ML17153A001

Staff Observations of Testing for Generic Safety Issue 191 During a May 10 to May 11, 2017, Trip to the Alden Test Facility for Control Components Inc. Strainer Tests

ML17153A001
Person / Time
Site:	Arkansas Nuclear
Issue date:	06/06/2017
From:	Russell A P, Smith S J Safety Issues Resolution Branch
To:	Cusumano V G Safety Issues Resolution Branch
Russell A; Smith SJ
References
CAC MC4663, CAC MC4664
Download: ML17153A001 (12)

Text

June 6, 2017

MEMORANDUM TO: Victor G. Cusumano, Chief Safety Issues Resolution Branch Division of Safety Systems Office of Nuclear Reactor Regulation FROM: Stephen J. Smith, Senior Reactor Systems Engineer /RA/ Safety Issues Resolution Branch Division of Safety Systems Office of Nuclear Reactor Regulation Andrea P. Russell, Reactor Systems Engineer /RA/ Safety Issues Resolution Branch Division of Safety Systems Office of Nuclear Reactor Regulation

SUBJECT: STAFF OBSERVATIONS OF TESTING FOR GENERIC SAFETY ISSUE 191 DURING A MAY 10 TO MAY 11, 2017 TRIP TO THE ALDEN TEST FACILITY FOR CONTROL COMPONENTS IN STRAINER TESTS On May 10 through 11, 2017, three members of the U. S. Nuclear Regulatory Commission (NRC) staff traveled to the Alden Research Laboratory (Alden) in Holden, Massachusetts to observe testing associated with the resolution of Generic Safety Issue-19 The objective of the trip was to observe an Emergency Core Cooling System strainer fiber penetration test for Arkansas Nuclear One (ANO) and to ensure that testing is being conducted consistent with NRC staff guidanc The participating NRC staff members were Vic Cusumano, Steve Smith, and Andrea Russell of the Office of Nuclear Reactor Regulatio The NRC staff members interacted with personnel from the ANO licensee along with vendor personnel from Alden and Enercon Services, In The enclosure summarizes the NRC staff's visit on May 10-11, 201

Enclosure:

As Stated CONTACTS: Stephen J. Smith, NRR/DSS Andrea P. Russell, NRR/DSS 301-415-3190 301-415-8553

V. Cusumano STAFF OBSERVATIONS OF TESTING FOR GENERIC SAFETY ISSUE-191 DURING A MAY 10 TO MAY 11, 2017 TRIP TO THE ALDEN TEST FACILITY FOR CONTROL COMPONENTS INC. STRAINER TESTS DATED JUNE 6, 201 DISTRIBUTION: ASmith ARussell SSmith VCusumano Public PKlein MYoder RidsNrrPMANO ADAMS Accession No.: ML17153A001 NRR-106 OFFICE NRR/DSS/SSIB NRR/DSS/SSIB NRR/DSS/SSIB/BC NAME SSmith ARussell VCusumano DATE 6/6/2017 6/6/2017 6/6/2017 (SSmith for)OFFICE NRR/DSS/SSIB NRR/DSS/SSIB NAME SSmith ARussell DATE 6/6/2017 6/6/2017 OFFICIAL RECORD COPY ENCLOSURE OBSERVATIONS OF TESTING AT ALDEN RESEARCH LABORATORY MAY 10 TO 11, 2017 Trip Summary This trip was conducted to observe the Emergency Core Cooling System (ECCS) strainer fiber penetration testing for Arkansas Nuclear One (ANO), Units 1 and 2 and more generally to evaluate the methodology used at Alden Research Laboratory (Alden) for strainer fiber penetration testin The U.S. Nuclear Regulatory Commission (NRC) staff considered the test observations necessary because Alden developed a new strainer bypass test facility for ANO for this tes The trip allowed the NRC staff to gain confidence that testing is being conducted in a manner consistent with staff guidanc This testing will determine how much fiber may pass through the strainer to aid in evaluating how equipment downstream of the strainer may be affecte NRC staff observations during testing did not identify any significant concerns with the test facility or methodolog Testing and Facility Overview On May 10 and 11, 2017, the NRC staff observed a fiber bypass test for ANO at Alde Alden has the capability to perform tests in several facilitie Alden has been conducting testing of ECCS strainers with technical assistance from strainer vendors and other engineering consultants for several year The test observed by the NRC staff was performed in a custom built test tank for ANO made of acrylic (Photo 1). The test tank contained the test strainer modules as shown in Photos 2 and Figures 1, 2, and 3 show the tank geometry and schematic of the test loo The test tank is comprised of an upstream section, strainer box, and plenu The test loop is comprised of the test tank, pumps, piping, heat exchanger, filter bag housings, isokinetic sampler, a main recirculation pump, and debris hoppe The test loop contains valves necessary to isolate or throttle flow, and fill and drain the tan Instrumentation for test strainer head loss, test flow rates (test strainer, plenum cross-flow, and debris introduction), filter housing head loss, and water temperature are installed in the loo Water pH and conductivity were measured with hand held instrument Some of the instrumentation is connected to a desktop computer for display, trending, and data collectio The test facility also incorporates a parallel loop for the introduction of the debris source The loop diverts some of the primary loop pump discharge to a hoppe Debris is poured into the hopper and mixed with turbulent water flow to dilute and break up the debri The debris then flows out of the hopper and gravity drains into the test tan Hard copies of the test plan, test procedure, and design specifications were provided to the NRC staff prior to the testin Test Setup and Strainer Details The test tank contained three Control Components, Inc. (CCI) strainer cartridges (Photos 2 and 3), with 400 mm long pockets (applicable to both Units 1 and 2). The strainer array was contained within the walls of the tank (Photo 4). Both ANO Units 1 and 2 strainers are designed and manufactured by CC Each strainer consists of several modules, each module consists of several cartridges, and each cartridge is made up of several pockets formed out of perforated plate The ANO Unit 1 strainer is a monolithic design installed over the containment sum The total surface area of the ANO Unit 1 strainer is 2,715 square feet (ft2). The ANO Unit 2 strainer consists of two branches of strainer modules that extend from the east and west side of a common sump plenu The plenum encloses the containment sump pi The total surface area of the ANO Unit 2 strainer is 4,837 ft The cartridges used in the test are spare cartridges of the 400 mm modules installed at Unit The area of the test strainer modules was 81.05 ft The resulting scale factor for ANO Unit 1 is 0.0299 and for Unit 2 is 0.0168 based on the prototypical strainer surface areas presented in the paragraph abov Flow for Units 1 and 2 is 4,867 gallons per minute (gpm) and 3,532.5 gpm per train maximum, respectivel Test debris amounts and flows were scaled based on the ratio of the area of the plant strainer to the test straine Some NRC staff visited Alden around 12:00 pm on Wednesday, May 10, 2017 to witness test preparatio The NRC staff met with representatives from the ANO licensee, Alden, and Enercon Services, In Testing began at 8:30 am on Thursday, May 11, 201 Test Parameters A week prior to the penetration test discussed in this report, the licensee performed an initial penetration tes The results from that test were used to inform the parameters used for the test discussed in this repor For the subject test, the following parameters were use

• Fiber Type: Nukon (used as surrogate for other fiber types on an equal mass basis)

• Water Chemistry: 2,154 parts per million Boron; 7.545 grams per liter Sodium Tetraborate Decahydrate (NaTB)

• Approximate pH: 8.0

• Fiber Concentration: 0.00170 pounds mass (lbm) per cubic feet (ft3) lbm/ft3 - 0.00816 lbm/ft3

• Water Temperature: 100 °F (based on first penetration test, the temperature was lowered from 120 °F to 100 °F due to damage to the test tank from the higher temperature)

• Approach Velocity: 0.008 ft/s

• Fiber Preparation: High-pressure water jets in accordance with the NEI guidance

• Plant spare strainer cartridges were used for the testing

• Flow Condition Approaching Strainer: Sizing of the test strainer shall ensure flow conditions approaching the strainer are comparable to the actual strainer at the plant The NRC staff observed the preparation of debris prior to its addition to the tes Fiber Penetration Test Performance The fibrous debris was created from sheets of Nukon fiberglass that has been heated on one side to simulate being installed on hot pipin The sheets were cut into smaller pieces using a large paper cutter, then the tough unburnt outer layer was further torn into smaller piece This fibrous debris was then placed into a large tan The tank contains a manifold fed from a high pressure pum The discharge of the pump exits the manifold through small nozzle The high pressure and high velocity fluid renders the fiber into fine piece The tank is manually stirred during the process to ensure that all of the fiber is exposed to adequate jet forces to attain the desired size distributio The method produces fine fiber of the desired characteristic The system is capable of preparing about 2 lbs. of fiber (one five gallon bucket of dry cut up fiber) at a tim The NRC staff noted that the fiber could agglomerate into larger clumps after preparation, but that stirring, or adding via the hopper resulted in the agglomerations breaking apar Debris additions for the penetration test began in the morning on May 11, 201 The water was at about 100 ° Flow was maintained at +5/-0% of the prescribed test flow rat The fluid in the test was buffered and borated demineralized water to simulate plant conditions following a LOC The minimum submergence level of the strainer during testing was at least 6" to ensure that debris was allowed to prototypically transport and distribute along the test straine The submergence level was also adequate to prevent surface vortexin A fiber debris load equivalent to 213 lbm at ANO Unit 2 plant scale was used for the tes Once a cumulative debris load equivalent to approximately 115 lbm at ANO Unit 2 debris load with some margin, was added to the tank, sufficient time was provided to quantify shedding (or long term release of fiber through the strainer) at this debris loa Incremental fiber additions were used for the penetration testing, where the batch sizes were increased gradually throughout the penetration testin Before the introduction of each additional debris batch, it was confirmed that little to no debris was suspended in the test tank from the previous batc The filter bag change schedule was such that it ensured that fiber penetration data obtained from the testing was adequate to evaluate both prompt penetration occurring as fiber arrives at the strainer as well as long-term penetration due to fiber that accumulated on the strainer migrating through the debris bed and strainer (shedding). Long-term penetration was evaluated for the last batch of debris, as well as some intermediate batche The long-term penetration data will be used to extrapolate the penetration results out to 30 day The test loop was run a minimum of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> after the final debris addition (maximum hot leg switchover time for ANO Unit 2). The NRC staff left prior to the test endin After the test, the filter bags with collected fibers were rinsed with de-ionized water and then dried and weighed, with the weight gain of each bag taken to be the amount of fiber collecte The licensee for ANO will develop a curve-fit to adequately capture the testing results and apply them to plant condition The curve-fit will characterize both prompt and long-term penetratio In-vessel fiber accumulation will be quantified deterministically using penetration fractions from the fiber penetration curve-fi The NRC staff conducted a short exit meeting with the licensee and other test personnel from Enercon Services, Inc. and Alde The NRC staff expressed appreciation for the opportunity to observe the testin Observations The NRC staff considered the results of the observed test to be of significant interes The major points are as follows: 1) Testing appeared to be conducted per the staff guidance on penetration testin ) Observation of the debris collected on the strainer indicated that most of the debris was captured and did not penetrate the strainer. (Photos 5 and 6) 3) The wet filter bags from the testing observed by the staff did not appear to contain a significant amount of fibe (Photo 7) 4) The dried filter bags from the testing the prior week did not appear to contain a significant amount of fibe (Photo 8)

Summary The NRC staff observed ECCS strainer performance testing conducted for ANO by Alden and Enercon Services, Inc. at the Alden Research Laborator Debris surrogates used in the test were representative of those expected following a LOC The testing observed by the NRC staff and the test conducted the prior week provide confidence that the licensee's testing adequately represents the plant conditions and therefore is sufficient to predict penetration at the plan The NRC staff will continue to engage the licensee and vendors as sump strainer testing progresses and is incorporated into their evaluation Figure 1 - ANO Test Tank (Isometric View)

Figure 2 - Upstream Tank Section (Plain View) Figure 3 - Piping and Instrumentation Diagram Photo 1 - Test Tank Photo 2 - Front View Strainer Module Photo 3 - Side View of Strainer Module Photo 4 - Strainer in Test Tank Photo 5 - Strainer with Fiber Photo 6 - Strainer with Fiber Photo 7 - Wet Filter Bags from Current Test Photo 8 - Dried Filter Bags from Prior Test