ML20086C030

Final Deficiency Rept Re Pressurizer Snubber Malfunction. Initially Reported on 760402.Caused by Heavy Corrosion Buildup.Nine Units Replaced W/Pacific Scientific Units & 54 Units Replaced W/Combination of Redesigned Units

ML20086C030
Person / Time
Site:	Salem
Issue date:	06/10/1976
From:	Schwalje E Public Service Enterprise Group
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20086C026	List: ML20086C030
References
10CFR-050.55E, 10CFR-50.55E, NUDOCS 8311220538
Download: ML20086C030 (3)

Text

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J% G g. (- IE FILE COPY Public Servico E'cctric avd Gas Company 80 Park Place Newayk, N.107101 Phone 201/G22-7000 -

June lo, 1976 .

Mr. James P. O'Reilly, Director U. S. Nuclear Regulatory Commission

• Office of Inspection and Enforcement Region 1 631 Park Avenuo King of Prussia, Pennsylvania 19406

Dear Mr. O'Reilly:

PRESSURIZER SNUBBER MALFUNCTION PRESSURIZER SAFETY AND RELIEF VALVE PIPING NO. 1 UNIT SALEM NUCLEAR GENERATING STATION DOCKET NO. 50-272 Supplementary to our letter of April 2, 1976, submitted herewith is our concluding report on the subject equipment malfunction in accordance with 10CFR50.55(e).

ANALYSIS The original deficiency discovered during Hot Functiona'l Test, SUP 50.0 involved removal of twelve (12) snubber units, ten (10) of which were restricting thermal pipe movements and two (2) which were removed for evaluation purposes. Subject units were returned to the manufacturer, International Nuclearsafeguards (INC) for operational load testing and disassembly inspection which was witnessed by PSE&G QA Engineer. The results of the retest and disassembly indicated the following:

1. F'ive units functioned within required operational load limits and disassembly was no,t performed. These units were identified as: Size No. 1, S/N 271 and S/N 273; Size No. 2, S/N 75 and S/N 118; and Size No. 3, S/N 002281.

2. Seven units were disassembled on the basis of the unit being either completely jammed or showing operational load values that exceeded manufacturer's specifications during retest.

The completely jammed units that were disassembled on the basis of excessive operations loading during retest are:

Size No. 2, S/N 73, 74*, 78 and Size No. 3, S/N 002276**.

• Typographical error on report of 4/1/76, which listed this as S/N 47 on Page 1, Par. 4.

• • Erroneously reported as S/N 00'2281 on report of 4/1/76 (second reference only) on Page 2, Par. 1.

8311220538 760628 PDR ADOCK 05000272 S PDR ,

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Mr. James P. O'Reilly 6/10/76-  ;

4 Results of the investigation of disassembled units revealed the  !

following: four (h) units malfunctioned due to heavy corrosion '

buildup on the units' internal components. These were all Size No. 2, S/N 92, 110 and 111 (all three were completely jammed) and S/N 78 vhich displayed heavy corrosion primarily on the i needle thrust bearing surfaces. The remaining three (3) units of the seven (7) units disassembled were Size No. 2, S/N 73 and 7h; and Size No. 3, S/N 002276, none of which' visually displayed any obvious reason for malfunction.

Five of the twelve units were installed with the shipping preset screv left in place. These screws sheared during Hot Functional i Test were on Size No. 1, S/N 271; Size No. 2, S/N 74, 78 and 1181 and Size No. 3, S/N 002281. The fact that these units were installed with the preset screw in place has lead PSE&G Engineering to conclude that this factor was not a major contributing cause of the malfunctions. This conclusion was reached on the basis that three units remained operable after removal from the Salem Site, (Size No. 1, S/N 271; Size No. 2, S/N 118; and Size No. 3, S/N 002281) and the other two units malfunctioned due to other obvious reasons; Size No. 2, S/N 78 for heavy corrosion on the

. thrust bearing and Size No. 2, S/N Th for heavy hammer marks on Housing OD inflicted during the removal operation which affected alignment and operational retest values.

SUMMARY

AND CORRECTIVE MEASURES PSE&G Energy Laboratory conducted a chemical analysis and evaluation of the heavy corrosion compounds removed from the' internal parts of Unit S/N 111. The Energy Laboratory's. report identifies the source of corrosion of the carbon steel internals as possible from rainwater containing carbon dioxide that entered the unit between the travel screw and the housing bushing.

Access of. vater to the snubber internals was attributed to the vertical position of the snubber as installed.

Replacement units consisted of: A. Redesigned INC units that have corrosive resistant hardened stainless steel wear surfaces

.and other features which will prohibit water entry and, B. Pacific Scientific Corporation (PSA) units Sizes 1, 3, lo and 35 The Pacific Scientific units have been subjected to extensive physical and environmental tests by the manufacturer and have been evaluated acceptable by PSE&G Co. for the intended service.

The corrective action taken for'the original sixty-three (63)

(INC) snubbers with carbon steel internals is as follows:

9 Units have been replaced with Pacific Scientific Units 5h Units are being replaced with a combinat.on of redesigned (INC) units and Pacific Scientific Units. ,

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Mr. James P. O'Reilly 6/10/76 Any additional snubbers which may be required for No. 1 Unit will be of the redesigned (INC) units or Pacific Scientific Units.

The replacement installations vill be completed by July 15, 1976.

Snubbers to be used for No. 2 Unit will be based on the per-formance of No. 1 Unit snubbers.

SAFETY IMPLICATIONS We are continuing our investigation of the restraining effects on the pressurizer piping system due to malfunctioning snubbers during hot functional test heat up period. From our analysis it appears that no damage to the piping system occurred during this event. We are however continuing our investigation through the use of Ultrasonic Testing of areas of interest in the subject piping and vill compare these results with the data from the previously completed preservice Ultrasonic Test history. Positive results from this test will further verify that the piping is acceptable and consequently the system vill be approved for service and no further reports vill be made.

This investigation vill be completed by July 5, 1976 and the results will be available at the plant site.

If additional information is desired,,we vill be pleased to discuss it with you.

Very truly yours,

)1 E. N. Schwa e Manager of Quality Assurance Engineering and Construction-Department

- CC Dr. Ernest Volgenan Bethesda, Md.

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