ML15245A167
| ML15245A167 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 11/23/1979 |
| From: | Reid R Office of Nuclear Reactor Regulation |
| To: | Parker W DUKE POWER CO. |
| References | |
| NUDOCS 7912100416 | |
| Download: ML15245A167 (9) | |
Text
Dockets Nos. 50-269 2VENDER 2
50-287 and 50-270 Lo Mr. Wiltiam 0. -Parker, Jr.---
Vice President Steam Production Ouke-Power Comipany P.' 0. Box 21781 422 South Church Street Charlotte, Iorth Carolina '28242 D~ear Mir.
Parker:
S-igniftzant wear of the. Z i r al oy control roe, 906i-AAUbishas been observed in facf Iities des~gned by cod'-usti~n Engineering ICE simfi',r wear has also been repprted in ths ciifsdsge yWsig~e(W).
In our letter of June 13,1078, w 'equeste4 ~ipfoyrlation frog bna~~iox(&)o h
susceptability of 6he -Facilities doesignee. by BW -to guido tube wear.
The inF'Oration Provided 3y~W by Iletter dated January 12, -159 was i nsuf f ici ent.
for us to conclude that'~Saide tube wear was not a sigjnificant probler, In tbe facilities designed by D&1 This vias documented in our letter to. BOW -dpted
- August 22, 1919.
Because significaiit guide tube wear could iimpd the control rbd scram capability, iind also effect the requi".d coolable genetrT.5f the rector corm, we consider this wear phen"s: non a potential safety concern.. Thigrelore, we are requesting~ that ycvu provide detailed infomation on the wear character istics f the control rads on the guide tubes in fue, assemblies in Oconee, Units Nos. 1, 2 and 3.
The eclos-ed W~C concerns are provided to assist you in plarining your 'control rod and guide tube survaillance program.
When. you have completedi your surveil 16nce program, plart, 'we request that this programa Le subraitted for KIRC review before implementatiori.
Although this date-gathering program f.my be performed on availtble irradiated assemblies 'in spent'fuefl pools, we find t~hat this issue should be resolved for each facilfty before startup from your next scheduled ref ueling outage commning after Januaryj, 198N.
To expidite our reiwof y mlr propr~
a etigatRC headquarters in Bethesda* Mlarylands has been scheduled for December 20, 1979, at 9:30 a-ill This m~eeting will provide you. the opportunity to clarify and disctissth enlosed R.RC concerms and the details of~ your proposed program.
Your agenda of the rneating should be provided by ecerter 17., 197%.
7912100 74 i
S IR N A M E+
NRC FORM 318 (9-76) NRCM 0240
- U.S.
GOVE RNMENT PRINTING OFFICE: 1979-289-369
Should you have any qUeStlenls on the, type of information we need or scheduling reqsirerlents, pleas *e contact our Operating Reactors Branch. #4 Project N~nagar assigned to your facility.
Sincerely, Rtobert W. Reid Robert W. Reid* Chie-F Operating Re actors aranch #4 Diviston of Oper titg eactors EnCI 0sure c c W~enclosure See next page Distribution:
Docket file RReid
.___PCheck fWRC POR Rlngrarn TJICarter L PDR
__WRussell TERA MConner Attorney, QELD MRuchanan, NSIC OB&E (3)
NRR Rd.~
MFairtile ACRS (16) w/list of other distribution ORB#4 Rdg.
__Riggs
- o~c~ISee preViOul yellow for Ci ncurrenceS
- SURNAE)]..........
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RReid......
NRC FORM 318 (9-76) NRCM1/ cJTWpGVENIETPNTN FIE 1979-289-369.
1979 To expedite our review of your program a meeting at NRC headquarters in Pethesda, Maryland, has been scheduled for December 20, 1979, at 9:30 a.n.
This meeting will provide you the opportunity to clarify and discuss the enclosed NOC concerns and the details of your proposed program.
Your agenda of the meeting should be provided by December 17, 1979.
Should you have any questions on the type of information we need, or scheduling requirements please contact our Operating Reactors 2ranch #4 Project Manager assigned for your facility.
Sincerely, Robert W. Reid, Chief Operating Reactors Branch #4 Division of Operating Reactors Enclosure cc: w/enclosure DistrSbetient page Docket file RReid DDilanni PCheck NRC PDR RIngram TJCarter L PDR PKreutzer WRussell TERA MConner Attorney, OELD JRBuchanan, NSIC GVissing OI&E (3)
NRR Rdg.
MFairtile ACRS (16) w/list of other distribution ORB#4 Rdg.
DGarner Riggs SURN IME
.7 DATE Rc P
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) NR RC 2
U. S. GOVRNM ENT PRINTIN OFFICE: 1979-2F9-369
SREG&
OS UNITEDSTATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 November 23, 1979 Dockets Nos. 50-269 50-270 and 50-287 Mr. William 0. Parker, Jr.
Vice President - Steam Production Duke Power Company P. 0. Box 2178 422 South Church Street Charlotte, North Carolina 28242
Dear Mr. Parker:
Significant wear of the Zircaloy control rod guide tubes has been observed in facilities designed by Combustion Engineering (CE).
Similar wear has also been reported in those facilities designed by Westinghouse (W). In our letter of June 13,1978, we requested information from Babcock and Wilcox (B&W) on the susceptability of the facilities designed by B&W to guide tube wear. The information provided by B&W by letter dated January 12, 1979 was insufficient for us to conclude that guide tube wear was not a significant problem in the facilities designed by B&W. This was documented in our letter to B&W dated August 22, 1979.
Because significant guide tube wear could impede the control rod.scram capability, and also effect the required coolable geometry of the reactor core, we consider this wear phenomenon a potential safety concern. Therefore, we are requesting that you provide detailed information on-the wear character istics of the control rods on the guide tubes in fuel assemblies in Oconee Nuclear Station, Units Nos. 1, 2 and 3.
The enclosed NRC concerns are provided to assist you in planning your control rod and guide tube surveillance program. When you have completed your surveil lance program plan, we request that this program be submitted for NRC review before implementation. Although this data-gathering program may be performed on available irradiated assemblies in spent fuel pools, we find that this issue should be resolved for each facility before startup from your next scheduled refueling outage commencing after January 1, 1980.
To expedite our review of your program, a meeting at NRC headquarters in Bethesda, Maryland, has been scheduled for December 20, 1979, at 9:30 a.m.
This meeting will provide you the opportunity to clarify and discuss the enclosed NRC concerns and the details of your proposed program. Your agenda of the meeting should be provided by December 17, 1979.
79121 00
-2 Should you have any questions on the type of information we need or scheduling requirements, please contact our Operating Reactors Branch #4 Project Manager assigned to your facility.
Sincerely, R 6ert W. Reid, Chief Operating Reactors Branch #4 Division of Operating Reactors Enclosure cc:
w/enclosure See next page
Duke Power Company cc:
Mr. William L. Porter Duke Power Company Post Office Box 2178 422 South Church Street Charlotte, North Carolina 28242 J. Michael McGarry, III, Esquire DeBevoise & Liberman 700 Shoreham Building 806 15th Street, N.W.
Washington, D. C. 20005 U. S. Nuclear Regulatory Commission Region II Office of Inspection and Enforcement ATTN:
Mr. Francis Jape P. 0. Box 85 Seneca, South Carolina 29678 Mr. Robert B. Borsum Babcock & Wilcox Nuclear Power Generation Division Suite 420, 7735 Old Georgetown Road Bethesda, Maryland 20014 Manager, LIS NUS Corporation 2536 Countryside Boulevard Clearwater, Florida 33515 Oconee Public Library 201 South Spring Street Walhalla, South Carolina 29691
Enclosure NRC CONCERNS ON CONTROL ROD GUIDE TUBE WEAR IN FACILITIES DESIGNED BY B&W The B&W surveillance experience on worn control rod guide tubes, as described in their January 12, 1979 letter, consists of (a) air testing of sixteen guide tubes from an Oconee-1 15x15 fuel assembly that had experienced one cycle of operation under a control rod assembly and (b) clam-shell sectioning of two guide-tubes from a 17x17 fuel assembly that had undergone a 1000-hour flow test under a control rod assembly. As documented in our letter of August 22, 1979, we find that this experience is not sufficient to support the B&W con clusion that there is strong.evidence for the absence of wear in B&W-designed plants. In fact, to the contrary, worn guide tubes have been observed in Crystal River, Unit 3 spent fuel (see BAW-1490 Rev. 1, July 1978). Our position is further based on observations made by other NSSS vendors who have found a "plant-specific" and."core-position" dependence in the observed wear.
Furthermore, out-of pile flow tests have demonstrated that the wear rate is a function of several design and operating variables.
- 1. Propose a post-irradiation examination (PIE) program with a schedule for its implementation and a commitment to execute the program for NRC review.
This data-gathering program should be completed expeditiously considering the availability of irradiated assemblies in all B&W-designed plants.
Details of the surveillance plan should include the following:
- a. Methods of examination (e.g., destructive, eddy current probe, boroscope, mechanical gage) accompanied by qualification of those methods.
- b.
Characterization of the examined guide tubes, including their in-core locations, EFPHs, flow rates, fluence, and wear time under rods (control, instrument, axial-power shaping, burnable poison, startup source, and orifice).
- c. Examination of those rods (control, instrument, axial-power shaping, burnable poison, startup source, and orifice) contained within the guide tubes to iderntifv fatigue, stress corrosion
-2 cracking, wear, denting, or any other conditions that can degrade their design function, reduce their design lifetime, or impede their movement.
- d. Analysis of results including quantification of guide tube wall wear depth and distribution. This PIE program may be satisfied in part of totality by reference to data taken from another B&W designed plant(s) that uses the same type of fuel assemblies. In such case, justification must be given that wear in the referenced plant adequately represents that of the plant design in question.
Provide all correlations supported by your tests and discuss how these correlarions are used to predict guide tube wear during reactor operations over the fuel lifetime.
- 2. Provide an evaluation on the predicted guide tube wear on the stress analyses contained in the FSAR. The evaluation should address loadings associated with Condition-1 through -4 events including fuel handling accidents, control rod scrams, and seismic and LOCA transients. The discussion should describe the state.of stress in the worn guide tubes and how the wear affects the loadbearing characteristics of the worn tubes.
(Note that nonuniform wear results in a shift of the neutral tube axis which then induces not only direct stresses but also bending stresses.)
Show that the loadbearing capacity of the worn guide tubes satisfies the acceptance criteria for these loading events.
- 3. Provide or reference all material property correlations that are used in the guide tube stress analyses. These correlations should accommodate the effects of hydrogen absorption and the propensity for hydrogen uptake in the Zircaloy guide tubes as a function of accumulative wear.
-3
- 4. Address the consequences of hole formation in worn guide tubes.
Consider the extent and distribution of wear to see if hole formation is possible. If the potential for hole formation can hot be discounted, evaluate the impact of such holes on the guide tube integrity, control rod motior and local thermal-hydraulic performance. This evaluation should account for flow-induced vibration resulting in crack propagation and possible fatigue frac ture in locally thinned areas of the tube wall.
This discussion should also address the entire core residence time, both during periods of wear (under rods; i.e., control, instrument, axial-power shaping,.burnable poison, startup source, and orifice) and when the tubes are not rodded.