IR 05000413/1998016
| ML20198A775 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 12/04/1998 |
| From: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML20198A755 | List: |
| References | |
| 50-413-98-16, 50-414-98-16, NUDOCS 9812170122 | |
| Download: ML20198A775 (21) | |
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U.S. NUCLEAR REGULATORY COMMISSION REGION 11 Docket Nos:
50-413 and 50-414 License Nos:
NPF-35 and NPF-52 Report Nos.:
50-413/98-16 and 50-414/98-16 Licensee:
Duke Energy Corporation Facility:
Catawba Nuclear Station, Units 1 and 2 Location:
422 South Church Street Charlotte, NC 28242 Dates:
September 15 - November 4,1998 Inspectors:
S. Shaeffer, Senior Resident inspector, McGuire (Lead Inspector)
W. Bearden, Reactor inspector, DRS, Rll Approved by:
P. E. Fredrickson, Chief Maintenance Branch Division of Reactor Safety l
Enclosure 9812170122 981204 PDR ADOCK 05000413
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EXECUTIVE SUMMARY Catawba Nuclear Station NRC Inspection Report 50-413/98-16 and 50-414/98-16 The report ciiscusses aspects of the licensee's maintenance, surveillance and engineering programs involving the Unit 2 ice condenser (IC). NRC review of the material condition of the Unit 2 IC system and corrective actions for identified problems are also discussed.
Maintenance Appropriate resources and management attention were being applied to support
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activities associated with maintaining the Unit 2 IC system and its associated sub-systems in an operable state. The initial scoping of material condition problems had improved from previous Unit 1 outage related activities. (Section M1.1)
Maintenance supervision responsible for servicing the IC exhibited improved oversight
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and accountability for performing work activities in the Unit 2 IC. (Section M1.1)
The licensee's use of an IC rotating team approach which utilized aggregate experience
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in servicing all four (McGuire and Catawba) of the licensee's IC units promoted an increased awareness of critical maintenance and surveillance practices. (Section M1.1)
The licensee's initiative to begin an industry improvement review of the IC TS was
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considered responsive. (Sections M1.1 and M1.2)
At the end of the Unit 2 refueling outage, IC TS surveillance requirements were being
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met and in many cases exceeded minimum TS requirements. Ice bed surveillances were being performed in a timely manner and in accordance with applicable procedures.
(Section M1.2)
IC TS surveillance requirements involving ice basket weight were being met and, in
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general, the licensee exceeded minimum TS requirements by attempting to weigh all IC baskets. The licensee's process for eliminating and/or evaluating stuck IC baskets was considered conservative. (Section M1.2.b.1)
The weight of ice in baskets were being closely tracked by a computer program and
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weights were documented and evaluated to predict sublimation rates across the IC to assure IC operability through the next operating cycle. (Section M1.2.b.1)
Implementation of the Unit 2 end of cycle 9 refueling outage flow channelinspections
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exceeded the requirements of TS. The condition of the flow channels in Unit 2 at the end of the outage was considered excellent and was evidence of increased attention in this area. (Section M1.2.b.2)
100 percent flow channel blockage inspections which exceeded TS requirements were
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formalized into procedures to improve overall effectiveness of the inspections.
(Section M1.2.b.2)
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Flow channel blockage analysis methods recently incorporated into licensee procedures
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provided additional verification of IC as-lef t operability and were conservatively implemented. (Section M1.2.b.2)
Temperature monitoring of the Unit 2 IC system was being performed in accordance
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with the TS and maintained within allowable limits. (Section M1.2.b.3)
An apparent violation of 10 CFR Part 50 Appendix B, Criterion XVI, was identified for
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failure to identify and correct ice basket deformation. Corrective actions taken for the IC basket denting problems were adequate to support restart of the unit. (Section M1.2.b.4)
Overall activities associated with maintaining and servicing IC components were
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considered adequate. Damaged ice baskets were effectively identified and appropriate repairs were performed. (Sections M1.2.b.4 and M1.3). Inspections for missing or broken screws were being performed in a conservative manner by adequately trained personnel. Supervision was present for guidance as needed and the level of licensee oversight was appropriate for the observed activities. (Section M1.3)
An apparent violation of TS 4.5.2.c was identified regarding inadequate IC debris visual
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inspections. The licensee's efforts to exclude foreign material from the IC during previous outages had not been rigorous as evidenced by the amount of debris fvund l
during this outage. During this inspection, the inspectors noted a relatively high sensitivity in this -area. Corrective actions for the identified foreign material in the Unit 2 10 were adequate to support unit restart. However, an inspection followup item was identified to review the results of an NRC research project regarding the potential l
clogging of ECCS sump screens during an accident. (Section Mi.4)
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Engineering oversight was considered to have improved, implementing lessons learned
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l from the recent Unit 1 forced IC outage. Technical problems were pursued in a i
conservative manner. (Section M1.1)
The licensee has an effective program in place to document and evaluate issues for
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reportability/ operability. The inspectors' review of problem reports involving IC components, determined that the licensee's reviews and evaluations for reportability/ operability were satisfactory. (Section E1.1)
By observation of ice basket modification work, the inspectors verified that current
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activities were being appropriately performed; tne technicians were adequately qualified to perform their assigned tasks; and that the level cf oversight provided by the contractor and the licensee was appropriate for the task. (Section E1.2)
l Preventive measures to limit excessive loading during ongoing ice basket modifications
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were not as rigorous as other ice basket lifting activities. (Section E1.2)
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With the exception of several previously identified design control deficiencies,
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modifications to the Unit 2 IC system were completed in accordance with approved modification procedures. Corrective actions for the previously identified problems were adequately implemented. (Section E1.2)
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No significant problems with Updated Final Safety Analysis Report (UFSAR) accuracy
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were identified by the NRC. The licensee was continuing their UFSAR review and update in accordance with industry guidance. (Section E1.2)
An apparent violation was identified regarding inoperable IC lower inlet doors due to ice
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blockage. (Section E1.2)
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Report Details Summary of Plant Status Unit 1 Unit 1 began the inspection period in Mode 1 operating at 100 percent power. The unit operated at or near 100 percent power for the duration of the period.
Unit 2 Unit 2 began the inspection period in Mode 6 and entered core off-load (No Mode) on September 16 for the end-of-cycle 9 (2EOC9) refueling outage. Ice Condenser (IC) servicing, maintenance, surveillance and engineering work were conducted during the outage. The unit entered Mode 1 on October 23 and was operating at or near 100 percent power at the end of the period.
11. Maintenance M1 Conduct of Maintenance M1.1 General Comments (62707)
During the Unit 2 2EOC9 refueling outage, the inspectors reviewed a variety of i
maintenance, surveillance, and engineering activities associated with maintaining the IC l
and its associated sub-systems in an operable state. General observations of licensee l
activities concluded that appropriate resources and management attention were being l
applied to support the above activities. The initial scoping of Unit 2 material condition problems had improved from previous Unit 1 outage related activities.
Maintenance supervision responsible for servicing the IC exhibited improved oversight and accountability for performing quality work activities. Engineering oversight was considered to have improved, implementing lessons learned from the recent Unit 1 forced IC outage. Technical problems were pursued in a conservative manner.
The licensee used an IC rotating team approach which utilized IC personnel experienced in servicing the two Catawba, as well as the two McGuire IC units. This
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promoted an increased awareness of critical maintenance and surveillance practices which were considered necessary in maintaining the ICs in an operable status.
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At the end of the inspection period, the licensee, working with industry counterparts, had initiated broad based reviews to improve ihe existing IC Technical Specifications (TS).
The licensee had recognized the need for TS clarification and/or revision in a number of areas to increase the effectiveness of the TS to assure system operability.
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M1.2 Ice Condenser Surveillance Testina (Unit 2)
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Inspection Scope (62726)
l The inspectors determined by observation, review of completed surveillances and procedures, and discussions with cognizant personnel, the adequacy of completed TS surveillances on the Unit 2 IC system. The reviews included, but were not limited to: IC mass integrity; flow passage availability; inlet / outlet door operability; ice basket material condition, and ice bed temperature monitoring.
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Observations and Findinas b.1. Ice Basket Weiaht Surveillance TS requires that the ice inventory in the IC contain sufficient heat removal capDility to condense the reactor coolant system volume released during a loss of coolant accident (LOCA). In order to enable the IC to perform this function, TS 4.6.5.1.c requires that at least once per 18 months a representative sample of at least 144 ice baskets are weighed to verify that each ice basket contained at least 1,199 pounds of ice. The total minimum weight of ice required to be in the IC is 2,330,856 pounds. The representative sample is required to include six ice baskets from each of the 2410 bays. TS also provides additional requirements for selecting specific ice baskets from designated rows within specified IC bays. This preferential selection is intended to assure that weight surveillances reflect conditions that are representative of the IC environment. The inspector reviewed the licensee selection of baskets for weighing using final outage results and concluded that it was adequately performed.
In order to avoid problems in accessing ice baskets for weighing, the licensee removed the intermediate deck docrs and associated structural steel supports from the work area. Weighing of the baskets was performed in accordance with Procedure MP/0/A/7150/005, Rev. 019, Ice Basket Weight Determination. This procedure re,uires
the use of a calibrated load cell assembly which utilized a hydraulic jack, a digital readout unit and a lifting bridge. The procedure also requires that prior to weighing, ice baskets be checked to determine if they are frozen or stuck. If an ice basket is found stuck and can not be freed, it is emptied with the aid of vibrators, inspected, repaired as
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needed, replenished with ice and weigned. This weight is subsequently documented and becomes a part of the computer database program. The aforementioned procedure places limits on the lifting force (i.e.,3000 pounds maximum) that could be applied to raise and free stuck ice baskets. This limitation was imposed for the purpose of minimizing basket damage.
By observation, the inspectors verified that sampled ice baskets were weighed in the prescribed manner which provided the assurance that weight accuracy was within a 10 l
pound band. Upper and lower limits controlled total weight for each ice basket. The lower limit was set at 1449 pounds for normal baskets without cable cruciforms and 1481 pounds for baskets with cable cruciforms and swivel brackets while the upper limit was 1877 pounds for all baskets. This work was performed on Work Orders (WOs)
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9802998-05, Ice Basket Weighing, and 98070350-01, Technical Specification Ice Basket Weighing. The licensee's program attempted to weigh all of the ice baskets prior to the startup from the refueling outage, which exceeded the TS requirement of weighing 144 baskets every 18 months. Through discussions with cognizant licensee personnel and review of as-left data, the inspectors determined that, following replenishment of approximate 219 baskets, both the individualice basket weights and the total ice weight in the IC exceeded all requirements identified in the TS regarding ice mass.
During the weighing process, a total of 180 stuck baskets were identified in the Unit 2 lC. The majority of these baskets were located in outer rows of the condenser. All 180
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stuck baskets were serviced during the current outage. The licensee's process for treating stuck baskets generally required emptying the affected baskets, attempting to free the basket, then refilling. However,if the predicted sublimation of a stuck basket location would provide assurance for the rninimum basket weight limit to be mainta ned i
for the next cycle, basket servicing may be delayed for a one cycle only exclusion. The inspectors reviewed the licensee's as-left weight analysis and servicing of the stuck baskets and concluded that the licensee process conservatively evaluated or eliminated the identified stuck baskets. No concerns were identified in this area.
Conclusion-s IC TS surveillance requirements involving ice basket weight were being met and in general, the licensee exceeded minimum TS requirements by attempting to weigh all IC baskets. The licensee's procas for eliminating and/or evaluating stuck IC baskets was considered conservative.
The weight of ice in baskets were being closely tracked by a computer program and weights were documented and evaluated to predict sublimation rates across the IC to assure IC operability through the next operating cycle.
b.2. Flow Passaae Surveillances As required by TS 4.6.5.1.b.2, et least once per nine months, a minimum of two flow l
passages per IC bay are visuah inspected for blockage. The maximum allowable ice l
accumulation on lattice grid steel members in the space of these flow passages was 0.38 inches. This surveillance was performed in accordance with Procedure SM/A/8510/010, Rev.1, Cleaning and inspection of Ice Condenser Flow Passages. The system engineer utilized a random number generator to select the flow passages for TS surveillance inspection and also precluded repeat inspection of flow passages on subsequent outages. Neither the inspectors nor the licensee identified any areas of significant flow blockage in the Unit 2 IC, similar to previous problems found in the Unit 1 IC as discussed in inspection Report 50-413,414/98-13.
I By observation, the inspectors noted that the flow passages associated with the first two l
rows of ice baskets, located nearest to the annulus / containment wall and some near the polar crane wall, exhibited some ice buildup. The buildup was attributed to sublimation
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and/or residual ice deposited in inaccessible areas from the ice basket refill process.
l The majority of the remaining flow passages in rows three through nine, next to the
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crane wall, were relatively free of any ice accumulation and considered in excellent
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condition. Typically, the licensee has exceeded TS minimum surveillance inspection l
requirements by inspecting additional flow passages at or near the completion of the outage, when all maintenance activity including replenishment of emptied and serviced ice baskets has been completed. Near the end of the Unit 2 outage, the inspectors performed several walk-through inspections in the lower level, intermediate deck, and top deck of the IC and determined that the ice accumulation and material condition of inspected flow passages was very good. At the completion of this inspection, technicians were continuing to inspect and reduce ice accumulation in certain flow channels.
l Due to the identification of several small flow areas in the IC which were difficult to thoroughly inspect and clean due to their location, the licensee revised the flow channel inspection procedure (Procedure SM/0/A/8510/001) to incorporate an additional means of verifying IC flow passage operability based on actual percentage of flow blockage l
found in the IC. These areas were predominantly between the ice bed and the adjacent IC walls. The analysis method as allowed by recently supplied vendor design information separated the IC into six segments and reviewed the as-left flow blockage in each to assure that no total blockage greater than 15 percent existed. The inspectors reviewed the completed procedure and concluded that the new analysis method provided additional assurance that the IC was left in an operable state. Assumptiom of frost buildup due to inaccessibility were considered very conservative. in addition, the licensee revised the above procedure to formalize 100 percent flow channel blockage inspection for the IC.
Conclusions Implementation of the Unit 2 2EOC9 refueling outage flow channelinspections exceeded the requirements of TS. The condition of the flow channels in Unit 2 at the end of the outage was considered excellent and was evidence of increased attention in this area.
100 percent flow channel blockage inspections which exceeded TS requirements were formalized into procedures to improve overall effectiveness of the inspections.
Flow channel blockage analysis methods recently incorporated into licensee procedures provided additional verification of IC as-left operability and were conservatively implemented.
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l b.3. Ice Bed Temperature Monitorina
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Observations and Findir,as ?
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TS requires a maximum ice bed temperature of s27 F. The ice bed temperature is
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monitored in the control room through the use of temperature sensors attached to the Y
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lattice frames through the ice bed. TS requires that the ice bed temperature is monitored at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. The inspectors observed selected ice bed
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temperature monitoring devices in the IC and verified that temperature monitoring was being performed as required by the applicable procedure. No periods of ice bed temperatures exceeding the TS limits were identified.
Conclusions Temperature monitoring of the Unit 2 IC system was being performed in accordance with the TS and maintained within allowable limits.
b.4. Ice Basket Damaae Surveillance TS 4.6.5.1.d, requires that at least once par 40 months, two ice baskets shall be selected from each one-third of the IC and inspected to verify that they are free of detrimental structural wear, cracks, corrosion or other damage. The TS specifies that the selected baskets be raised at least 12 feet for the inspection. The six ice baskets were selected with emphasis on baskets whose history showed no maintenance activities having been performed over recent outages. Specifically, ice baskets selected for this inspection were 11-5 7,12-7-4,3-1-3,2-9-4,17-7-5 and 20-5-6. These baskets were inspected for material condition as stated above and the results were documented i
as required by Procedure SM/0/A/8510/002, Rev.1, Ice Basket Inspection. This inspection revealed one small dent in the upper section of Ice Basket 2-9-4. However, l
no evidence of significant material damage o.r degradation was identified during i
performance of this inspection.
Based on a significant number of dents identified on the lower ice oaskets in the Unit 1 1C, the licensee performed additional reviews of all the Unit 2 iC baskets for material condition problems.
During the Unit 2 outage, approximately 73 basket dents were identified, repaired and/or evaluated by the licensee. Denting or buckling of baskets could potentially affect the ability of the ice basket to sustain as-designed loading conditions. The licensee's vendor supplied allowable criteria for denting was 0.75-inches deep and six-inches in length. The licensee repaired the identified dents with a special tool developed to pull out the dents. The repair process was adequately evaluated for adverse material property effects via Problem Investigation Process Report (PIP) 2-C98-3189. This PIP was similar to the Unit 1 PIP documented for the IC ice basket damage observed during the Unit 1 forced outage in August 1998 and further discussed in Section M8.3. The NRC reviewed PIP 2-C98-3189 and determined that the damage sustained by the Unit 2 ice baskets would not significantly degrade the performance of the IC during an accident. Therefore, the baskets were considered to have been in an operabic, but degraded condition. The majority of the identified dents were located on the but.cm six-feet of the ice baskets. The licensee postulated that the majority of the dents were likely the result of originalinstallation practices. The inspectors found that the licensee had numerous opportunities to identify and correct the identified dented baskets during flow passage inspections, weighing activities, and lower IC bay cleaning. The licensee is
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required by 10 CFR Part 50 Appendix B, Criterion XVI, to establish measures to ensure that conditions adverse to quality are promptly identified and corrected. This failure to promptly identify and correct Unit 2 ice basket material condition problems is identified as Apparent Violation (EEI) 50-414/98-16-01, Failure to identify and Correct Ice Basket Deformation.
In addition to the TS required 1C basket damage inspection and the expanded review of all ice baskets for damage, the licensee also inspected all ice baskets that were emptied of ice during servicing with an internal camera inspection. This inspection exceeded that which is required by the TS surveillance and provided additional assurance that no detrimental ice basket damage occurred during the removal of ice from the baskets.
Conclusions An apparent violation of 10 CFR 50, Appendix B, Criterion XVI was identified for failure to promptly identify and correct IC basket material condition problems. Corrective actions taken for the IC basket denting problems were adequate to support restart of the unit.
Ice basket damage inspections performed during the current refueling outage were
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being performed in a conservative manner, in many cases exceeding the requirements of TS.
Overall Conclusions Reaardina Ice Condenser Surveillances At the end of the Unit 2 refueling outage, the inspectors concluded that the above and other reviewed IC TS surveillance requirements were being met and in many cases exceeded minimum TS requirements. Ice bed surveillances were being peiformed in a timely manner and in accordance with applicable procedures.
M1.3 Ice Basket Maintenance and Servicina a.
Insoection Scope (62707)
The inspectors determined by work observation and record review, the adequacy of the licensee's inspection procedures and work practices for servicing / repairing ice basket components.
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Observations and Findinas b.1. General ice Basket inspection. Maintenance. and Reoair During the refueling outage, the licensee unloaded certain ice baskets that had been declared stuck during the weighing process. The unloaded ice baskets were inspected for damage and repaired as necessary in accordance with Procedure SiWO/A/8510/007 Rev. 5. Ice Basket Corrective Maintenance and Tracking. Essentially this procedure focused on vibration related damage to basket surfaces, and associated rings and
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l cruciforms. By document review and discussions with technical personnel, the inspectors determined that a total of 219 ice baskets required ice evacuation and replenishment during the outage. This included 180 that had been declared stuck
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(unweighab!c), as well as others that were found damaged as a result of other l
inspections. In addition, baskets were serviced that the computer tracking program l
(Iceman) had projected would lose sufficient ice, due to sublimation, to fail the minimum weight required over a predetermined length of time (i.e., one fuel cycle plus six months added for conservatism).
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Based on a material condition inspection of all 219 unloaded ice baskets (via camera inspections), the licensee identified additional baskets requiring some repairs. These repairs included removal of damaged basket sections and their replacement with short length sections. This work was performed on WO 97030083-01, Repairs to Ice Baskets and WO 97030083-02, ice Basket Dent Repairs. The inspectors observed work in progress which included vibration of ice to unload baskets; both visual inspections and remote inspections with the aid of a video camera; and removal and installation of coupling, stiffener and top rings. Damage to the top rings was attributed to the use of certain tools used to free-up frozen or stuck baskets. The licensee adequately repaired the damage to top rings and other areas as verified during final NRC material condition walkdowns.
b.2. Inspection for Missina or Broken Screws During the review, using Procedure SM/0/A/8510/007, technicians were performing inspections of emptied ice baskets to look for maintenance-related damage, which included missing or broken screws, Visualinspections were performed using the direct observation method or with a remote video monitoring device that provided sufficient resolution and magnification to detect abnormal conditions. This wo,-k was performed on WO 98029998-03, Ice Baskets Inspections.
Damaged ice basket sections and associated components, (i.e. rings), were replaced with components produced from like material. The replacements were assembled and fastened to their designated basket locations with locking torque-head self-tapping l
sheet metal screws. Typically the new screws were driven through the material with the
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aid of a hand held drill and tightened until the joint was firmly secured. Efforts were made to capture old screws being removed from baskets during dicassembly. The screws were from the original screw design that was used during constructiun until torque-head screws were introduced. In addition, the licensee retrieved a number of torque-head screws which appeared new/ unused and other Phillips-head screw caps, whose fracture surfaces exhibited chisel marks, indicative of intentional removal during maintenance. The inspectors did not identify any baskets or coupling rings having missing screws. However, a number of screws were retrieved by the licensee and l
appeared to be the result of planned maintenance activities involving the removal of the l
screws.
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Conclusions Overall activities associated with maintaining and servicing IC components were considered adequate. Damaged ice baskets were effectively identified and appropriate l
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repairs were conducted. Inspections for missing or broken screws were being performed in a conservative manner by adequately trained personnel. Supervision was present for guidance as needed and the level of licensee oversight was appropriate for the observed activities.
M1.4 Foreion Material Control a.
Inspection Scope (62707. 61726)
The inspectors determined by work observation, walk-through inspections, discussions with the cognizant engineer and record review, the adequacy of the licensee's control of foreign material in the Unit 2 (C.
b.
Observations and Findinas Based on previous foreign material problems identified in a recent Unit 1 forced outage IC inspection, the licensee performed extensive reviews of the Unit 2 condenser throughout the outage. The Unit 1 problems were discussed in inspection Report 50-413,414/98-13. The licensee identified similar items in the Unit 2 condenser which appeared to have been previously covered with ice and that were now exposed through sublimation and/or basket servicing.
The licensee inspected 100 percent of the IC basket bottoms to identify and retrieve all the accessible debris observed. In general, material retrieved from the ice baskets included duct and electrical tape, tie wraps, leather and cotton gloves, pieces of small gage electrical wire, paper, and cellophane material. The licensee also identified severallarge sections of flow channel servicing bags used when blowing ice into baskets. All debris found was segregated in terms of the bay where it was found and basket location (i.e., inside, outside). Of these materials, tape, cellophane and paper were considered to pose the greatest risk to sump clogging based on their potential for becoming neutrally buoyant and covering large surface areas. The licensee's calcu!ation/ evaluation determined that the emergency core cooling system (ECCS)
sumps for Units 1 and 2 were operable and that the amount of debris found and assumed to be present in the Unit 2 IC was insufficient to constitute a serious blockage problem that could challenge design margins for sump screens. Identification of the debris found and the ensuing evaluation was documented under PIP 2-C98-3399. This PIP was similar to the Unit 1 PIP documented for the IC basket debris observed during the Unit 1 forced outage in August 1998 and further discussed in Section M8.2.
However, the NRC has initiated a research project to evaluate the potential for debris from the IC and other sources to clog the ECCS sump screens during an accident. In light of similar foreign material problems at the DC Cook plant, a further review of this issue at Catawba may be conducted should the results of the NRC research project identify any significant vulnerabilities. Reviewing the effects of IC debris on ECCS
sumps is identified as inspection Followup Item 50-413,414/98-16-02, Ice Condenser l
Foreign Material Effects on ECCS Sumps.
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The inspectors reviewed the regulatory requirements. associated with identification of foreign material in the containment and requirements for maintaining areas inside the l
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containment free of foreign material which could adversely impact the containment sump. TS 4.5.2.c requires, in part, that each ECCS subsystem shall be demonstrated operable by a visual inspection which verifies that no loose debris is present in the containment which could be transported to the containment sump. The visual inspection shall be performed for all accessible areas of the containment prior to establishing
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containment integrity. Implementation of this TS surveillance is accomplished, in part by PT/0/A/4200/002, Containment Cleanliness inspection. In addition, Duke Energy Nuclear Site Directive 104.7, Standards for Foreign Material Exclusion, provides a program to prevent the insertion of foreign materialinto open systems or components.
The inspectors concluded that the above foreign material exclusion control requirements were not adequately implemented to meet the requirement of TS 4.5.2.c as evidenced by the amount of foreign materialidentified in the Unit 2 IC system. This failure to maintain lC foreign material exclusion control is identified as eel 50-414/98-16-03, Inadequate Ice Condenser Debris Visual Inspection.
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Conclusions An apparent violation of TS 4.5.2.c was identified regarding inadequate IC debris visual inspections.
The licensee's efforts to exclude foreign material from the IC during previous outages
had not been rigorous as evidenced by the amount of debris found during this outage.
l However, during this inspection, the inspectors noted a relatively high sensitivity in this area. Corrective actions for the identified foreign material in the Unit 2 IC were adequate to support unit restart. However, an IFl was identified to review the results of l
an NRC research project regarding the potential clogging of ECCS sump screens during l
an accident.
M8 Miscellaneous Maintenance issues (92902)
M8.1 (Closed) URI 50-413/98-13-02: Past Ice Condenser Flow Blockage Operability Review.
PIP 1-C98-2786 was documented for a block-ice machine leak in Bay 5, identified l
during the forced Unit 1 outage in August 1998. Based on this PIP, the licensee l
determined that the IC was past operable with this condition. The NRC reviewed this
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PIP,in addition to appropriate portions of the TS and Updated Final Safety Analysis Report (UFSAR), and determined that the ice bed had been in an operable, but degraded condition.
M8.2 (Closed) URI 50-413/98-13-04: Past Ice Condenser Foreign Material Effect on ECCS l
Sump Operability Review. PIP 1-C98-2786 also documented the containment sump l
blockage operabihty concern related to debris identified in the IC baskets and flow I
channels during the forced Unit 1 outage in August 1998.
The NRC reviewed this PIP and could not identify any deficiencies in the licensee's past-operability determination. -However, an NRC research project is ongoing to assess the potential for debris to clog ECCS sump screens during an accident, as discussed in
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Section M1.4. A further review of IC debris at Catawba will be conducted by the NRC, if
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this project determines any significant vulnerabilities.
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M8.3 (Closed) URI 50-413/98-13-06: Past Ice Condenser Dented Basket Operability Review.
PIP 1-C98-2896 was documented for the IC ice basket damage operability concern identified during the forced Unit 1 outage in August 1998. The NRC reviewed this PIP and determined that the damage sustained by the ice baskets would not significantly j
degrade the performance of the IC during an accident. Therefore, the baskets were
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considered to have been in an operable, but degraded condition, 111. Enoineerina E1 Conduct of Engineering E1.1 Reportabilitv/ Operability Evaluations (Units 1 and 2)
a.
Inspection Scope (37551)
The inspectors determined through document review the adequacy of the licensee's evaluation with regards to items concerning reportability and operability issues relative to the IC.
b.
Observations and Findinas The licensee used the PIP program to document concerns identified in the field, including those associated with material condition and documentation errors. Under this system, concerns are assessed, evaluated for plant operability and reportability to the NRC (i.e.,10 CFR 50.73 and 10 CFR 21), and appropriately corrected or resolved.
Issues with potential operability /reportability concerns are evaluated, and a determination made and documented using PIPS. The inspectors reviewed PIPS issued for both Catawba Units between 1990 and the present that addressed problems associated with IC ice doors, low boron concentration, and ice baskets, for the purpose of verifying that reportability and operability issues were adequately evaluated and whether appropriate actions were taken as required. The inspectors noted that only a relatively small population of the reviewed PIPS actually involved issues that would qualify as potential reportability candidates. The primary potentially reportable PIPS were as follows:
PIP 2-C93-0715, this PIP invohred Unit 2 IC intermediate deck doors that had been found to be potentially restrained from opening due to ice buildup on the doors.
PIP 2-C93-0733, this PIP involved Unit 2 IC intermediate deck doors that were considered potentially restrained from opening due to ice buildup on the door hinges.
I PIP 0-C97-2882, this PIP involved the review of an operating experience item L
from McGuire Unit 2 associated with a degraded condition for certain lower inlet doors. The affected doors at McGuire had failed to open freely due to interference from the door flashing that had resulted from melting and refreezing of ice.
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PIP 1-C97-4325, this PIP involved a failure of certain Unit 1 lower inlet doors to l
open freely due to interference from the door flashing. The affected flashing had
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been previously damaged during ice removal activities.
PIP 0-C97-2541, this PIP involved the incorrect storage of compressed gas cylinders in the ice bin annex.
PIP 1-C98-0018, this PIP involved sample results for one ice basket of the required nine samples per TS 4.6.5.1 that had been less than 1800 ppm boron.
PIP 1-C98-1812, this PIP involved the potentially inadequate boron sampling methodology. The licensee had previously then nine samples per TS 4.6.5.1 but had combined the samples such that a single chemical analysis had been performed to verify boron concentration was not less than 1800 ppm boron.
l PIP 1-C98-2786, this PIP involved blockage in several flow channels of the Unit 1 IC PIP 2-C98-2827, this PIP involved failure to properly verify, by visual inspection, that ice accumulation in the flow passages had been less than 0.38 inch per TS 4.6.5.1.b.2. Existing procedures at Catawba and McGu:re had not included the top deck floor grating or turning vanes.
PIP 2-C98-2994, this PIP involved bolting discrepancies in Unit 2 IC.
PlP 2-C98-3216, this PIP involved a finding that the lower inlet doors on the Unit 2 IC could potentially be restricted from opening due to ice accumulation on the beam coolers and associated glycol tubing.
PIP 2-C98-3628, this PIP involved sample results for several freshly blown ice baskets with less than 1800 ppm boron.
Through this review, the inspectors determined that for the most part, the findings as documented in these PIPS did not meet the reportability threshold of either 10 CFR 50.73 or 10 CFR 21. However, in ir stances where the licensee's evaluation determined that the problems identified were rr. portable (i.e., PIP 1-C98-2786, PIP 2-C98-2827, and PIP 2-C98-3216), the licensee performed detailed evaluations for operability and reportability require'nents, and appropriately reported the issues to the NRC. In all cases, the licensee's completed current operability and reportability reviews were considered acceptable.
The inspectors also reviewed the licensee's actions with respect to IC issues identified at other facilities. Specifically the inspectors reviewed an issue involving D. C. Cook ice baskets found in an unanalyzed condition due to bad or missing welds on the bottom l
crossbars and bottom basket grids of the IC ice baskets. This issue was reported to the
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NRC in June 1998. The licensee's initial review indicated the following: The problems j
identified appeared to be associated with welding practices and/or welding process control. Also, their review disclosed that Catawba's and D. C. Cook's IC ice baskets and associated components were fabricated by different vendor facilities. The inspectors i
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l determined that Catawba's past and present inspections on the affected IC ice basket areas had not identified similar problems. However, the licensee issued PIP 0-C98-2663 to further investigate the concern and to document their findings.
c.
Conclusions Through document reviews and discussions with the licensee's cognizant engineer, the inspectors determined that the licensee has an effective program in place to document and evaluate issues for reportability/ operability. The inspectors' review of problem reports involving IC system components, determined that the licensee's reviews and evaluations for repedabi'ity/ operability were satisfactory.
E1.2 Ice Basket Modifications and Repair a.
Inspection Scope (37551)
The inspectors determined by work observation, document review and through discussions with the cognizant engineer the adequacy of ice basket and other modifications. The inspectors reviewed modifications of damaged ice baskets using short-length basket sections, dented basket repair methods, replacement of ice basket
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lower plenum u-bolts with a swivel bolt design, and modification to the lower plenum j
beam coolers. Throughout the inspection, the inspectors reviewed engineering design basis documents including the UFSAR, the Catawba Design Basis Document, and applicable as-built and design drawings. The inspectors also focused on identifying unapproved modifications which may have been made to the IC system.
b.
Observations and Findinas
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b,1. U-bolt Modifications
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The inspectors observed portions of the modification work activities associated with the
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removal of existing ice basket u-bolt mounting assemblies and installation of swivel mounting brackets. This modification was being performed in accordance with Procedure SM/0/A/8510/009 and was intended to allow for weighing of ice baskets without the need of entry into the lower IC compartment. Completion of this modification
on approximately 800 of the ice baskets would allow the licensee to begin the ice basket weighing process prior to the start of a scheduled refueling outage. The inspectors observed ice basket lif ting and other ongoing work activities. The inspectors noted that the ice baskets were properly supported with support bars while work was ongoing.
However, the inspectors noted that craft personnel did not utilize a load cell to monitor lifting force while raising ice baskets with lifting equipment. Although Procedure SM/0/A/8510/009 did not require the use of a load cell during these modification activities, load cells had been used by the licensee during other basket lifting activities to verify that lifting force had not exceeded 3000 lbs. Examples of basket lifting activities where licensee procedures required the use of a load cellincluded ice basket weighing and inspections of ice baskets for damage. The inspectors discussed this concern with l
licensee management and were informed that the licensee's lifting and rigging program
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had no requirement for use of a load cell during this modification actRity and that the i
baskets which were being lifted for the U-bolt replacement had all just recently been
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ir' 1tified as not being stuck baskets during the current outage. During the tvations, the inspectors did not identify any evidence of lifting activities which vamaged baskets and also noted that maintenance oversight of the lifting activities was being actively monitored from both above and below the baskets. The inspectors
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concluded that, although the licensee had not incorporated a load limiting device, adequate measures were being maintained to identify potential damage to ice baskets
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during the modifications.
The inspectors also sampled the as-left configuration of swivel bracket replacements during final IC walkdowns. All necessary components for each bracket were observed to have been properly installed.
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b.2. Damaaed Basket Reoair Sections of ice baskets exhibiting torn or damaged ligaments were repaired in accordance with Procedure SM/O/A/8510/007 using short length replacement sections.
The replacement sections came in two, three and twelve foot lengths that were designed and approved by Westinghouse for use on the Unit 1 and 2 IC ice baskets.
Use of these replacement sections was authorized under Westinghouse Qualification SID 2016.01-00-001, and by letter from Westinghouse to R. L Spada of Duke Power Company, dated September 19,1991. In general, the subject letter stated that the short ice basket replacements were compatible with all existing plant ice baskets, interfacing structures and hardware in the ice bed; that they were made from similar material and were designed to fit the same specifications as the original ice baskets; that they were qualified by analysis to the seismic and design basis accident loads and criteria of the original Duke IC ice baskets. In conclusion, the subject letter stated that the additional coupling rings had no discernible effect on the thermal perforrnance of the IC. The inspectors determined that the licensee had taken adequate steps via the performance of a 10 CFR 50.59 review to assure that the use of short length replacement ice basket sections would not prevent the IC from performing its safety function.
If not replaced with smaller basket sections, dented baskets were repaired utilizing a special dent pulling tool. The inspectors reviewed areas where repairs had been performed and did not identify any concerns with the licensee's repair process. The repair technique was discussed with the basket vendor and appropriate reviews were conducted within PIP 1-C98-2896 to address the adequacy of the repair method.
Walkdown reviews were conducted in all areas of the Unit 2 IC comparing the as-built configuration to the design basis of the 10. In general, the inspectors identified that the IC system was being maintained and operated in accordance with the design basis and changes were being accomplished in accordance with approved procedures. No dents were identified by the NRC during final inspections which exceeded the established allowable limits.
l In addition, the inspectors expanded their modification review to include previous PIP reports which were related to a variety of issues between 1990 and the present.
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Throughout this time period, the inspectors confirmed that resolution of these sampled issues were completed within the licensee's approved modification processes.
b.3. Lower Plenum Beam Cooler Modification During initial outage inspections of the Unit 2 IC, the licensee identified that 22 of the 24 bays' lower plenum door beam cooler lines had a significant amount of frost or ice buildup. Each bay has a beam cooler (attached tubular glycol line) located inside the IC lower plenum just above the lower inlet doors. The accumulation was enough to cause the lower inlet door to be impaired from opening freely. Upon identification of the concern, the licensee documented the problem via PIP 2-C98-3216. After documenting the as-found condition of the frost buildup and door interference, the licensee remcved the frost buildup and implemented a modification to install insulation on the beam cooler lines. The inspectors reviewed the modification package and observed the final installation of the beam cooler modifications in the Unit 2 IC. The inspectors concluded that the installation was accomplished in accordance with the design modification and that the proposed corrective action for the frosting of the beam cooler lines was adequate. The inspectors noted that the beam coolers at the McGuire facility previously had been insulated in accordance with original design specifications. The Catawba existing design specifications did not include the subject beam cooler insulation.
TS 3.6.5.3 requires, in part, that the ice condenser inlet doors be closed and operable.
TS 4.6.5.3.1.b.2 requires, in part, that each inlet door be demonstrated operable by:
" Verifying that each door is capable of opening automatically in that it is not impaired by ice, frost, debris, or other obstruction." In that the licensee determined that this door obstruction existed while the unit was in operation for an estimated time in excess of the 14 day Limiting Condition for Operation (LCO), the inspectors concluded that the problem constituted a violation of TS 3.6.G.3. This failure to meet the Unit 2 IC inlet door operability requirements is identified as eel 50-414/98-16-04, Failure to Maintain Ice Condenser inlet Doors Operable.
The inspectors also reviewed licensee's Licensee Event Report (LER) 50-414/98-005 submitted October 6,1998, regarding this licensee identified ice door blockage. The licensee reviewed the safety significance of the partial door blockage and determined that the function of the IC was not impaired based on the identified problem. The ice condenser must be capable of handling tne blowdown load from a high energy line break in order to maintain peak containment pressure below 15 psig (with initial peak occurring at approximately 2 seconds). For this reason, the ice condenser inlet doors must open as designed. For small break LOCAs, the inlet doors must open at relatively low pressure to prevent steam from bypassing the ice condenser. Based on the subject blockage not preventing partial initial opening of the doors, the licensee concluded that small break LOCAs were not adversely affected. In addition, the licensee stated that the blowdown load from large break LOCA would bound all other sized LOCAs as well as feedwater and steam line breaks. As such, the licensee concluded that even though blockage would have restricted the door opening, they expected that the inlet doors
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would still have opened since the amount of frost was generally less than 1 inch below (on average) the top of the inlet doors. The licensee considered that the buildup would
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have been swept away by the door or quickly melted. Also, the licensee noted that the l
frost build-up did not impact the function of the beam cooler.
The licensee concluded that the root cause of the problem was inadequate design. The licensee also determined that, although some frosting of the lines had been identified in l
the past, the frost buildup had not been previously identified as a potential for door
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interference. Additional planned corrective actions included insulating of the Unit 1 beam cooling lines similar to the modification completed on Unit 2. The licensee had inspected the lower beam cooler area on Unit 1 during the August 1998 forced IC outage. No lower door interference problem was apparent at that time.
c.
Conclusions By observation of ice basket modification work, the inspectors verified that the localized ice basket damage repair, initial modifications involving ice basket lower plenum bracket replacement, and modifications to the lower plenum beam coolers were adequately accomplished in acc7rdance with established procedures. Technicians were adequately qualified to perform their assigned tasks; and adequate oversight was provided by the contractor and the licensee. Corrective actions for the previously identified problems were adequately implemented. Preventative measures to limit excessive loading were not as rigorous as other ice basket lif ting activities. No significant problems with current UFSAR accuracy were identified by the NRC. The licensee was continuing their UFSAR review in accordance with industry guidance.
An apparent violation was identified regarding inoperable IC lower inlet doors due to ice blockage.
E8 Miscellaneous Engineering issues (92903)
E8.1 (Closed) LER 50-414/98-005: Violation of Technical Specification 3.6.5.3 due to Inoperable Ice Condenser Lower Inlet Doors Caused by Ice / Frost Buildup Restricting Door Movement.
This LER was satisfactorily evaluated as part of the inspector's review of the lower plenum beam cooler modification discussed is Section E1.2.b.3 V. Mananement Meetinas X1 Exit Meeting Summary
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The inspectors presented the inspection results to members of licensee management at the conclusion of the inspection on November 4,1998. The licensee acknowledged the findings presented. Although proprietary information was reviewed during the inspection, none was identified in the report.
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PARTIAL LIST OF PERSONS CONTACTED
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i Licensee S. Bradshaw, Regulatory Compliance Manager P. Herran, Engineering Manager R. Jones, Station Manager i
B.-Lifsey, System Engineer
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G. Peterson, Catawba Site Vice-President NRC'
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D. Roberts, Senior Resident inspector M. Giles, Resident Inspector INSPECTION PROCEDURES USED IP 62707:
Maintenance Observations IP 61726:
Surveillance Obsen/ations
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IP 37551:
Onsite Engineering
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IP 92902:
Maintenance Followup IP 92903:
Engineering Followup l
ITEMS OPENED L
50-414/98-16-01 eel Failure to identify and Correct Ice Basket Deformation -
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(Section M1.2.b.4)
50-413,414/98-16-02 IFl ice Condenser Foreign Material Effects on ECCS Sumps
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(Section M1.4)
50-414/98-16-03 eel Inadequate Ice Condenser Debris Visual Inspection (Section M1.4)
50-414/98-16-04 eel Failure to Maintain Ice Condenser inlet Doors Operable
'(Section E1.2.b.3)
ITEMS CLOSED 50-414/98-005 LER Violation of Technical Specification 3.6.5.3 due to inoperable Ice Condenser Lower Inlet Doors Caused by Ice / Frost Buildup Restricting Door Movement
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(Section E8.1)
50-413/98-13-02 URI Past Ice Condenser Flow Blockage Operability Review (Section M8.1)
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i 50-413/98-13-04 URI Past Ice Condenser Foreign Material Effect on ECCS Sump Operability Review (Section M8.2)
50-413/98-13-06 URI Past Ice Condenser Dented Basket Operability Review (Section M8.3)
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