ML030800243
| ML030800243 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 11/04/2002 |
| From: | - No Known Affiliation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| FOIA/PA-2003-0094 EWR 99-031 | |
| Download: ML030800243 (3) | |
Text
{{#Wiki_filter:ACTION ITEM STATUS REPORT PAGE S~11/04/02 Responsible Person: ALEX FOLTYNOWICZ
- Trkid: EWR 99-031 Urgency: DONE
.*--* Action Number: 1 Work Priority: 4 Activity Pending is: DONE
TITLE AND TASK DESCRIPTION------------------------------------------
AF Pump Recirculation Noise in Control Room Operation of the AF pumps in the.recirculation mode results in Control Room noise (CR 97-0720). Determine if the restriction orifices in the recirculation lines should be replaced with multiple stage restriction orifices. A boroscope inspection of one of these orifices (RO-4008) indicated damage to the orifice due to cavitation. (See J. P. Schroeder to review this video). If the noise is determined not to be a result of cavitation (for example: simply "flow" noise), then provide structural insulation to reduce noise transmission to the Contro Room.
- Also, Operations has stated that Control Room noise was reduced when operating with the B CST at a level of 20 feet and a temR of approximately 100 deqrees F.
These CST conditions were present during U2R23 to fill the SG with heated water for lay-up and Main Feed Pump Check Valve Testing (IT-305A/B) BENEFIT: Reduce Control Room distractions and cavitation damage to AF piping. SUGGESTED SOLUTION: Analyze flow characteristics of AF recirculationpip inq to determine if a multi-stage orifice will reduce o eration noise. Ynstall orifices as required. Flowserve Inc. has stated that they can provide the engineering an replacement orifices. They will need the code that the orifice is required to be designed to before they can provide a cost estimate. Provide sound insulation design if needed. EXPECTED ACTION BY ENGINEERING: Implementation of design change (WO or Modification) SUPERVISOR COMMENTS (SJY): This is an operator distraction of low safety significance, but does present the potential to affect operator response due to increased noise +/-eve+/-.. Signficance Level = 4
DATES-Source Record: 12/08/98
- Evaluation ********* ****** Correction
- Commitment:
Eval Due: 08/01/99 CorrAct Due: Action Create: 04/15/99 Orig Eval Due: 06Z/5Z99 Orig CA Due: Action Closed: 07/29/99 Eval Done: 07/21/99 Corr Act Done: ---PEOPLE------------------------------------------------------------- Responsible for Overall Action: SDM ALEX FOLTYNOWICZ Responsible for Current Pending Activity: Issue Manager: CATHY SOUKUP Initiator: JOHN P SCHROEDER Punchlist Administrator: CATHY SOUKUP
UPDATE--------------------------------------------------------------
(04/15/99 CAS2) Set Work Priority to 4. (04/19/99 LJA1) Received Action into Group: SDC No Priority Assigned Responsible Person: RFH:DICK HORNAK No Due Date Assigned (04/23/99 RFH) Changed Responsible Person: From (RFH) to (AF) Changed Responsible Group: From (SDC) To (SDM).. Consolidate this with other open items tracking this issue. Close redundant items. (04/23/99 RFH) Changed the Due Date from: << BLANK >> to 06/15/99 (06/04/99 AF) CR 96-0574, CR 97-0720, and EWR 99-031 had been written to report that operation of the AF pumps in the recirculation mode results in high level of noise in Control Rpoom and Operation offices. The entire subject of noise in recirculating lines can be traced to two separate areas: 1. The piping itself. 2. The pressure-reducing orifice installe\\n the line to es a lish a specific flow under the prevailing pressure
ACTION ITEM STATUS REPORT PAGE 2 differentials. SEach of the above areas have been reviewed for the possible contribution
- tothe high level'.of noise in the AF recirculating piping system. Field walkdown of the affected piping confirmed existence of high level noise in the area. In addition, high frequency-low amplitude vibra ion was also observed. Inspection of plping supports performed by J.
McNamara-Civil indicated that some of the U-bolts could be tightened whichwould possibly alleviate some of the vibration. However, this will not helpin elimination or significant reduction of noise caused by cavitation erosion of recirculating line pressure reducing orifice. The pressure-reducing. orifice in AF recirculating line controls the amount of water that is recirculated for the AF pump and provide initial pressure reduction of this high pressure fluid (1190 psig to 14.7 psig). The orificeis typically a stainless steal pipe with a multiple pressure reducing orifice plates inside. High pressures drops require multiple orifices in series to revent cavitation and the associated noise. The solution to cavitation is o reduce the pressure from the inlet to the outlet gradually - without allowing the liquid pressure to drop below its vapor pressure. By always keeping the pressure through the component above the vapor pressure, cavitation can be successfully avoided. In this case, orifice with six (6) to nine (9) stages is required to eliminate cavitation and to have predicted noise level of less than 70 decibels. Although, drawing of the installed pressure-reducing orifice was not located therefore, making verification of the number of stages not fissible.Based on the lengtR of the orifice -7 §", it was concluded that the installed orifices do not have required number of stages (6 to 9) to preclude cavitation. Furthermore, the type of noise, which sounds like gravel flowing through the piping is typical to the noise associated with cavitation. Therefore, it is conclud*dythat the noise problem in AF pumps recirculating.piping is caused by cavitation erosion inthe pressu reducing orifice. Tnis conclusion is also supported by the results of the past visual instpection of pressure-reducing orifice RO-4008 (Pump P-35A), where deterioration was found to have resulted from cavitation erosion. NRC Information Notice 98-45 has been issued to address similar problem caused by cavitation erosion in orifices. Review of this notice reveals that orifice damaged by cavitation can cause flow-induced vibration. The vibration, in turn may cause socket welds to fail and also caused some damage to pipe supports and increased component failures. Based on the above it is recommended that an EAC evaluation be performed tolook at three options to resolve this issue. A. Installation of a multi-stage pressure-reducing orifice. B. Replace existing pressure-reducing orifice with a pressure-reaucing flowelement in valve body. C. Retrofit Copes Vulcan control valve with multi-stage pressure-reducing trim. (06/08/99 AF) Requested Due Date: 08/01/1999 (06/08/99 RFH) Changed the Due Date from: 06/15/1999 to 08/01/1999 Evaluation is completed. Refer to above update. As discussed with R. Hornakthis EWR should be submitted for evaluation to EAC. EAC meeting to discuss this EWR is scheduled for 6/15/99. This extention is requested to give enough time to initiate any action itemrequested by EAC. (06/11/99 RFH) CR 96-574, Item 5 is being closed to this EWR. (07/15/99 RFH) CR 96-0720, Item 1 is being closed to this item. (07/16/99 AF) The EAC evaluation of this EWR is summurized in Meeting Minutes NPM 99-0749EAC recommended to work on the two electric motor driven AF pumps in the year 2000. Evaluate performance of the new installation, then if necessary replace the orifices on turbine driven AF pumps in the year 2001. Based on the EAC recommendation, modification request for each AF pump wa s initiated. The following are the MR numbers associated with each pum : P-38A MR 99-029*A Electric motor driven P-38B MR 99-029*B Electric motor driven IP-29 MR 99-029*C Turbine driven 2P-29 MR 99-029*D Turbine driven (07/16/99 AF) Passed to DICK HORNAK for acceptance of work. (07/21/99 RFH) Passed to CATHY SOUKUP for Verification. Based on the latest update, it is recommended that EWR 99-031 may be closedto the action being taken under the MRs 99-029*A thru 99-0 9*D. (07/29/99 CMW) PLA Closure of Item. (09/02/99 JRM) CR 97-0720 action #1 has been closed to EWR 99-031.
ACTION ITEM STATUS REPORT PAGE 3 11/04/02 REFERENCES CR 97-0720 IT-305A/B CR 96-0574 MR 99-029"A THRU 99-029*D -AISN$TA1-x---------------------MISCELLANEOUS Originating Agency: System: AF NRC Open Item Number: iRC Status: Related Outages: Plant Conditions: PLNTCODCSOO***** Operability: OPERDC 000.**** Root Cause Evaluation: N Restart Issue: N Person Hours: Original Estimate = Current Estimate = Actual Hours =}}