IR 05000293/1993008
| ML20045H310 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 06/29/1993 |
| From: | Heggie A, Kay L, Ruland W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| Shared Package | |
| ML20045H308 | List: |
| References | |
| 50-293-93-08, 50-293-93-8, NUDOCS 9307200072 | |
| Download: ML20045H310 (8) | |
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U.S. NUCLEAR REGULATORY COMMISSION
REGION I
REPORT NO.
50-293/934)8 DOCKET NO.
50-293 LICENSE NO.
DPR-35 LICENSEE:
Boston Edison Company RFD No.1 Rocky Hill Road
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Plymouth, Massachusetts 02360 FACILITY NAME:
Pilgrim Nuclear Power Station, Unit 1
INSPECTION DATES:
April 26 - 30,1993 I k$ddky'
K'ym M INSPECTORS:
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'lianne M. Kaj Reactor Engineer Dfte y
Electrical Section, EB, DRS-e]e 6-2F93 is Allison G. Heggie, Efiglneering-Aide Date
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Materials Section, EB, DRS APPROVED BY:
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/-/l 4 29-93
%)411iam H. Ruland, Chief Date Electrical Section, EB, DRS
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9307200072 930712 PDR ADOCK 0500
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Area Insoected: This was an announced inspection to review the licensee's corrective actions of previous findings identified in a system-based instrumentation and control inspection
conducted by the office of Nuclear Reactor Regulation (NRR) in November 1991.
Results: No violations or deviations were identified. Six deficiencies previously identified in inspection report 50-293/91-201 were closed. The inspectors concluded that resolution of
these issues was supported by thorough evaluations and calculations. The licensee's corrective actions were timely and adequate. These items are discussed in Section 2.0.
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DETAILS 1.0 PURPOSE This inspection reviewed and verified the licensee's corrective actions for previously identified NRC findings of NRR's system-based instrumentation and controls inspection for Pilgrim Nuclear Power Station.
2.0 FOLLOWUP OF PREVIOUS IDENTIFIED FINDINGS 2.1 (Closed) Deficiency No. 50-293/91-201-01 involving the inadequate low pressure setpoint for salt service water discharge header j
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During the original review, the inspection team determined that the setpoint for the salt -
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service water (SSW) pumps discharge pressure switches was inadequate. The original setpoint of 15 psig was above the minimum discharge pressure expected during design basis-conditions. This could permit the automatic starting of a second standby SSW pump. A second SSW pump start had not been considered in the diesel loading calculation or final safety analysis report (FSAR). At the team's request, the licensee calculated the minimum discharge pressure expected with one pump running in each SSW system loop. The pressure that would exist during a design basis event was determined to be as low as 3.3 psig. The licensee took immediate corrective actions following this determination and reset the pressure switches to 3.3 psig. This new setpoint would ensure that only one SSW pump per loop would automatically load on the emergency diesel generator (EDG). Subsequent to the original inspection, the licensee reevaluated the EDG loading calculation and stated that the EDG could have carried the extra load should an additional SSW pump have automatically started.
In the response letter to the original inspection report, the licensee stated that a more detailed review of the diesel loading sequences revealed that loads of greater size than the additional
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SSW pump would terminate nineteen seconds prior to starting the standby pump and that sufficient capacity would have been available for the EDG to carry the load. Potential Condition Adverse to Quality (PCAQ) number 91-220 addressed the diesel loading concern.
Diesel loads are made up of continuous loads and short-term loads that operate'only once automatically. The diesel loading calculation included margin by assuming short-term loads operate continuously. Based on analysis of the actual diesel loading and time-delay relay settings that control the start of the second SSW pump, the licensee determined that the necessary diesel capacity was available to start a second SSW pump if header pressure was too low with a single pump operating.
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In addition, the licensee prepared a hydraulic model for the SSW system under emergency l
conditions. This model included testing one loop of the system to gather flow and pressure
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data for calculating the lowest header pressure during single pump operation. Data collected during this test resulted in a pressure value that exceeded the original pressure switch setpoint whereby a second pump would not have started.
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The inspectors reviewed the control logic for sequencing loads to the EDG and emergency
diesel generator capacity presented in loading calculation number PS-79, revision 2. Based on this review and the testing and development of the model for evaluating the lowest header i
pressure, the inspectors determined that sufficient capacity existed on the limiting diesel generator to accommodate the extro loading due to the inadequate SSW pump setpoint.
Based on the licensee's corrective acdons and NRC review, this item is closed.
2.2 (Closed) Deficiency No. 50-293/91 201-02 regarding installation inadequacies During the NRC Setpoint Control Inspection, physical walkdowns were performed of-instrument PS-3828A, PS-3828B, and PT-3828 which monitor SSW discharge header pressure and provide an automatic start feature for SSW pumps. The walkdowns identified
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missing impulse line supports that did not agree with the as-built drawings. In addition, the as-built drawing did not include instrument PT-3828.
The licensee issued a PCAQ to address the configuration, installation, and drawing discrepancies. Plant design change (PDC) 91-70 was prepared and implemented to lower the setpoint of PS-3828A, PS-3828B, PS-3829A, and PS-3829B. This change was performed to ensure that only one salt service water (SSW) pump would start automatically on each diesel generator following a loss of coolant accident (LOCA) coincident with a loss of off site
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power (LOOP).
The licensee provided a calculation that determined the correct spacing between tubing supports. Based on this determination, tubing supports were installed and impulse line slopes were corrected. In addition to these corrective actions, the as-built drawings were corrected to include instrument PT-3828.
The inspectors performed a walkdown of the intake structure where the instruments were installed and verified that the tubing supports and impulse line slopes were corrected. The inspector also reviewed the revised drawing FSK-I-336 (M8328) to verify the as-built condition of instruments PT-3828, PS-3828A, and PS-3828B. No discrepancies were
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identified, this item is closed.
2.3 (Closed) Deficiency No. 50-293/91-201-03 regarding lack of calibration procedure for Instrument PT-3828 This item pertained to the lack of a calibration procedure for instrument PT-3828. Pressure transmitter PT-3828 is located on the discharge header for continuous monitoring of SSW
}, amp discharge pressure and provides indication in the control room. Documentation reviewed revealed that calibration of the instrument had not been perfonned since March, 1982. Further review of calibration procedures 8.E.29.1, " Salt Service Water (SSW)
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Instrumentation Calibration and Functional Test," indicated that calibration for PT-3828 did not exist. Setpoint calculations for the pressure transmitter were also not available, and as a result, the team could not compare field data with the setpoint calculation.
In response to this concern, the licensee initiated PCAQ 91-218 to address the discrepancy.
PT-3828 was calibrated during the team inspection and a revision to Procedure 8.E.29.1 was made. This procedure revision included calibrating PT-3828 at a frequency of once every 18 months.
The inspector reviewed the setpoint calculation and verified that PT-3828 had been included in Procedure 8.E.29.1. This item is closed.
2.4 (Closed) Deficiency 91-201-04 regarding drawing and procedure discrepancies During the team inspection, the NRC identified several examples of inadequate or contradictory drawings and procedures. Three examples are:
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Discrepancy between drawing M-212 and schematic E-170. Drawing M-212
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specified a time delay of 2 minutes for TDR-74-3828 while schematic E-170 specified a 10 second delay. Alarm response procedures ARP-CIR-F1 and ARP-CIR-F2 referenced a 2 minute delay.
(2)
Calibration procedure 8.E.23 for high pressure coolant injection (HPCI)
suction high pressure instrument PS-2360 failed to establish the correct setpoint of 70 1.35 psig, as stated on drawing MIP335-3 and instrument data sheet 225A5757. Instead, procedure 8.E.23 determined an incorrect setting of 77 i 1.35 psig.
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Calibration procedures 8.E.9 and 8.E.10 for torus water level instruments LS-
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5066 and LS-5037 failed to establish the correct setpoint of (-) 5.5 inches from the appropriate reference line, as indicated on Drawing M-263, Sheet 115, Revision 2. Instead, these procedures determined incorrect settings of (-) 5.75 and (-) 6.0 inches from an unknown " marked line."
The licensee determined that a 10-second delay was appropriate for TDR-74-3828. Piping and Instrumentation Drawing (P&lD) M-212, SM415, revision E4 and procedures ARP-CIR-F1 and ARP-CIR-F2 were revised to reflect the proper 10-second delay. Calibration
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procedure 8.E.23 was revised to reflect a 70 1.35 psig setpoint. The licensee determined that the setpoints were inadvertently changed due to a typographical error when the calibration procedure was revised. Additionally, procedures 8.E.9 and 8.E.10 and alarm response procedures ARP-9031-D4 and ARP-9041-H4 were revised to reflect the correct setpoints. These setpoints were incorrectly typed when procedure revisions were made to 8.E.9 and 8.E.10.
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6 The inspectors reviewed the procedure and drawing revisions and concluded that the
licensee's corrective actions were appropriate. Based on this review this item is closed.
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2.5 (Closed) Deficiency No. 50-293/91-201-05 regarding inadequate forus level lustrumentation During the original setpoint inspection, the team determined that the torus water level operating limits established by procedure were found to be the same as the Technical Speci5 cation (TS) limits with no margin available to account for loop inaccuracy. TS 3.7. A.1.M requires that during normal plant operation the water level in the suppression pool shall be maintained between -6 inches and -3 inches referenced to instrument zero. This
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requirement translates to a maximum allowable tolerance of i 1.5 inches water level.
Contrary to this, the torus water level instruments, LT-5049 and LT-5038 used for maintaining water level within TS limits were found to have a tolerance of 1.7 inches. This 1.7 inches of total instrument error exceeded the 1.5 inches allowable. The 1.7 inches error consisted of 1.3 inches total loop uncertainty and 0.4 inches of transmitter installation elevation error over a 16" range.
In response to this concern BECo performed a preliminary loop uncertainty calculation and confirmed the actual elevation of the level transmitters. Based on the calculation results, the operational range for the torus water level was narrowed to the range of -5.25 to -3.75 inches by administrative procedures to include instrument error. This operating band ensures that these plant parameters remain within the design basis and TS requirements at all times.
Further actions by the licensee included replacement of the torus level transmitters with transmitters of greater accuracy. PDC 92-10, " Replacement of Torus Level Transmitter LT-5030 and LT-5049" included modification to the transmitter piping to accommodate the new 14" range transmitters, replacement and recalibration of the scales and chart papers for the records, and recalibration of the torus water level computer points. The newly installed transmitters have an expanded operating band compared to the original transmitters.
Calculation number PI-N1-73, revision 0, "LT-5038 and LT-5049 - Torus Water Level Loop Accuracy Calculation" evaluated the new loop uncertainties and determined that the newly installed transmitters have an expandable operating band from 1.5" to 2.4" of indicated scale. This band increase is due to the new transmitters having less moving parts and a displacer of shorter length thereby reducing the uncertainties of the torus level loop and subsequently allowing for a greater operating band.
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The inspectors performed a walkdown and reviewed the newly installed transmitters. The inspectors determined that the licensee's corrective actions were appropriate and a good effort was completed for determination of a datum in support of establishing a benchmarx with known tolerance for instrument calibrations. Based on the above licensee actions, the inspectors concluded that the required torus level parameters would remain within the design basis and TS limits. This item is closed.
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1 2.6 (Closed) Deficicucy No. 50-293/91-201-06 regarding inadequate torus temperature instrumentation During the initial inspection it was noted that TS 3.7.A.I.C required that the torus bulk j
temperature be maintained at 80'F during normal continuous power operation. Contrary to this, the design basis requirement for torus water temperature was not correctly translated into specifications and procedures. Administrative procedure 2.1.15, revision 87, daily log test number 17 and standing order 1.3.54 for operations specified that the torus water temperature be reduced when it reached 78 F. This requirement provided only a 2*F margin to account for instrument loop uncertainty. However, instrument loop uncertainty for the safety-related torus water terrperature instruments (T5021-01 A,B through -04, A,B) were calculated in accordance with Reg Guide 1.105, and was found to be i 5.2 F which
exceeded the allowable margin.
j In response to this concern, the licensee administratively lowered the allowable indicated
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operating temperature via Standby Order 91-07 utilized o Operations personnel. Further
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actions by the licensee included replacement of the reconn and indicators with instruments of i
increased av ( tcy.
In addition, the licensee told the inspectors that the BWR Owner's Group is in the process of resolving this issue on a generic basis. The Owner's Group was analyzing existing margins between the analytical limit ind TS limits for suppression pool temperature. The BWR Owner's Group analysis demenstrates that a minimum margin of 20"F exists between these two limits.
The inspectors review ed calculation number I-N1-52, and I-N1-52 revised, "R.G.I.97 Loop Accuracy Calculation for the Terus Water Temperature Monitoring System for Channel A and B", respectively. Results of this calculation demonstrated a target totalloop inaccuracy of i 3.9 F for the newly installed recorders. This inaccuracy was determined to be less than the existing 5 F idmimstrative limit for torus water temperature. Based on the licensee's actions to replace the recorders and indicators with instruments of greater accuracy, established administrative measures to limit bulk temperature, and recent industry data supporting an existing margin between analy.ical and TS limits, the inspector concluded that the torus water temperature was being maintained to ensure the safe operation of the plant as required by TS.
3.0 DEFICIENCIES A deficiency is defined as either an apparent failure to comply with a requirement or satisfy a written commitment to conform to a rule, regulation, or industry practice as defined in
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inspection report 50-293/91-201.
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4.0 EXIT MEETING The inspectors met with licensee personnel, denoted in Attachment 1 of this repon, at the conclusion of the inspection on April 30,1993. At that time, the scope of the inspection and inspection results were summarized. The licensee acknowledged the inspection findings as detailed in this rep t and had no additional comments regarding the inspection results.
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ATTACIIMENT 1
PERSONS CONTACTED I
Boston Edison Company
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Basilesco Senior Compliance Engineer
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Dasgupta Control Systems Division Manager.
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Boulette Senior Vice President, Nuclear R. Fairbank Nuclear Engineering Department Manager
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Keene S&SA Engineer J. Keyes Acting Compliance Division Manager
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Kirven Engineering Design Section Manager
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Oheim Regulatory Affairs & Emergency Preparedness Manager
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Rancourt Senior Instrumentation & Control Engineer U.S. Nuclear Reculatory Commission
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J. Macdonald Sr. Resident Inspector, Pilgrim site
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- Denotes personnel present at the exit meeting on April 30,1993.
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