ML17331A988
| ML17331A988 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 09/30/1993 |
| From: | Kobetz T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML17331A986 | List: |
| References | |
| 50-315-93-18, 50-316-93-18, NUDOCS 9310050161 | |
| Download: ML17331A988 (23) | |
See also: IR 05000315/1993018
Text
U.
S.
NUCLEAR REGULATORY COMMISSION
REGION I I I
Report
Nos.
50-315/93018(ORP);
50-316/93018(DRP)
Docket Nos.
50-315;
50-316
Licensee:
Company
1 Riverside
Plaza
Columbus,
OH
43216
License
Nos.
Facility Name:
Donald
C.
Cook Nuclear
Power Plant, Units
1
and
2
Inspection At:
Donald
C.
Cook Site,
Bridgman,
MI
Inspection
Conducted:
July 28,
1993 through
September
7,
1993
Inspectors:
J.
A.
Isom
D. J. Hartland
E.
R. Schweibinz
Approved
y:
etz,
ng Chief
R actor Pr
ects Section
2A
te
Ins ection
Summar
- Inspection
from July 28,
1993,
through September
7,
1993.
(Report
Nos.
50-315/93018(ORP);50-316/93018(DRP).
Areas
Ins ected:
Routine,
unannounced
inspection
by the resident
inspectors
of: plant operations;
reactor trips; maintenance
and surveillance;
actions
on
previously identified items; reportable
events;
NRC Bulletins and Generic
Letters;
and,
balance of plant
(BOP)
and reactor protection
system
(RPS)
instrument replacement.
Results:
Two Severity Level
IV violat'ions were identified.
In addition,
two
new Unresolved
Items were identified and are discussed
in paragraphs
2.d.
and
4.a.
p <
censee's Licensee Event Report (LER) submittal for adequate root cause determination and corrective action at a later date. On August 27, 1993, Unit 2 tripped again from 90 percent power due to low SG level coincident with steam flow/feed flow mismatch. Just prior to the trip, the reactor operators took manual control of both main feed pumps (NFPs) after they observed the speed of the "East" pump decreasing. However, the "East" pump did not respond to manual control, and the operators were unable to regain steam generator (SG) level. The licensee determined the root cause to be a failure of the pressure setter-in the speed, control circuit of the "East" pump. The licensee returned the unit to service on August 28, 1993, and was manually controlling the "East" pump operating device while maintaining the "West" in auto. The licensee intended to repair the pressure setter at a later date. The inspector will review the licensee's LER submittal for adequate root cause determination and corrective action. The inspector did not observe any significant post-trip abnormalities to either event, as all safety-related systems responded as designed. The inspector also conducted tours oF containment during the plant shutdowns and observed portions of plant startup activities. The inspector did not identify any concerns. No violations, deviations, unresolved, or inspection followup items were identified. ~ ~ ~ 4. Naintenance Surveillance 62703 61726 42700 The inspector reviewed maintenance activities as detailed below. The focus of the inspection was to assure the maintenance activities were conducted in accordance with approved procedures, regulatory guides and industry codes or standards, and in conformance with Technical Specifications. The following items were considered during this review: the Limiting Conditions for Operation were met while components or systems were removed from service; approvals were obtained prior to initiating the work; activities were accomplished using approved procedures; and post maintenance testing was performed as applicable. The following activities were inspected: a ~ Reactor Head Conoseal Leak On August 2, 1993, the licensee discovered a leaking conoseal during the post-trip containment walkdown. To repair the leak, the licensee was required to cool the plant down to Mode 5 and drain RCS inventory to 1 foot below the reactor vessel flange. The conoseals provide an RCS pressure boundary for the thermocouple port column penetrations on the reactor head. The lower conoseal package consisted of male and female flanges sealed by a gasket and a Harmon clamp. The clamp is a three-section 'll 0 clamping ring that is attached to the flanged connection using three cap screws/nuts spaced 120 degrees apart. The bolts are required to be torqued to 120-126 ft lbs by paragraph 7. 1. 18.a of licensee procedure "Instrumentation Port Conoseal Assembly," 02- OHP 4050.FHP.004, Rev. 1, dated February 26, 1992. During disassembly of the conoseal for inspection and repair, the licensee observed that the cap screws were easily loosened using a crescent wrench. In addition, 4 of 6 jack screws that push downward against the top of the male flange and are used to seat the upper conoseal gasket were bent. The licensee contractor attributed the leak to an indication discovered in the gasket" sealing area of the female flange at the location of the leak. Another deformation was noted at about 180 degrees from the location of the leak on the inner diameter of the female flange'hich appeared to have resulted from removal of the gasket during , a previous outage. This deformation, however, was not on the seating surface and did not appear to the inspector to contribute to the cause of the leak. The inspector noted during review of the conoseal assembly procedure referenced above that paragraph 7, 1.4.a included a gC inspection sign-off that verified the seating surfaces were free of visible nicks and scratches prior to assembly. The inspection did not document the deformation which was located 180 degrees from the leak location. Although not on the seating surface, the deformation should have been documented by the gC inspector and evaluated by the plant engineering staff to verify that the deformation would not affect the sealing function of the gasket. In response, the licensee provided a training session to gC personnel regarding inspection of conoseal assembly activities, which included a mock-up demonstration by a contractor representative. The licensee initiated Condition Report 8 93-1143 to document the leaking conoseal, and their investigation into the root cause(s) is in progress. As preliminary corrective action to repeated problems with conoseal leaks over the last few years, the licensee has committed to refurbish or replace all conoseal assemblies, including the flanges, during the next refueling outage for each unit scheduled for next year. The inspector's review of the licensee's root cause determination, including the origin of the female flange deformations, the loose cap screws, and the bent set screws is an unresolved item (Unresolved Item 50-315/93018- 02(DRP);50-316/93018-02(DRP)). The inspector also noted that the procedure did not contain inspection signoffs to verify the torquing of the cap and jack screws. In addition, the inspector discovered that the licensee had added inspection sign-offs to Rev. 1 of the record copy of the procedure but that, for unknown reasons, the sign-offs did not appear in the working copy used. The inspector also noted that the sign-offs were never added to the Unit 1 procedure. Paragraph 10.3.2 of "Plant guality Control Program," PHI-7090, Revision 5, February 24, 1992, required that " Inspection sign-offs in a procedure... shall be identified and space provided for signature of the inspector and date. Inspections performed shall include...for safety related items...tightness of connections and fastenings for pressure boundary components." Failure to provide inspection sign-offs in the conoseal assembly procedure, as required by PHI 7090, is' Severity Level IV violation of Technical Specification TS 6.8. 1 (Violation 50-315/93018- 02(DRP);50-316/93018-02(DRP)). Unit 2 Motor-Driven Auxiliar Feedwater HDAFW Pum Thrust ~Bearin s: The inspector continued to monitor the licensee's actions in response to the Unit 2 East HDAFW 'pump bearings which were identified as severely damaged during the routine oil change on April 20, 1993, by reviewing the circumstances regarding the discolored oil found on August 7, 1993, from the Unit 2 East HDAFW pump. The mechanics noted that the oil from the Unit 2 East HDAFW outboard thrust bearing housing was green in color, The oil sample was obtained as part of the licensee's increased oil monitoring program to detect for possible degradation in the bearing oil for the auxiliary feedwater pumps. The inspector, through discussion with the maintenance engineer, found that the oil discoloration was caused by wear of the brass retaining cage. The cause of the cage wear appears to be attributable to the high as-found balance drum setting of .011 inches (11 mils). The licensee indicated that the high as-found balance drum setting was probably caused by the incorrect installation of one of the two thrust bearing assemblies. The inspector reviewed job order C0006188 and found that during the last pump reassembly on April 22, 1993, the mechanics had set the balance drum at 3 mils. The licensee's procedure, "Motor Driven Auxiliary Feed pump Maintenance,"
- 12HHP5021.056.001,
Revision 5, March 12, 1993, in effect on April 22, 1993, required the balance drum setting to be set between 2 to 5 mils. The inspector discussed the importance of the balance drum setting thrust readings with the system engineer and found that the difference of 1 mil can potentially be significant in terms of higher loading on the bearings with resultant higher bearing temperatures. On the Unit 2 West HDAFW pump, the inspector learned that the bearing temperature was lowered from 153 to 120 degrees Fahrenheit by reducing the balance drum setting from 5 to 2 mils. The current licensee administrative limit on the maximum allowable bearing temperature is 145 degrees Fahrenheit. The maximum allowable bearing temperature was reduced from 160 to 145 degrees Fahrenheit as a result of the bearing damage found on the Unit 2 East HDAFW pump on April 20, 1993. The thrust bearing assembly in the Ingersoll-Rand pump is designed to absorb any axial thrust loading which occurs during transient conditions. Under steady operation, the balance drum automatically assumes a position where axial thrust forces are balanced. In order for the balance drum to work properly, the proper balance drum setting must be obtained during the reassembly of the pump. The mechanics attributed the as-found balance drum setting of 11 mils to one of the bearing assemblies being installed backwards. The inspector found by discussion with the mechanic that in the course of investigating the oil discoloration, the mechanic was able to identify that the inboard thrust bearing was installed improperly. The inspector had previously discussed the possibility of installing the bearing assembly improperly 'during the previous inspection period with the maintenance engineer. At that time, the inspector was informed by the maintenance engineer that the mechanics probably had received training on the proper installation of the bearing assembly by the vendor and during their normal training process. The inspector was concerned that because the "Hotor Driven Auxiliary Feed Pump Haintenance," procedure contained no written instruction on installation of the bearings in their "back-to-back" configuration, it might be possible for the bearing assembly to be installed incorrectly. Although the diagram of the thrust bearing assembly on Page 2 of Attachment 1 of the "Hotor Driven Auxiliary Feed Pump Haintenance" procedure contains a cross-sectional view of the thrust bearings in their back-to-back configuration, the inspector noted that installation of the thrust bearings in their "back-to-back" configuration using the diagram alone may not always ensure proper installation because some interpretation of the diagram is required by the mechanics. Further, the inspector's review of the Ingersoll-Rand vendor manual, "Auxiliary Feedwater Pump 3-HHTA-S," found that the manual specified the importance of installing the thrust bearings in their back-to-back positions It stated: o "Heat bearings and install on the shaft in the back to back position as shown in sketch." As a result, the mechanics installed one of the two thrust bearings incorrectly on April 22, 1993, while the licensee was in a 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Limiting Condition for Operation to repair the pump. Title 10 of the Code of Federal Regulations, Part 50, Appendix B, Criterion V, requires that activities affecting quality shall be prescribed by documented procedures of a type appropriate to the circumstances and shall be accomplished in accordance with these 10 procedures. Procedures shall include appropriate quantitative or . qualitative acceptance criteria for determining that important activities have been satisfactorily accomplished. Failure to provide sufficient detail to properly install the thrust bearings on the Unit 2 East HDAFW pump is considered a violation of Appendix B, Criterion V (Violation 50-316/93018-03). The licensee changed the oil and replaced the bearings on the Unit 2 East MDAFW pump on August 7, 1993. At the time of the bearing replacement, the pump had accumulated 144 hours0.00167 days <br />0.04 hours <br />2.380952e-4 weeks <br />5.4792e-5 months <br /> of operation. The inspector asked the system maintenance engineer if thrust bearing assemblies were installedI correctly on the other pumps. The inspector was informed that based on the oil samples taken over the last couple of months, and the vibration and temperature information available, it appeared that these parameters did not indicate improperly installed thrust bearings. However, the inspector did note that the oil drained out of the Unit 2 West NDAFW pump outboard bearing was dark in color. The inspector asked the system engineering department whether the darkening of the oil was indicative of an improperly installed thrust bearing assembly or other bearing degradation phenomenon. The licensee agreed to investigate the reason for the discoloration of the oil from the Unit 2 West outboard bearing. The licensee is currently monitoring the bearing. oil performance closely by performing the following: Oil samples are obtained after pump runs. The oil will be analyzed to obtain baseline data by about September 30, 1993. Pump bearing temperatures are obtained during post- maintenance and routine surveillance tests. This will continue until the end of the year at which time the licensee will evaluate the data. Vibration measurements are obtained at the beginning and end of each pump run. Also, some frequency analysis is performed to determine whether any frequency nodal is evident which may be indicative of any potential problem with the pump. Haintenance procedure upgrade is being considered to incorporate: specifying back-to-back installation requirement for the tandem thrust bearings requirement to set the drum setting to 2 plus or minus 1 mil. 11 changing the location where bearing temperature measurements are taken possibly installing live-load packing on the pumps to minimize packing leakage improvements in the work control process to require periodic review of old job orders to determine whether their priorities should be changed Two violations, and one unresolved item were identified. Actions on Previousl Identified Items 92701 92702 (Closed) Violation 316/89028-01(DRS): Violation of TS 3.7. 1.2 For Ino erable Flow Orifice Size This item was administratively closed and is being tracked by inspector follow-up item 316/92018-03(DRP). No violations, deviations, unresolved, or inspection followup items were identified. Re ortable Events 92700 92720 The inspector reviewed the following Licensee Event Reports (LERs) by means of direct observation, discussions with licensee personnel, and review of records. The review addressed compliance to reporting requirements and, as applicable, that immediate corrective action and appropriate action to prevent recurrence had been accomplished. a. (Closed) LER 315/92013-LL: Hissed Surveillance of the Turbine Room Sum Sam le Due to Personnel Error This LER was closed based on adequate root cause determination and corrective action. On October 13, 1992, the licensee determined that compensatory samples required by TS 3.3.3.9 were not taken after the turbine room sump composite sampler was declared inoperable'he licensee determined that the root cause was personnel error. As corrective action, the licensee took appropriate administrative action with respect to the individuals involved. In addition, the licensee provided training to Chemistry technicians to ensure that TS required activities are performed on a timely basis. This event involved a violation of TS; however, the event had minimal safety significance because the licensee determined that no potential source of radioactive effluent was released to the turbine room sump during the period of time when the required samples were not taken. In addition, the licensee properly reported the event and took appropriate corrective action. 12 Therefore, pursuant to the NRC enforcement policy (10 CFR 2 , Appendix C), the NRC is exercising enforcement discretion for this matter, and no Notice of Violation will be issued. b. (Closed) LER 316/92010-LL: Exceeded Technical S ecification LCO as a Result of Inaccuracies in Control Rod Position Indication This LER was closed based on adequate root cause determination and corrective action. On December 25, 1992, the licensee entered TS 3.0.3 for approximately two hours after it was discovered that the position indication for two rods in Control Bank D, Group 2 were reading greater than 12 steps from their demand indication. As immediate corrective action, the licensee pulled the rod bank out four steps and started an additional control rod drive mechanism (CRDH) ventilation fan. The licensee exited TS 3.0.3 after one of the position indicators drifted back to within 12 steps. The licensee determined the root cause of the drifting indicators to their sensitivity to temperature changes at the linear variable differential transformers located at the top of the CRDNs. The licensee attributed the temperature changes to movement of the control bank rods approximately 9 steps over the course of eight hours prior to the event. In response, the licensee has provided guidance to the reactor operators to stabilize reactor power in the event that a rod position indication (RPI) drifts out of TS compliance and to contact Plant Engineering for further instructions. One non-cited violation was identified. No deviations, unresolved, or inspection followup items were identified. NRC Bulletins Notices and Generic Letters 92703 The inspector reviewed the NRC communications listed below and verified that: the licensee has received the correspondence; the correspondence was reviewed by appropriate management representatives; a written response was submitted if required; and, plant-specific actions were taken as described in the licensee's response. The inspector performed followup of the licensee's review of Information Notice (IN) 93-33, "Potential Deficiencies of Certain Class 1E Instrumentation and Control Cables," to ensure that any operability determinations were made and that environmental qualification issues were addressed. The licensee determined that most of the cables discussed in the IN were used in the plant. However, the licensee concluded that the cables in the plant would be exposed to a less severe post-accident environment than those simulated in the test. Therefore, per the guidance in NUREG/CR-5772, "Aging, Condition Monitoring, and 13 LOCA Tests of Class 1E Electrical Cables," Volume 2, the licensee concluded that there was no need for additional qualification requirements. No violations, deviations, unresolved, or inspector followup items were identified. Balance of Plant BOP and Reactor Protection S stem RPS Instrument Re lacement 37700 During an August 9-11 and August 30 - September 3, 1993, followup inspection of the analog-to-digital process instrumentation replacement program (scheduled for 1994 installation) at the D.C. Cook Nuclear Plant, the inspector learned that a recurrent problem had been identified by the licensee. This problem was first observed during testing at the site on April 27, 1993, and involved intermittent failures of various process control units. The control unit's internal monitoring system would detect a problem and shut the instrument down (i.e., cause its outputs to reduce to zero and remain in an audible alarm state). The failure rate among the 256 instruments in testing was determined to be approximately 15 percent through July 1993. During a meeting between the licensee and the manufacturer (ABB-KENT-TAYLOR), the " problem was isolated to the sockets for the integrated circuits (ICs). A deficiency in the socket resulted in intermittent contact between the IC and its socket, thus interrupting signal processing and causipg it to
stop. These sockets (Manufactured by AUGAT INC.) are made in various grades and a lower grade socket was used. The sockets are located on an internal component identified as a "digital board." There are 7 sockets per digital board, 5 of the sockets are 28 pin and used for programmed PRONs (programmable read only memory), one 20 pin socket is used for a programmed logic array IC, and one 40 pin socket is used for' single chip microprocessor unit. There are 1 digital board per instrument, 520 instruments, and 3,640 sockets. The inspector questioned the generic nature of the deficiency and subsequent discussions with the licensee produced additional information. The 20, 28, and 40 pin sockets had the following respective AUGAT part numbers: 520-AG12D-ES 528-AG12D-ES 540-AG12D-ES The sockets are being replaced, at no cost to the licensee under their warranty, with 520-AG12D, 528-AG12D, and 540-AG12D sockets. The " -ES " suffix indicates that a socket is an ECONOMY SERIES socket which was , introduced by Augat in 1985 in order to provide a cost reduced version of their traditional machined contact. The contact portion of the economy series socket is produced by a stamping process vice a machining process for the replacement socket. 14 The process control units (Taylor MOD 30) were built as commercial grade equipment in 1989 by Asea Brown Boveri-Combustion Engineering (ABB-CE) Taylor and not delivered to the licensee until 1992, and were shipped to the site in the Spring of 1993. The original purchase order included both safety related and non-safety related units. The ABB-CE Taylor equipment used for safety related applications was to be qualified by ABB-CE. Prior,to release and shipment of the safety related equipment to D.C. Cook, the contract was amended to exclude safety related equipment. While the licensee does not know the root cause of the intermittent contact between the IC and its socket, they have been informed by ABB- KENT-TAYLOR that the delay between construction and shipment while the units sat unenergized may have been a contributing factor. The inspector pointed out that instruments stored in the warehouse as spare parts would also be unenergized. The licensee informed ABB-CE of this potential generic product deficiency in an August 20, 1993 letter (attached). The inspector contacted ABB-CE on September 17, 1993, and was informed that they have not sold any of TAYLOR MOD 30 instruments to nuclear power plants for safety related applications. Generic communication documents are being developed in the NRC to address the AUGAT socket deficiency issue. AUGAT, Inc., is an international supplier of interconnection systems for the computer, automotive, and telecommunications industries. The inspector checked a sample of the Foxboro instruments that will be used for the RPS replacement and verified that a completely different socket design was used in the Foxboro instruments. No violations, deviations, unresolved, or inspection followup items were identified. Unresolved Items Unresolved Items are matters about which more information is required in order to ascertain whether they are acceptable items, violations, or deviations. Unresolved Items disclosed during the inspection are discussed in paragraphs 2.d. and 4.a. Mana ement Interview The inspectors met with licensee representatives, denoted in paragraph 1, on September 13, 1993, to discuss the scope and findings of the inspection. In addition, the inspector also discussed the likely informational content of the inspection report with regard to documents or processes reviewed by the inspector during the inspection. The licensee did not identify any such documents or processes as proprietary. 15 Attachment: American Electric Power Service Corporation (AEPSC) August 20, 1993, letter from Robert C. Corruth to George J. Roebelen III, ABB Combustion Engineering Nuclear Services, Windsor, CT. 16 Mr. George J. Roebelen III ABB Combustion Engineering Nuclear Services P.O. Box 500 1000 Prospect Hill Road Windsor, CT 06095-0500 August 20, 1993 Dear Mr. Roebelen: As you know, AEPSC has uncovered what appears to be a generic product deficiency on the Kent-Taylor MOD 30 equipment which we received from ABB-CE under Contract C-7756. This deficiency was uncovered while we , were in our testing phase of the effort to reapply this equipment. Last week we had the opportunity to discuss the problem and its solutions with Kent-Taylor. We would like to share some of the information, which was presented to us during the course of those discussions, with your people at ABB-CE. The generic product deficiency has been diagnosed by Kent-Taylor to be the result of the use of a particular IC socket. Apparently, this socket is available in a range of grades and constructions. The sockets applied to our equipment are purportedly of a grade which will not support Kent-Taylor's product performance standards. Kent-Taylor is presently making repairs to all affected equipment purchased by AEPSC In our reapplication, we are not applying this equipment in any safety related applications. We thought, however, that it would be prudent to inform your organisation of the nature of this possible deficiency so that you may evaluate the potential implications to other ABB-CE projects where this equipment may have been applied in systems that have a safety significance. If we can be of any further assistance in this matter, please call me at (614) 223-1960. Sincerely, 11DRCCX2022.WP S. K. Farlow/N. C. Farr/D. R. Cloyd J. B. Kingseed D. A. Ferg (ABB) Pile: Kent-Taylor MOD 30 Equipment