ML19209A598
| ML19209A598 | |
| Person / Time | |
|---|---|
| Site: | Surry, 05000434  |
| Issue date: | 07/12/1979 |
| From: | Berry W Advisory Committee on Reactor Safeguards |
| To: | Shewmon P Advisory Committee on Reactor Safeguards |
| References | |
| ACRS-CT-1146, NUDOCS 7910050043 | |
| Download: ML19209A598 (2) | |
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[pn nacq#'o UNITED STATES E
g' n NUCLEAR REGULATORY COMMISSION
$.h,,d'; [5 ADVISORY COMMITTEE ON RE ACTOR SAFEGUARDS 0, b.
A p' WASHINGTON, D. C. 20555 E DVE0 July 12,1979
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1979 J'JL 13 141 9 31 u.s.suct m a cmM.
ADVISORY c; t RE UN gg To:
Paul Shewnon M
b7-M From:
Warren Barry jsgg 77gj79
Subject:
Comments on ACRS Subcommittee Meeting on Metal Components on
~~ ~ ~ ~
July 10,1979 fly comments are directed toward corrosion and corrosion related phenomena.
1.
General In order to carry out its objectives relating to safety in the nuclear industry, it is necessary that NRC fund research in areas where needed infornation is not available.
In many corrosion related areas, much of the needed information is available or is being obtained by other organizations.
Where not available, l'RC should sponsor or cosponsor research.
2.
Speci fic a.
Surry Steam Generator Cadaver _
I am in favor of continuing with the examination of the steam generator being removed from the Surry Plant, if for nothing more than ensuring that no other (as yet recognized) problems exist.
- 'oreover, the information gained from this examination should provide valuable direction for the continued operation of existing PUR steam generators.
I believe that because of design, materials, and operating incidents, the corrosic.1 probleg in present stean generators will continue, although probably at
_a much slower rate (despite elimination of phosphate, change to AVT, and tightening up on secondary water chemistry--reduced condenser leaks, etc.)
Cosponsoring of the examination by EPRI is an added bonus, b.
Uater Specifications Research should be conducted (continued) to develcp optimum water specifications, particularly in the areas of Bl!R primary coolant and P',lR secondary coolant. Model boilcr and stress corrosion type testing will be required to help define these limits.
i10c/07(1 (1)
BWR Primary Coolant Information is needed on the effect of 02 and H 02 2 content in BWR coolant during operation and startup/ shutdown on 5LC of sensitized f)%.5
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7910050 O M to ascertain what (if any) oxygen limits are required to approach trouble-free operation conditions.
' (2).'PUR Secondary Coolant Information is needed on the effect of pH, 0, Cl, and other 2
contaminants on corrosion and SCC of existing and future steam generator components.
Of particular interest is the establishnent of time-concentration tolerance limits for out of specification operation.
c.
Environmental Cracking (1 ) SCC Emphasis in SCC should be directed toward establishing the environmental, fabrication, and operating variables (and their limits) that affect SCC rather than attempting mechanistic studies where the past track record is poor.
SCC crack growth rates appear to be relatively fast and thus cannot be used to predict probable continued life of a component.
- Thus, research on SCC crack growth rates should be limited to their use in evaluating parametric effects within SCC research studies.
(2)
Corrosion Fatigue Research on corrosion fatigue crack growth rates is justified since for the most part, they are sufficiently slow that life time pre-dictions can be made.
Research on corrosion fatigue should be expanded to include off-chemistry conditions such as accidental introduction of oxygen, low pH excursions, and shut down/ start up conditions (high 0, Hp0, etc).
2 2
Also needed is the effect of small cyclic loads that occur during steady state operating conditions, and the effect of the strain-environment spectrum for an actual plant during start up/ shut down operation.
Prelimi-nary research in the area of low cyclic loads in high 07 simulated BWR conditions, have produced cracks with the appearance and high propagation rates of SCC.
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