ML20236H713
| ML20236H713 | |
| Person / Time | |
|---|---|
| Issue date: | 10/18/1987 |
| From: | Naidu K, Stone J Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20236H687 | List: |
| References | |
| REF-QA-99900824 NUDOCS 8711040293 | |
| Download: ML20236H713 (6) | |
Text
{{#Wiki_filter:- ____-_- _ _ _ _ _ _ _ _ - ORGANIZATION: STATIC-0-RING OLATHE, KANSAS i REPORT INSPECTION INSPECTION NO.: 99900824/87-01 DATES: 08/05-07/87 ON 9TTF Holm9 1a CORRESPONDENCE ADDRESS: Static-0-Ring ATTN: Mr. J. Johnson
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Vice President 11705 Blackbob Road Olathe, Kansas 66061 ORGANIZATIONAL CONTACT: Harry Hartman TELEPHONE NUMBER: 913-764-961n NUCLEAR INDUSTRY ACTIVITY: Pressure & differential pressure switches. ASSIGNED INSPECTOR: 4' L b /t M 7 K. R. Naidu, Program Develpment and Reactive I) ate InspectionSection(PDRIS) OTHER INSPECTOR (S): J. C. Stone APPROVED BY: ,,ctu .
/0 7 J.C/ Stone, Chief,PDRIS,VendorInspectionBranch at INSPECTION BASES AND SCOPE:
A. BASES: 10 CFR Part 21, Appendix B to 10 CFR 50. B. SCOPE: Review actions taken to correct setpoint drift in differential , pressure switches; action taken to select diaphragm material in pressure switches and verify implementation of QA program in selected areas. PLANT SITE APPLICABILITY: LaSalle Unit I and 2(50-373,50-376), Davis-Besse (50-346). B711040293OhhNO PDR GA999 E PDR l i 99900024 j
ORGANIZATION: STATIC-0-RING OLATHE, KANSAS s REPORT INSPECTION l NO - QQQnnA7a/A7 01 RFSUITS* PArJ 7 nf 6 l A. VIOLATIONS: No violation was identified during this inspection. B. NONCONFORMANCES: Contrary to Criterion X of Appendix B to 10 CFR 50, and Section 10.6 of the SOR Quality Assurance Manual, 8303-100, the inspectors observed that the adjustment screw for manipulating the setpoint for 102/103 differential pressure switches, which was manufactured to Drawing 8305-034, Revision 2, dated November 13, 1986, was inspected by S0R QC and documented to be in accordance with Revision 1, dated June 22, 1984 of this drawing. C. UNRESOLVED ITEMS: i No unresolved items were identified during this inspection. D. INSPECTION FINDINGS AND OTHER COMMENTS: ,
- 1. Background Information On June 1, 1986, LaSalle County Station (LSCS) Unit 2 was operating ;
at 95 percent power level when a feedwater transient occurred which ' caused the water level in reactor vessel to drop to the level 3 trip setpoint. One of the four differential pressure switches (DPS) manufactured by SOR responded to the drop in level and actuated , resulting in a half scram. The LSCS operator recovered water level and continued operation. Subsequent investigation determined that three DPSs failed to trip at their set level. The NRC issued Bulletin 86-02 and Information Notice 87-47 to alert other users of potential problems with SOR DPSs. LSCS took corrective actions to establish revised setpoints, modify the calibration methodology and instituted surveillance programs to verify the calibration of the DPSs at predetermined intervals depending on the function, location of the DPS, and procedures. Conservative action and rejection ; limits for the DPSs were established. If a DPS exceeded the action limit for two consecutive calibrations, it was scheduled to be replaced within 14 days. If any DPS exceeded its rejection limit, the switch was to be replaced and the rejected switch was to be disassembled, inspected, and the results o.f the inspection sent to the NRC. The following are the typical action limit and rejection limit values for a switch.
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ORGANIZATION STATIC-0-RING OLATHE, KANSAS REPORT INSPECTION wn . 000nnp ? A /R7.n1 RFRill TS. PAGF 3 nf 6 Inches of Water Column Nominal Level Setpoint I J translated to differential 23.00 During calibration, the DPS is set between 22. - 23.6" Action Limit 21.3" (23-1.7) (theswitchshouldactuate 24.7 (23+1.7) ' betweenthesesetpoints) Tech Spec Limit of tolerance 1.78" Rejection Limit 17.7" (23-5.3) (theswitchactuatesat 28.3"(23+5.3) theselimits)
- 2. Corrective Action Taken by 50R SOR received eight switches consisting of five 103AS-B212 type and three 103AS-B203 type DPSs. SOR's findings and the corrective actions are discussed below,
- a. During receipt inspection of the switches, SOR determined that seven of the eight DPSs actuated within the specified action limits. SOR attributed the acceptable results to calibration under laboratory conditions.
- b. Burrs were observed on the adjusting screws in five DPSs. The burrs may cause problems in adjusting the setpoint during calibra- l tion in the field; at the factory, however, the burrs did not ;
affect calibration. SOR revised the design of the adjusting screw to eliminate the burr.
- c. Traces of brown deposit were observed inside several switches.
SOR was unable to determine the origin of the deposit. SOR plans to electro-chemically clean the switch bodies to improve cleanliness of the switch bodies. In addition tc the cbove, during calibretime, setpoint instabilities were encountered on some switches. On disassembly, the diaphragm was observed to be perforated. Perforation of the diaphragm does
l 1 ORGANIZATION: STATIC-0-RING l OLATHE, KANSAS ; i REPORT INSPECTION NO . QQODnp7a/A7-n1 RESULTS: PAGF 4 of 6 not cause the switch to fail completely due to the large volume of water on either side of the DPS; however, it is difficult to adjust the setpoint. SOR examined the DPS bodies in which the diaphragms were perforated under a microscope and observed the presence of microscopic metal residues from machining process. LSCS also initiated an investigation of the DPSs with perforated diaphragms. On May 6, 1987, LSCS informed S0R that their investiga-tion indicated that the switches could have been contaminated with foreign material during assembly and testing. To reduce foreign debris and remove burrs from cut edges CECO recommended changes in the manufacture and testing of the SOR switches. Specifically, CECO recommended that a) the machined switch body be electro-polished or electro-deburred, b) immediately prior to assembly, all switch body internal parts including the diaphragm be washed & cleaned, and c) deionized water used for testing and calibration be filtered through a 15 micron filter. SOR opted to electro-deburr the DPS body blocks, and selected a contractor. Three procedures using solutions with three different chemical cleaning concentrations were developed. Two body blocks , were deburred in each of the three processes. One set of the bodies ! were retained by S0R and one set was sent to LSCS for examination. j S0R intends to use the procedure which yields the best results. The 1 inspectors examined the diaphragms of several 103 type DPS and concurred that the diaphragms had been damaged by contaminants of , l unknown origin.
- 3. Followup on 6TA Series Pressure Switches 1
On January 11, 1987, Davis Besse nuclear power plant (DB) reported I to the NRC that they were experiencing drift in setpoints in l 6TA-B4-NX-C1A-JJTTX6 type pressure switches (PS), manufactured by , I S0R.
- a. Background Information The following two factors exposed the kapton diaphragms in SOR PSs to the adverse effects of hydrazine.
The first factor was that the application was changed from intermittent to continuous duty. Following the June 9, 1985 l feedwater transient, DB modified the steam inlet to the two ] l I
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ORGANIZATION: STATIC-0-RING OLATHE, KANSAS 1 REPORT INSPECTION I on . ooonnn9a/n7.n1 RESULTS: ) AGE 5 of 6 Auxiliary Feedwater Turbine Pumps (AFTP) to preclude condensed , water impingement on the AFPT. After modifying the steam lines l the pressure switches are now pressurized when the main steam i line is pressurized instead of only being pressurized during j operation of the Auxiliary Feedwater Pump. ' Secondly, the j existing unqualified SOR PS: which contained pressure sensing diaphragms made of stainless steel (SS-316) were replaced with environmentally qualified PSs containing kapton diaphragms.
- 4. Identification of the Problem -{
The combination of the above two factors exposed the incompatibility of kapton and hydrazine. Hydrazine, an additive in the secondary water system to control water chemistry in PWRs, reacts with oxygen l to form ammonia. Ammonia permeates kapton. Dupont, the manufacturer J of kapton, stated that certain concentrations of chemicals such as ammonium hydroxide, sodium hydroxide, and potassium hydroxide wi_ll cause kapton to degrade. Based on the above information, SOR issued product information letter dated January 15, 1987 to all users. The letter advised i them that gas bubble fonnation (due to hydrazine) between the diaphragm layers will cause the setpoints to drift. On April 20, 1987 the NRC issued Information Notice 87-16. Three months later, SOR determined that hydrazine also permeated SS diaphragms. On April 27,1937, S0R informed all users that the use of SS-316 diaphragms did not completely eliminate the problem. The . j letter stated that an indication of a bubble formation increases the deadband of the PS but also stated that the root cause had not been determined.
- 5. Corrective Action Taken by SOR SOR now believes that the gas was leaking by the "0" ring that seals the diaphragm. They are now testing a pressure switch that has the SS-316 diaphragm welded to the pressure port fitting. This PS is undergoing long term tests with helium as the process medium, because of its small molecule size. SOR considers this to be a worst case scenerio which will give more rapid results and is safe for the personnel involved in the test. The inspectors reviewed the results of the tests conducted to date and determined it acceptable.
SOR is in the process of performing a supplemental Environmental Qualification evaluation with the revised design.
1 0 ORGANIZATION: STATIC-0-RING
'o 0 LATHE, KANSAS REPORT INSPECTION wn . ooonno?A/A7_n1 DFtHIT9a PACF A Af 6
- 6. Observation of Tests in Progress The NRC personnel witnessed the periodic testing of switches. These switches are undergoing long term tests to determine any trends in setpoint drifts. Approved procedures were used to verify drifts in setpoint. Records on the data collection were legible and retrievable. The results indicate no adverse tread in setpoint drift.
- 1. Observation of Manufactured Parts in Storage i
During a tour of the storage area, where parts for assembly of I switches to be used in nuclear applications are stored, it was noted that the adjustment screw for differential pressure switches 102/103AS i (drawing number 8305-034, Revision 2 dated November 13, 1986) was of l the latest design. The revised design changed the physical l appearance of the part. However, the receipt inspection documenta- l tion referenced drawing number 8305-034, Revision 1 dated June 22, j 1984. The S0R~QC inspector had verified that the part met the requirements of the earlier drawing. (Nonconformance 99900824/ G7-01-01wasidentified.) Eight additional parts stored in the i nuclear storage area were compared to the reccipt inspection ! documentation and no additional discrepancies were observed. ] E. EXIT INTERVIEW: l The inspector met with 50R representatives mentioned in Section F at the conclusion of the inspection and discussed the scope of the inspection and findings. F. PERSONS CONTACTED: R. C. Dunlop, President J. Peternel, Manager, Nuclear Sales L. Ganser, Project Engineer W. A. Priest, Project Engineer H. P. Hartman, Manager, Quality Assurance R. C. Davidson, Production Engineer R. C. Engel, Manager, Sales S. Baras, Nuclear Coordinator i t -_}}