ML17174A428
| ML17174A428 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 01/17/1980 |
| From: | Ziemann D Office of Nuclear Reactor Regulation |
| To: | Peoples D COMMONWEALTH EDISON CO. |
| Shared Package | |
| ML17174A429 | List: |
| References | |
| TASK-03-08.C, TASK-3-8.C, TASK-RR NUDOCS 8002110038 | |
| Download: ML17174A428 (7) | |
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. * * *** * * ~pnoN q Docket.No. 50-237 Mr. o. Lout~ People~
Director of Nuclear Licensin*g.
. *common~'4ealth Edison Company P. o. Box 767 Chicago. 11 Hno1 s 606~0
Dear Mr. Peoples:
C P R Local-PDR ORB Reading
- NRR Reading DEisenhut RVollmer OELD OI&E (3)_.
.. DLZiemann
- P0 1Connor HSmjth.
- NSIC.
TERA ACRS (16)
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RE:-
SEP TOPIC Iil-8.C Irradiation Damage,. Us_e of Sens1~1zedSta1nles*s Ste~i,
.and Fatigue Resistance I
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- Enclos~d is a copy of our draft evaluation. Qf Systematic *Evaluation PrograJ11* i. l'
-Topic III-a *.c. _You are-requested to examine the* facts upon which the_ staft, :.. L.*
has based its eva 1 uati on and respond e1 the~ by* conf1 rmi ng that the f ac_ts / : *:-
- t are correct. or* by* identifying aey errors_., If fn error, please suppJy CQrr~p1'.fd * *
- i nformC1t1on. for* th~ docket *. \\~~ encourage *yoµ* to.supply for the docket*. anyi \\; :.J.. *.
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- .oth_er materfal r~lated to these topics that. m1ght_ affect* t~*e *staff'~ evaH1,~t1qJ..
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YQyr respo_nse.within 30 days of the dat~ you.receive this letter h 'req~~~it~9*:i; *
.If no !re. sp. ons_e 1s re_ ce1ved wi~h1nth$t
.. time,. we w111 assume that* you hav~)i\\,. :*\\*<1.
no comments* or corrections.
~f :>>)-.<i.\\:~t Si~cerely*, *
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Enclosure:
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- . *NRC F.ORM ~18 (9'76)".NRCM*02Jio *
- "~ R U;S: GOVERNMENT PRiNT'ING"O'FFICE:' 1979-2-89"369"' ", > ~.._.. ;***:
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~r. D. Louis Peoples cc
- Isr.aw, Lincoln & Beale Co~nselors at Law One First National Plaza, 42nd Floor Chicago, Illinois 60603 Mr. B. BA Stephenson Plant Superintendent Dresden Nuclear Power Station Rural Route #1
~orris, Ill ino is 60450
- Anthony Z. Reisman Natural Resources Defense Council 917 15th Street, N. W.
~ashington, D. c.
20005 U. S. Nuclear Regulatory Commission Am~: Jimmy L. Barker P. o. Box 706
~orris, Illinois 60450 Susan N. Sekuler Assistant Attorney General Envfronmental Control Division l8E W. Randolph Street Suite 2315 Chicago, Illinois 60601
~orris Public Library 60L Liberty Street
~orris, Illinois 60451 Che iman Bocrd of Supervisors of Grundy County Gr~ndy County Courthouse
~orris, Illinois 60450 Jantllry 17, 1980 Depart~ent of Public Health ATTN:
Chief, Division of Nuclear Safety 535 West ~efferson Springfield, Illinois 62761
/
Director, Technical Assessment Division Office of Radiation Programs
. (AW-459)
U. S. Environmental Protection Agency Crystal Mall #2 Arlington, Virginia 20460 U. S. Environmental Protection Agency Federal Activities Branch Region V Office ATTN:
EIS COORDINATOR 230 South Dearborn Street Chicago, Illinois 60604 Mr. Neil Smith Commonwealth Edi son Con.~any P.O. Box 767 Chicago, Illinois 60690
SYSTEMATIC EVALUATION PROGRAM PLANT SYSTEMS/MATERIALS DRESDEN NUCLEAR POWER STATION UNIT NO. 2 Topic III-8.C - Irradiation Damage, Use of Sensitized Stainless Steel and*
Fatigue Resistance The safety objective of this review is to detennine whether the integrity of the internal structures of operating reactors has been degraded through the use of sensitized stainless steel.
The effect of neutron irradiation and fatigue resistance on materials of the internal structures was eliminated from the safety objective of Topic III-8.C in memorandum to D. G. Eisenhut from D. K. Davis and V. S. Noonan dated December 8, 1978.
The memorandum concluded that operating experience indicated that no significant degradation of the materials of the reactor internal structures had occurred as a result of either irradiation or fatigue.
Furthennore, the Standard Review Plan (Section 4.5.2) does not address neutron irradiation nor fatigue resistance of the materials of the reactqr internal structures.
As a result of incidents of intergranular stress corrosion cracking in piping
- in the BWR system, special study groups were formed by NRC and industry to evaluate the cause, extent and safety implications of the use of sensitized.
stainless steel in the nuclear steam supply systems.
The study groups identified the incidents with the recirculation system bypass lines, the core spray lines, and the control rod drive return lines. It was concluded that the problem was caused by a combination of high total stresses, sens.tization of the austenitic stainless steel in the heat affected zones of welds, and the relatively high oxygen content of the coolant.
The NRC study grouprec01T111ended an augmented inservice inspection program for stainless steel piping, more stringent monitoring of the leak detection system, modification of plant operating practice, and the use of alternate materials*
irrmune to intergranular stress corrosion cracking.
The study group concluded in NUREG-0531, "Investigation and Evaluation of Stress-Corrosion Cracking in Piping of Light Water Reactor Plants," that intergranular stress corrosion cracking in piping would be detected prior to unstable crack growth because of the adequacy of the inservice inspection program and the leak detection system.
Reactor operating experience has validated the leak-before-break concept of piping integrity, and, it was concluded, that through-wall cracks in the piping systems would be detected before they presented a hazard to the health and.
safety of the public.
The regulatory position on the use of sensitized stainless steel in reactor internal materials is addressed in the Standard Review Plan Section 4.5.2, "Reactor Internal Materials." The areas currently reviewed in.the applicant's SAR are materials specification and the controls imposed on the reactor coolant chemistry, fabrication practices and examination and protection procedures.
8 002110
~.. The materials specification should comply with Section III of the ASME Boiler and Pressure Vessel Code and th_e components should satisfy the recommendations of Regulatory Guide 1.31, "Control of Ferrite Content in Stainless Steel Weld Metal" and Regulatory Guide 1.44, "Control of the Use of Sensitized Stainless Steel".
The reactor is described in Sections 3 and 4 of the Safety Analysis Report for the Dresden Nuclear Power Station Unit Nos. 2 and 3.
The internal components were designed to provide support for the fuel and maintain structural clearances during normal and accident conditions.
In addition, the internal components provide passageway for the coolant to cool the fuel and means for adequately separating the steam from the coolant water.
The vessel was designed, fabricated and tested in accordance with Section III of the ASME Boiler and Pressure Vessel Code, 1963 Edition, including Surmner 1964 Addenda.
The materials used for the construction of the reactor internals were identified as Type 304 and Type 308 stainless steel, Inconel, and minor quantities of special purpose alloys. The identified structural materials have been used on other General Electric designed reactors and have proven adequate by the results of extensive tests, prior usage and satisfactory performance.
The regulatory position on the use of sensitized stainless steel in reactor internal materials was not addressed in the Safety An~lysis Report for the Dresden Nuclear Power Station Unit No~ 2~ Experience has shown that at least three elements in combination are necessary to cause cracking in SL11sitized stainless steel components.
Thes~ are material susceptibility, an oxygenated water environment, and a threshold total stress.
We assume for this evaluation that the Dresden Unit No. 2 reactor internal components contain sensitized stainless steel in contact with an oxygen saturated coolant water environment.
However, the calculated stresses on the reactor internal components do not exceed the threshold stress values associated with intergranular stress corrosion cracking.
The threshold stress values are near or greater than the 0.2% off-set yield stress at temperature. Further, in the reactor environment, stress relaxation may occur due to irradiation and temp~rature effects.
The licensee Event Reports and the BWR Nuclear Power Experience~were reviewed for the Dresden Nuclear Power Station Unit No. 2 *in order to correlate reactor internal materials failure to the use of sensitized stainless steel in the components.
The events are summarized~as follows:
In LER's beginning in September 1974, and continuing through 1977, leaks were reported in the 4-in recirculation bypass line, the 10-in core spray lines, the 14-in HPCI lines, and the control rod drive penetration.
The cause of these failures was intergranular stress corrosion cracking, resulting from either furnace or weld sensitization. The defective material* was replaced with material immune to sensitization.
An augmented inservice inspection program was conducted to reduce the consequence of the failure incidents in the affected piping.
- In December 1974, cracks in the feedwater spargers were discovered.
This problem is an item under review by Generic 1echnical Activity A-10, nswR Feedwater Nozzle Cracking 11
- During inservice inspection of reactor internals in March 1976, loose restrainer clamp bolt keepers were found on the jet pumps.
The cause of the failure was fatigue cracking of the tack-welded restrainer assembly.
The loose keepers were rewelded to the original specification.
We conclude from our review of the Licensee Event Reports and the BWR Nuclear Power Experience that the integrity of the reactor internal components was degraded by the use of sensitized stainless steel. The reported events were detected by the inservice inspection and testing program.
The events were considered by the NRC Pipe Crack Study Group in NUREG-0531, 11 Investigation and Evaluation of Stress Corrosion Grading in Piping of Light Water Reactor Plants 11 and in the Generic Technical Activity A-10, 11 BWR Feedwater Nozzle Crack ing 11
- The inservice inspection program for the reactor internal components is being conducted during the current interval to the requirements of Section XI of the*
ASME Boiler and Pressure Vessel Code, 1974 Edition, including Su!T1ller 1975 Addenda.
The program is in compliance with paragraph (g) of Section 50.55a of 10 CFR Part 50.
It will assure that the integrity of the components is maintained during reactor operation.
We conclude from our review of the information submitted by the licensee that the materials in the reactor internal components are sensitized and are operated in an oxygen saturated water environment, and that the incidents of stress corrosion cracking are rare because the total stress level is relatively low, not exceeding the 0.2% offset yield strength at operating temperature.
In the unlikely event that intergranular stress corrosion cracking should occur, cracks in the components will be detected by inservice inspection procedures prior to component failur~
We conclude that the inteqritY of the reactor internal components w111 be assured by the inserv1ce 1nspect1on program conducted to the requirements of Section XI of the ASME Boiler and Pressure Vessel Code, 1974 Edition, including Summer 1975 Addenda, in compliance with paragraph (g) of Section 50.SSa of 10 CFR Part 50. Further, we conclude that intergranular stress corrosion cracking in the reactor internal components is not a hazard to the health and safety of the public.
Docket Hos. 50-1~*
Mr. D. Louis Peoples Cirector of Nuclear Licensing Cor~nom'leal th Edi son Compaey Post Office Box 767 Chicago, I 11 i no1 s 60690
Dear Mr. Peoples:
TRIBUTION NR
BG rimes PC heck RRiggs NSIC ACRS (16)
JAN l 1 70.... a
... o TERA In response to our letter of September 6, 1978, you provided infonttation on your 1977 experience of control rods failing to fully insert.
We evaluated your response along with those provided by other BWR owners.
We concluded that such events are general and that the frequencies of occurrence vary among the BWRs, apparently because of different maintenance programs *.
Our Septer:iber 6, 1978 letter recorrmended that you maintain an ongoing tabulation of any additional such events. To deter:Jine whether or not the frequency of these events has changed for a given plant, we nrA-J request that you report your more recent ~xperience. This report shou-ld include the experience from the tine of the last reported
- occurrence through 1979.
In addition, please provide a summary of<'
other control rod drive malfunctions, such as unlatching, for the same time period.
The infonaation should be provided w1th1n 90 days. For each event, identify the number of rods not fully inserted, the position of the rods, the cause for failure to fully insert, and any related maintenance activities.
This request for additional generic inforr:lation is in accordance with the GAn blanket clearance number B-180225 (R0536) which expires June 30, 1981.
cc:
See next page NRC FORM 318 (9*76) NRCM 0240 Sincerely, Dennis L. Ziemann, Chief Operating Reactors Branch #2 Division of Operating Reactors
-CC U.S. GOVERNMENT PRINTING OFFICE: 1979*289*369
- '*~r. D. Louis Peoples
- cc
- Isham, Lincoln & Beale Counselors at Law One first National Plaza, 42nd Floor
- Chicago, Illinois 60603 M~ *. B. B. Stephenson Plant Superintendent Dresden Nuclear Power Station
- Rural Route # l Morris, Illinois 60450 Anthonyl. Rois~~n
- Natural Resources Defense Council 917 15th Street, N. W.
Washington, D. C.
20005 U. S. Nuclear Regulatory Commission ATTN:
Jimmy L. Barker P. 0. Box 706 Morris, Illinois 60450.
Susan N. Sekuler
- Assistant Attorney General En~ironmental Control Division 188 W. Randolph Street Suite 2315 Chicago, Illinois 60601 Morris Public Library 604 Liberty Street Morris, Illinois 60451 Chairman Board of Supervisors of Grundy County Grundy County Courthouse
-Morris, Illinois 60450 January.11~ 1980 Department of Public Health ATTN:
Chief~ Division of
. Nuclear Safety 535* West Jefferson*
Springfield, Illinois.62761 Director, Technical As~essment Division *
- Offic~ of Radiation Programs (AW-459)
U. s. Environmental Protection Agency*
Crystal Ma.1 l #2 Arlington, Virginia 20460.
U. S. Environmental Protection*.
Agency Federal Activities Branch.
Region V Office ATTN:
EIS COORDINATOR 230 South Dearborn Street Chi~ag6, Illinois 60604
,.