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{{Adams
#REDIRECT [[IR 05000259/2008009]]
| number = ML081510829
| issue date = 05/30/2008
| title = IR 05000259-08-009, 05000260-08-009 and 05000296-08-009, on 04/27/08 - 05/02/08, Browns Ferry Nuclear Plant, Units 1, 2 and 3, Event Followup
| author name = Wert L
| author affiliation = NRC/RGN-II/DRP
| addressee name = Campbell W
| addressee affiliation = Tennessee Valley Authority
| docket = 05000259, 05000260, 05000296
| license number = DPR-033, DPR-052, DPR-068
| contact person =
| document report number = IR-08-009
| package number = ML090210101
| document type = Inspection Report, Letter
| page count = 28
}}
See also: [[see also::IR 05000260/2008009]]
 
=Text=
{{#Wiki_filter:UNITED STATES
                              NUCLEAR REGULATORY COMMISSION
                                              REGION II
                                SAM NUNN ATLANTA FEDERAL CENTER
                                61 FORSYTH STREET, SW, SUITE 23T85
                                    ATLANTA, GEORGIA 30303-8931
                                          May 30, 2008
Mr. William R. Campbell, Jr.
Chief Nuclear Officer and Executive Vice President
Tennessee Valley Authority
6A Lookout Place
1101 Market Street
Chattanooga, TN 37402-2801
SUBJECT:        BROWNS FERRY NUCLEAR PLANT - NRC SPECIAL INSPECTION REPORT
                05000259/2008009, 05000260/2008009 AND 05000296/2008009
Dear Mr. Campbell:
On May 2, 2008, the Nuclear Regulatory Commission (NRC) completed a special inspection at
your Browns Ferry facility. The enclosed report documents the inspection findings which were
discussed on May 2 with Mr. R. West and other members of his staff.
Between March 24 and March 30, 2008, your staff disassembled both Division I 3A and 3C, and
Division II, 3B and 3D, residual heat removal heat exchanger service water (RHR HX SW) outlet
flow control valves (FCVs) and found significant degradation in each valve including stem-to-
disc separation in several. During the last Unit 2 refueling outage, your staff had identified
similar degradation in two of the Unit 2 RHR HX SW outlet FCVs.
On April 18, 2008, NRC Region II management established a Special Inspection Team using
the guidance contained in Management Directive 8.3, NRC Incident Investigation Program. The
Special Inspection Team was chartered to identify the degradation mechanisms that had
affected these valves, review the past and current root-cause evaluations, review the interim
and long-term corrective actions, and verify that the interim corrective actions are adequate to
ensure the operability of the Units 2 and 3 RHR HX SW outlet FCVs, until a long-term resolution
is implemented. The inspection examined activities conducted under your license as they relate
to safety and compliance with the Commissions rules and regulations and with the conditions of
your license. The inspectors reviewed selected procedures and records, conducted field
walkdowns, observed activities, and interviewed personnel.
Based on the results of this inspection, the inspectors identified one issue of very low safety
significance (Green) that was determined to involve a violation of NRC requirements. However,
because of its very low safety significance and because it has been entered into your Corrective
Action Program, the NRC is treating this issue as a non-cited violation, in accordance with
Section VI.A.1 of the NRCs Enforcement Policy. If you deny the non-cited violation, you should
provide a response with the basis for your denial, within 30 days of the date of this inspection
report to the Nuclear Regulatory Commission, ATTN: Document Control Desk, Washington DC
20555-0001, with copies to the Regional Administrator, Region II; the Director, Office of
 
TVA                                            2
Enforcement, United States Nuclear Regulatory Commission, Washington, DC 20555-0001; and
the NRC Resident Inspector at the Browns Ferry facility.
In accordance with 10 CFR 2.390 of the NRC's "Rules of Practice," a copy of this letter and its
enclosure will be available electronically for public inspection in the NRC Public Document
Room or from the Publicly Available Records (PARS) component of NRC's document system
(ADAMS). ADAMS is accessible from the NRC Web site at http://www.nrc.gov/reading-
rm/adams.html (The Public Electronic Reading Room).
                                              Sincerely,
                                              /JHM RA for/
                                              Leonard D. Wert, Director
                                              Division of Reactor Projects
Docket Nos.: 50-259, 50-260, 50-296
License Nos.: DPR-33, DPR-52, DPR-68
Enclosure: Inspection Report 05000259/2008009, 05000260/2008009 and 05000296/2008009
              w/Attachment: Supplemental Information
cc w/encl.: (See page 3)
 
 
_________________________
OFFICE            RII:DRP        RII:DRP        RII:DRP          RII:DRP          RII:DRP
SIGNATURE          JBB /RA/        CRS /via email/ RCH /via email/  RLN /via telecon JHM /RA/
NAME              JBaptist        CStancil        BHagar          RNease          JMoorman
DATE                  05/30/2008      05/30/2008      05/30/2008      05/30/2008      05/30/2008
E-MAIL COPY?        YES        NO  YES        NO  YES        NO  YES          NO  YES        NO YES    NO    YES NO
       
TVA                                      3
cc w/encl:                                Larry E. Nicholson
Ashok S. Bhatnagar                        General Manager
Senior Vice President                      Performance Improvement
Nuclear Generation Development and        Tennessee Valley Authority
Construction                              Electronic Mail Distribution
Tennessee Valley Authority
Electronic Mail Distribution              Michael A. Purcell
                                          Senior Licensing Manager
William R. Campbell, Jr.                  Nuclear Power Group
Chief Nuclear Officer and Executive Vice  Tennessee Valley Authority
President                                  Electronic Mail Distribution
Tennessee Valley Authority
6A Lookout Place                          H. Rick Rogers
1101 Market Street                        Vice President
Chattanooga, TN 37402-2801                Nuclear Engineering and Technical
                                          Services
(Vacant)                                  Tennessee Valley Authority
Vice President                            Electronic Mail Distribution
Nuclear Support
Tennessee Valley Authority                Beth A. Wetzel
3R Lookout Place                          Manager
1101 Market Street                        Corporate Nuclear Licensing and Industry
Chattanooga, TN 37402-2801                Affairs
                                          Tennessee Valley Authority
R. G. (Rusty) West                        Electronic Mail Distribution
Site Vice President
Browns Ferry Nuclear Plant                Senior Resident Inspector
Tennessee Valley Authority                Tennessee Valley Authority
Electronic Mail Distribution              Browns Ferry Nuclear Plant
                                          U.S. NRC
D. Tony Langley                            10833 Shaw Road
Manager                                    Athens, AL 35611-6970
Licensing and Industry Affairs
Tennessee Valley Authority                Chairman
Electronic Mail Distribution              Acting Licensing Manager
                                          Limestone County Commission
John C. Fornicola                          310 West Washington Street
General Manager                            Athens, AL 35611
Nuclear Assurance
Tennessee Valley Authority
Electronic Mail Distribution
General Counsel
Acting Licensing Manager
Tennessee Valley Authority
Electronic Mail Distribution
 
TVA                                        4
Letter to William R. Campbell, Jr. from Leonard D. Wert dated May 30, 2008
SUBJECT:        BROWNS FERRY NUCLEAR PLANT - NRC SPECIAL INSPECTION REPORT
                05000259/2008009, 05000260/2008009 AND 05000296/2008009
Distribution w/encl:
E. Brown, NRR
L. Raghavan, NRR
C. Evans, RII
L. Slack, RII
OE Mail
RIDSNRRDIRS
PUBLIC
 
            U. S. NUCLEAR REGULATORY COMMISSION
                              REGION II
Docket Nos:          50-259, 50-260, 50-296
License Nos:        DPR-33, DPR-52, DPR-68
Report No:          05000259/2008009, 05000260/2008009 and
                    05000296/2008009
Licensee:            Tennessee Valley Authority (TVA)
Facility:            Browns Ferry Nuclear Plant, Units 1, 2 & 3
Location:            Corner of Shaw and Nuclear Plant Roads
                    Athens, AL 35611
Dates:              April 27 - May 2, 2008
Inspectors:          R. Hagar, Senior Resident Inspector - Robinson
                    C. Stancil, Resident Inspector - Browns Ferry
Approved by:        Rebecca L. Nease, Chief
                    Reactor Project Branch 6
                    Division of Reactor Projects
                                                                    Enclosure
 
                                      SUMMARY OF FINDINGS
IR 05000259/2008009, 05000260/2008009 and 05000296/2008009; 04/27/08 - 05/02/08;
Browns Ferry Nuclear Plant, Units 1, 2 and 3; Event Followup.
The special inspection team (SIT) inspection was conducted by a senior resident inspector and
a resident inspector. One finding of very low safety significance (Green) was identified. The
significance of most findings is indicated by their color (Green, White, Yellow, Red) using
Inspection Manual Chapter (IMC) 0609, Significance Determination Process (SDP). The
NRCs program for overseeing the safe operation of commercial nuclear power reactors is
described in NUREG-1649, Reactor Oversight Process, Revision 4, dated December 2006.
A. NRC-Identified and Self-Revealing Findings
    *  Green. The inspectors identified a Green non-cited violation of 10 CFR 50, Appendix B,
        Criterion XVI, for the licensees failure in March, 2000, to take action to preclude
        repetition of stem-to-disc separation events in residual heat removal heat exchanger
        service water outlet valves. The finding is more-than-minor, because if left uncorrected
        the condition would become a more significant safety and regulatory concern. In Phase
        1 of the SDP, described in IMC 0609, Attachment 4, this finding screened as Green
        because it affected the Mitigating Systems cornerstone and was a design deficiency
        confirmed not to result in loss of operability or functionality. The finding has a cross-
        cutting aspect in the area of problem identification and resolution (P.1(c)) because the
        licensee did not thoroughly evaluate a problem such that the resolutions addressed
        causes and extents of condition. (Section 4OA3.3)
B. Inspection Results
    *  Degradation that occurred in the residual heat removal heat exchanger service water
        outlet flow control valves included broken motor lugs, broken motor leads, separations of
        valve discs from their stems, broken stem-to-disc tack welds, stem shear, slipped anti-
        rotation collars, separations of valve handwheels from their shafts, a gasket leak, a
        broken disc flute, and dislodging of a stem cap.
    *  In all cases, the degradation mechanism was a combination of operating the valves
        under conditions that induced high levels of vibration in the valves and the vulnerability
        of the valves to vibration-induced damage.
    *  Repairs have been sufficient to support continued operation and the current operability
        determination in the near term, because the repairs have reduced the vulnerability of the
        valves to vibration-induced damage. However, no evidence suggests that those repairs
        have eliminated that vulnerability.
    *  Planned long-term corrective actions include replacing the currently-installed Walworth
        and Anchor-Darling valves in Units 2 and 3 with Copes-Vulcan valves identical to those
        in Unit 1, to further reduce the valves vulnerability to vibration induced damage.
                                                                                            Enclosure
 
                                      3
* The implemented corrective actions only partially address the root cause, in that those
  actions have reduced the vulnerability of the valves to vibration-induced damage, but
  have not yet effectively changed the conditions under which the valves are operated.
  The planned corrective actions are expected to further reduce the vulnerability of the
  valves to vibration-induced damage, but no changes are planned to change the
  conditions under which the valves are operated.
* The only generic safety issue associated with this inspection (vibration-induced damage
  to safety-related components) has been adequately addressed in generic
  communications.
                                                                                  Enclosure
 
                                          REPORT DETAILS
Initial Conditions
During the period of March 24 to March 30, 2008, Unit 3 was shutdown in Operating Mode 5 for
a planned refueling outage which had begun on March 18, 2008, and Units 1 and 2 were
operating at 100% reactor power.
Event Description
On March 24, 2008, the licensee disassembled and inspected the 3A residual heat removal
heat exchanger service water (RHR HX SW) outlet valve and found that it had experienced
stem-to-disc separation with severe erosion of the valve body and internal rib guides. On March
25 and March 28, respectively, the licensee disassembled and inspected the 3C and 3B RHR
HX SW outlet valves and found that they had also experienced significant internal damage, as
well as, stem-to-disc separation. On March 30, the licensee determined that the 3D RHR HX
SW outlet valve had not experienced stem-to-disc separation but had experienced tack weld
breakage and minor valve body erosion.
Special Inspection Team (SIT) Charter
Based on the criteria specified in Management Directive 8.3, NRC Incident Investigation
Program, and Inspection Procedure 71153, Event Follow-up, a special inspection was initiated
in accordance with Inspection Procedure 93812, Special Inspection. The objectives of the
inspection, described in the charter, are listed below and are addressed in the identified
sections:
  1.    Develop a complete description of the degradation found in the Units 2 and 3 RHR HX
        SW outlet flow control valves (FCVs), and the various degradation mechanism(s)
        observed over multiple operating cycles. (Section 4OA3.1)
  2.    Review the licensees repair efforts of all units RHR HX SW outlet FCVs to determine if
        repairs are sufficient to support operation and the current operability determination.
        (Section 4OA3.2)
  3.    Review the licensees root cause analysis and extent of condition. Assess the adequacy
        of the licensees implemented and/or planned corrective actions to address the root
        cause. (Section 4OA3.3)
  4.    Review industry operating experience and the licensees actions in response to any
        related operating experience items including Information Notice 2006-015, Vibration-
        Induced Degradation and Failure of Safety Related Valves. (Section 4OA3.4)
  5.    Identify any potential generic safety issues and make recommendations for appropriate
        follow-up actions (e.g., Information Notices, Generic Letters, Bulletins). (Section
        4OA3.5)
                                                                                          Enclosure
 
                                            5
OTHER ACTIVITIES
4OA3 Event Followup
.1    Degradation Found in the RHR HX SW Outlet FCVs
  a. Inspection Scope
      The inspectors walked down the RHR HX SW outlet FCVs in Units 1, 2, and 3,
      interviewed selected plant personnel, and reviewed problem evaluation reports (PERs)
      and work orders (WOs) associated with the degradation that occurred in these valves to
      develop a complete description of the degradation that had been found in these valves
      and to identify the degradation mechanisms.
  b. Observations and Findings
      The inspectors noted that valves from different manufacturers were installed in the
      different units: Copes-Vulcan valves were installed in Unit 1, Walworth valves with fluted
      discs were installed in unit 2, and Anchor-Darling valves are installed in unit 3. Licensee
      records show that these valves have all been installed in their respective units since
      each units restart date, except for the 2C and 2D HX valves in Unit 2. With respect to
      those valves:
      *    The 2C RHR HX SW outlet valve (2-FCV-23-0040) operated for a short period with a
          non-fluted disc. That period began in March, 2003, after the valve experienced a
          broken disc flute and the licensee installed a non-fluted disc to replace the broken
          disc. That period ended in October, 2003, when the licensee re-installed a fluted
          disc after the valve experienced seat leakage and a stem-to-disc failure.
      *    During the 2007 Unit 2 refueling outage, the licensee identified a stem shear with
          severe valve body and rib guide erosion on the 2D RHR HX SW outlet valve (2-FCV-
          23-52). The licensee subsequently replaced this valve with a 12-inch Anchor Darling
          model like those in Unit 3.
      Licensee records also show that the subject valves had experienced the following
      damage since each units restart:
                                            Number of damage occurrences since unit restart
        Type of Damage                          in Unit 2 valves            in Unit 3 valves
        broken motor lugs                                2                          2
        broken motor leads                              0                          5
        stem-to-disc separation                          1                          4
        broken stem-to-disc tack welds                  0                          1
        stem shear                                      1                          0
        slipped anti-rotation collar                    0                          5
        handwheel separation                            4                          1
                                                                                          Enclosure
 
                                            6
        broken disc flute                                1                        0
        stem cap separation                              1                        1
        gasket leakage                                  1                        0
      Records reviewed by the inspectors showed no damage to the RHR HX SW outlet FCVs
      in Unit 1.
      Comprehensive timelines of the damage that occurred to the RHR HX SW outlet FCVs
      in Units 2 and 3 are provided in Attachments 1 and 2 to this report. Those timelines
      show, in part, that:
      *    In Unit 2, the earliest occurrence of damage to these valves was in December, 1994,
          when a handwheel separated from Valve 2-023-040. That date was approximately
          42 months after the July, 1991, restart of the unit.
      *    In Unit 3, the earliest damage occurrence was a broken motor lug in March, 1997,
          approximately 17 months after the October, 1995, restart of that unit.
      *    Damage events generally occurred earlier in plant life in Unit 3 than they did in
          Unit 2.
      *    More damage events affected Unit 3 valves than Unit 2 valves.
      *    The licensees responses to these events included 2 B-priority root-cause analyses,
          11 C-priority apparent-cause evaluations, 7 C-priority no-cause evaluations, and 2 D-
          priority apparent-cause evaluations.
      Licensee evaluations of these damage states consistently indicated that all of the
      damage identified above was caused by vibration; several evaluations referred to that
      vibration as normal. The inspectors determined that the damage had actually been
      caused by a combination of two factors:
      *    During shutdown cooling, the licensee operated these valves in a way that allowed
          relatively-severe cavitation to occur immediately downstream of the valve discs.
          That cavitation induced vibration that affected both the valve body and the valve
          stem-disc assembly.
      *    The valves were vulnerable to vibration-induced damage.
.2    Efforts to Repair the Subject Valves
  a. Inspection Scope
      The inspectors reviewed licensee records to determine whether repairs are sufficient to
      support operation and the operability determinations documented in Functional
      Evaluations 42538 (Unit 2) and 42520 (Unit 3) .
                                                                                        Enclosure
 
                                          7
b. Observations and Findings
  The inspectors determined that the licensee had repaired the damage the valves had
  experienced, and that the licensee had also made several changes to the valves to
  reduce the valves vulnerability to vibration-induced damage. The damage states and
  the corresponding changes made by the licensee are summarized in the table below.
    Damage state                  Change(s) made to address
    Broken motor lugs & leads      Removed all motor terminal blocks (no longer
                                    requiring lugs) and replaced with Raychem splices
    Stem-to-disc separation        Replaced threaded and tack-welded connections
                                    between the valve stems and the discs with full-
                                    welded connections
    Slipped anti-rotation collar  Slightly drilled the valve stems at the set-screw
                                    locations and replaced the standard set screw with a
                                    dog-point-style set screw
    Handwheel separation          Removed set screws, spot-drilled the handwheel
                                    shafts, and then on each shaft installed two set
                                    screws back-to-back
  The inspectors considered that the damage states that had the greatest safety
  significance were broken motor leads and lugs, because those can disable the valve
  actuators, and slippage of the anti-rotation collar, because that event can prevent the
  valve from responding to actuator operation. The other damage states would degrade
  the valves, but would not render the valves incapable of performing their safety
  functions, which are to open to remove reactor decay heat and to close to isolate flow
  from a heat exchanger tube rupture.
  Using engineering judgment, the inspectors determined that the changes made by the
  licensee had reduced the vulnerability of the valves to vibration-induced damage. In
  particular, as shown in the table above, the licensee has made changes to address the
  damage states that had the greatest significance (broken motor leads and lugs and
  slippage of the anti-rotation collar). However, the inspectors noted that the licensee had
  no evidence to indicate that these changes had eliminated that vulnerability.
  Furthermore, the inspectors noted that the licensees long-term plan to address this
  issue included replacing the Walworth and Anchor-Darling valves currently installed in
  Units 2 and 3 with Copes-Vulcan valves identical to those currently installed in Unit 1.
  Because the Copes-Vulcan valves contain approximately 50% more mass than do the
  Walworth and Anchor-Darling valves, the inspectors considered that completing that
  replacement should further reduce the vulnerability of the valves to vibration-induced
  damage. However, the inspectors also noted that the licensee had no evidence to
  indicate that Copes-Vulcan valves are immune to vibration-induced damage.
                                                                                      Enclosure
 
                                                8
      For this charter item, because the licensee has taken action to reduce the vulnerability of
      these valves to vibration-induced damage, the inspectors concluded that repairs are
      sufficient to support operation and the operability determination. However, continued
      monitoring of these valves during shutdown-cooling operation will be required to
      determine whether additional actions are necessary.
.3    Root-Cause Analyses and Extent of Condition
  a. Inspection Scope
      The inspectors reviewed the licensees root-cause analyses and extent-of-condition
      determinations to determine whether the licensees implemented and/or planned
      corrective actions address the root cause.
  b. Observations and Findings
      As mentioned above, the inspectors determined and the licensee staff agreed that the
      damage the RHR HX SW outlet FCVs had experienced had been caused by the
      combination of operating those valves in a way that induced vibration and the
      vulnerability of those valves to vibration-induced damage. The root cause was
      therefore that combination.
      As the timelines in attachments 2 and 3 show, the licensee completed two root-cause
      analyses that address the damage these valves have experienced: (1) PER 35419,
      which the licensee initiated in April of 2000 after the first stem-to-disc separation event;
      and (2) PER 104621, which the licensee initiated in June of 2006, after the RHR SW
      system had exceeded the performance criteria established in accordance with 10 CFR
      50.65 (Maintenance Rule) and had, therefore, been classified under paragraph (a)(1) of
      that rule.
      With respect to the combination of causes described above, the inspectors noted the
      following in PER 35419:
        *    This PER had been initiated to address a stem-to-disc separation event that
            occurred in Valve 3-FCV-023-0046 in Unit 3.
        *    The licensee determined that the root cause of the subject event had been fatigue
            placed on the valve disc when the flow rate was low causing a high differential
            pressure across the valve.
            With respect to the actual root cause described above, this statement mentions
            low-flow conditions but does not mention cavitation, vibration resulting from
            cavitation, or the valves vulnerability to vibration-induced damage. This PER,
            therefore, did not fully identify the root cause of the damage.
        *    The corrective action to address the identified root cause was to change the
            operation instruction for the RHR SW system so that when one RHR SW heat
            exchanger (and its associated outlet FCV) is operated at low flow rates, operators
                                                                                          Enclosure
 
                                      9
    would establish flow through another RHR HX so that the combined flow through
    both HXs would be approximately 4000 gallons/minute. The licensee expected
    this change to  lower the pressure the valve has to work against thereby
    lessening the probability of damage to the valve. The corresponding procedure
    change was implemented in Revision 45 of Procedure 0-OI-23, Residual Heat
    Removal Service Water System, which was issued on May 30, 2000.
    Subsequent experience demonstrated that this procedure change was not effective
    at preventing stem-to-disc separation events. Implementation of corrective actions
    for this PER, therefore, constituted the performance deficiency documented below
    (following the observations regarding PER 104621).
*  The record for this PER did not include a review of the effectiveness of this
    corrective action. This record, therefore, did not indicate that the licensee had
    attempted to verify that the procedure change had the intended effect.
*  The record for this PER indicated that the valve vendor (Anchor Darling) had
    specified the maximum differential pressure that the RHR HX SW outlet FCVs
    should experience, and had recommended that the valves, which had been
    subjected to a differential pressure outside the recommended maximum, should be
    disassembled and inspected. In this PER, the licensee asserted without support
    that the valve that experienced the failure (3-FCV-023-0046) was the only valve
    that had been subjected to the conditions that caused the failure, and therefore
    determined that disassembly and inspection of the other valves was not necessary.
    However, that assertion was not consistent with operating records, which indicated
    that the four RHR HX SW outlet FCVs in Unit 3 and the four RHR HX SW outlet
    FCVs in Unit 2 had all been operated for approximately the same amount of time
    during shutdown cooling.
The inspectors noted the following in PER 104621:
*  This PER had been initiated after valve 3-FCV-23-34 had failed to stroke
    electrically due to two broken motor leads, and thereby caused the 3A RHR heat
    exchanger train to exceed its Maintenance Rule performance criteria.
*  The identified cause of the damage was hard strain and excessive vibration, and
    the identified cause of the cause was excessive vibration at lower flow
    conditions. The valves are not big enough physically to minimize this vibration.
    With respect to the actual root cause described above, this statement mentions
    low-flow conditions and vibration, but does not mention the valves vulnerability to
    vibration-induced damage. However, the corrective actions taken (described
    below) indicate that the licensee recognized that vulnerability. The inspectors,
    therefore, considered that in this PER, the licensee identified the actual root
    cause of the damage.
                                                                                  Enclosure
 
                                        10
  *  Corrective actions taken to prevent recurrence (of broken motor leads) were to
      initially replace hard-strained lugs and insulated lugs with uninsulated lugs; retrain
      the motor-lead wiring; and shrink Raychem on the barrel of the lugs, the insulation
      on the motor leads, and the control wiring for additional support. In this PER, the
      description of these corrective actions includes the statement, These WO's are for
      the interim fix, long term fix will be the replacement of the valves with valves similar
      to those used on U1.
  *  Final valve motor actuator corrective actions, as developed in this PER, resulted in
      removal of all terminal blocks and installation of Raychem splices. By February,
      2008, these corrective actions were completed on all of the RHR HX SW outlet
      FCVs in Units 2 and 3.
  *  Since implementing these corrective actions, no broken motor leads have occurred
      on the affected FCVs.
With respect to this charter item, these observations indicate that the corrective actions
implemented by the licensee as a result of their root-cause analyses do not fully address
the root causes, in that:
  *  The only root-cause analyses initiated to address damage to these valves were
      PERs 35419 and 104621;
  *  The corrective action described in PER 35419 to change how the valves are
      operated during shutdown cooling was not effective at preventing stem-to-disc
      separation events; and
  *  The corrective actions described in PER 104621 had addressed only the broken-
      motor-lead damage state.
However, as noted above in section 4OA3.2.b, the licensee had taken corrective action
through other PERs and/or work orders to address the other failure states as well.
Considering the corrective actions described in PER 104621 along with the other
corrective actions discussed above, the inspectors consider that the corrective actions
implemented by the licensee has addressed part of the root cause, in that those
corrective actions have reduced the vulnerability of the valves to vibration-induced
damage. However, the licensee has not yet planned or implemented corrective actions
to reduce the vibration that these valves experience by changing how they operate these
valves during shutdown cooling.
Development and implementation of corrective actions for PER 35419 constituted the
performance deficiency described below.
Introduction: The inspectors identified a Green non-cited violation of 10 CFR 50,
Appendix B, Criterion XVI, for the licensees failure in March, 2000, to take action to
preclude repetition of stem-to-disc separation events in RHR HX SW outlet FCVs.
                                                                                    Enclosure
 
                                      11
Description: In March, 2000, after RHR HX SW outlet FCV 3-FCV-023-0046
experienced a stem-to-disc separation event, the licensee initiated PER 35419 to
address that event, completed a root-cause analysis of that event, and developed a
corrective action that was intended to prevent recurrence of stem-to-disc separation
events. That corrective action, implemented in May 2000, was to revise an operating
procedure to reduce the differential pressure the valves would experience during
shutdown-cooling operations. That corrective action was shown to be not effective when
in March, 2008, the licensee discovered that stem-to-disc separation had occurred in
Valves 3-FCV-023-0034, 3-FCV-023-0040, and 3-FCV-023-0046.
Analysis: This finding was more-than-minor because if left uncorrected the condition
would become a more significant safety and regulatory concern, in that failure to
adequately address the conditions that caused a stem-to-disc separation event in one
valve could allow those conditions to cause not only stem-to-disc separation events in
other valves, but also more-risk-significant damage that could render the valves
incapable of accomplishing their safety functions. In Phase 1 of the Significance
Determination Process described in MC 0609, Attachment 4, this finding affected the
Mitigating Systems cornerstone and was a design deficiency confirmed not to result in
loss of operability or functionality. The finding, therefore, screened as Green.
The inspectors determined that the cause of this finding was that while evaluating the
event that prompted PER 35419, the licensee did not determine that the cause of the
event had been a combination of operating the valves under conditions that induced
vibration and the vulnerability of the valves to vibration-induced damage, and
consequently did not develop effective corrective actions to address both of those
factors. The inspectors also determined that although the performance deficiency
associated with this finding occurred in 2000, this finding is representative of current
licensee performance, because since 2000, the licensee has not changed their
corrective action program root cause determination methodology in a way that clearly
addresses the weaknesses the inspectors noted in the PER 35419 evaluation. The
finding therefore has a cross-cutting aspect in the area of problem identification and
resolution, because the licensee did not thoroughly evaluate a problem such that the
resolutions address causes and extent of conditions, in that the licensee did not
thoroughly evaluate the April, 2000, stem-to-disc separation of valve 3-FCV-023-0046
such that the resolutions addressed the causes of the vibration. (P.1(c))
Enforcement: 10 CFR 50, Appendix B, Criterion XVI requires, in part, that for significant
conditions adverse to quality, licensees assure that corrective action is taken to preclude
repetition.
Contrary to the above, the licensee failed to take corrective action to preclude repetition
of a significant condition adverse to quality, in that:
*  the stem-to-disc separation event described in PER 35419 was a significant
    condition adverse to quality with respect to Criterion XVI, because for that event,
    licensee procedures required both determination of the cause and corrective action
    to preclude repetition; and
                                                                                  Enclosure
 
                                          12
      *  the licensees actions taken in April, 2000, in response to the stem-to-disc separation
          event described in PER 35419, failed to preclude repetition of stem-to-disc
          separation events, in that three such events occurred in 2008.
      Because this finding was of very low safety significance and has been entered into the
      licensees corrective action program as PER 143502, consistent with Section VI.A of the
      NRC Enforcement Policy, this violation is being treated as a non-cited violation, and is
      designated as NCV 05000260/2008009-01, Failure to prevent recurrence of stem-to-
      disc separation events in residual heat removal service water heat exchanger outlet
      valves.
.4    Response to Industry Operating Experience
  a. Inspection Scope
      The inspectors reviewed industry operating experience and the licensees actions in
      response to related operating experience items including:
      *  NRC Information Notice (IN) 2006-015, Vibration-Induced Degradation and Failure
          of Safety Related Valves;
      *  NRC IN 83-70 and Supplement 1, Vibration-Induced Valve Failures;
      *  NRC IN 2005-23, Vibration-Induced Degradation of Butterfly Valves;
      *  NRC IN 2002-26, Failures of Steam Dryer Cover Plate After a Recent Power Uprate
          at a BWR;
      *  INPO Significant Event Report (SER) 02-005, Lessons Learned from Power
          Uprates; and
      *  INPO SER83-20 Supplement 1, Improper Seating of Velan Swing Check Valves
          Due to Disc/Hangar Arm Binding.
  b. Observations and Findings
      The inspectors determined that the licensee had reviewed and appropriately responded
      to the operating experience items identified above.
.5    Potential Generic Safety Issues
  a. Inspection Scope
      The inspectors reviewed the circumstances within the scope of this inspection to
      determine whether those circumstances included any potential generic safety issues.
  b. Observations and Findings
      The inspectors determined that no new generic safety issues were associated with
      damage to the subject valves, because the inspectors considered that the only related
      generic safety issue (vibration-induced damage to safety-related components) had been
      adequately addressed in generic communications.
                                                                                        Enclosure
 
                                        13
4OA6 Meetings, Including Exit
    On May 2, 2008, the inspectors presented the inspection results to Mr. R. West and
    other members of the plant staff. The inspectors confirmed that proprietary information
    was not provided or examined during the inspection.
ATTACHMENT: SUPPLEMENTAL INFORMATION
                                                                                    Enclosure
 
                              SUPPLEMENTAL INFORMATION
                                KEY POINTS OF CONTACT
Licensee personnel
S. Armstrong, Performance Improvement
T. Chan, Corporate Engineering
S. Douglas, General Manager Site Operations
B. Eberly, Corporate Engineering
R. Godwin, Site Support Manager
D. Hughes, Operations Superintendent
K. Harvey, Site Engineering
W. Justice, Engineering Manager
D. Langley, Site Licensing Manager
B. Mitchell, Performance Improvement Manager
B. Trappett, Site Engineering
R. West, Site Vice President
A. Yarbrough, Site Engineering
NRC personnel
T. Ross, Senior Resident Inspector - Browns Ferry
                                                      Attachment 1
 
              LIST OF ITEMS OPENED, CLOSED, AND DISCUSSED
Opened
None
Closed
None
Opened & Closed
05000260/2008009-01      NCV  Failure to prevent recurrence of stem-to-disc separation
                              events in residual heat removal service water heat
                              exchanger outlet valves (4OA3.3)
Closed
None
Previous Items Closed
None
Discussed
None
                                                                        Attachment 1
 
                              LIST OF DOCUMENTS REVIEWED
Problem Evaluation Reports
35419, Valve 3-FCV-023-0046 Disk Found Separated from Stem
38168, Anti-Rotation Plate for BFN-3-FCV-023-0046 Found On Top of Packing Gland
38915, 2-FCV-23-52, 2D Outlet Valve Handwheel Fell Off
39727, 2-FCV-23-40 Would Not Electrically Cycle to the Full Closed Position
41912, 3-FCV-23-46 Anti-Rotation Device Out of Position Several Occasions
44050, 2-FCV-023-0040 Valve Seat Requires Machining for Proper Leakage Prevention
44056, 2-FCV-23-46 Failure to Operate
50732, Valve 2-FCV-23-0040 Repeat Maintenance Due to Gasket Leakage
50734, 2-FCV-023-0040 Would Not Completely Close
52672, Valve 2-FCV-023-0046 Three Motor Leads Broken at Terminal Lug Connections
59437, Handwheel for 2-FCV-23-52 Dislocated From Limitorque Stem
69087, Valve 3-FCV-23-34 Indication Remained Double Lit at Full Open
80790, 3-FCV-23-34 Would Not Open from the Control Room
81108, Broken Motor Lead Found on 3-MVOP-23-34
85910, Unplanned Maintenance Rule Unavailability 3A RHR HX
91267, 2-FCV-23-34 Failed to Open On A2 Pump Start
99498, Broken Motor Lead for 3-MVOP-23-34
101897, 2-FCV-23-52 Stem Cover Fell Off
104621, MR PC exceeded on 3A RHR HX
114173, Handwheel for valve 2-FCV-23-52 Found On the Floor
122218, Stem failure of 2-FCV-23-52
127137, 3-FCV-23-34 Failed to Open or Close
136712, RHR SW 3-FCV-23-40 Valve Electrical Failure
140768, 3-FCV-23-34 Stem Separated from Disc
140824, 3-FCV-23-40 Stem Separated from Disc
141137, 3-FCV-23-46 Stem Separated from Disc
141219, 3-FCV-23-52 Broken Tack Welds
Work Orders
94-020161-000, Reinstall 2-MVOP-23-40 Handwheel
96-004063-000, Repair 2-MVOP-23-34 Motor Lugs
97-002514-000, Troubleshoot and Repair 3-MVOP-23-52 Thermalling Out
98-011029-000, Troubleshoot 3-MVOP-23-46 Not Opening
98-011271-001, Reinstall 3-MVOP-23-46 Stem Anti-Rotation Collar
00-003802-000, Disassemble and Refurbish 3-FCV-23-46
00-008114-000, Take Vibration Data On 3-FCV-23-46
02-003214-000, Reinstall 2-MVOP-23-52 Handwheel
02-004605-000, Reinstall Handwheel With Mod On 2-MVOP-23-52
02-004605-001, Install Handwheel Mod On 2-MVOP-23-46
02-004605-002, Install Handwheel Mod On 2-MVOP-23-40
02-004605-003, Install Handwheel Mod On 2-MVOP-23-34
02-004605-004, Install Handwheel Mod On 3-MVOP-23-52
02-004605-005, Install Handwheel Mod On 3-MVOP-23-46
02-004605-006, Install Handwheel Mod On 3-MVOP-23-40
                                                                            Attachment 1
 
                                                4
02-004605-007, Install Handwheel Mod On 3-MVOP-23-34
02-006589-001, Repair Operator Shaft and Reinstall Handwheel On 2-MVOP-23-52
03-003010-000, Disassemble, Inspect, and Repair 2-FCV-23-40
03-006967-001, Install New Valve Disc On 2-FCV-23-40
03-007163-000, Realign 3-MVOP-23-46 Anti-Rotation Collar
03-021389-000, Repair 2-MVOP-23-46 Broken Motor Leads
04-714325-000, Realign 3-MVOP-23-46 Anti-Rotation Collar
04-717160-000, Install Anti-Rotation Collar Mod On 3-MVOP-23-46
04-717160-001, Install Anti-Rotation Collar Mod On 3-MVOP-23-52
04-722062-000, Realign 3-MVOP-23-34 Anti-Rotation Collar
04-722067-000, Realign 3-MVOP-23-40 Anti-Rotation Collar
05-714220-001, Troubleshoot and Repair 3-FCV-23-34 Not Opening
05-722104-000, Machine 2-FCV-23-40 Fluted Disc
06-713538-000, Troubleshoot and Repair 3-FCV-23-34 Not Opening
06-716018-000, Reinstall 2-MVOP-23-52 Stem Cap
06-718716-000, Replace 3-MVOP-23-52 Stem Cap
06-725311-000, Disassemble and Inspect 2-FCV-23-52
07-711409-000, Repair 3-MVOP-23-34 Motor Leads
07-720665-000, Replace 3-FCV-23-34 Packing, Handwheel Key, and MOVATS
07-721848-000, Replace 3-MVOP-23-40 Motor Terminations With Raychem Splices
08-710819-000, Inspect and Repair 3-FCV-23-40 Not Moving
08-711543-000, Disassemble, Inspect, and Refurbish 3-FCV-23-34
08-711544-000, Disassemble, Inspect, and Refurbish 3-FCV-23-40
08-711545-000, Disassemble, Inspect, and Refurbish 3-FCV-23-46
08-711546-000, Disassemble, Inspect, and Refurbish 3-FCV-23-52
Procedures
TVA Corporate Procedure SPP-3.1, Corrective Action Program, Rev. 13
TVA Corporate Procedure SPP-3.1, Corrective Action Program, Rev. 1
TVA Business Procedure BP-250, Corrective Action Handbook, Rev. 12
MCI-0-000-GLV001, Generic Maintenance Instruction For Globe Valves, Rev. 21
Surveillance Instruction 2-SI-3.2.1, First and Augmented In-Service Test Valve Performance,
  Rev. 23
Surveillance Instruction 3-SI-3.2.1, First and Augmented In-Service Test Valve Performance,
  Rev. 9
Surveillance Instruction 2-SI-4.5.C.1(3), Residual Heat Removal Service Water Pump and
  Header Operability and Flow Test, Rev. 98
Surveillance Instruction 3-SI-4.5.C.1(3), Residual Heat Removal Service Water Pump and
  Header Operability and Flow Test, Rev. 30
Functional Evaluation 42538 (PER 141380) Unit 2 Heat Exchanger Outlet Valves 2-FCV-23-34,-
  40,-46 & 52
Functional Evaluation 42520 (PER 140768) Unit 3 Heat Exchanger Outlet Valves 3-FCV-23-34,-
  40,-46 & 52 and 2-FCV-23-52
Operations Instruction 0-OI-23, Residual Heat Removal Service Water System, Rev. 45
Operations Instruction 2-OI-74, Residual Heat Removal System, Rev. 137
                                                                                  Attachment 1
 
                                            5
Other Documents
Engineering Design Change 69327, Revise design output to allow repair of valves as needed
NRC Information Notice 2006-015, Vibration-Induced Degradation and Failure of Safety Related
  Valves
NRC IN 83-70 and Supplement 1, Vibration-Induced Valve Failures
NRC IN 2005-23, Vibration-Induced Degradation of Butterfly Valves
NRC IN 2002-26, Failures of Steam Dryer Cover Plate After a Recent Power Uprate at a
  Boiling-Water Reactor
INPO Significant Event Report 02-005, Lessons Learned from Power Uprates
INPO Significant Event Report 83-20 Supplement 1, Improper Seating of Velan Swing Check
  Valves Due to Disc/Hangar Arm Binding
                                                                                Attachment 1
 
                                        Attachment 2: Damage Summary for Unit 2 Valves
The table in this attachment shows the damage experienced by the four RHR HX SW outlet FCVs in unit 2 (valves 2-023-0034, 2-
023-0040, 2-023-0046, and 2-023-0052) versus time since the unit was restarted. In this table,
  *  The first two columns show various times described by year and month.
  *  The t column shows the number of months that had elapsed between the unit restart date and the corresponding date.
  *  The four columns labeled Damage in valve and the valve numbers include code letters that indicate the damage experience
      by each valve during each corresponding month and year. The code letters are decoded below. In these columns, the valves
      are referred to by only the last two characters of their valve numbers.
  *  The column labeled PER/WO/Comment either identifies the problem evaluation report (PER) initiated to address the issue,
      the work order (WO) under which repairs were completed, or a related comment.
  *  The Priority Column identifies the relative priority the licensee assigned to the corresponding PER (the priority codes are
      decoded below).
  *  The Corrective Actions column summarizes the licensees response as described in the corresponding PER or WO.
                      Damage1 in valve:
Year M        t    34 40 46 52          PER / WO / Comment              Priority2 Corrective Actions
1991 7                      n            Unit 2 restart
1994 12        42          f              WO 94-020161-000                          reinstalled handwheel
1996 3        57      a                  WO 96-004063                              repaired motor lugs
2001 11      126                      f  PER 59437                          CA      initiated PER to initiate handwheel mod
                                          WO 02-004605-000                          repaired handwheel
2002    3    130                      f  PER 38915                                  initiated WO 02-004605-xxx for handwheel
                                                                                      modification development and implementation
                                          WO 02-003214-000                          reinstalled handwheel
        8    135      n                  WO 02-004605-003                          installed handwheel mod
                          n              WO 02-004605-002                          installed handwheel mod
                                      n  WO 02-004605-000                          installed handwheel mod
                                n        WO 02-004605-001                          installed handwheel mod
2003    2    141          g              PER 39727                          CA      initiated EDC 51557 to allow fluted or non-
                                                                                      fluted disc
                                          PER 50734                          D      cause not determined
                                                                                                                            Attachment 2
 
                                      WO 03-003010-000                      replaced fluted with non-fluted disc
        3  142            h        PER 50732                      CA    revised gasket-torquing procedures
        10  149            c        WO 03-006967-001                      replaced with fluted disc
        11  150                  a  PER 52672                      CA
                                      WO 03-021389-000                      repaired broken motor leads
2004    3  154                  j  PER 41912                      CA    revised setscrew design & installation
2006    4  180                    i PER 101897                      D    closed to WO
                                      WO 06-716018-000                      re-installed stem cap
        11  187                    f PER 114173                      D    closed to WO
                                      WO 02-006589-001                      re-installed handwheel & repaired operator
2007    3  191            n        WO 05-722104-000                      machined fluted disc for better flow
                                    d PER 122218                      CN    initiated DCN 68948
                                      WO 06-725311-000                      replaced Walworth valve with Anchor-Darling
                                                                            12 valve via DCN 68948
1                                      2
  Damage states:                        Classification of the PER:
  a. broken motor lugs                  A: A priority
  b. broken motor leads                  BA: B priority, apparent cause
  c. stem-disc separation                BR: B priority, root cause
  d. stem shear                          CA: C priority, apparent cause
  e. slipped anti-rotation collar        CN: C priority, no cause evaluation
  f. separated handwheel                CR: C priority, root cause
  g. broken disc flute                  D: track and trend
  h. gasket leakage
  i. stem cap separation
  j. trend
  n. non-damage comment
                                                                                                                  Attachment 2
 
                                        Attachment 3: Damage Summary for Unit 3 Valves
The table in this attachment shows the damage experienced by the four RHR HX SW outlet FCVs in unit 3 (valves 3-023-0034, 3-
023-0040, 3-023-0046, and 3-023-0052) versus time since the unit was restarted. In this table,
  *  The first two columns show various times described by year and month.
  *  The t column shows the number of months that had elapsed between the unit restart date and the corresponding date.
  *  The four columns labeled Damage in valve and the valve numbers include code letters that indicate the damage experience
      by each valve during each corresponding month and year. The code letters are decoded below. In these columns, the
      valves are referred to by only the last two characters of their valve numbers.
  *  The column labeled PER/WO/Comment either identifies the problem evaluation report (PER) initiated to address the issue,
      the work order (WO) under which repairs were completed, or a related comment.
  *  The Priority Column identifies the relative priority the licensee assigned to the corresponding PER (the priority codes are
      decoded below).
  *  The Corrective Actions column summarizes the licensees response as described in the corresponding PER or WO.
                      Damage1 in valve:
Year  M      t      34 40 46 52          PER / WO / Comment                  Priority2 Corrective Actions
1995  10                    n            Unit 3 restart
1997    3    17                      a    PER 97-0541-000
                                          WO 97-002514-000                              re-lugged the leads
1998  10    35                a          PER 38168                                      changed procedure to prevent set
                                                                                  CA
                                                                                          screw from backing out
                                          WO 98-011029-000                              re-lugged the leads
                                e          PER 38168                                      revised a maintenance procedure to
                                                                                          require that measures be taken to
                                                                                          prevent the set screw from `backing off`
                                          WO 98-011271-001                              realigned & lock-tightened collar
2000    4    53                c          PER 35419                              BR      refurbished the valve
                                          WO 00-003802-000                              chased threads and re-tack welded disc
                                                                                          assembly
      10    59                n          WO 00-008114-000                              took vibration data at 600 GPM
2001    8    69                n          WO 02-004605-005                              installed handwheel mod
                                                                                                                            Attachment 3
 
2002 8  81  f          WO 02-004605-007                    installed handwheel mod
              n      WO 02-004605-006                    installed handwheel mod
                    n WO 02-004605-004                    installed handwheel mod
2003 4  88        e  WO 03-007163-000                    re-aligned collar
2004 4 100        e  WO 04-714325-000                    re-aligned collar
                  h  PER 41912 for adverse trend      CA revised vendor drawing for alternate
                      on anti-rotation collar failures    style setscrew, initiated WO 04-717160-
                                                          000
    9 105  e          PER 69087                        CA initiated ECD for anti-rotation collar mod
                      WO 04-722062-000                    re-aligned collar
              e      WO 04-722067-000                    re-aligned collar
2005 4 112  b          PER 81108                        CN initiated WO to install new terminal lead
                      WO 05-714220-001                    installed new terminal lead
2006 3 123 b,b        PER 99498                        CA closed action to WO
                      WO 06-713538-000                    replaced & installed Raychem splice
                  n  WO 04-717160-000                    installed anti-rotation collar mod
                    n WO 04-717160-001                    installed anti-rotation collar mod
    6 126      n    PER 104621 for MR PC            BR initiated 10-point plan for improvement
                      exceeded; valves in (a)(1)
2007 7 138  b          PER 127137                      CN initiated WOs to remove terminal blocks
                                                          and install Raychem splices
                      WO 07-711409-000                    removed terminal blocks & installed
                                                          Raychem splices
            n          WO 07-720665-000                    repaired cocked gland follower &
                                                          reinstalled handwheel key
2008 1 144    b      PER 136712                      CA referred to PER 127137 actions
                      WO 07-721848-000                    removed terminal blocks & installed
                                                          Raychem splices
                      WO 08-710819-000                    investigated valve not moving
    3 146  c          PER 140768                      CN initiate WO to refurbish the valve
                      WO 08-711543-000                    installed full weld per EDC 69327
              c      PER 140824                      CN initiated EDC 69327 to install full weld
                                                                                              Attachment 3
 
                                                                              instead of tack welds
                                      WO 08-711544-000                        installed full weld per EDC 69327
                                  c  PER 141137                          CN referred to EDC 69327 to install full
                                                                              weld instead of tack welds
                                      WO 08-711545-000                        installed full weld per EDC 69327
                                    k PER 141219                          CN referred to EDC 69327 to install full
                                                                              weld instead of tack welds
                                      WO 08-711546-000                        installed full weld per EDC 69327
                                    i WO 06-718716-000                        re-installed stem cap
1                                      2
  Damage states:                        Classification of the PER:
  a. broken motor lugs                  A: A priority
  b. broken motor leads                  BA: B priority, apparent cause
  c. stem-to-disc separation            BR: B priority, root cause
  d. stem shear                          CA: C priority, apparent cause
  e. slipped anti-rotation collar        CN: C priority, no cause evaluation
  f. separated handwheel                CR: C priority, root cause
  g. broken disc flute                  D: track and trend
  h. gasket leakage
  i. stem cap separation
  j. trend
  k. stem-to-disc tack welds broken
  n. non-damage comment
                                                                                                                Attachment 3
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