ML20034F311
| ML20034F311 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 02/24/1993 |
| From: | Gagliardo J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | |
| Shared Package | |
| ML20034F301 | List: |
| References | |
| 50-298-93-06, 50-298-93-6, NUDOCS 9303030016 | |
| Download: ML20034F311 (11) | |
See also: IR 05000298/1993006
Text
{{#Wiki_filter:. . . A?PENDIX U.S. NUCLEAR REGULATORY COMMISSION REGION IV Inspection Report: 50-298/93-06 Operating License: DPR-46 Licensee: Nebraska Public Power District P.O. Box 499 Columbus, Nebraska 68602-0499 Facility Name: Cooper Nuclear Station In pection At: Brownville, Nebraska Inspection Conducted: February 1-9, 1993 Inspector: W. C. Walker, Resident Inspector w\\'\\ ad % Approved: / , ' 4_-{.E.pgliardo, Chief,ProjectSectionC Date ' Inspection Summary Areas Inspected: Special, unannounced inspection concerning safety significance of unmarked strainers / spacers found in safety-related systems. Results: e The licensee's conclusion that the reactor equipment cooling and reactor core isolation cooling systems were operable with temporary strainers installed appeared to be sound (Section 2).
Licensee inspections confirmed.that no additional temporary-strainers existed in safety-related systems, including the disposition of unmarked spacer rings (Section 2). The licensee was proactive in evaluating a potential condition (i.e.,
strainer installed in reactor core isolation cooling suction piping), however, Operability Determination 93-007 was weak in that it was not updated to assess the new conditions after subsequent investigations (Section 2). e Visual inspections of the flanges, observation of activities, and _ drawing and document reviews indicated that there were no temporary strainers or unmarked spacer rings in the high pressure coolant injection, residual heat removal, and core spray system pump suction piping (Section 3). 9303030016 930226 PDR ADOCK 05000298 G PDR
- . < -2- Preoperational and startup testing documentation was incomplete e regarding the status of the temporary hoods used on permanent torus strainers during startup testing. Video tapes of the most recent inspection of the torus indicate that they have most likely been removed (Section 3). Information supplied to the NRC in response to the Notice of Violation e addressing the core spray system temporary strainers, NRC Inspection Report 50-298/92-19, was: Inaccurate, regarding the removal of the temporary strainer for the Reactor Core Isolation Cooling System. Incomplete, in that the licensee's 1986 identification that temporary strainers potentially existed tn the reactor equipment cooling system, and absence of resolution, was not discussed. Incomplete, in that the licensee's 1986 identification of temporary strainers in the residual heat reraoval system, which apparently invalidating the licensee's earlier evaluation, was not discussed. j Incomplete, in that the licensee's identification in 1992 of spacer rings in the reactor equipment cooling system was not discussed. This is an apparent violation of 10 CFR 50.9 (Section 4). e The licensee failed to identify a condition adverse to quality regarding ] temporary strainers that may be installed in the retctor equipment 1 cooling system and did not resolve the-potential condition until the presence of temporary strainers were discovered in the system in January ) 1993 during maintenance activities. This is an appa ent violation-of j 10 CFR Part 50, Appendix B, Criterion XVI (Section 4). Summary of Inspection Findings: Two apparent violations were identified in Section 4.
Attachment: Persons Contacted and Exit Meeting
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. . -3- DETAILS 1 BACKGROUND in August,1992, temporary strainers were found in the alternate suction for Core Spray Systems A and B. The temporary strainers were apparently left installed after system preoperational and startup testing and were not part of - the permanent system design. The licensee removed the temporary strainers in September 1992. A Notice of Violation (NRC Inspection Report 50-298/92-19) was issued for the failure to identify and correct a condition adverse to quali in the core spray system. On January 27, 1993, during replacement of Reactor Equipment Cooling Pump C, the licensee discovered a temporary strainer in the pump suction piping. On , January 29, the licensee radiographed Reactor Equipment Cooling Suctions A, B, and D and the reactor core isolation cooling pump suction. Results of the radiographs conf rmed that temporary strainers were present. These strainers a had no tabs or markings ard, therefore, gave the appearance of a spacer ring. The temporary strainers may have been fabricated onsite with no identification tabs. - l The discovery of temporary strainers in the reactor equipment cooling and- reactor core isolation cooling systems raised questions regarding the adequacy of the licensee's corrective actions in response to the discovery of temporary strainers in the core spray system and evaluation of Information Notice 85-96 on temporary strainers left installed in pump suction piping. 2 RESPONSE TO FINDING ADDITIONAL STRAINERS 2.1 Operability Determinations The inspectors reviewed the licensee's Operability Determinations (93-006 and 93-007), which were performed on January 27, 1993, to evaluate the effects of teraporary strainers on the reactor equipment cooling and reactor. core isolation cooling systems, respectively. For the reactor equipment cooling system, the licensee considered that the ~ system was closed and that the condition of the strainer which was removed from Pump C was good with no visible sign of degradation or blockage. Additionally, performance testing of the remaining pumps showed no evidence of blockage of the pump suctions. The licensee concluded that the system was ' operable. For the reactor core isolation cooling system, the licensee assumed.that a strainer was installed. The licensee concluded that the likelihood of significant base metal loss due to corrosion was low because the condition of strainers which had been removed from the core spray and reactor equipment cooling systems was very good. Pump eperational data indicated that there was no apparent blockage in the pump suction. The licensee further indicated J - . _ _ _ .
.- . . _ - - - -- . . . - . - , . . j -4- that, if a detectable amount of blockage should occur, the strainer could be back-flushed. Seismic concerns were eliminated based on the close proximity , of an anchor point and the relatively low mass and stiffness of the structure of the strainer, , The existence of the strainer was confirmed by using radiography on January 29, 1993. Operability Determination 93-007 was not updated, however, [ to show the actual configuration of the temporary strainer which was found. ~ The results of the radiograph showed that the reactor core isolation cooling system strainer was installed backwards. The inspector questioned licensee representatives as to whether this configuration would effect 'the conclusions 4 in the operability determination. The licensee stated that the orientation of the strainer would not effect the operability of the reactor core isolation- , cooling system. 6 The inspector concluded, however, that it was not feasible to back-flush the I reactor core isolation cooling strainer. With the strainer installed backwards, there was no apparent flow path to remove foreign material from the strainer basket. Additionally, no procedure existed for back-flushing the strainer. The inspectors also noted that Operability Determination 93-007 did not address the relative size of the strainer mesh at the pump suction as; compared
to the size of the permanent torus strainer holes. The alternate suction ' source for the reactor core isolation cooling system was the suppression pool, and the potential existed for the reactor core isolation cooling suctien- .j strainer to become blocked if the screen mesh size of the torus strainer was - larger than the screen mesh size of the reactor core isolation cooling system
temporary strainer. The licensee provided information which showed that the screen size of the reactor core isolation cooling system temporary strainer + was about 1/8 inch, and this was confirmed to be about the same size as the ! pr*manent torus suction strainer. The licensee concluded that this did not - i adversely affect the operability of the reactor core isolation cooling system. i 2.2 Additional System Reviews , The licensee performed walkdowns and visually inspected the core spray, fuel pool cooling, high pressure coolant injection, residual heat removal, reactor -! water cleanup, turbine equipment cooling, condensate make-up, main condensate, reactor feedwat3r, and service water systems.
i The licensee identified that the turbine equipment cooling, condensate make- , up, main condensate, and reactor feedwater systems also appeared to have , strainers installed. -l.: I The process and instrumentation diagrams for the turbine equipment cooling.and condensate make-up systems indicated temporary strainers'were installed. The process and instrumentation diagrams for the fuel pool cleanup, main condensate, and reactor feedwater systems indicated that strainers were installed, however they were not identified as temporary. The condenshte; i > D - ~~ ---.-n-. . wa-- e- -e
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, & booster pumps and feedwater pumps were found to have tabs. in suction flanges',
which indicated that strainers were most likely installed. Licensee. , representatives-believe that the apparent strainers in the turbine equipment cooling and condensate _ make-up systems did not adversely affect plant safety, but no safety . evaluations were found to substantiate this conclusion. , . 2.3 Planned Actions ' The licensee planned to remove the reactor core isolation cooling system . 1 strainer during the next refueling outage. Thel licensee planned to remove the. ' strainers from the reactor equipment cooling system pumps during targets of 1 opportunity. i 2.4 Conclusions ,
The licensee's conclusion that the reactor equipment cooling and reactor. core 9 isolation cooling systems were operable with temporary strainers installed appeared to be sound. 1 Licensee inspections confirmed that no additional temporary strainers. existed
in safety-related systems, including the disposition of unmarked spacer rings.
The licensee had been proactive in evaluating a potential condition (i.e. " strainer installed in reactor core isolation cooling suction piping), however, - Operability Determination 93-007 was weak in that it was not updated to assess the specific condition after it was known. Specifically, the operability.
determination did not include the comparison of the mesh sizes of the permanent torus strainer with the temporary strainer, evaluation of the fact that the strainer was installed backwards, the fact that the ability.to back- .' flush the strainer in the event of blockage was not known, and that no procedure existed to specify how to back-flush the temporary strainer. . A safety evaluation of the apparent temporary strainers believed'to be
installed in nonsafety-related systems had not been performed. , i 3 REVIEW OF SAFETY-RELATED. SYSTEMS 3.1 Walkdown of Safety-Related Systems The inspectors performed a review of other safety-related systems to ensure no other strainers or spacers were installed. On February 3 the inspectors performed a walkdown of the high pressure" coolant injection suction piping and verified a spool piece was located in the - .1 suction piping with no spacers visible. Process and instrumentation diagram Burns and Roe Drawing 2044,. showed the location of the spool piece with no mention of the presence of a strainer. The removal of temporary strainers in the core spray system was observed by. inspectors in. September 1992. 1 --
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-6- , , ' In November 1986, the licensee identified temporary strainers in the residual heat removal shutdown cooling inlet suction piping. The licensee issued. Maintenance Work Requests 86-4749 and -4829 to remove the temporary startup , strainers. I Inspectors reviewed Work Packages 86-4749 and -4829 and verified that- documentation existed indicating that the temporary strainers'were removed. In addition, the inspectors visually inspected the spool piece flanges for i Residual Heat Removal Pumps A and C and found only a single gasket in.the flan.,es indicating that no other component was installed in the flange joint. The inspector reviewed preoperational test information on the residual heat removal system which contained a signature verifying installation of suction - sh ainer hoods on the torus strainers for testing. No documentation was found to verify removal of these hoods. The licensee stated that direct-inspections of the torus since startup have verified removal of the torus suction strainer i hoods. The inspectors verified this through viewing of a video tape taken in 1 1989 of one residual heat removal torus suction strainer which indicated that - ' no hoods were installed on the torus suction strainer. The process and instrumentation diagrams for residual heat removal and core spray indicated that no spool pieces were present; plant walkdowns, however, i verified spool pieces were installed. The process and instrumentation 1 diagrams for high pressure core injection and reactor equipment cooling both indicated the presence of spool pieces, and they were verified to be ' ' installed. The inspector questioned the licensee concerning apparent inconsistencies in the process and instrumentation diagrams and the as-found , conditions in the plant. The licensee indicated that information contained in 3 the process and instrumentation diagrams should reflect the as-built plant- 1 design. Additional information was supplied by the engineering staff indicating that spool pieces would not be shown on process and instrumentation diagrams unless a strainer was installed in the spool. 3.2 Conclusions Inspectors concluded, based on visual inspections of the flanges, observation of activities, and drawing and document reviews, that there were no i indications of temporary strainers or unmarked spacer rings in the high pressure coolant injection system, residual heat removal system, and core spray system pump suction piping.
Although preoperational and startup_ testing documentation was incomplete, . video tape information indicated that the temporary hoods used on permanent torus strainers during startup testing had most likely been removed. J -j
. . - -7- 4 REVIEW OF THE LICENSEE CORRECTIVE ACTIONS 4.1 Corrective Action Identified in Response to the Notice of Violation On December 1,1992, the licensee responded to the Notice of Violatien concerning strainers in the core spray system. In this response, the licensee concluded that the root cause was programmatic in-that the corrective action taken to address Information Notice 85-96 was less than adequate. The licensee identified that the preoperational test for the core spray system did not have specific steps to remove the temporary strainer and concluded that this was a procedural deficiency. Steps to be taken as corrective actions included performing walkdowns to - ensure similar strainers were not located in the reactor core isolation cooling, high pressure coolant injection, residual heat removal, service water and reactor equipment cooling systems. The results of these walkdowns, as reported in the response to the Notice of Violation, indicated that the licensee found no visible indications of temporary strainers installed in the service water, reactor equipment cooling, residual heat removal, or high - pressure coolant injection systems. , The licensee's walkdown of the reactor core isolation. cooling system identified an unlabeled spacer ring in the flange on the pump suction spool i piece. In the response to the Notice of Violation, the licensee committed to- verify the presence of a strainer in the reactor core isolation cooling system, either physically through inspection of the spool piece or by radiograph during the 1993 outage. Upon discovery of the strainer in Reactor Equipment Cooling Suction Line C, a radiograph was performed on January 29, -) and the presence of a strainer was confirmed. Reactor Core Isolation Cooling Drawing BR 2043 indicated a spool piece existed and contained words referencing a strainer. 4.2 Reactor Core Isolation Cooling System i The licensee also indicated that, unlike -the core spray system preoperational test, the reactor core isolation cooling system preoperational test had a specific completed sign-off indicating that the strainer had been removed prior to startup testing. The inspector reviewed the reactor core isolation cooling preoperational test summary dated November 27, 1973, and Startup Test Instruction STI-14 dated March 3,1974, and was unable to find documentation i for removal of the reactor core isolation cooling strainer. The ! preoperational test summary contained a step to remove startup strainers when appropriate per procedure STI-14, which was signed-off indicating completion. However, the step removing the temporary strainer in procedure STI-14 was not signed-off, indicating that the step was not completed. Licensee representatives stated that they.were aware of the missing signature i on the startup test instruction before preparing their response to the Notice of Violation on the core spray system. Their response was based on information obtained through interviewing an engineer involved in the startup
FT ' , 9; . -8- . testing who assured the licensee that signed verification for the removal of a ! ! temporary strainer from the reactor core isolation cooling system existed. The engineering staff stated that their commitment to verify existence of the . ; strainer in the reactor core isolation cooling system during the 1993 outage provided sufficient commitment. Inspectors concluded that no specific completed sign-off in the reactor core isolation cooling system preoperational or startup test existed. -The response
to the Notice of Violation dated December 1,1992, was inaccurate. ' , 4.3 Reactor Equipment Cooling System ! The licensee indicated in their response to the Notice of Violation that no externally visible indications of temporary strainers were present in the , reactor equipment cooling system. Inspector discussions with licensee personnel indicated that the licensee had identified what appeared to be' four spacer rings in the four pump suctions. .This was in apparent contradiction i with the process and instrumentation diagram, BR 2031, which indicated that
strainers were installed and identified them as temporary strainers. The , licensee's evaluation of the unmarked spacer rings consisted:of discussions ^ l with maintenance personnel, who indicated that' they could recall no strainers in the reactor equipment cooling system. , The inspector concluded that the licensee's corrective actions upon 1' identifying unmarked spacer rings in the Reactor Equipment Cooling System were inadequate in that the spacer rings, according to Infornation Notice 85-96, could indicate temporary strainers. The licensee's conclusion that. temporary ' strainers did not exist was based solely upon verbal discussions and did not reconcile the information contained in approved drawings with the believed . ; field configuration. Additionally, no discussion of'the unmarked spacer rings in the reactor ! equipment cooling system was . included in.the response to the Notice of Violation. The inspector concluded that the response to the Notice of . - Violation was incomplete since Information Notice 85-96 specifically indicated that temporary strainers could appear as unmarked spacer rings. The discovery i of additional potential indications of temporary strainers, and their disposition, would have been important in the NRC's evaluation of the 1 ' licensee's corrective actions to the identification of temporary strainers in- ' f the core spray system. Also, the licensee's.1986 evaluation for Information Notice'85-96 identified'
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that temporary strainers may be installed in the. reactor equipment cooling ! system and that further evaluation was required. This evaluation was not performed. While the licensee concluded that the root cause was inadequate corrective action to Information Notice 85-96, the licensee's discussion of _ the cause, in the response to the Notice of Violation, did not. include. i discussion that indications of temporary strainers in the reactor equipment cooling system had been known and were not resolved. . , D - - - - - - - , - .w . ..____. __-,- s - , , , .s ~ - . , . , . , ,Ey. s , +,
. . . -9 > The licensee also evaluated the residual heat removal system in response to NRC Information Notice 85-96. This evaluation, completed in July of 1986, concluded that only permanent strainers were present in the torus for the residual heat removal system. In November 1986, the licensee identified ' temporary startup strainers in the spool pieces for the residual heat removal shutdown cooling suction piping. The licensee issued Maintenance Work Requests 86-4749 and 86-4829 to remove the temporary startup strainers. The , licensee's identification of temporary strainers in the residual heat removal system, apparently invalidating the original evaluation of Information Notice 85-96, did not result in any review of additional systems for temporary ' strainers. The identification of temporary strainers in the residual heat- removal system in 1986 was not discussed in the licensee's response to the core spray system Notice of Violation, even though this discovery was directly relatec to the licensee's identified root cause. 4.4 Conclusions 4.4.1 Apparent Incomplete and Inaccurate Information 10 CFR 50.9 requires that information provided to the Commission by a licensee shall be complete and accurate in all material respects. Information supplied , to the NRC in response to the Notice of Violation addressing the core spray system temporary strainers, NRC Inspection Report 50-298/92-19, was:
Inaccurate in that the licensee indicated that a reactor core isolation cooling system preoperational test step was signed-off indicating that ' the temporary strainer, installed for testing, had been removed. The procedural step removing the reactor core isolation cooling system temporary strainer, actually in the startup test, was not signed-off, indicating that the step was not completed. e Incomplete in that the licensee's 1986 identification that temporary strainers potentially existed in the reactor equipment cooling system, absence of resolution, was not discussed. '
Incomplete in that the licensee's 1986 identification of temporary strainers in the residual heat removal system, apparently invalidating the licensee's earlier evaluation of Information Notice 85-96, was not discussed. Incomplete in that the licensee's identification in 1992 of spacer rings
in the Reactor Equipment Cooling System, which, according to Information Notice 85-96, could be an indication of temporary strainers, was not discussed. This is an apparent violation of 10 CFR Part 50.9. . ' . . .
-. .. , .. . l' i L ' ' ! -10- , L ,! l l i 4.4.2 Apparent Inadeauate Corrective Actions . The licensee did not identify a condition adverse to quality in that .the licensee identified in 1986 that temporary strainers, contrary to system. . design, may be installed in the reactor equipment cooling system and:did 'not' ' ,J resolve the potential condition; and, in 1992, the licensee identified that: unmarked spacer rings existed .in the reactor equipment. cooling system,. also indicating that temporary strainers may be installed, and did not. identify the' presence of temporary strainers until January 1993 during corrective maintenance. Additionally, the operability determination which'was performed i for.the Core Spray System contained several weaknesses and the licensee ^did. .i not perform written evaluations of strainers which-were found in -l nonsafety-related systems. 10 CFR Part 50, Appendix B, Criterion XVI, .) requires that the license identify and correct conditions adverse to quality.
This is an apparent violation of 10 CFR Part 50, Appendix B, Criterion ~XVI. j , , h I i 1 . , -l ! - 1 . . .-- ,- - ._ ,
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... . - .. . . ATTACHMENT 1 1 PERSONS CONTACTED ~ C. Bean, Construction Manager L. Bray, Regulatory Compliance Specialist M. Dean, Nuclear Licensing and Safety Supervisor. J. Flaherty, Engineering Manager S. Freeborg, Plant Engineering Supervisor R. Gardner, Plant Manager H. Hitch, Site Services Manager B. Jansky, NPPD Manager J. Myers, Senior Technical Staff Engineer S. Peterson, Senior Manager of.0perations J. Sayer, Radiological Manager G. Smith, Quality Assurance Manager V. Stairs, Assistant Operations Manager M. Unruh, Maintenance Manager . . The licensee personnel listed above attended the exit meeting held on February 9, 1993. In addition to the personnel listed-above, the inspector contacted other personnel during this inspection period. 2 EXIT MEETING , An exit meeting was conducted on February 9, 1993. During this meeting, the inspector reviewed the scope and findings of this report. The licensee did not identify as proprietary any information provided to, or reviewed by, the , inspector, i > t I , o P }}