ML19247A871
| ML19247A871 | |
| Person / Time | |
|---|---|
| Site: | Atlantic Nuclear Power Plant  |
| Issue date: | 07/18/1979 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Collier A OFFSHORE POWER SYSTEMS (SUBS. OF WESTINGHOUSE ELECTRI |
| References | |
| NUDOCS 7908030046 | |
| Download: ML19247A871 (1) | |
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'n NUCLEAR REGULATORY COMMISSION 9., [E REGION 11 o,
b 101 MARIETT A ST., N.W., SUITE 3100 kv ATLANT A, G EORGI A 30303 e
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In Reply Refer To:
RII:JPO 50-437 Offshora Power Systems Attn:
A. R. Collier, President P. O. Box 8000 Jacksonville, Florida 32211 Centlemen:
The attached enclosure, Circular 76-06, was inadvertently omitted in the July 17, 1979 issue of Information Notice 79-19.
Siucerely, Q_lh
~f M James P. O'Reilly Director
Enclosure:
Circular 76-06 f
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[9 JR O p }. 31 November 26, 1976 IE Circular No. 76-06 STRESS CORROSION CRACKS IN STACNANT, LOW PRESSURE STAINLESS PIPING CONTAINING BORIC ACID SOLUTION AT PWR's DESCRIPTION OF CIRCW! STANCES:
During the period Ncvember 7, 1974 to November 1, 1975,
- veral incidents of through-wall crac king have occurred in the 10-inch, schedule 10 type 304 stain 3 css steel piping of the Reactor Building Spray and Dc:ay Heat
'Removn) Systems at Arkansas Nuclear Plant No.1.
On October 7,19'6, Virr. inia Electric and Power also reported through-vall cracking in the 10-inch schedule 40 type 304 stainless diccharge piping of the "A" recircuistion spray heat exch;nger at Surry Unit No. 2.
A rec'.:nt inspcetion of Unit 1 Containnant Recirculation Spray Piping revealed cracking - 1 pilar to Unit 2.
On October 8,1976, another incident of similar cracking in 8-inch schedule 10 type 304 stainless piping of the Sefety Injection Pump Suction I.ine at the Cinna facility was report by the licensee, i
f Information roccived on the r.etallur*1cci ana.
5 conducted to date
.ndicates that the fa13ures were the result o.
- granuler stress corrosion cracking that initinted on the insida of the piping.
A comunality of f actors observed associated with the corrosion teechanism l
were:
1 1.
n e cracks were adjacent to and propagated along weld zones of the thin-valled low pressure piping, not part of the rc : tor coolant i
system.
l 2.
Cracking occurred in piping containing relatively stagnant boric acid solution not required for normal operating conditions.
i 3.
Analysis of surface producta at. this timo indicate a chloride ion I
interaction with oxide fore.ation in the relativaly stagnant boric acid solution as the probable corrodant, with the state of stresc probably due to velding and/or fabrication.
he source of the chloride ion is not d finitely known.
However,.at ANO-1 the chlorides and sulfide level observed in the surf ace tarnish film near welds is believed to have been introduced into the pipinn during tenting of the sodium thinsulf ate discharge va3 vee, or valva leakage. Similarly, at Cinns the chlorides and potential oxygen b
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'D USNRC REGI' A T L A N T &. r.c Enclos ure 1 IE Circular No. 76.46d dl. l7 Pl*,.3L Novesber 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, d ioving
. buildup of contaminated water in an otherwise normally dry spray piping.
ACTION TO BE TAKEN BY LTCENSEE:
1.
Provide a descripcion of your program for assuring continued integrity of those safety-related piping systems which are not frcquently flushed, or which contain nonflowing liquids.
This program should include consideration of hydrostatic testing in accordance with ASME Code Section XI rules (1974 Edition) for all active systemc required for safety injection end containment spray, including their recirculation modes, from source 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 voluraetric examination of a representative number of circumferential pipe welds by non-destructive examination sechniques.
Such examinations should be performed generally in accordance with Appendix I of Section XI of the ASME Code, except that the examined area should cover a distance of approximately six (6) times the pipe wall thickness (but not 3 css than 2 inches and need not exceed 6 inches) on each side of the weld.
Supplementary exaraination 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.
De 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 condestructive evaluation of the accessibic piping welds identified above.
5.
A sumaty report of ' Se examinations and evaluation of results should be submitted Ithin 60 days from the date of completion of proposed testing and examinations.
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USf!RC REOl'-:
a 'i '. N T/. r IE Circular No. 76-06 ' g,t g[ g p,
3l November 26, 1976 i
This summary report should also include a brief description of plant conditions, operating procedures or other activitica which provide assurance that the ef fluent chemistry will n.aintain low levels of potential corrodants in such relatively stagnant regions within the piping.
Your responses should be nubmitted to the Director of this office, Division with a copy to the NRC Office of Inspection and Enforcement, of Reactor inspection Programs, Washington, D.C.
20555.
t Approval of HRC requirements for reports concerning possible generic proble'; has been obtained under 44 U.S.C 3152 from the U.S. General Accot ating Of fice.
(CAO Approval d-180255 (R0062), expires 7/31/77.)
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