effects Testing Related to the Emergency Core Cooling System, Suction Strainer Project Boiling Water Reactor Owners Group (BWROG) and U.S. Nuclear Regulatory Commission (NRC) Staff May 27-28, 2015 Name Organization Steve Sawochka NWT Corporation Matt Leonard NWT Corporation Mike Miller NWT Corporation M.L. Hyde NWT Corporation B.L. DeBold NWT Corporation Rob Choromokos BWROG / SIA Mike Iannantuono BWROG / GEH Phil Grissom BWROG / Southern Jason Drake NRC Victor Cusumano NRC Paul Klein NRC Matthew Yoder NRC