ML20087A820
| ML20087A820 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 05/13/1970 |
| From: | Harold Denton, Pomeroy D US ATOMIC ENERGY COMMISSION (AEC) |
| To: | |
| Shared Package | |
| ML20086U000 | List:
|
| References | |
| FOIA-95-36 NUDOCS 9508070180 | |
| Download: ML20087A820 (12) | |
Text
{{#Wiki_filter:.. . -...~. ~. v. y f,', } r l l [ REPORT OF ASSIST INSPECTION j .E Licensee: Jersey Central Power & Light Company Oyster Creek 1, Docket No. 50-219 I .y i Date.of Inspection: April 21, 22 and 23, 1970 Inspected by: g>m'W /3 gl) D. L. Pomeroy, Eca p Engineer. / bate / Y#f 70 Reviewed by: H. -R. Denton, Chief, Technical Support Branch Date Proprietary Information: None SCOPE. A special, announced inspection was conducted to review.recentgeported operatin's difficulties'with the control rod drive (CRD) system-and to assess the licensee's program for evaluation and correction. The assigned inspector, D. L. Caphton, CO:1, was present during the first day of the inspection. SUMARY' 1. The reactor was shut down on April 19, 1970, by the licensee because of. deteriorating operation of the control rod drive system. After an exami-nation of the first two drives removed 'from the reactor, the licensee decided to rebuild all the drives. T 2. On February 23, 1970, a st411 flow tests on each CDR indicated leakage in excessive of 3 spm for 108 drives. (See Section II A) 3. On April 14, 1970, 52 drives required increased drive water pressure to unistch. (See Section II B) 4. One or more drives failed to fully insert during the last three scrams. (See Section II C) 1 5. Examination of the first four CRD's indicated broken stop and drive piston seales, swollen index tubes and plugged cooling water orifices..(See Section III.) IfInquiry Memo 219/70-D April 9, 1970 9500070100 950227 PDR FOIA DEKOK95-36 PDR
r p (I .I DETAILS I.' Persons Contacted Jersey Central L T. McCluskey, Station Superintendent [ J. Carroll, Operations Supervisor D. Ross, Technical Supervisor W. Riggle, Maintenance Supervisor CPU N. Goodenough, QA Section L. Ludstrom, QA Section G-E N. Biglieri, Design Engineer, CRD's, San Jose II. Result of Record Review A. Withdrawal Stall Flow Tests Periodic measurements of the flow to each CRD with the drive fully withdrawn was undertaken last December. One criterion in the G.E. CRD Manual for accepting a new or rebuilt drive is that the withdrawal stall flow shall be less than 1.1 gpm (drive pressure 250 psi above reactor pressure). Normal seal wear is expected to increase this flow to about 2 gps. Previous discussions with GE representatives indicate that 3 gym is considered to be abnormally high seal leakage. The upper range of the flow instrument is 5 spa. The following are the results of four withdrawal stall flow tests, with each test including 136 drives. (One drive has been out of service since the CRD screen changing program in October 1969.) Date of Test Number of Drives Greater than 3 gpa Greater than 5 gpa 12/5/69 35 7 1/30/70 79 37 3/4/70 94 54 2/23/70 108 65
w N ,9 , n According to the GE CRD Nanual these tests indicate that increased leakage is being experienced at one or more the F following points: 1 1. the collet piston seals, .h.[ 2. the drive piston internal seals, 7 [ 3. the stop piston seals. B. High Pressure to Unistch During the recovery from scram #42 on April 7,1970, the normal-CRD drive water header pressure of 250 paid was insufficient to cause unistching for 38 of the drives.. During the recovery from scram #43 on April 14, 1970, the normal pressure was insufficient for unistching 52 drives. The drives were un-latched in each case (with one exception) by increasing the drive water pressure. Three drives on April.7 and five on April 14 required pressure above 400 psi. (The pressure instrumentation in the control room reads up to 400 psi above reactor pressure). One drive (42-19) on April 14 could not be unlatched and with-drawn even using pressures above 400 paid. This drive was declared unoperable and valved out. Following the shutdown on . April 19 this drive was successfully unlatched after repeated attempts. C. Scrans to the 02 Position On three occasions following a scram, one or more drives were found to be latched at the first notch (02 position, 6 inches withdrawn) rather than fully inserted (00 position). Attachment 1 gives the details graphically. The drives were subsequently driven to 00, indicating that no mechanical interference existed. It is theorized by G-E that the scram motion is. stopped between 02 and 00 and that the drive then settles back to 02. The cause of the stoppage is theorised to be high leakage of reactor water through the top pair of stop, piston seals. This leakage-causes a high back pressure in the buffer zone above the moving drive piston, balancing the force of the scram water. G-E believes that the large buffer _ flow area between position 04 and 02 will prevent the back pressure from building up below the 02 position and thus prevent the drive from stopping further withdrawn than 02.
,i/: l r l i .~- o y ^ D. Scram Dump Fill Time The station event recorder was used to determine the time' from the initiation of a reactor scram to the filling of the ,I scram dump volume to 37 gallons. (At 37 gallons, a high dump j. volume scram occurs.)' In February, the time was measured to be about 26 seconds._ The April 7 scram menseured 10.6 and the I April 17 scram 8 seconds. 6 E. Scram Times i A review of scram. times to 10, 50 and 90 percent insertion for the last three scrans indicated normal drive performance. A review of the scram buffer times (last 10 percent of travel) indicated a wide variation (from 0.2 to 0.7 seconds for the drives that went to 00). F. Control Rod Exercising Following the April 14 scrag /with 2 CRD's out of service, daily rod exercising was required-. Records of this were available for April 16,17, and 18 but not the 15. These records indicated that several drives could not be moved with the normal notching sequence and required the use of the notch override system. Many l drives required over 250 paid drive water preneure, some more than the maximum gauge reading of 400 psid. G. October 1%9 CRD Rebuilding During the October 1969 internal filter removal program, 22 CRD's were rebuilt. The records for this work indicated that the following was found during the drive examination: Stop piston seals Drive piston, internal Drive piston, external Broken 61% Buffer seals broken 68% Seals broken 14% Worn 10% Buffer springs broken 68% Seals' worn and Stuck 5% Up seals broken 52% scored 18% Up springs broken 64% Collet Piston Down seals broken 43% rings stuck 14% l Down springs broken _ 43% 1/ Tech Spec 4.2D l
l c .1 ym a i l Q "Y ' i No records were available to indicate if any index tubes were measured or replaced during this rebuilding. ff III. Results of CRD Inspection v (( .The inspector observed the removal from the reactor and disassembly I of the. first four CRD's. The following summarizes the principal j findings of the inspections: 1 A. Seals 1. Stop piston seals - all four seals on all four drives were - broken. 2. Two of the four drives had broken drive piston internal' seals and springs.
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3. Collet seals on all drives appeared normal. B. Index Tubes Two of the four drives examined had swollen index tubes. The swelling was in the area of the threaded connection to the drive piston and ranged from a 20-40 mils diametrical increase. C. Cooling Water Orifices Three of the four drives were found to have plugged or partially plugged cooling water orifices. The material found was not the normal reactor crud but white or transparent material. It has not been identified nor has its source been located. D. Dirt and Radiation Levels The drives were found to be relatively free from foreign material. One of the three drives had a 10 mil inner filter. Examination of this drive did not reveal a detectable cleaner condition. A small amount of dirt was found in externa 1' filters, t Radiation levels in the drive area were lower than expected by C-E and J. C. personnel. The spud-filter and of the drive read v 60 aren gamma on contact. These parts are removed from the drive first and stored in a pail of water until reassembly begins. A selective review of pencil dosimeter records indicated personnel-exposures generally less than 10 arem per day. No instances of personnel contamination were observed.
/ ,) e 'INDEX TUBE , Indicate Corrosion & Nicks by following key. 48 46 ~ 44 42 06 04 02 00 i ~TT i I I $El i 1 3 s t. Check Bow COLLET AND PISTON ASSDiBLY - Are Rings free in grooves? 1 Are Grooves OK7 , Are Fingers OK7 ' Fingers free on Retsiner? ~ , Is Collet Spring corroded? Is Guide Cap Chipped? ..Is thers West on ID of Guide Capt ~~ PISTON TUBE ASSDiBLY - Chart any Corrosion I i MLIM! - 4} 1 Condition of 0-Rings
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i e , _, _.,,,,,.,.. g.; 9 1,. 7.... 4. 7 O a p: I t. ,s r y, y. 'i PRESSIRE SEAL TEST REPORT FORN .t RE-DISASSEMBLY m o. [ P-l!NDER e. Allowed ML/ Min. Actual ML/ Min. ~ 160 psig. 200 psig. l u Coupling Spud 211' i 189 ,, i 7 t. Co11st Port 1267 1135 Over Pressure Water Port Ph5 757 I \\ Total 2323 !2081 I i - j ( POST ASSEMBLY i l ce, ' P-OFER AllowedML) Min. 9 .,q.. Actual ML4 tin. ~ s' 160 psig. ~200 psig. f r .,s Coupling Spud 12(>7 1135
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v.. Collect Port 2 958 26h9 s. P,T&. . 1,_ .r<.p.. -.gm,. I [h.nN[hunder Pressure Water Pert w ' l-8h5 757 i . t .' g,CE M. e> ;...y.m,.. ~ w,;. . a <.p "i.M. Total % - 5070 h5h1 -{ ~J f'l-[.)r'f ,7; n
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r-t. c1 -) w . IV. Q/A and Requalification Program At the time of the inspection the Q/A program had not been fully L developed and the requalification program had not been planned. (. A Q/A representative from GPU was assigned to each of the two 1 work shifts. They were provided with a disassembly report form it (attachment 2) but were not provided with any reassembly check .k sheets. This was discussed with Mr. Riggle who stated that he would review the G-E CRD manuals and work up a form for their use. 1 At the close of the inspection a pressure seal test report form had been printed for use during the final leak test. The form (attacionent 3) was set up so that either the 160 psig or the 200 psig demineralized water he.sder could be used for the test. The inspector observed that the pressure correction to the allowable I leakage had been made in the wrong direction. Mr. Riggle stated that this would change before the form was used. L I s s .n
r fl } EAST a i 51 s .r i I h 3 i i i t e t - - 35 ) 1,3 1,2,3 i 3 ) S N O ~ ~ 27 U ' 1 1,3 R. 3 H T H j i i I 3 ~~ i l l l/ g i _ i _ _ _11 i .l 1 l l I I ____l______p-_03 \\ l 3 l I I-i l l i e i i 1 18 26 3h h2 50 02 10 y Rods at.02 'l 1 - Scram 42 2 - Scram 43 3 - scram 44 \\
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7 _ =.. _ { DISASSDtBLY REPORT MITROL ROD DRIVE 237E179 }FicngoNo. d Serial No. Plant Identification Date Removed from Location RADIATION LEVELS AS RDt0VED: At Coupling Spud-Max. Along Drive l i i ( . At Flange At Outer Screen i RADIATION LEVELS AFTER CLEANINGt At Coupling Spud i Max. Along Drive At Flange At Outer Screen s ' f, Using the DISASSDtBLY INSTRUCTION & the INSPECTION INSTRUCTION in CEl-29808 as, guides, check the following items. Cosament on any observations that could contribute to drive 1 i failure that are not listed on this form. I UNCOUPLING ROD' ASST. - Are tack welds securef Is right drive number on rodt 'FILTLRS & COUPLING SFUD - What is condition of threads? Art the Fingers Bent? Condition of Wear Surface Condition of Outer Filter Amount of Dirt Condition of Inner Filter Amount of Dirt CfLINDER TUBE 6 MANGE - Bore Condition is Honing Required? Is 0-Ring Sealing Area OK7 s Condition of Strainer Did you' replace the ball retainer 0-Ringt 'Has the Collet Housing area been dentedt (use sleeve as gage) '. DRIVE FISTON ASST. - Are Seal Grooves OKf Did Magnet' Housing Seal Cups come out freely? Are Seal Cups OKf Condition of Seals & Bushings per the sketch & number below. l i s 9 6 1}0 1) 12-i 't t - i -[ g M w v e w A W 4 W N 'Hilic W Gs si t h6' d ' M E Z s u h h o o h o n n j ~ l .J IO I 0 'Ak'TACHMENT'2;./.,[,,,... ,,.I II 4 ,________.m ~ v w---
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- Was Stop Piston tight on Piston Tube?,
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