ML20031F242
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UNITED S TATES y
g NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555
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MEMORANDUM FOR: Acting Chief Technical and Administrative Support Branch Office of Nuclear Reactor Regulation FROM:
Darrell G. Eisenhut, Acting Director Division of Operating Reactors Office of Nuclear Reactor Regulation
SUBJECT:
CONFIRMATORY RESEARCH STUDY OF A REPLACED STEAM GENERATOR FOR VARIOUS CAUSES AND FORMS OF DEGRADATION
References:
1.
Memorandum E. G. Case to S. Levine, " Request for Confirmatory Research Study of a Replaced Steam Generator for Various Causes and Forms of Degradation" dated June 26, 1978.
2.
Memorandum, S. Levine to H. R. Denton, " Confirmatory Research on Replaced Surry II Nuclear Steam Generator" dated July 18, 1979.
3.
MerJrandum, J. P. Knight to Acting Chief, Technical Support Branch, " Review of RES Program Research Study of Replaced Surry 11 Nuclear Steam Generator" dated August 2, 1979.
4.
Memorandum, 8. Turovlin to Acting Chief, Technical Support Branch, " Review of RES Program Research Study of Replaced Surry II Nuclear Steam Generator" dated August 2, 1979.
5.
Memorandum, D. G. Eisenhut to D. M. Crutchfield, " Confirmatory Research Study of a Replaced Steam Generator for Various Causes and Forms of Degradation".
The purpose of this memo is to address concerns expressed by J. P. Kright (re-i ference 3) and 8. Turovlin (reference 4) regarding the proposed research study l
of a replaced Surry Unit 2 steam generator (references 1 and 2). The concerns are addressed in the same sequence as they were presented in reference 4.
A.
The Office of Nuclear Regulatory Research has considered potential damage or disturbance to the steam generator and its internals during transport and has determined that this is not a sianificant problem. Sludge deposited in the steam generator is a cementitious material which adheres l
firmly to the tubes, tube support plates, and tubesheet'. Normal operating I
conditions and lancing and flushing operations have not dislodged the sludge. In fact, during recent operations at the Surry Unit 2 site, a sludge sample could only be removed by chipping. Furthermore, even if a small portion of the sludge does dislodge, a sludge mapping can still be made j
using the marks left on the tube surfaces.
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. Handling of the steam generator has been and will continue to be very delicate. Visual inspection of the steam generator and its internals following removal from containment revealed no damage. The overland portion of the journey at each end of the trip is quite short and is performed using a slow moving crawler. A stress analysis of the steam generator package for shipping is being performed and instrumentation of the steam generator during shipment is under consideration. Additional supports can be provided to the steam generator internals if results of the stress analysis so warrant. Examinations of the steam generator and its internals will be performed upon arrival at PNL to confirm the success of the shipping.
B.
The introduction in reference 2 does not state that 'he research program -
t will provide direct input to Task Action Plans A-3, A-4, and A-5.
It states "the research will also provide further supporting data to validate the conclusions of Task Action Plans A3,4 and 5."
Regarding the establishment of any near term secondary water treatment, the program is long term, however, early chemical analysis of sludge and corrosion products may provide useful data regarding the principle actors in the corrosion process.
C.
The basis for the selection of the Surry Unit 2 steam generator was delineated in a' March 11, 1978 memo from L. C. Shao, Chief, Engineering Branch, 00R to D. G. Eisenhut, Assistant Director for Operational Technology, 00R. The Surry Unit 2 record of steam generator operating history is one of the most comprehensive of any operating plant and VEPC0 has committed to providing all steam generator operating data to the NRC.
Even though Surry Unit 2 operated for a period with phosphate secondary water treatment, which "new plants" will not use, this chemistry is typical of almost all operating plants. Furthermore, the Surry steam generator has almost every type of degradation which is known to exist in recirculating type steam generators.
D.
Field degraded tubes are the most desirable for NOT/NDE because inservice corrosion, possible thermal aging and operational stresses will uniquely affect the conductivity of the tubes which is a significant parameter in most NOT/NDE systems. Furthermore, realistic defects representing i
these conditions are difficult if not impossible to create in the laboratory.
Inspection will first be performed using the NDT/NCE systems most commonly used in the industry and using ASME Code procedures.
Additional testing will be performed to qualify advanced NDE/NDT systems.
Regarding the statistical analyses the most significant contribution of this program will be to evaluate the distribution of eddy current l
testing error for various systems. This analysis will be equally valid for other steam generators. The actual distribtuion of degradation in the steam generator can vary from generator to generator; however, the steam generator will provide at least a qualitative assessment of ISI programs which.are.under development.
1
4.
e
,.* E.
The potential effects of transport on corrosion product dit,tributtor.,
as mentioned in A above, are not considered significant.
Welding of a divider plate in the steam generator is considered feasible without removing or damaging a large portion of the steam generator internals.
Chemical cleaning studies are a valuable benefit of this program.
Confirmation of the quality of chemical cleaning processes, the effectiveness of solvents and more importantly the short term and long term effects on the integrity of the steam generator are necessary and important for future NRC licensing actions.
F.
The structure of the research program includes decision points which allow evaluation and approval for the continuation of the program and commitment of funds in stages.
The above responses have been developed in conversations with the Office of Research and represent what we believe to be acceptable responses to the concerns..which have been expressed. We therefore continue to endorse the proposed steam generator aquisition program.
Please inform me if additional information is necessary regarding the program.
d#n a.. t nGbut DarrellG.ifisenhut,ActingDirector I
Division of Operating Reactors Office of Nuclear Reactor Regulatio' i
cc:
F. Schroader l
L. Shao J. Knight V. Noonan S. Pawlicki C. Serpan, Jr.
W. Paulson I
- 8. D. Liaw J. Muscara H. Comrad R. Gamble T. Sullivan
- 8. Turovlin F. Almeter J. Strosnider l
E. Murphy