ML20031F111
| ML20031F111 | |
| Person / Time | |
|---|---|
| Site: | Indian Point, Surry, Turkey Point, San Onofre  |
| Issue date: | 03/15/1977 |
| From: | Strosnider J Office of Nuclear Reactor Regulation |
| To: | Stuart R Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML13319A640 | List:
|
| References | |
| FOIA-81-313 NUDOCS 8110190196 | |
| Download: ML20031F111 (5) | |
Text
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4 UNITED ST ATES O '-
i M'j NUCLEAR REGULATORY cOMMIS!;ON WASHINGTON, D. C. 20555
- 5. %[* /
MAR 151977
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MEMORANDUM FOR:
R. Stuart, Section B Leader Engineering Branch, Division of Operating Reactors FROM:
J. Strosnider, Engineering Branch, Division of.
Operating Reactors
SUBJECT:
SUMMARY
OF "HOURGLASSING" IN STEAM GENERATOR TUBE SUPPORT PLATES AT TURKEY POINT UNITS 3 AND 4. SURRY UNITS 1 AND 2 INDIAN POIhi UNIT 2. AND SAN ON0FRE UNIT 1 Attached is a table summarizing the results of inspections of itaam generator tube support plates for "hourglassing" at Turkey Point Units 3 and 4. Surry Units 1 and 2. Indian Point Unit 2, and San Onofre.
The table includes the available data on inspect.icn dates, measured flow slot width on those dates, and the closure rates based on those measurements.
0s 8W p
'J. Strosnider 1
l Engineering Branch Division of ' Operating Reactors
Attachment:
As stated
Contact:
l B. D. Liaw i
J. Strosnider 2806J cc:
L. Shao B. D. Liaw F. Almeter J. Strosnider h.lYbf g 0g 196 810827
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$seWWIT OF
- Hour-m ASSING" IN STEAM GEERATOR TuSE SurroRT PLATC$
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DRAFT #2 2/22/U 51DIt R -s Ilt5PECTION fl INSPECTIG6 N TIE SETWEN CLOSURE il 3
^
W GEMA4Tet PLATE SLOT WIOTN DATE SLOT WIOTil INSPECTIM5 RATE i
gggggg ggggggy DATE (Ef7N) lil/0PN le.
- 3. CLO5DRE RATES FOR THE TOP PLATES WERE CALCULATED uslNE THE LINEAR Settem 2-7/16 12/76
~2 12/76 9.08
.044 RELATION:
j Tes 2
12/76
.044I i
Turt y Betten 2-114 12/75 I
12/76 9.es -.
.126 Top Plate Too Plate y
Closure Rate psiermettom of I_ Tee 2-1/4 12/76 i
.0363 Closure Rate
'aeformation er to Settan Plate setten Plate
- tton 2-7/16 12/75 1-3/4 12/76 9.88
.069 H:
Too Easeple For T' day Pelet 3. 5.4. 3B
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2-1/4 12/76
.035I
- rey,
.,In
.otie.
i-M m
., M i
ii,,6 2.u Closure pate t M -i.02.75-2.25 = =
a '
T., Pia.
1 los 1-7/8 11/76
.110I
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uhere 2.75 original width 1A Tos 1/2 10/76 i
Surry 1 15.4
.146 l II. CLOSURE RATES FOR GENERATORS WHIC f
is To.
1-n/i6 iO/M 16.4
.06,11 OET ONE INSPECTION WM CALCIA.ATED l
IC Teo 1-1/2 10/M USINE TM l.INEAA MLATim:
16.4
,0stil Setten Plates The hottom plates were visually inspected -
Closure
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heurglasslag was evident but measurements were act made Rate i Of Opere' 6 E g /76
-., 2 2AII III.
I IR'.PECTION RESULT 5 FOR 5.4.'s 4A Am Rottes 1.95 5
1.0
- 10/76 6.0*"I/Ms..190 "/ cal.mo 4C AT TURKET POINT 4 U"RE NOT REPORTE Top
,..38 30/g
.llo / cal.amg RE m 5E 5.G. 48 WAS THE WORST CASE
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$NOWING TE GREATEST MEM 6LA55fNE
[2 22 sottes 10/M Average flow slot closure I/8 of an inch IV. STEAM GENERATOR 2A 15 CONSIDERED Tit Top 10/M lb appreciable hourelastine measured WORST CASE AND PLUGGING CRITERIA 04 2/1/77 SuteIttel reports unmessered Inst alw hourglassing evident la the lower lit 5PECTIONS OF 5.C.2A HAVE SEEN APPLIE See theefta support Flates of 5.G.'s A and C, only. Measurements of flow slots 14 the top support siste in 5.4. C Indicate ao hourelassins
- Minimum flow slot width'= 0.44 inch, which was used to co mpute the closure rate at ths top support plate.
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/W BROOKHAVEN NATIONAL LABORATORY I
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MEMORANDUM l
oATE: March 29,'1577 To:
F.M. Almeter 9
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FRoM:
J.R. Weeks E
hV
SUBJECT:
Technical Specifications For PWR Secondary Water Chemistry By Mr. Shao's letter of February 15, 1977, our Corrosion Group was asked to provide written comments on the proposed Technical Specifica-tions received from several licensees.
Our comments are given belcw.
The proposed Technical Specifications from the licensees with once-through steam generators, i.e. Duke Power Company (Oconee Units 1, 2 and 3), SMUD (Rancho Seco Unit 1), and Metropolitan Edison (Three-Mile Unit #1), are essentially identical in that cation conductivity limits are established for the feedwater.
Th e prop _osed limits are tig.h,t, a.nd ar type of steam generator.
I think seem reasonable for this p'v~e'ticularto make the'se'T clinical Specifications
~-
i should be carefuM ~h737e r,
.fficiently flexible that operation of the plant will not be curtailed by unnecessary paperwork.
These steam generator materials are quite tolerant to temporary water chemistry excursions.
With a once-through steam generator,, control of stress corrosion in the turbines may re-quire tighter limits on the water chemistry than are needed to control corrosion of the steam generator tubing.
M.et ropolitan Edison,_ in addi.-
_i;lon, added_a._p_H. limit _.
pH controls, I think, represent good practice, l
but I ucader if thay need to have a Technical Specification for pH.
The responses from the Westinghouse units all reflect the Westing-house position that Technical Specifications should not be placed on the secondary coolant.
The Westingrause position paper stated,' " deviations from secondary water quality gui lelines are not a safety problem".
Wectinghouse also states that in their judgement, "it would not be I
appropriate to legally limit potential causes of degradation of the racctor coolant pressure boundary".
With these two statements I dis-l agree.
Their acceptance by the NRC would mean that no Technical Speci-fication ' limits need~ be placed on primary coolant chemistry in any LWR. By the time degradation is detected by inservice eddy current
[
inspections or leakage, a sufficient number of serious defects may have aircady formed to constitute a safety consideration.
At the same time, however, recent experience has shown that deter-ioration of steam generator tubing has occurred under water chemistry (Page 1 of 3)
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\\.M. Almeter March 29, 1977 conditions previously believed adequate to protect the material.
Any Technical Specifications, therefore, on the secondary coolant of these unics snould be, in my opinion, very flexible and allow for transients over and above the limits.
However, as stated in our memo of Septem-bsr 13, 1976, these specifications should also limit the permissable time allowed above the steady state limit to something like four weeks par year.
The submittals from Wisconsin Electric Power Company (Point Beach Units 1 and 2), Indiana and Michigan Power Company (Donald C. Cook) and _~
Rochester Gas and Electric (R.E. Ginna) all propose Technical Specifi-cations on monitcring, with the acceptable limits being placed in the plant procedures or to be proposed at a later date.
It seems to me that some limits need to be placed in a Specification if it is to have any value.
The responses from Florida Power and Light (Turkey Point Units 3 and 4), and from Virginia Electric and Power Company (Surry Units 1 and 2), offer no Technical Specifications whatsoever.
The NRC should de-termine what action will be taken in these matters.
The responses from Carolina Power and Light (Robinson Unit #2) and Southern California' Edison (San Onofre Unit #1) reflect units still on phosphate treatment.
Robinson has had secondary water Technical Speci-fications for several years, so their only change is to specify the frequency of monitoring the secondary water coolant.
San Onofre agai,n references plant operating procedures.
I think the NRC should be very cautious in attempting to force either of these units to change their water chemistry at the present time.
The need for Technical Specifications on the secondary coolant 3
arises from a situation several years back, in which several units ran
.into stress corrosion difficulties while operating under a low phosphate treatment because they did not, in my opinion, put sufficient emphasis on maintaining good secondary water quality in their steam generators.
This situation was reviewed by me in the spring of 1973, in a report in which I recommended. Technical Specifications be placed on secondary coolant in order to. ensure that the licensees paid proper attent. ion to this item.
The subsequent experiences with phosphate wastage, denting, and possible fatigue in the various units, however, have not per se crisen because of poor control of water chemistry compared to what were than acceptable standards.
We still do not have available sufficient information' to determine exactly what limits will be required to be offective in controlling steam generator corrosion.
Such information
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m N
M.
Almeter March 29, 1977 can only be obtained by several years' experience with the individual or similar units.
Until that time, any Technical Specifications should be flexible.
I think that Technical Specifications on secondary water chemistry covering at least the feedwater and/or blowdown conductivity may still be a good idea to encourage proper attention in this area, but that they should be written as loosely as possible, so as not to provide un-dun hardship and paperwork to the licensee.
But Specifications that merely state surveillance without indicating some limits at which actions should be taken are meaningless.
In a recent review for D.S.S.
of stress corrosion in turbines, I concluded that secondary water chem-istry recairements to prevent stress corrosion in the turbines may in the long cerm ba more stringent than those to prevent stress corrosion or wastage of the steam generator tubing.
This leaves the question, what should the NRC require as a Techni-1 Specification, and Nhat should the licensee consider for its own
.uirements for good practice?
If the NRC is primarily interested in
. equiring some control to ensure' that the licensee is paying proper
.tention to their steam gererator water chemistry, then a Technical opecification on feedwater 'and blowdown cation conductivity may be sufficient.
If the NRC is interested in applying controls to ensure that deterioration of the reactor coolant pressure boundary will not occur or will be' minimized in an operating unit, then I think they may ba asking for the impossible at this time.
When long term (% 5 years or more) experience with AVT or ZST units with a given condenser coolant have been successfully demonstrated, detailed Technical Speci-fications may be reasonably considered.
The Maine-Yankee and Prairie l
Island exp9riences, if subsequent inspections bear out their good records to date, may be able to serve as guidelines for future Tech-nical Specifications, but not, 'in my opinion, at thi's early date.
The l
licensees, however, should be taking advantage of this experience to dato in order to establish their own operating procedures.
I l
Distribution:
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L.C. Shao R.J.
Stuart B.D. Liaw M This Copy For W.Y.
Kato l
D.
van Rooyen j
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