View source for 3F0998-04, Provides Supplemental Info to Assist NRC Technical Staff in Finalizing Review of Operational Assessment of SG Tube Degradation at Crystal River Unit 3.No New Commitments Made

{{Adams
| number = ML20151Z420
| issue date = 09/14/1998
| title = Provides Supplemental Info to Assist NRC Technical Staff in Finalizing Review of Operational Assessment of SG Tube Degradation at Crystal River Unit 3.No New Commitments Made
| author name = Terry J
| author affiliation = FLORIDA POWER CORP.
| addressee name = 
| addressee affiliation = NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
| docket = 05000302
| license number = 
| contact person = 
| document report number = 3F0998-04, 3F998-4, TAC-MA2071, NUDOCS 9809210333
| document type = CORRESPONDENCE-LETTERS, INCOMING CORRESPONDENCE
| page count = 12
| project = TAC:MA2071
| stage = Supplement
}}

=Text=
{{#Wiki_filter:- -
    '   ~
Fl:rida Pswer CORPORATION oAY.NoYNz*
Operating Ucense bio. OPR-72 September 14,1998 3F0998-04 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001

==Subject:==
Supp;emental Information to Assist NRC Staff's Review of Operational Assessment of Steam Generator Tube Degradation at Crystal River Unit 3 (TAC No. MA2071)

==References:==
FPC to NRC letter,3F0598-08, dated May 18,1998, " An Operational Assessment of Steam Generator Tube Degradation at Crystal River Unit 3"

==Dear Sir:==

The purpose of this letter is to provide supplemental information to assist the NRC's technical staff in finalizing their review of the subject operational assessment submitted in the referenced letter.
The need for this information was recently conveyed to Florida Power Corporation (FPC) by the NRC's Project Manager for Crystal River Unit 3 (CR-3). FPC's understanding of the questions was confirmed in a subsequent discussion with the NRC technical staff reviewer.
l FPC's answers to the NRC reviewer's questions are detailed in tne attachment to this letter.                              ]
There are no new commitments established by this letter or its atachments. If you have any                                j questions regarding this submittal, please contact Ms. Sherry Bernhoft, Manager, Nuclear Licensing, at (352) 563-4566.
Sincerely, I
J. I. Terry,         ector                                                                                              /
uclear Engineering and Projects JHT/TWC                                                                                                             T Attachments xc:      Regional Administrator, Region II , ,                , ,
Senior Resident Inspector                  2  -
NRR Project Manager Crystal Ruer Energy Complex: 15760 W. Power Line Street e Crystal Rwer + Florida 34428 + (352) 7954486 A Fkeda Progress Company 9809210333 980914 i            PDR      ADOCK 05000302 P                               PDR l

r                                                                                                          i j   .   .                                                                                                  ;
U. S. Nuclear Regulatory Commission                                                Attaciunent   l
!         3F0998-04                                                                          Page 1 of 7   )
\
ATTACilMENT SUPPLEMENTAL INFORMATION TO ASSIST NRC STAFF'S REVIEW l
OF OPERATIONAL ASSESSMENT OF STEAM GENERATOR TUBE DEGRADATION AT CRYSTAL RIVER UNIT 3 l
Introduction Florida Power Corporation (FPC) submitted License Amendment Request (LAR) #221, Revision 0, to the NRC on October 1,1997 (Reference 1). In this LAR, FPC proposed a              i specific methodology for monitoring long term growth of the "B" Once Through Steam Generator (OTSG) first span pit-like Intergranular Attack (IGA) indications. The submittal proposed implementing enhanced reporting requirements requiring FPC to perform                   j
          " operational assessments" to determine the adequacy of the structural integrity of the OTSGs    !
during future OTSG inspections.           Following the submittal of LAR #221, FPC issued a      i combined Mode 4 and 90-day Special Report on December 5,1997 (Reference 4) outlining the tube inspections performed and the results obtained during the 1997 inspections. Included with this submittal was a detailed assessment of the indicated growth trends for the "B" OTSG first span pit-like IGA indications. FPC committed, in the 90-day Special Report, to submit an operational assessment for first span pit-like IGA within 90 days following plant restart which was provided by FPC's lett r dated May 18,1998 (Reference 5).
Recently, FPC became aviare of three questions requiring additional information to assist in the NRC's review of the Operatiou: Assessment submitted by Reference 5. The questions are in italics below, with the FPC response and additional information immediately following in normal font.
Question 1 In a FPC submittal dated August 20,1997 (3F0897-09),lReference 2}, the licensee stated that additional items will be provided in the 90-day report, outside of the TS reporting requirements (see page 9 and 10 of the subject submittal) as background information. Not all of the items appeared in the December 5,1997, 90-day report (Reference 4}. Where is that information availablefor NRC review?
FPC Response The additional items referenced above were identified in Reference 2 as items a) through f).
l         Following is a description of each of these items along with the references containing the information available for NRC review:
I a) Number of and identities of tubes with "B" OTSG first span IGA indications left in service.
This information is located in Reference 2, Table 1, pages 1 and 2.

U. S. Nuclear Regulatory Commission                                                 Attachment          ,
3F0998-04                                                                           Page 2 of 7         I l              b) Number of and identities of tubes with "B" OTSG first span IGA indications plugged I
or sleeved.                                                                                  !
This infom1ation is located in Reference 2, Table 1, pages 3 through 6 and in Appendices 5 and 6 of Reference 4.
c) A distribution curve showing axial location of indications for those tubes left in            I service with "B" OTSG first span IGA (to verify the one inch clearance from support structures was implemented).
This information is located in Reference 2, Figure 1. Reference 4, Appendix 3,               I contains the data for the in-service first span IGA in a tabular format. The plugged         !
indications are listed first, the tubes in-service are listed on pages 63 through 72 of this appendix.
d) A distributien curve showing the sizes of the "B" OTSG first span IGA as determined by the regression technique. The curve shall distinguish between indications left in service and indications removed from service.
This information is being provided as Figure 1 in this submittal. Figure 2 is also being provided in this submittal which demonstrates the indication voltage distribution for the first span IGA. Both of these curves are generated from the data shown in Appendix 3 of Reference 4.
e) A distribution curve showing the apparent growth of"B" OTSG first span IGA as                 ]
determined by the regression technique sizing. The curve shall distinguish between indications left in service and indications removed from service.
Reference 4, Appendix 1, is a detailed assessment of growth as indicated by the regression technique. However, this assessment did not distinguish between the indications which were left in service and indications removed from service. Figure 3 of this submittal contains a curve containing this information. It is important to note that the majority of the data in Figure 3 is based on indications left in service.
Because of the number of first span IGA indications identified in 1997 (over 2,700),
the analysis team was focused on assessing those tubes which could possibly be left in service. Thus, the majority of data is from tubes which had indicated %
throughwall values of <40% from the 1997 inspections. This data is provided in tabular format in Refuence 4, Appendix 3. Similarly, Figure 4 of this submittal is provided to demonstrate the apparent change in voltage for the first span IGA indications. Again, the majority of the data is from tubes which were left in service.
f) A distribution curve showing the apparent axial and circumferential growth of"B"
,                  OTSG first span IGA indications as determined by clip plot sizing (when performed).
Reference 4, Appendix 1 contains an assessment of clip plot indicated growth for the IGA indications. Due to data management . limitations the curves shown in Reference

l U. S. Nuclear Regulatory Commission                                                     Attachment
              ,3F0998-04                                                                               Page 3 of 7
                               '4, Appendix 1 did not explicitly document the changes in axial length or circumferential length (prior to 1997, the data management program was not configured to store the axial and circumferential lengths in specific data fields, the
                                                                                                                                 ]
soflware simply recorded the longer dimension first, then the shorter dimension).
However, the curves provided in that appendix are a conservative representation of growth, since the previously recorded minimum dimensions were compared to the maximum recorded dimensions in 1997 (see Figures C2 and C3 in Reference 4, Appendix 1).
Question 2 How many tubes will be added to the " tubes with pit-like IGA " list; i.e., how many tubes were newly identified this past inspection with 1Gil in thefirst span?
FPC Response -
Table 1 from Reference 2 contains the tube identities of the known tubes with first span pit-like IGA left in service following the 1997 OTSG inspectiocs. This table lists 159 tube identities.
A revision to Table 1 from Reference 2 is provided towards the end of this attachment. This i
revision to Table 1 contains only the tube identities for newly identified tubes. The format of the               ,
table, and location of the tube identities in the table was not altered, to aid the reviewer when                 >
comparing to Table 1 submitted in Reference 1. The reviewer should note that there are 101                        ;
newly identified tubes shown. Thus, roughly 64% of the tubes with IGA remaining in service ve newly identified.
l It is important to note that this does not imply these tubes have new indications. These tubes                    -
have historical eddy current data which was reviewed in accordance with FPC's response to                         !
Question 4 in Reference 2. If the indications did not have an associated historical bobbin coil l              signal, then the initial % throughwall value for the growth rate assessment would have defaulted                  -
to 0% per the CR-3 protocol. This default value would result in the tube being plugged due to                     !
exceeding the 10% growth rate criteria . delineated in the FPC response to Question 4 in                          :
             - Reference 2.                                                                                                      t Overall, the total number of tubes identified with first span pit-like IGA has increased from an j_             initial value of 366 tubes, as documented in Reference 3, to 590 tubes identified in the 1997 CR-3 OTSG inspections. Four hundred thirty-one (431) of the 590 tubes were removed from service in 1997. The FPC response to Question 1 in Reference 2 documents how the initial 366 i              tubes for Table I were identified. As described above, the increase in number of tubes does not l              indicate that new defects are being initiated in service. The primary reason that the number has increased is that prior to 1997, CR-3 has not performed a 100% bobbin coil inservice inspection e              of the OTSGs. The percentage of"B" OTSG tubes inspected since 1987 is as iollows:                                 ,
L

U. S. Nuclear Regulatory Commission                                                   Attachmcnt     i
                      . 3F0998-04                                                                            Page 4 of 7    ;
I YEAR        % INSPECTED                                               l 1987        0%                                                        ,
1989        11 %
1990        25 %
1992        73 %                                                      i 1994        25 %
                                                                                                                           .{
1996        21 %                                                      :
I 1997        100 %                                                      i Thrlow inspection percentages, combined with changing eddy c vent interpretation and~
dispositioning criteria each refueling outage, resulted in an inaccurate estimate of tubes affected with these indications. Since a rigid protocol has now been established and implemented for these indications, future inspections should not result in a substantial change in the value of 159 tubes left in service with indications.
Question 3 -                                                                                         ;
What is the basisfor FPC concluding that thefirst span IGA is a dormant mechanism?
FPC Response Appendix 1 of Reference 3 is an assessment of growth in the "B" OTSG tubes affected with pit-like IGA in the first span. Eddy current data from inspections performed from 1992 through       !
1997 was used to assess'whether any discernible growth.was evident in the IGA. Two eddy             1 current variables were assessed: (1) percent throughwall as indicated by the use of the regression
                     - technique and (2) indicated voltage of the indication from the 600 kHz high frequency bobbin coil channel. These assessments document that the change in percent throughwall and change in
                      ~ indicated voltage for these indications is centered about the zero axis, and the distributions appear to be normal in nature. Appendix 1 of Reference 3, page 2 of 19 states, "The CR-3 bobbin data gathered in 1997 indicates that the growth distributions are centered about the zero point, as has been observed in the past. "Thus, one can assert that the majority of the indications are not exhibiting any discernible growth." Apparent depth changes are primarily attributed to measurement errors (see Attachment B to Reference 5). Thus, the mechanism appears to be dormant.
i t
l   '
l

U. S. Nuclear Regulatory Commission                                                Attachment 3F099844                                                                           Page 5 of 7 B OTSG KNOWN TUBES WITil FIRST SPAN IGA PREVIOUSLY UNIDENTIFIED TUBESINSERVICE ROW     ,
l ROW       - lNURISER :, ]      l ROW ~
jNURISER -
l59           l80            l   l85       l92 16            22                                                 5        96 l60           l34            l 89        89 l62           l15            l l62         . l28            l 41            39                2             44                          88 l
42                              3             26                92        26 l63 43 l48               l63            l41           l   l92       l34 l                 l65            l37           l   l92       l39 43 l82               l65            l42           l   l93       l39 45                                                              93        46 l40               l65            l44           l 93        8 l67            l50           l 48            43                8             38           I 48 l61 70             38 50            41 l70            l58           l 51            30 l73            l44           l l74            l110          l 77             86                          91 l96 l97       l37 52            37 l97       l11 52                             79             22 l49                                                l97       l49 53             4 l98       l39 80             99                98        45 57            33 58            25               84             31                100       36 100       38 l84            l93           l 58            89               M              %
59 l30                ;-y-( -~ [f t j. .f,'qj{
* 00       45 59 l40                ;};'..
j.L' ,j. . l;.;{jgg.        l100      l66 TABLEI Page 1 of 2

1 U. S. Nuclear Regulatory Commission                                       Attachment 3F099844                                                                  Page 6 of 7 B OTSG KNOWN TUBES WITH FIRST SPAN IGA PREVIOUSLY UNIDENTIFIED TUBESINSERVICE l Row:e        l NUMBER <l 100            92 101            47
          '102            41 103            41 l104           l40         l l' 4           l'4         l 104            90 l
106             8 106             2 107             7 l107           l66         l                                                              ,
l107           l74         l l103           l34         l                                                              l l108           j74         l l109           l46         l         159 B OTSG TUBES REMAININ SERVICE l110           l40         l         WITH FIRST SPANIGA.
l l110           l43         l                                                              l l110           l46         l l110           l52         l l111           l42 -       l l111           l51         l l113           l44         l l113           l45        ]
l114           l42         l l114           l43         l W                                                 TABLEI Page 2 of 2

l*        -
U. S. Nuclear Regulatory Commission                                             Attachment 3F0998-04                                                                       Page 7 of 7 i                                                                                                                 !
References
                                                                                                                  )
: 1) .   . FPC to NRC letter 3F1097-21, dated October 1,1997, License Amendraent Request (LAR) #221, Revision 0
: 2)      FPC to NRC Letter 3F0897-09, c,ated August 20, 1997, Request ' for Additional               !
Information Regarding Technical Specification Change Request Notice No. 211, Rev. 0 l
: 3)      FPC to NRC Letter 3F0397-16, dated March 27, 1997, Technical I                     Specification Change Request Number 211, Rev. 0
: 4)      FPC to NRC Letter 3F1297-22, dated December 5,1997, Special Report 97-05 Once Through Steam Generator (OTSG) Notifications Required Prior to MODE 4, and Complete Results of OTSG Tube Inservice Inspection Performed During the Current Outage (90-Day Report)
: 5)      FPC to NRC Letter 3F0598-08, dated May 18, 1998, An Operational Assessment of               f Steam Generator Tube Degradation at Crystal River Unit 3 i
1 1
l 1
I
!                                                                                                                 I I
l l
I i
(
I'                 .                                                     _  _

i
                                                                                                                                                                                                                                                                           . I Depth Distribution for First Span IGA: B OTSG Crystal River Unit 3 - 6/97 Inspection 1000 r      --              . - -                '-                                                   -                           - - - - -                               -                    - -
9004     -                                            -          --                                          -                     --                                      -               -                                                -
e    800                                   -                 -                                                                                                                       -
g                                                                                                                                                                                                      --- -]Eplug Oin-service [
g    700j--
                                                                                                                                                                                                                                             ~
                                                                                                                                                                                                                                                         -)
   @    600t-                 -                       -            --          -                         ---                           -                                 -                  -- -           - --                  -
i
[
O 500 f ---
                                                                  --                - ---- ---                 -----                                   ---- - ~ - - -                                         -
                                                                                                                                                                                                                                                         )!
u e
400 '                                                                                                                                                                                                                                             '
i i
j    300j-j    200 2                                      --                 -                           -                                                                                       --                            -
1 i
100 l                                                                                                                                      ---
j 0+-          -       B -                             ,           -                  -                     -                                                      -- - -                        -- -                         -        - -       \
0         9 I
9         Rf R1 8.
G
                                                                                 ?,
Oi 2   I S                       S(
S l Ri C
i e t e
                                                                                                                                                                                                                                                      /s I         T    R          R            E       8                   G                  $                      5                       2                        G                              R Percent Throughwall Note: An additional 201 indications were identified as non-quantifiable and were plugged. These indications are not included in this distribution.
FPC Letter 3F0998-04                                                                                                                                                                                                                                              Figure 1

Voltage Distribution of First Span IGA: B OTSG CR 6/97 Inspection 900 ,                                  -                     -                                   -          -                        -                 -                                              -                 - - - -                         --                    - - - - -                                                                          -
i 800 i.   >
E O 700 l--   4
                                                                                                                                                                                                                                                                                                                                                                              -- J   I li.9 600 i      i
                                                                                                                                                                                                                                                                   -- ,Mplug Qin-service t-
         'E 500 1 4
                                  -                               ---                           - -                                      -              - - - - - -                 - - ~                     - - - - - - -                                                                - - -                                                                                   , -
o 400
         $ 300                        -                                        -              -        -                            --                                                  - -              -                              -           -                          - - --~                                                                                     --
E i
j 200                                      -                                                                                                                -        - - --- -                             -                             - - -                      - - .                                                                               - ---
100 '                             ---                                 - - -              - - - -                                                                            -- - - - -                             ~ - - - -                                --                          -- - - - - !
0                                                                        ,                        -                 - , - " - -                  - - - - - - - - - -                                                         - - , --                             -                                                                                   -
                               -          ~                ~,            n       =                  w                  ~.                          w                 en               o                    -                              ~              ~,                        v                                  o                                                    c 6          6                6             6       6                  6                  6                           6                 6 f
f                                        -                                  -                                                    -
R             G                                             G                                             E                                                                                   K                         G                                  G
                                                                                                    ~
C                                      G                                                                 C                                  5                    5:                             C
* 6                6             6       6                  6                  6                           6                 6                6                                                   =              -                         -                                  =
Volts Note: An additional 201 indications were identified as non-quantifiable and were plugged. These indications are not included                                                                                                                                                                                                                                                             ,
in this distribution.
I i
t 6
FPC Letter 3F0998-04                                                                                                                                                                                                                                                                                                                                                              Figure 2        ,
r
: l.                                                                                                                                                                                                                                                                                                                            .
t
                                     %TW Growth Distribution for First Span IGA: B OTSG Crystal River Unit 3 - 6/97 Inspection 300 ,         -     -                                                                              - - - -                -                                 --                                                                  -- --- -- - - - - - -                               -
                                                                                                                                                                                                                                                                - lE plug Din-service ,
275 i -
e                                                                                                                                                                                                                                                                                    _
c 250 &-                                                                                                                                                                                                                                                                                                 '
O 225                                   --        --                                                                   -   -             -- --      -                           - ---                                                                      -           - - -
                                                                                                                                                                                                                                                                                          ------l j 200 *                     --                                                                                 -                                                                                                     --                                                                            -
u 175                                                                                                                                                                                                                                                                           -
f 150    t                                     -                                                                                                                                                                                                -
                                                                                                                                                                                                                                                                                                                -- i o 125 i                                    --                                                                       --            -- -                  --                                                                                 -               - - - --                            --
i j 100f                                                                                                                        --                                                 --                                                       -                           -
l E   75 t                                                                                                            --                         --                                                                                                     -                   - -          - - - -          i z'   50 i                                            -                                                                                                                                                                                       --           -                       ---
                     ! i    i,       ,                                ,                                                     ,               ,                 T. L                                        I                                _                               -              .
                                                                                                                                                                                                                                                                                                                  ~j R       i          '
* 7                         "
* e                                                             e                                  R                  R
                                                                                                                                                                                                                                                                                                   ^
l,    $=
                                          $e 2
e 2
                                                                                                            .n
                                                                                                                                     $             $                           ~
2                                                            2 2
e Change in %TW f
FPC Letter 3F0998-04                                                                                                                                                                                                                                                                                              Figure 3

v 2
E K
k i D5 .                                                                    9VO <
61
                                  ;i g ' i
: a.:                                                        ,
9Fo i5;                ,
i                                     01 99~0 i
9f'O                                      !
ol 9CO l                i                                 !        >
                                                                                 '        !                        9CO g                                                                                   .
                   ..                                                                                         01 9 t '0 hh                           i 01             0 sc          ,
g 01 V 10--        .
O                            i g ,(y                             -
90'0
                  .g g                                                                                         -- 01 P L 'O E.
d 9 t '0 i                  01 PCO--
1
                                                                                 ,                                      GC0 01 WO -
4f'O 01vf0-
                                  ,                                                                           GVO- >                                    ,   .
* l x   '
                              $@$$$$$hSO                                                                                                                k suoneolpui jo JaqwnN                                                                                                  $
U J
m}}