ML19247A854
| ML19247A854 | |
| Person / Time | |
|---|---|
| Site: | Crystal River  |
| Issue date: | 07/18/1979 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Stewart W FLORIDA POWER CORP. |
| References | |
| NUDOCS 7908030008 | |
| Download: ML19247A854 (2) | |
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[o, UNITED STATES s (f( %
NUCLEAR REGULATORY COMMISSION e
E REGION 11 5.h'V,I 101 M ARIETT A ST., N.W., SUIT E 3100 w: [o,8 AT LANT A, GEORGIA 30303
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JUL 181979 In Reply Refer To:
RII:JPO S0-302 Florida Power Corporation Attn:
W. P. Stewart, Manager Nuclear Operations P. O. Box 14042, Nail Stop C-4 St. Petersburg, Florida 33733 Gentimen:
The attached enclosure, Circular 76-06, was inadvertently ocitted in the July 17, 1979 issue of Information Notice 79-19.
Sincerely, (O
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James P. O'Reilly A Director
Enclosure:
Circular 76-06 498 174 3
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JUL 181979 Florida Power Corporation '
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G. P. Beatty, Jr.
Nuclear Plant Superintendent Post Office Box 1228 Crystal River, Florida 32629
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[9 JUL Il November 26, 1976 1E Circular No. 76-06 STRESS CORPOSION CRACKS IN STACNANT, LOW PRESL'lRE STAINLESS PIPING CONTAINING BORIC ACID S.wUTION AT FWR's D.ESCRIPTION OF CIRCWfSTANCES:
During the period November 7, 1974 to November 1, 1975, several incidents of through-wall cracking have occurred in the IO-inch, schedule 10 type 304 stain]cus steel piping of the Reactor Building Spray and Decay Heat
" Removal Systern at Arkansas Nuclear Plant No. 1.
On October 7, 1976, Virginia Electric and Power also reported through-wall cracking in the 10-inch schedule 40 type 304 stainless diccharge piping of the "A" recirculation spray heat exchanger at Surry Unit No. 2.
A recent inspection of Unit 1 Containnent Recirculation Spray Piping revealed cracking 6imilar to Unit 2.
On October 8,1976, another incident of similar ccccking in 8-inch schedule 10 type 304 stainless piping of the Sefety Injection Pump Suction I.f.ne at the Cinna f acility was reported by the licensee.
l Info' matian received on the r.etallurgical analysis conducted to date e
indicates that the failures were the resu.t of intergranular stress 1
corrosio's cracking that initiated on the inside of the piping.
A cocmona?.ity of f actors observed associated with the corrosion mechanism vere:
I 1.
The cracks were adjacent to and propagated along veld zones of the thin-walled low pressure piping, not part of the reactor coolant i
system.
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2.
Cracking occurred in piping containing rcJatively stagnant boric acid solution not required for normal operating conditions, t
3.
Analysis of surface products at this time indicate a chloride ion I
interaction with oxide formation in the relativaly stagnant boric acid solution as the probable cerrodant, with the state of strest probably due to welding and/or fabrication.
The source of the chloride ion is not definitely known.
However..at ANO-1 the chlorides and sulfide level observed in the sur f ace tarnish film near welds is believed to have been introduced into the piping during centing of the sodium thinsulf ate discharge va]ves, or valvo leakage.
Similarly, at Cinna the chlorides and potential oxygen kk i
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t.T t A trT A. 6 IE Circular No. 76_ g g[ l7 Pl.3L November 26, 1976 availability were assumed to have been present since original construction of the borated water storage tank which is vented to atmosphere.
Corrosion attack at Surry is attributed to in-leakage of chlorides through recirculation spray heat exchange tubing, allowing i
. buildup of contaminated water in an otherwise normally dry spray pip ng.
ACTION TO BE TAKEN BY LICENSEE:
1.
Provide a description of your program for assuring continued integrity of those safety-related piping systems which are not This f requently flushed, or which contain nonflowing liquids.
program should include consideration of hydrostatic testing in accordance with ASME Code dection XI rules (1974 Edition) for all active systemc required f or safety injection and containment spray, including their recirculation modes, from wource of water supply up to the second isolation valve of the primary system.
Similar tests should be considered for other safety-related piping systems.
2.
Your program should also consider volumetric examination of a representative number of circumferential pipe welds by non-destructive examination techniques.
Such examinations should be perf ormed generally in accordance with Appendix I of Section XI of the ASME Code, except that the examfued area should cover a distance of approximately six (6) times the pipe wall thickness (but not Jess rSan 2 inches and need not exceed 8 inches) on each side of the weld.
Supplementary examination technigecs, such as radiography, should be used where necessary for evaluation or confirmation of ultrasonic indications resulting f rom such cxamination.
3.
A report describing your program and schedule for these inspec-tions should he submitted within 30 days af ter receipt of this Circular.
4.
The NRC Regional Of fice should be informed within"24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, of any adverne findings resulting during nondestructive evaluation of the acces.ibic piping welda identified above.
5.
A sunsaty report of the examinations and evaluation of results should be submitted within 60 days f rom the cate of completion of proposed tecting and examinations.
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USf!RC REGli.
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IE Circular No. 76-06 g g[t[ l7
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,e November 26, 1976 i
i This summary report should o include a brief description of plant conditions, operating procedures or other activities which provide assurance that the ef fluent chemistry will maintain low levels of potential corrodants in such relatively stagnant regions within the piping.
1 Your responses should be cubmitted to the Directo. of this office, with a copy to the NRC Of fice of Inspection and Enforcement, Division of Reactor Inspection Programs, Washington, D.C.
20555.
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Approval of NRC requirements for reports concerning possible generic problems has becn obtained under 44 U.S.C 3152 from the U.S. General l
Accounting Office.
(GAO Approval B-180255 (R0062), expires 7/31/77.)
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