ML20009F290
| ML20009F290 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 07/24/1981 |
| From: | Stolz J Office of Nuclear Reactor Regulation |
| To: | Hukill H METROPOLITAN EDISON CO. |
| References | |
| NUDOCS 8107300252 | |
| Download: ML20009F290 (7) | |
Text
.
.b
'JEY 2( 21 DISTorn ninti:
TERA EHylton
.:21 "' 9 USIC IE-3 P' NR.C PDR : ?
ORB #4 Rdg AE0D L PDR DEisenhut 0 ELD m?f/f4
[
JStolz ACRS-10 Docket flo. 50-289 DDilanni Gray File NLU(jh(g (ff N N
RJacobs H0rnstein V
/
N HSilver EBlackwood Mr. Henry D. Hukill, Vice PresidentSnydce
' 97 M
THI Site Pouch M-2 SIS 8]w Q 1
and Director - THI-1 u
Metropolitan Edison Company 9
L P. O. Cox 480
/
Middletown, Pennsylvania 1705'i 4
[
u t
Dear Mr. Hukill:
I t
The staff has cor.pleted its review of the B&W Report, BAU-1623, June 1980, l
" Control Rod Guide Tube Wear ficasurenent Program". The results of our l
review of this report are contained in the enclosed Safety Evaluation
[
Report.
Based on this review, the staff has concluded that the issue of Contrcl Rod Guice Tube Wear has been adequately addressed for B&W facilities and con-sir'ers this fiulti-Plant issue to be closed.
If you have any questions on this subject, please conte ' tour NRC Project Manager.
Sincerely, a0RIGUL'1 UIG'O UI Jos F. STOLTZ" John F. Stolz, Chief Operating Reactors Branch #4 7
Division of Licensing s
Enclosure:
Safety Evaluation Report cc w/ enclosure:
[
dee next page l
l 1
8107300252 810724
/DR ADDCK 05000289 P
PDR t
ORB #4:DLbf &C "B#4:DL t
i
- omcc, suamur >....D.D i..l..a..n n i../..c.,t J S..t..o..
..l M.81.......1/L.81.......
l om>
nac rosu m oo.q uncu ano OFFICIAL RECORD COPY usamm !
Metropolitan Edison Company <
I itcw/ enclosure (s):
Mr. Marvin I. Lewis Dr. Walter H. Jordan 6504 Bradford Terrace 881 W. Outer Drive Philadelphia, Pennsylvania 19149 Oak Ridge, Tennessee 37830 Walter W. Cohen, Consumer Advocate Dr. Linda W. Lit'tle Department of Justice 5000 Hermitage Drive Strawberry Square,14th Floor Raleigh, North Carolina 27612 Harrisburg, Pennsylvania 17127 Ms. Gail P. Bradford Robert L. Knupp, Esq.
Anti-Nuclear Group Representing Assistant Solicitor York Knupp and Andrews 245 W. Philadelphia Street P. O. Box P Yorkt Pennsylvania 17404 407 N. Front Street
. Harrisburg, Pennsylvania 17108 John Levin, Esq.
Pennsylvania Public Utilities Comm.
John E. Minnich, Chairman Box 3265 Dauphin Co. Board of Commissioners Harrisburg, Pennsylvania 17120 Dauphin County Courthouse Front und Market Streets Jordan D. Cunningham, Esq.
Harrisburg, Pennsylvania 17101 Fox, Farr and Cunningham 2320 North 2nd Street
- Atomic Safety and Licensing Appeal Board Harrisburg, Pennsylvania 17110 U.S. Nuclear Regulatory Commission Washington, D. C.
20555 Ms. Louise Bradford l
TMIA
- Atomic Safety and Licensing Board Panel 1011 Green Street U.S. Nuclear Regulatory Commission Harrisburg, Pennsylvania 17102 Washington, D. C.
20555 Ms. Marjorie M. Aamodt
- Docketing and Service Section R.D. #5 U.S. Nuclear Regulatory Commission Coatesville, Pennsylvania 19320 Washington, D. C.
20555 Ms. Karen Sheldon Robert Q. Pollard Sheldon, Harmon & Weiss 609 Montpelier Street 1725 I Street, N.W. - Suite 506 Baltimore, Maryland 21218 Washington, D. C.
20006 Chauncey Kepford Earl B. Hcffman Judith H. Johnsrud Dauphin County Commissioner Environmental Coalition on Nuclear Power Dauphin County Courthouse 433 Orlando Avenue Front and Market Streets State College, Fennsy'lvania 16801 Harrisburg, Pennsylvania 17101 Ms. Frieda Berryhill, Chairman Ms. Ellen R. Weiss, Esq.
Coalition for Nuclear Power Plant Sheldon, Harmon & Weiss Postponement 1725 I Street, N.W.
2610 Grendon Drive Suite 506 Wilmington, Delaware 19808 Washington, D. C.
20006 Mrs. Rhoda D. Carr Mr. Steven C. Sholly 1402 Marene Drive Ifnion of Concerned Scientists Harrisburg, Pennsylvania 17109 1725 I Street, N. W., Suite 601 Washington, DC 20006
Metropolitan Edison Company-,
Mr. Thomas Gerusky Ms. Jane Lee Bureau of Radiation Protection R.D. 3, Box 3521 Department of Environmental Resources Etters, Pennsylvania 17319 P. O. Box 2063 Harrisburg, Pennsylvania 17120 Karin W. Carter, Esq.
505 Executive House
'P. O. Box 2357 Harrisburg, Pennsylvania 17120 Honorable Mark Cohen 512 D-3 Main Capital Building Harrisburg, Pennsylvania 17120 G. F. Trowbridge, Esq.
Dauphin County Office Emergency Shaw, Pittman, Potts & Trowbridge Preparedness 1800 M Street, N.W.
Court House, Room 7 Washington, D. C.
20036 Front & Market Streets Harrisburg, Pennsylvania 17101 Hr. E. G. Wallace Licensing Manager Department of Environmental Resources GPU Service Corporation ATTN: Director, Office of Radiological Health 100 Interpace Parkway Parsippany, New Jersey 07054 P. O. Box 2063 Harrisburg, Pennsylvania 17105 Ms. Lennie Prough U. S. N. R. C. - TMI Site P. O. Box 311 Middictcwn, Pennsylvania 17057 Ms. Virginia Southard, Chairman Citizens for a Safe Environment 264 Walton Street Lemoyne, Pennsylvania 17043 Mr. Robert B. Borsum Babcock & Wilcox Government Publications Section Nuclear Power Generation Division State Library of Pennsylvania Suite 420, 7735 Old Georgetown Road Box 1601 (Education Building)
Bethesda, Maryland 20014 Harrisburg, Pennsylvania 17126
- Ivan W. Smith, Esq.
Mr. David D. Maxwell, Chairman Atomic Safety & Licensing Board Panel Board of Supervisors U.S. Nuclear Regulatory Commission Londonderry Township Washington, D. C.
20555 RFD#1 - Geyers Church Raod Middletown, Pennsylvania 17057 Ms. Kathy McCaughin Three Mile Island Alert, Inc.
U. S. Environmental Protection Agency 23 South 21st street Region III Office Harrisburg, Pennsylvania 1710; ATTN:
EIS C0ORDINATOR Curtis Building (fixth Floor)
Mr. C. W. Smyth 6th and Walnut Streets Supervisor of Licensing TMI-l Philadelphia, Pennsylvania 19106 Metropolitan Edison Company P. O. Box 480 Middletown, Pennsylvania 17057 m
Metropolitan Edison' Company Mr. R.J. Toole Allen R. Carter, Chairman Manager. TMI-1 Joint Legislative Committee on Energy Metropolitan Edison Company P. O. Box 142 P. O. Box 480 Suite 513 Middletown, Pennsylvania 17057 Senate Gressette Building Columbia, South Carolina 29202 Daniel M. Pell, Esq.
ANGRY 32 South Beaver Street York, Pennsylvania '17401 William S. Jordan, III, Esq.
Harmon & Weiss d
b0 ing n J. B. Lieberman, Esq.
General Counse?
Berlock, Israel & Liberman Federal Emergency Management Agency 26 Broadway ATTN: Docket Clerk New York, NY 10004 1725 I Street, NW Washington, DC 20472 1
I York College of Pennsylvania Country Club Road York, Pennsylvania 17405 I
[
Mr. Donald R. Haverkamp Senior Resident Inspector (THI-1)
{
U.S.N.R.C.
P. O. Box 311 i
Middletown, Pennsylvania 17057 3
Mr. Richard Roberts The Patriot 812. Market Street i
Harrisburg, Pennsylvania 17105 p
and Development ATTN:
Coordinator, Pennsylvania State Clearinghouse P. O. Box 1323 Harrisburg, Pennsylvania 17120 t
y y.-,
__m-
-,,i.
e
t,
%o,'n UNITED STATES NUCLEAR REGULATORY COMMISSION h.
tj WASHINGTON, D. C. 20S55 e
e
\\.,,,/
Enclosure SAFETY EVALUATION REPORT BY THE OFFICE OF NUCLEAR REACTOR REGULATION CONTROL ROD GUIDE TUBE WEAR IN FACILITIES DESIGNED BY BABC0CK AND WILCOX (B&W)
A degradation of control rod guide tube walls was observed during post irradia-
' tion examinations of fuei assemblies removed from several pressurized water reactors.
In the investigation of this problem the NRC requested information from B&W designed facilities related to the susceptibility of their facilities to significant guide tube wear. B&W prepared report BAW-1623, June 1980,
" Control Rod Guide Tube Wear Measurement Program" for the B&W Mk-B User's Group to orovide this requested information. The findings of this report are as follows.
Several flow-related mechanisms may cause Control Rod Assembly (CRA) vibration and guide tube wear; two of thev appear to be the most probable. The first is turbulent flow along the rod or crossflow across the control rods in the upper internals, resulting in wear at the lower tip of the rod when in the park post-tion.
The second hypothesized mechanism is axial flow inside the guide tube and l
a turbulent vibration response.
In both cases, an increase in primary coolant flow could result in higher rod vibration and possible higher wear; however it is felt that turbulent flow with some possible crossflow in the internals area is the most probable cause of rod vibration.
B&W's 15x15 array fuel assembly design includes 16 Zircaloy guide tubes for the control rods. Each CRA has 16 stainless steel clad control rods connected to a stainless steel spider which is in turn connected to the drive mechanism.
Full length guidance for each CRA is provided by the guides in the upper plenum assembly and in the fuel assembly. The control rod tip always remains inside the fuel assembly guide tube during normal operation. When the control rod is in the full ouf (parked) position, the tip of the control rod is approx (mately nine inches inside the fuel assembly guide tube.
The CRAs and guide tubes are designed with flexibility and clearances to permit freedom of motion within the fuel assembly guide, ubes throughout the stroke of the CRA.
t The B&W upper reactor internals design, in addition to the full-length guidance for the CRAs, has two features that minimi.e crossflow excitation and turbulence i
on the CRAs. The first is an upper pleram, which directs approximately 82% of the flow in an axial direction while e~. lowing only 18% of the flow to be taken k
5
a
_2 out directly into the outlet nozzles. This strong tendency towards axial flow will minimize any dependence of CRA vibration on outlet nozzle location. The second feature is the use of the full-length upper plenum tubes enclosing each CRA in the upper reactor internals.
These full-length tubes provided additional protection for the CRAs against crossflow and turbulence.
Fuel assemblies wc-re selected from across the core and for various effective full-power _ days (EFPD) of control rod operation in the safety position to determine the effect of core-position, time, fluence exposure, To obtain the effect of flow rates on guide tube wear, fuel as-etc.
semblies were examined at Oconee 1, Oconee 3, and Rancho Seco, the nominal Two flows of which run from approximately 109 to 114% of design flow.
The first concern is that potential areas of concern were investigated.
any one guide tube could wear through at the control. rod park position
-(approximately 9 inches from the top of the control rod guide tube).
The second concern is that smaller amounts of wear in all 16 guide tubes in a fuel assembly could cause high stresses in that fuel assembly.
The results from the Rancho Seco examination (high flow rate) indicates that the largest measured wear was 57% (through-wall wear).
In general, the wear was located approximately 9 inches down from the top of the guide tube, which corresponds to the location of the lower tip of the control rods of the safety banks in their park position.
This location also cor-responds to the control rod park position for control banks in some reactors.
Four Rancho Seco fuel assemblies indicated wear ranging from 6.9 to 14.9%
for one and one half cycles of operation. The other five assemblies examined indicated no wear.
The results from the Oconee examination (low flow rates) indicate less wear than Rancho Seco, with a maximum measured indication of 27% (in Oconee 3).
The average wear for each Oconee fuel assembly was low, with a maximum of 6.7%.
The second concern was that each guide tube would have some wear and that A stress analysis was performed that unacceptable stresses could occur.
Ttfs showed that through-wall wear for a single tube was acceptable.
Two analysis also considered the case with some wear in each guide tube.
types of wear were considered - localized wear on only one side of the The results of this tube and uniform wear around its circumference.
analysis show an allowable of 100% wear for localized (one-sided) defects Therefore, if the average and 55% wear for uniform circumference wear.
wear in any fuel assembly (average of 16 tubes) does not exceed 55% uni-form wear, the fuel assembly will maintain a positive design nargin.
s,
. The results of both the Oconee and Rancho Seco measurements show small average wear-with the maximum average of 14.9% for one Rancho Seco assembly with 1 1/2 cycles of operation. The 14.9% was one-sided wear which is compared to an allowable wear of 100%.
The results from the Rancho Seco stettstical analysis indicate the pro-bability of one guide tube wearing a hole is very low and is not expected.
The probability that a hole will occur in 150 weeks.of operation is 0.000011. The results from this analysis also indicate that the proba-bility of the average of 16 tubes in one assembly r;8ching 55% wear is also very low and is not expected. The probability of the average of 16 tubes reaching 55% wear is 0.000001 for 150 weeks of operation. This case assumes uniform circumferential wear, which is not expected. The aore likely case is wear occurring on only one side of the guide tube.
This case has a higher allowable wear (100% versus 55%) and hence a signi-ficantly smaller probability of reaching this wear.
(The assumed. maximum core residence time for a fuel assembly with an installed CRA is 150 weeks.)
The NRC staff has found that the B&W Report accounts for all of the major variables that affect the control rod guide tube wear process. Based on our review, we conclude that the control rod guide tube wear has an occeptably low likelihood of keeping within allowable wear limits.
Dated:
' JULY 2 4 1581 c
l e
,. _