ML20091M435
| ML20091M435 | |
| Person / Time | |
|---|---|
| Site: | Bellefonte  |
| Issue date: | 05/31/1984 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| REF-PT21-84-301-000 NCR-2517, PT21-84-301, PT21-84-301-000, NUDOCS 8406110301 | |
| Download: ML20091M435 (4) | |
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TENNESSEE VALLEY AUTHORITY CH ATTANOOGA. TENNESSEE 37401 400 Chestnut Street Tower II Nf/ S May 31, 1984
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E3 BLRD-50-438/83-59 BLRD-50-439/83-52 U.S. Nuclear Regulatory Commission Region II Attn: Mr. James P. O'Reilly, Regional Administrator 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30303
Dear Mr. O'Reilly:
BELLEFONTE NUCLEAR PLANT UNITS 1 AND 2 -DEFICIENT SQUARE ROOT EXTRACTOR MODULES FOR REACTOR PROTECTION SYSTEM BY BAILEY METER COMPANY
- BLRD-50-438/83-59, BLRD-50-439/83 FINAL REPORT The subject deficiency was initially reported to NRC-0IE Inspector Linda Watson on November 14, 1983 in accordance with 10 CFR 50.55(e) as NCR J
2517 This was followed by our interim reports dated December 8,1983 and
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February 17, 1984. Enclosed is our final report. We consider 10 CFR Part 21 applicable to this deficiency.
If you have any questions, please get in touch with R. H. Shell at FTS 858-2688.
Very truly yours, TENNESSEE VALLEY AUTHORITY L. M. Mills, nager Nuclear Licensing Enclosure oc:
Mr. Richard C. DeYoung, Director (Enclosure)
Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, D.C.
20555 Records Center (Enclosure)
Institute: of Nuclear Power Operations 1100 Circle 75 Parkway, Suite 1500 Atlanta, Georgia 30339 8406110301 840531 PDR ADOCK 05000438
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=wM7 1983-TVA SOTH ANNIVERSARY g
g An Equal Opportunity Employer e
t ENCLOSURE BELLEFONTE NUCLEAR PLANT UNI'131 AND 2 DEFICIENT SQUARE ROOT EXTRACTOR MODULES FOR REACTOR PROTECTION SYSTEM BY BAILEY METER COMPANY BLRD-50-438/83-59, BLRD-50-439/83-52 l
NCR 2517 10 CFR 50.55(e)
FINAL REPORT Description of Deficiency Square root extractor modules were returned to the manufacturer, Bailey Meter Company (BCCo), Wickliffe, Ohio, for rework to incorporate Babcock &
Wilcox (B&W) field change package (FCP) No. 54. The rework was to add an enhanced input filter which would help to suppress turbulence-induced noise in the reactor protection system (RPS) measurement of reactor coolant system (RCS) flow, and thus, increase overall accuracy of the flow measuremen t.
When the reworked modules were returned from Bailey to the site, it was discovered that the module subcircuit board retaining hardware was loose, missing, or improperly installed.
B&W and BCCo have reviewed the rnnconformance report (NCR) and determined that the following represents the root cause of the subject deficiencies.
1.
Loose subcircuit boards - At some point after the final inspection at BCCo, some of the subcircuit boards became disengaged from their retaining clips. It is not possible to determine the exact cause/ mechanism of this problem; however, testing conducted on the module frames has revealed that distortion of the module frame can cause some or all of the subcircuit boards to become disengaged from their retaining clips.
It is believed that forces imposed upon the modules during packing / shipment / unpacking / handling could produce enough distortion to cause the suboircuit boards to disengage. While this is the most likely cause of the loose subcircuit boards, it cannot be stated to be the exact cause of the problem.
2.
Nonfunctional suboircuit boards - Four of the modules contain an extra, nonfunctional subcircuit board. The root cause of this deficiency is failure by BCCo to visually detect the extra suboircuit board during final inspection of the modules.
Additionally, BCCo did not allow representatives from TVA's Division of Engineering Design's (EN DES) Quality Engineering Branch (QEB) to inspect the modules at their facilities before returning them to Bellefonte.
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- 3. <Daractiva/ missing subcircuit board retaining h rdware - Some of the tubcircuit board retaining dsvicss (ovsrhssd retaining clips'and terminal. blocks) are cracked. This defect is similar to that reported in NCR 1795 (BLRD-50-438/82-30, BLRD-50-439/82-27) for retaining
' devices in other BCCo plug-in modules. The exact cause of the cracking is indeterminate. B&W and BCCo believe that the most likely cause of the cracking is the same distortion of the module which caused disengagement of the subcircuit boards. However, this cannot be stated to be the exact cause of the problem.
Also, some modules are missing nonfunctioning overhead retaining clips for some of the spare subcircuit board locations. This is not in accordance with design drawings which indicate overhead mtaining clips at all spare locations. The root cause of this discrepancy is the same as that indicated above for the nonfunctional subeircuit boards.
Safety Implications The square root extractor modules are part of the electrical equipment that enable the plant operator to monitor power, RCS hot and cold leg tempera-
_ tures, RCS flow and pumps status, pressurizer level, and main feedwater flow and pump status. The retaining hardware deficiencies could have led to equipment malfunctions due to loosened or shortened electrical connections caused by loose subcircuit board movement, especially during a seismic event. If this equipment had been installed and left uncorrected, the operator might not have been able to monitor vital, essential, and operational control functions of the primary and secondary systems. Thus, the safe operation of the plant could be adversely affected.
Corrective Action The defective modules are to be returned to the manufacturer (BCCo) for correction of the reported deficiencies. Upon delivery, TVA's Division t
of Construction (CONST) will install the repaired modules by February 1, 1985.
The following action has been taken to prevent mourrence of the reported deficiencies.
1.
Loose circuit boards - To prevent distortion of the modules during
. shipping and handling, BCCo will place a retainer strip around the center of the module frame to restrain the frame. The strap must be removed before installation of the module.
- 2. _ Nonfunctional suboircuit boards - BCCo has taken steps to prevent
. ~ recurrence of this problem by increasing the education of employees assembling the units and placing additional emphasis on the visual inspection of these modules. BCCo Quality Assurance is increasing its surveillance of this process to verify that these measures correct the problem.
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Addititnally, B&W hns cgreed to cdvisa TVA (QEB) when equipm;nt
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will b2 rerdy for shipment. This will parmit TVA to inspect Mworked equipment at BCCo fccilitics bafora shipment to Bellefonte.
- 3. - Defective / missing suboircuit board retaining hardware - The action required to prevent recurrence of the cracked connector defect is the same as that for NCR 1795 (restated below).
i "QEB will inspect all new plug-in modules which contain the subject components at BCCo facilities before shipment to the site. Any components which contain the subject defects will be re jec ted. BCCo will be required to mplace all defective components before TVA's approval for shipment.
Additionally, EN DES has moommended that construction personnel inspect the polycarbonate componer.ts in the subject modules on a periodic basis for six months subsequent to their return to the site. Any mourrence of the defect in NCR 1795 in the replacement components must be reported to EN DES as soon as detected."
The action required to prevent recurrence of the mLasing subcircuit board retaining hardware is the same as that outlined above for the nonfunctional subcircuit boards.
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