ML19224D584

RO 50-26/79-13/03-L-0 on 790412:365 Hydraulic Snubbers Found to Be Inoperable During First Functional Test,Causing Both Unacceptable Lockup & Bleed Characteristics.Caused by Setpoint Drift,Dirty Oil & Clogged Valves.All Repaired

ML19224D584
Person / Time
Site:	Fort Saint Vrain
Issue date:	07/03/1979
From:	Frost R PUBLIC SERVICE CO. OF COLORADO
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19224D582	List: ML19224D581 ML19224D584 ML19224D585
References
NUDOCS 7907120658
Download: ML19224D584 (3)

Text

REPORT DATE: July 3. 1979 REFORTABLE OCCURRENCE 79-13 ISSUE O OCCURRENCE DATE: April 12, 1979 Page 1 of 3 FORT ST. VRAIN NUCLEAR GENERATING STATION PUBLIC SERVICE COMPANY OF COLORADO

'. O. B0X 361 r

PLATTEVILLE, COLORADO 80651 REPORT NO. 50-267/79-13/03-L-0 Final IDFNTIFICATION OF CCCURRENCE:

During performance of the hydraulic snubber functional test required by the Fort S t. Vrain Technical Specifications, snubbers were found to'be inoperable.

It cust be assumed that these snubbers were incperable when the plant was at power. This is contrary to LCO 4.3.10, constitutes operation it. a degraded mode, and is reportable per Section AC 7.5.2(b)2 of the Fort St. Vrain Techni-cal Specifications.

EVENT DES CRIPTION :

Specification SR 5.3.8(d) of the Fort St. Vrain Technical Specifications re-quires that a representative sa=ple of ten hydraulic snubbers be tested once each refueling cycle starting with the first refueling. The specification requires a functional test for operability including verification of proper piston =ovecent, lockup, and bleed. The specification states that for each unit and subsequent unit found inop,erable, an additional ten snubbers shall be tested until no more failures are found or all units have been tested.

The Fort St. Vrain Nuclear Generating Station began its first refueling shut-down February 1,1979, and performance of the required testing was begun on April 12, 1979. During performance of the fuutional test, snubbers were found that did not meet the acceptance criteria.

The failure of the tested snubbers to meet the acceptance criteria was both unacceptable lockup characteristics and .aacceptable bleed characteristics.

The table below shows the results of 413 snubbers tested.

Total Snubbers Tested 413 Total Found Operable 48 Total Found Ir. operable 365 Failed Piston Mo vement Test 0 Failed Lockup Test Only 16 Failed Bleed Test only 173 15 053 Failed Lockup and Bleed Test 176 79071206 %

REPORTABLE OCCURRENCE 79-13 ISSUE O Page 2 of 3 EVENT DESCRIPTION (continued):

In addition to those snubbers found to be inoperable when tested, three other items of reportability were identified during perfor=ance of the surveillance test. First, three Class 1 snubbers were found that had been installed by an approved field change in 1976 but had not been added to the list in the Technical Specifications and were not added to tha periodic surveillance in-spection program. Second, sixteen snubbers installed on another approved field change were found not to have bleed capability. Third, approximately half of the snubbers tested were found to have seal =aterial other than ethylene propylene. Technical Specification SR 5.3.8(b) requires all hydraulic snubbers whose seal materials are other than ethylene propylene or other material that has been demonstrated to be compatible with the operating environ =ent be visu-ally inspected for operability every 31 days. Contrary to this requirement the snubbers with non-ethylene propylene seals were not identified and were not inspected every 31 days.

Permission was requestcd and received from the Nuclear Regulatory Commission to delay submittal of this report until completion of the testing and repair program.

CAUS E DESCR!PTION:

The snubbers at the Fort S t. Vrain plant have been installed and in operation for several years and this is the first functional test to be performed. The exact causes of failures were found to be setpoint drif t, dirty oil, and clogged valves.

The cause of the failure to incorporate the three snubbers added in 1976 to the Technical Specification list and surveillance program was the misclassifi-cStion of the change by the originating organization as a change not requiring a Technical Specification change.

The cause of the installation of sixte n snubbers without bleed capability .

was the omission of a bleed rate from che design specification and the resul- ~

tant pu chase of snubbers without bleed capability.

The cause of the failure to perform the inspection of snubbers with non-ethylene propylene seals as required by SR 5.3.8(b) was misinformation, as *o the seal material, which led the organization responsible for surveillance test prepara-tion to believe that all snubbers had ethylene propylene seals.

CORRECTIVE ACTION:

The corrective action for snubbers that failed the functional test was to re-pair or readjust each snubber to meet acceptance criteria. All tested snubbers were reinstalled in operable condition.

415 054

REPORTA3LE OCC'JRRENCE 79-13 ISSUE O Page 3 of 3 CORRECTIVE ACTION (continued):

The failure to properly identify the three Class 1 snubbers involved in a field change was the second occurrence of this type and actually occurred prior to the first identified occurrence (Feportable Occurrence Report No.

50-267/77-41). At the time of the first occurrence a letter was sent to the prime contractor admonishing them for failure to properly review and des,. ribe a Class 1 modification. Since the error described in this report occurr J prior to the issuance of the letter no additional action will be teken. The three snubbers will be temporarily added to Technical Specification Table 4.3.10-1 until a permanent revision to Table 4.3.10-1 is issued in a subse-quent amenneent. The surveillance procedure has been revised to include the three snubbers.

Those snubbers which were found to not have bleed capability were modified by installation of a valve asse=bly providing both lockup and bleed capability.

During the functional test those snubbers that had non-ethylene propylene seals were found to have their seals in good condition. Because there was no evidence of degredation specific to non-ethylene propylene sesis, the seals in use have been deuonsertted to be co= pat.ible with the operating environment.

Therefore, there are ne snubbers at Fort St. Vrain subject to the inspection requirements of SR 5.3.8(b) and no corrective action is required.

Prepared by:

~

S + /_. , A/

Richard R. Frost Technical Services Technician Reviewed by: . / / W- _

. W 'Gahm

'T hnical Services Supervisor Reviewed by:

Frank M. Mathie Operations Manager

/ /

Approved by: 2 / /. IIl[Lw.b. -<. ~ / k //

Don Warenbourg ./ ./

Manager, Nuclear Production