IR 05000498/1988012

Insp Repts 50-498/88-12 & 50-499/88-12 on 880208-25.No Violations Noted.Major Areas Inspected:Startup Testing Phase,Including Hot Precritical Tests Identified in Table I

ML20150E248
Person / Time
Site:	South Texas
Issue date:	03/18/1988
From:	Ireland R, Andrea Johnson NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
To:
Shared Package
ML20150E243	List: IR 05000498/1988012 ML20150E240
References
50-498-88-12, 50-499-88-12, NUDOCS 8803300187
Download: ML20150E248 (10)

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APPENCIX U.S. NUCLEAR REGULATORY COMMISSION

REGION IV

NRC Inspection Report: 50-490/88-12 Operating Licenses: NPF-71 50-499/88-12 Construction Permit: CPPR-129 l I

Dockets: 50-498 I 50-499 Licensee: Houston Lighting & Power Company (HL&P) l P.O. Box 1700 l Houston, Texas 77001 Facility Name: South Texas Project (STP), Units 1 and 2

Inspection At: STP, Matagorda County, Texas i I

Inspection Conducted: February 8-25, 1988 )

Inspector: h,. bf m,yp7 h/n /%

A. R. Johnson, Re ctor Insp~e~ctor, Plant Date Systeins Sectio , Division of Reactor Safety Accompanying Personnel: W. C. Seidle, Chief, Test Programs Section Division of Reactor Safety J. P. Clausner, Reactor Inspector Division of Reactor Projects Approved: O 4< 3/d/

R. E. Ireland, Acting Chief, Plant Systems ' ~

Date l Section, Division of Reactor Safety )

Inspection Summary Inspection Cenducted February 8-25, 1988 (Report 50-498/88-12); 50-499/88-12)

Areas Inspected: Routine, announced inspection of Unit 1 startup testing phase - hot precritical tests identified in Table I below, including witnessing i of tests, review of test data, and evaluation of test result No inspection of Unit 2 was conducte PDR ADOCK 05000498 p DCD

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Results: The NRC inspector, ascertained that the licensee complied with procedural requirements and that test program records were adequate. The NRC inspector also ascertained that uniform criteria by the licensee were being applied for evaluating completed startup tests to ensure technical and administrative adequac Within the areas inspected, no violations or deviations were identifie _ _ - _ _ _ _ _ _ _ _ _ .

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Table I HL&P Station Procedure N Title 1 PEP 04-ZL-0024, Revision 3 Rod Drop Time (Hot and Cold)

1 PEP 04-ZL-0050, Revision 5 Test Sequence for Hot Precritical Testing IPEP04-ZL-0054, Revision 2 RCS Flow Measurement at Hot Standby 1 PEP 04-ZL-0061, Revision 2 Incore Movable Detector System (Flux Mapping)

1 PEP 04-ZL-0062, Revision 2 RCS Flow Coastdown Measurements i

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DETAILS

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4 Persons Contacted

.HL&P

• Wisenburg, Plant Superintendent, Unit 1

• J. Loesch, Plant Operations Manager

• S. Dew, Manager, Operations Support J. Broadwater, Startup Manager '

G. Ondriska, Startup Engineer D. Leazar, Reactor Performance Supervisor M. Friedlander, Reactor Performance Department- ,

J. Gunn, Station Technical Advisor R. Dunn, Test Director

+*J. Nesrsta, Plant Engineering Manager '

G. Parkey, Plant Superintendant, Unit 2

+*S. Head, Superintendant of Licensing Engineering J. Broadwater, Startup Manager J. Westermeir, Project Manager D. Parker, Startup Manager .

J. Phelps, Supervisor, Project Compliance 1 J. Geiger, General Manager, Nuclear Assurance l S. Phillips, PCG Licensing, Engineer '

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J. Slabinski, Operations, Quality Assurance (QC)

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Westinghouse l

+J. Irons

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+W. Lyman

+S. Spiegelman NRC

+ Seidle, RIV, Chief, Test Programs Section

• 0. Carpenter, Senior Resident Inspector J. E. Bess, Resident Inspector

+ Clausner, Reactor Inspector

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D. Garrison, Resident Iospector

+P. Kadambi, NRR Project Manager

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+ Hodges, NRR Project Manager

+ L. Milhoan, Director, Division of Reactor Safety (DRS)

+ J. Callan, Director, Division of Reactor Projects (DRP)

+ B. Beach, Deputy Director, ORP

+ Murphy, Plant Systems Section, DRS

+ Johnson, Reactor Inspector

• Uenotes those present at the exit meetin +0enotes those present on conference call between NRR, RIV, HL&P, and Westinghouse on February 23, 198 ____ _ __

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5 , RCS Flow Measurement at Hot Standby (1 PEP 04-ZL-0054)

The NRC inspector verified by reviewing test data and evaluating test results from the RCS flow measurements at hot standby performed in late January 1988, that-the licensee was meeting the requirements and corditions of the facility licens The NRC inspector ascertained that'

the licensee adhered to the station procedure during the test.. Although ad)quate to assure that test requirements had been satisfied, the conclusions of the test report indicated high pressure values representing possible excessive RCS flow, NRC Observations on Indicated Excessive RCS Flow During the test documentation review, the NRC inspectors were concerned about the large disparity between the pressure measurements which indicated a possible RCS flow rate of 441,900 gallons per minute (gpm) and the minimum acceptable RCS flow rate of 343,400 gpm stated in Procedure 1 PEP 04-ZL-0054. (The_STP-1 FSAR identifies the thermal design flow as 381,600 gpm, and the minimum RCS flow rate at 90 percent of this value or 343,400 gpm.) The inspectors' concern was that the mechanical design flow limit, stated in the FSAR as 426,400 gpm, could have been exceeded. Westinghouse best estimate flow data for STP-1 were not contained in the test report package and the station procedure contained no upper limit for the mechanical 1 design flow, therefore it could not be determined if the upper limit had been exceeded, Background

STP-1 is one of the few plants which uses short radius elbows with pressure taps for flow measurement. The standard radius elbows with )

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pressure taps, supplied by Westinghouse (NSSS) for most four-loop i plants, consistently indicate higher than actual flow Westinghouse has ascertained from measurements in other plants that the standard elbow tap inaccuracy is consistently 110 percent. Since STP-1 has l short radius elbows, the error could be much highe I The purpose of the RCS flow measurement test-(1 PEP 04-ZL-0054) was to assure that the mielmum RCS flow rate, during hot standy conditions, was equal to or in excess of the minimum 343,400 gpm specifie During RCS flow testing, STP-1 short elbow pressure indication data  !

were taken and documented for purposes of comparison to elbow flow I history obtained from other Westinghouse four-loop plants. Later, l during the startup program, calorimetric flow data will be obtained,

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at the 75 percent power ascension plateau, to accurately establish '

flow values consistent with the Westinghouse "best estimate" flows for STP- , - -- .- , . . .- - . . _ _ - . -_ . ..- -

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c. NRC Assessment The NRC inspector reviewed the test data and the calculations contained in the test report package. Pressure indications from the elbow tap differential pressure (DP) instrumentation, indicated a total RCS flow rate of 441,900 gpm. During a conference call with NRC and the licensee on February 23, 1988, Westinghouse provided a best estimate flow rate of 410,000 gpm. This value was based on system hydraulic predictions using pump performance curves and best estimate component flow resistances. It was observed by the NRC inspectcr that the indicated RCS flow rate was 7.78 percent greater than the Westinghouse best estimate flow rate. This 7.7P is within the 110 percent accuracy experienced by other Westinghouse plant Concerning the possibility of excess RCS flow rate, Westinghouse stated that the mechanical design flow rate margin is 4 percent above the best estimate flow rate. Westinghouse believes that the actual RCS flow rate at STP-1 is within this design flow margin of 4 percen To exceed the mechanical design flow limit in these flow rate calculations (426,400 gpm), the pump performance and component flow resistances woul.1 have to be in error by 12 to 15 percen Westinghouse considers such an error to be unlikely, considering that excessive reactor t.;olant pump power input was not evident during the hot functicnal tests. However, calorimetric measurements to be made at the 75 percent power ascension plateau will be required to verify the Westinghouse best c:timate flow rate and to confirm the flow rate value is within the Westinghouse mechanical design flow rate margin of 4 percen d. Additional Testing by HL&P in Regard to the Potential for Excessive RCS Flow In considering the possibility of excessive RCS flow rate at STP-1 during January 1988, after the hot functional testing program was near completion, the licensee performed an eddy current examination of all 58 instrument guide thimbles for the incore movable detector syste Two known plants (Tihange 3 in Belgium and Paluel in France), both having 14-foot reactor core heights, have experienced instrument guide thimble degradation due to abnormal flow characteristics. The results of the eddy current tests demonstrated no degradation resulting from flow induced vibration, particularly at the lower part of the core. The licensee considers that RCP pump i performance characteristics and component flow resistances are within the Westinghouse mechanical design flow margin of 4 percen e. Westinghouse Recommendations Westinghouse considers the indicated elbow tap pressure measurements at STP-1 to be representative of 100 percant flow rate, and recommended that instrument span scaling should be corrected to agree l

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with the 100 percent flow rate indication on the main control board even though the present calibrations appear to be high. These adjustments'were performed on February 13, 1988, just prior to the RCS flow coastdown measurements testing (1 PEP 04-ZL-0062, see paragraph 3 below). HL&P and Westinghouse Commitments HL&P and Westinghouse, in response to NRC concerns expressed during a conference call on February 23,=1988, committed to the following:

(1) To resolve the NRC observations.of disparities,.which indicate high RCS flow. rate at STP-1, including the NRC assessment contained in this report (paragraph 2.c. above.)

(2) To establish an upper'RCS flow rate limit directly related to elbow tap pressure measurements taken at STP-1 for startup purpose This,information'is to be included or referenced in the RCS flow measurement at Hot Standby Test Report Package (1 PEP 04-ZL-0054) and should include bases and rational (3) To determine what special procedures were used to install the elbow taps at the fabricators shop (Southwest Fabricators) to demonstrate that instrument accuracy is within margins acceptable to Westinghouse. This includes' confirmation that the special procedures used to install the elbow taps have been implemented correctly as documente (4) To reference specific design criteria (including industry standards) used in NSSS design of short elbow flow tap measurement devices (e.g., ASME Power Test Codes on Flow Measurements; ASME Fluid Meters their Theory and Application, etc.).

(5) Tc adequately document all test results and to explain how these relate to the NRC observations of indicated inaccuracy in RCS flow rate The NRC considers the RCS flow measurement results to be an open item pending completion of documented test results and resolution of the actt!al RCS flow rates with the flow rates indicated by the short radius elbow differential pressure tap (498/8812-01)

The documented test results and test report for RCS Flow Measurements at Hot Standby (1 PEP 04-ZL-0054) lacked the substance necessary to assure that test requirements have been fully satisfied, in that the organization of documented test information and the test data were not readily understandable or traceable to permit independent verification of conclusions. Pending-completion of the records of testing and review by the NRC inspector, this is considered to be an open item (498/8812-02).

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3. RCS Flow Coastdown Measurement (IPEP04-ZL-0062)

The NRC inspector evaluated and verified that the licensee was meeting the requirements and conditions of the facility license by reviewing test data and evaluating test results (report) for the RCS flow coastdown measurement test performed on February 13, 198 The NRC inspector ascertained that the licensee was adhering to station procedures and that test program records were adequat The purpose of this test was to: (a) measure the rate at which the RCS flowrate decreases subsequent to a simultaneous trip of all four reactor coolant pumps (to verify that the measured coastdown rate is within the limits used in the FSAR analysis of a complete loss of flow transient);

and (b) measure the low-flow trip time delay (time from the low-flow trip initiation in the first loop to the time stationary grippers are deenergized and the control rods are free to fall).

The NRC inspector verified that the prerequisite RCS Flow Measurement at Hot Standby Test (1 PEP 04-ZL-0054), had been performed prior to commencing the coastdown measurement test. This included rescaling (span adjustments) of the RCS elbow tap flow measurements at full 100 percent (four-loop) flow during hot zero power standby conditicn Several field change requests (FCR) were initiated early in this test to correct inadequacies in the tcst procedure. In particular, FCR 88-0302 added the prerequisites of closing PORVs and steam dump valves to maintain temperature stability of the RCS following RCP trip. FCR 88-0304 added a l constant B to the (TAU u ) equation; this had been inadvertantly left out of the procedure. The NRC inspector confirmed the constant B value as l correct from Westinghouse startup procedure No. TGX/THX-SU-2.1.8, Revision During the end of the test, when the four RCPs were restarted, a safety injection (SI) signal occurred as a result of the low low compensated T parameter. However, all test data had been collected for the test prioh to this event. A station problem report was generated and dispositione The measured flow coastdown rate (taug ) of 12.99 seconds obtained during the test, was greater than the minimum acceptance criterion time constant TAUn of 12.02 second Also, the icw flow trip relay time delay TLF of 0.854 seconds, obtained during the test, was less than 1.0 second minimum as required by the acceptance criterion. Since these results met the acceptance criteria the NRC inspector concluded that the test was satisfactor Within the areas inspected, no violations or deviations were idantifie .- . - - - - .. - - . _ _ _

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9 Incore~ Movable Detector System (Flux Mapping) Hot Functional Test 1 PEPO 4-ZL-0061)

The NRC inspector evaluated and verified that the. licensee was meeting the requirements and conditions _of the facility license by reviewing test data and evaluating test-results (report) for the above hot'. precritical functional test performed on February 1-12, 1988.. The NRC inspector ascertained that the licensee was adhering to station procedures and the test program records were adequate except as noted belo During the test, the top and bottom of core limit switch setpoints with the six neutron flux detectors installed were established and ensured to be in proper operation. It was also verified that appropriate digital / analog signals were supplied to the Westinghouse supplied plant computer (PROTEUS) and movable incore detector control consol Each of the six drive units with detector and hobbed drive cable assembly were checked for proper operation; this included the five path transf u device (normal, calibrate, emergency, common group, and storage modes) and :

the ten path transfer device (58 penetrations into the reactor vessel '

lower head). The six detectors and cable assemblies were run to the end of the instrument guide thimbles (in core) in the shortest and longest cable conetuits (cable runs) to determine a variance from the lengths determined in an earlier test,1 PEP 04-ZL-0021, (Incore Movable Detector ,

System Checkout). The variance obtained in this test was used to establish.new limit switch setpoints with the neutron flux detector -

positions. Also, signals were sent through the detector circuitry to verify that the plant computer and the control console readout panel received proper signal .

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During the test, in an attempt to rotate drive "E" detector and cable through the 10 path transfer device, movement stopped at 1025.3 inches requiring detector and drivewheel "E" to be replaced. New limit switch setpoints were then re-establishe '

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checked out and that it was operationa t Within the areas inspected, no violations or deviations were identifie . Rod Drop Time Measurements (Hot and Cold) (PEP 04-ZL-0024)

The NRC inspector reviewed the rod drop tests performed during hot-full flow conditions. During this test some minor problems occurred, and the NRC inspector verified that the licensee took appropriate corrective actions. It was noted in the test records that four rods did not meet the acceptance criteria during initial testing because drop times were outside of the upper limi In accordance with the FSAR, Chapter 14 and RG 1.68 i these four rods were redropped three times before the licensee concluded that the acceptance criteria were met and the test was completed. Based

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on review of test results, the NRC inspector concluded that the test had been properly conducted and that the data show that each of the control rods consistently meets the acceptance criteri No violations or deviations were identifie . Exit Interview An exit interview was conducted with HL&P personnel on February 25, 1988, at the conclusion of the onsite inspection, during which the inspection findings were summarize (