IR 05000280/1993027
| ML18153B426 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 12/03/1993 |
| From: | Blake J, Kleinsorge W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML18153B425 | List: |
| References | |
| 50-280-93-27, 50-281-93-27, NUDOCS 9401040090 | |
| Download: ML18153B426 (4) | |
Text
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Report Nos._:
UNITED STATES -
NUCLEAR REGULATORY COMMISSION REGION II -
101 MARIETTA STREET, N:w,, SUITE 2900 ATLANTA, GEORGIA 30323-0199 50-280/93-27_and 50-281/93-27 Licensee: Virginia Electric and Power Company Glen Allen, VA 23060 Docket Nos.:
50-280 and 50-281 License Nos.:
'
12i'f3
.Date Signed
,2:M5 Da'te Signed SUMMARY Scope:
This special announced inspection was conducted in the area of through wall leaks in aluminum bronze Service Water (SW} system valve Results-:.
The licensee's actions to date, related to the SW system aluminum bronze valve degradation, are appropriate to the circumstances. - The depth of the metallur-gical failure analysis is commendabl In the areas inspected, violations or deviations were not identifie PDR ADOCK 050002SQ G
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REPORT DETAILS Persons tontacted Licensee Employees
- W. Benthall, Supervisor, Licensing
- R. £lount, Superintendent of Maintenance
- D. Christian, Assistant Station Manager
- J. Downs, Supe_rintendent of Outage and Planning
- T.- Sowers, Superintendent of Erigineering
- J. Swientoniewski, Supervisor, Station Nuclear Safety
- M. Wilda,.Service Water System Engineer
Other.licensee*empioyees contacted during this inspection included engineers, operators, technicians, and administrative personne NRC Resident Inspectors S. Tingen, Resident Inspector
- J. York, Resident Inspector
- Attended exit interview Through Wall Leaks in Aluminum Bronze Service Water (SW) Valves Oil October 12, 1993, operators making their rounds noted varying degrees of corrosion on a total of 22 cast aluminum bronze valves in the SW syste The corrosion conditions ranged from a slight weeping.of water to a buildup of verdigris (corrosion products) on the external part of*
the valve The valves are Jamesbury ball valves, with sand cast aluminum bronze bodies conforming to*ASTM B 148 Alloy C 95400. This issue is further discussed in NRC Inspection Reports 50-280,282/93-24. and 50-280,282/93-2 The licensee conducted.a metallurgical failure analysis on a total of five degraded aluminum bronze valves removed from the SW syste The metallurgical analysis included:
macroscopic examination; optical and scanning electron microscopic analysis; chemical analysis of the valve body base material and the corrosion products; a tensile test survey of the valve bodies; and a bacteriological analysis. The results of the licensee's metallurgical failure analysis indicate that the failure mechanism was dealuminification, accelerated by a microbial presence on the interior surfaces of the valves. The dealloying consisted of a preferential attack of the aluminum rich B-eutectoid phase leaving a residual porous structured a-phase. *
Because* the dealloyed material was known to exhibit significantly lower physical properties, the licensee conducted a structural integrity assessment of the valve Based on the macro and microscopic examina-tions of the valve bodies and the tensile test data from the tensile test survey, for the purpose of calculations, the licensee assumed the
,.
I
dealloying attack to be I through wall for 100% of the valve body circumference and localized 100% through wall for 25% of the circumfer-ence of the valve bodies. The analysis indicated that there was at least a factor of safety of 2.17 against a net section plasticity (ductil~
rupture will not occur} and a margin of safety* of 4.35 against brittle fractur The above formed the basis for the licensee's ASME Section XI relief reques *
To date the licensee has replaced, ~ubstituted or removed 24 aluminum
. bronze valves in the pl an The first leaking valve removed, l-SW-132, was repl~ced with an identical flange connected, aluminum bronze valv Additionally to date, three aluminum bronze valves in Unit 1 (l-SW-117, l-SW-125 ~nd 1-sw~126} and ten aluminum bronze valves in Unit 2 {2-SW-110, 2-SW-115, 2-SW-116, 2-SW-118, 2-SW-119, 2-SW-120, 2-sw-121,*2-sw-122, 2-SW-132, and 2-SW-171) wer~ substituted with flange connected, type 316,stainless steel valves of the same desig Ten aluminum bronze valves in Unit 2 (2-SW-117, 2~SW-123, 2-SW-124, 2-SW-125, 2-SW-126, 2-SW-127, 2-SW-128, 2-SW-131, 2-SW-169, and 2-SW-173) were removed from the system and replaced with flange connected 90:10 copper-nickel spool pieces. All the aluminum bronze valves {20) have been removed from Unit Three aluminum bronze valves have been replaced with stainless steel -
valves in Unit The remaining 17 Unit 1 aluminum bronze valves are planned to be removed by the end of the next Unit 1 refueling outage, which is scheduled to commence January 21, 199 The licensee has committed to conduct a weekly walkdown inspection of all the aluminum bronze valves remaining in the plan _
.
To evaluate the licensee's ongoing actions related to the degraded aluminum bronzj SW valves, the in~pector interviewed licensee personnel, observed work activities and examined selected documents as indicated_
belo The inspector accompanied the SW system engineer on his weekly walkdown inspection of the SW aluminum bronze valve The inspector examined the installed replacement valves and spool pieces, and confirmed that the control room drawings reflected those change The inspector e*xamined macro specimens and photomicrographs of degraded valve !dent; ficat;on 93-67 C-93-004 93-193,
Documents Examined Revhfoil Title 11/2/93 Virginia Electric Power Company Surry Power Station Units 1 and 2 ASME Sec-tion XI Relief Request
Continued Operation with Through Wall Leakage of CH SW System Valves 10/13/93 Safety Evaluation 11/29/93 Biomedical Technologies In Microscopic Analysis of Sludge Sam~
ples from the *Surry Electrical Power Plant Service Water System
. '.
Identification S-93-1350 SU-93-00075 SU-93-00076 11.448-FM-071 Sheet 1 of 2
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11548-FM-0718 Sheet 1 of 2 93-034-3
Documents Examined Revhfon
. Title 11/15/93 Summary Report Dealloying of Aluminum Bronze Valves Surry Power Station Station Deviation Report
Item Equivalency Evaluation Review
. O Item Equivalency Evaluation Review
Flow/Valve Operating Numbers Diagram**
Circulating and Service Water System Surry Power Station Unit 1 Virginia Power 32 and 35 Flow/Valve Operating Numbers Diagram Circulating and Service Water* System Surry Power Station Unit 2 Virginia Power
11/17/93 Engineering Review and Design-Nuclear Power Station SW Flow Indicatio*n /
Surry / 1&2
.
.
The inspector noted that valve t-SW-131, was indicated-~ "normally closed", on drawing 11548-FM-071B, Sheet 1 of 2, Rev,sion 32. This valve is among the ten valves that were replaced by pipe spool piece When asked how they could replace a*
11normally closed" valve with a pipe section, the licensee admitted that the "normally closed" indication for valve 2-SW-131 was a drawing error. The licensee stated that since 1991, valve 2-SW-131 has been operated as a "normally open" valve!.
On the latest revision (35), to drawing 11548-FM-071B, Sheet 1 of 2, located in the control room, this valve is appropriately not indicated. Therefor the _latest revision of drawing 11548-FM-071B is correc The licensee's actions,.to date, related to the SW aluminum bronze valve degradation, *are appropriate to the circumstance The depth of the metallurgical failure analysis is commendabl Within the area irispested, no violations or deviations were identifie.
Exit Interview The inspection scope and results were summarized on December 1, 1993,
- with those persons indicated in paragraph 1. The inspector described the areas inspected and discussed in detail the inspection results.* Although reviewed during this inspection, proprietary information is not contained in this repor No dissenting comments were received from the licensee.