IR 05000298/1993022
| ML20057F054 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 10/06/1993 |
| From: | Beach A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Horn G NEBRASKA PUBLIC POWER DISTRICT |
| References | |
| NUDOCS 9310140060 | |
| Download: ML20057F054 (4) | |
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REGION IV
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611 RY AN PLAZA DRIVE, SUITE 400
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AR LINGTON, T E XAS 760118064
OCT - 61993
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Docket:
50-298 License:
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Nebraska Public Power District ATTN:
Guy R. Horn, Vice President - Nuclear P.O. Box 98 Brownville, Nebraska 68321
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SUBJECT:
NRC INSPECTION REPORT 50-298/93-22 (NOTICE OF VIOLATION)
Thank you for your letter of September 20, 1993, in response to our letter and Notice of Violation dated August 20, 1993. We have reviewed your l
reply and find it responsive to the concerns raised in our Notice of
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Violation. We will review the implementation of your corrective actions
during a future inspection to determine that full compliance has been achieved j
and will be maintained.
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Sincerely,
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A. Bill Beach, irecto i
Division of Re r P ojhtts
cc:
Nebraska Public Power District ATTN:
G. D. Watson, General Counsel P.O. Box 499 i
Columbus, Nebraska 68602-0499
i Nebraska Public Power District ATIN: Mr. David A. Whitman i
P.O. Box 499 i
Columbus, Nebraska 68602-0499 i
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i 9310140060 931006 i
PDR ADOCK 05000298 l
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Nebraska Public Power District-2-
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Nebraska Department of Environmental Control
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ATTN: Randolph Wood, Director P.O. Box 98922
Lincoln, Nebraska 68509-8922
Nemaha County Board of Commissioners ATTH: Larry Bohlken, Chairman Nemaha County Courthouse 1824 N Street Auburn, Nebraska 68305 Nebraska Department of Health l
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ATTN: Harold Borchert, Director Division of Radiological Health j
301 Centennial Mall, South
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P.O. Box 95007
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Lincoln, Nebraska 68509-5007 Kansas Radiation Control Program Director
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Nebraska Public Power District-3-
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bcc to DMB (IE01) - DRS and DRP bcc distrib. by RIV:
J. L. Milhoan Resident Inspector Section Chief (DRP/C)
Lisa Shea, RM/ALF, MS: MNBB 4503 MIS System DRSS-FIPS Section Chief (DRP/TSS)
Project Engineer (DRP/C)
RIV File Senior Resident Inspector - River Bend
Senior Resident Inspector - Fort Calhoun
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Nebraska Public Power District-3-bec to DMB (IE01)
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J. L. Milhoan Resident Inspector Section Chief (DRP/C)
Lisa Shea, RM/ALF, MS: MNBB 4503 MIS System DRSS-FIPS Section Chief (DRP/TSS)
Project Engineer (DRP/C)
RIV File Senior Resident Inspector - River Bend Senior Resident Inspector - Fort Calhoun
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cooper NUCLEA A 5t ATtoN
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t CNSS931187 September 20, 1993 g
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U.S. Nuclear Regulatory Commission
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Attention: Document Control Desk Washington, DC 20555 Subject: NPPD Response to Inspection Report 50-298/93-22 (Rep 1'y to a Notice of Violation)
Centlemen:
During an NRC inspection (Inspection Report 50-298/93-22) conducted by R. A. Kopriva of the NRC and others, from June 6 to July 17, 1993, an activity
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identified as being in violation of NRC requirements. The violation was concerned inadequate corrective actions in identifying and correcting degraded Service Water (SV) System piping.
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STATEMENT OF VIOLATION Criterion XVI, Appendix B, states, in part, that meas tres shall be established to assure that conditions adverse to quality, such as failures, deficiencies, i
and nonconformances, are promptly identified and corrected; and that measures shall assure that the cause of the condition is determined and corrective action taken to preclude repetition.
Contrary to the above, historical measures taken upon the discovery of a i
through-wall leak in a service water sample return piping did not assure that the cause of conditions were determined and that corrective actions precluded repetition. The case in point is that on July 3, 1993, a through-wall leak was discovered in a service water sample return pipe; the same line in which a i
previous leak had been identified on January 13, 1993. Hensore. had not been j
taken following the first event to assure that the cause for the condition was
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determined and corrective actions taken to preclude repetition.
This is a Severity Level IV violation (298/9322-01) (supplement I).
REASON FOR VIO1ATION on January 13, 1993. Maintenance Work Request (MWR) 93-0147 was generated when a pinhole leak was discovered in the 3 inch Schedule 40 Carbon Steel Service Water (SW) Radiation Monitor return line upstream of manual valve SW-V-533.
This line transports the radiation monitor sample flow (approximately 2-3 gpm)
to the Service Water System 18 inch discharge headers from the Residual Heat Removal JRHR) and/or Reactor Equipment Cooling (REC) heat exchangers which are h7Nb "
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93- ( ~T i D
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Document Control Desk September 20, 1993
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in service. The water flows through the piping in an intermittent fashion as the SW Radiation Monitor cycles through its various sampling points. This intermittent service results in very low flow velocity through the 3 inch lines.
In addition, this line also forms a portion of the flow path from the j
radioactive waste system discharge to the river.
This operation results in an occasional flow of approximately 75 gpm through the piping.
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instances, the discharge pressure through the return lines is low (less than
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approximately 50 psig).
A visual inspection of the pinhole leak revealed no leakage or, spray emitting from the noted location. The only visual indication of the presence of a leak was residual rust marks on the underside of the 3 inch SW Radiation Monitor return line.
In the original analysis, NPPD assumed the cause to be related to general corrosion in the piping system.
Industry experience has shown that j
such leaks in low pressure piping do not result in sudden catastrophic failures; rather, the failure progresses in stages, from a rust mark, to a few drips per minute and, finally, if not addressed, to a spray or full stream of water.
A similar leak was discovered in 1991 in the 2 inch carbon steel, Service
Water supply piping to the HVAC fan coil unit in the Emergency Diesel l
Generator Room.
A portion of the affected piping was sent for laboratory analysis and it was subsequently determined that several factors (including
Microbiological-Influenced Corrosion [MIC)), had resulted in the localized i
through-wall pit.
The laboratory test report indicated that the corrosion
activity had been accelerated by a combination of extended stagnant flow periods, followed by short periods of higher volume flow.
The affected piping
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was subsequently modified and is no longer in service.
A review of the work item history for the SW system identified 23 items related to small through-wall leaks in SW piping or components since 1980.
Several of the leaks were in the small bore safety related SW pump and SW
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booster pump gland seal systems. Design Change (DC)90-174 A/B, Amendment 1
was implemented to remove a, majority of the affected small bore SW gland seal piping. Most of the remaining piping was replaced with stainless steel.
Two of the 23 failures involved pinhole leaks in the previously mentioned SW radiation monitor sample return piping.
As described above, the failure in the SW supply piping to the DC fan coil unit was analyzed to be partially due to MIC.
Examination of the failed components had shown the problem to be limited to small bore, low flow SW piping.
For safety related small bore SW piping, the preferred repair method was to upgrade or eliminate the affected piping.
For non-safety related small bore SW piping, the usual repair method was to replace the affected piping like-for-like. The latter method was chosen to repair the SW Radiation Monitor Return piping, since this piping was classified as non-safety related during
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the' time frame that MVR 93-0147 was generated, as. described below.
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At the time of the discovery of the pin hole leak in January 1993, the 3 inch SV Radiation Monitor return line and the 3 inch downstream manual isolation i
valves, SW-V-532 and SW-V-533, were classified as non-safety related based on a 1986 SW hydraulic pipe break analysis.
The hydraulic analysis assumed that only one pipe break would occur at a time
during a design basis accident event.
It was demonstrated that a pipe break in the 3 inch SW Radiation Monitor return line would not cause the SW System to be unable to perform its design basis functions. The 3 inch SW Radiation
Monitor return lines were, therefore, classified as non-safety related.
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Since the affected piping was classified non-safety related and was not actually leaking, MWR 93-0147 was assigned a priority rating of
"4" (rating 1 through 4, with 4 being the. lowest priority) in the CNS Work Item Tracking System.
Due to the safety classification, the low work item priority, the difficulty in isolating the piping for repair, and the maintenance workload during the time frame that MWR 93-0147 was generated (preparing for the 1993 Refueling Outage), the actual implementation of the work item was not
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accomplished until late March 1993. At that time, a 10-foot section of the SW i
Radiation Monitor return piping was replaced like-for-like.
In June 1993, as a part of design basis reconstitution efforts, the need for a
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re-evaluation of the safety classification of components classified under the
SU pipe break analysis was identified. The re-evaluation was driven by a concern that the 1986 SW system hydraulic analysis may not have been sufficiently conservative, since it had only assumed one line break during a design basis event.
The re-analysis used the conservative classification
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criteria of ANSI 52.1 and it was subsequently determined that the 3 inch SW i
Radiation Monitor return piping downstream of the valves should be classified as safety related.
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Following the reclassification, it was then noted that during the
~ f implementation of MUR 93-0147, non-safety related replacement piping had been
installed in the 3 inch SW Radiation Monitor return piping between the
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isolation valves and the safety related main SU diset.arge headers.
MWRs 93-2620 and 93-2712 were issued on June 28 and July 3, 1993, respectively, to replace the non-safety related ssetions of 3 inch SW
Radiation Monitor return piping with safety related components.
During preparations for the installation of a freeze seal on a section of original construction piping on the
"B" loop of the 3 inch SV Radiation Monitor return piping (approximately 20' upstream of the non-safety related section) for MVRs
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93-2620 and 93-2712, an additional through-wall leak in the SV Radiation Monitor return line was discovered.
i As a result of this discovery, an extensive evaluation of all potentially susceptible SW piping was undertaken to determine the extent and scope of the
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problem. This process, as described in Operability Evaluation 93-000-037,
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visually examined sections of small bore SW piping, UT examinations of
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September 20, 1993 PaSe 4
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sections of large bore SW " dead leg piping, eliminated other sections of SW
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" dead leg" piping, hydrostatically tested selected sections of SW piping,
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installed isolation valves on the 3 inch SV Radiation Monitor supply and I
return lines, and replaced the 3 inch SW Radiation Monitor return lines with new Schedule 80 stainless steel piping.
i In summary, NPPD concedes that a error in judgement was nade regarding the
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scope and need for root cause analysis for MUR 9310147 Due to the non-safety L
related classification of the piping at the time of the discovery and the
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existing process used for maintenance and engineering priorities of such classified systems, appropriate corrective action'vas not implemented in a timely manner te analyze and correct the failure and to provide proper
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resolution to prevent recurrence.
CORRECTIVE STEPS TAKEN AND THE RESULTS ACHIEVED Due in part to the circumstances described above, NPPD has re-examined its corrective action program. This re-examination included the review of numerous, previously issued and dispositioned Licensee Event Reports (LERs),
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Nonconformance Reports (NCRs), Deficiency Reports (DRs), and MWRs; the formation of a corrective action program overview group; augmentation of
existing onsite QA personnel; and emphasis of a " questioning" attitude among our personnel. These and other measures have previously been described in meetings and correspondence between NPPD and the NRC.
As a result of the actions we have taken, we are now more confident that situations such as that
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described herein would be properly documented, analyzed, and corrected.
CORRECTIVE STEPS WHICH WILL BE TAKEN TO AVOID FURTHER VIOLATIONS To ensure that events such as the one described in this NOV do not recur,
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several steps have been taken to enhance the effectiveness of the Corrective Action Program.
Some of these steps have been previously mentioned and
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salient points are described in more detail below.
A Deficiency Report program was established to ensure that conditions adverse to quality which fall below the threshold of a Nonconformance Report are promptly identified and corrected. The establishment of the Deficiency Report
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program, although not a result of the events discussed above, is relevant to the extent that malfunctions pertinent to non-safety related equipment which do not result in a Nonconformance Report will, nevertheless, be formally addressed in order to preclude long-term equipment performance concerns.
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purpose of the program is to address failures such as the discovery of the
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pinhole in the 3 inch SW Radiation Monitor Return'line.
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In addition, a rigorous and " questioning" attitude concerning the issue of nuclear safety is being instilled into our personnel. Management expectations
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have been set forth in this area and have stressed that no problem is too i
small or insignificant to address where nuclear safety is concerned.
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Document Control Desk o
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DATE VHEN FULL COMPLIANCE WILL BE ACHIEVED NPPD is currently in full compliance.
I ADDITIONAL INFORMATION With regard to the Corrective Action Program Overview Group (CAPOG) not consistently demonstrating a questioning attitude during its review of SW deficiencies, a letter taas issued by the Site Manager on July 10, 1993, directing that a special review of the circumstances surrounding this matter be conducted. The review was conducted, and it determined that the CAPOG review of past documentation should have identified this problem. However, this determination is somewhat tempered by the following.
The CAPOG review of past MVRs, which was the document type that would have revealed the repeat nature of the SW deficiencies at the time, covered 10,161 MWRs.
Due to the numbers inyttved, a sampling technique was used which included:
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All open MWRs,
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All safety related and Equipment Qualification HWRs issued since April 21, 1991, and 3.
All Preventive Maintenance (PM) items issued since April 1991.
This time frame was chosen to reflect a review of NWRs over approximately the previous two year time frame.
As stated earlier, at the time the leak was discovered in the SW System sample line in January 1993, the line was classified as non-safety related.
In addition, the previous leak'that had been experienced on the sample line was identified in January 1991; however, the NWR associated with it was out of the
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scope of the CAPOG review (i.e., it was before the April 1991 review cutoff date).
Since the MWR for the leak in January 1993 was classified as non-safety related and the NWR for the previous leak in January 1991 was outside the scope of review, the repeat nature of the fall'ures was not recognized.
Notwithstanding the circumstances described above, the CAPOG performed the following to assure that no other like situations existed:
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All closed 1991 and 1992 non-safety related NWRs were reviewed.
This review addressed the only remaining portion of MWRs not covered by the previous CAPOG review and entailed some 5,785 MWRs.
It should be noted that the CNS Safety Review Group assisted with this review.
As a result, three additional Deficiency Reports, one action item, and several notes to the Engineering Department were issued.
None of the items were safety significant.
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NWRs for selected safety related and non-safety related systems were
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i reviewed specifica11y'for leaks which may have involved-microbiological 1y influenced corrosion (the most probable failure
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mechanism for the SW 1eaks).
For the' systems included in the review, l
the only questionable MVRs found were associated with the SW System, j
However, further investigation showed that these NWRs were either for i
erosion (which is addressed as a part of the CNS Erosion / Corrosion I
J Program), or for SW gland water piping (which was recently removed).
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As a final item related to the CAPOG review, the correspondence associated
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with this matter has been sent to the CAPOG members, and the Site Manager has
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discussed it with the CAPOG members in the interest of lessons learned.
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C R. Ilorn j
Vi President-Nuclear
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CRil:sa/ya ec: J. L. Milhoan j
NRC Regional Administrator
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R. A. Kopriva
NRC Resident Inspector i
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