ML18054B450

Responds to Violations Noted in Insp Rept 50-255/89-26. Hamstad Rept Encl.Corrective Actions:Licensee Concludes That All Instrumented Insp Technique Testing Performed at Plant in Accordance W/Plant Specific Procedures

ML18054B450
Person / Time
Site:	Palisades
Issue date:	02/06/1990
From:	Berry K CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML18054B451	List: ML18054B450 ML18054B452
References
NUDOCS 9002260498
Download: ML18054B450 (5)

Text

• • MICHIGAN'S PROGRESS POWERING Kenneth W Berry Director Nuclear Licensing General Offices: 1945 West Parnall Road, Jackson, Ml 49201 * (517) 788-1636 February 6, 1990 Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 DOCKET 50-255 - LICENSE DPR PALISADES PLANT -

RESPONSE TO INSPECTJON REPORT 255/89026 NOTICE OF VIOLATION, "INSTRUMENTAL INSPECTION TECHNIQUE" (IIT)

Consumers Power Company was informed by letter dated November 2, 1989 that the ASME required hydrostatic pressure test performed during the 1988 refuelin~ outage is considered invalid. The Hydrostatic test requirement was met by utilizing the Instrumental Inspection Technique (IIT) an NRC approved alternative to the ASME code specified method. This letter requested CPCo to evaluate its examination procedures and the IIT test data.

If tests were confirmed to be invalid, Consumers was requested to identify all ASME systems and components subject to the hydrostatic pressure testing requirements of ASME Section XI which were tested using the IIT technique and to determine whether the affected systems could bejudged functionally operable. If the tests were determined to be valid, the NRC was to be informed of the basis for this determination and a description of the system or component tested and the date of the test.

In addition, an inspection report dated December 8, 1989 on the same subject identified deficiencies in content of and adherence to the detailed testing procedures. An extension of 30 days for the required response was granted during the telephone conference call with DDanielson of the NRC staff on December 21, 1989. This correspondence addresses specifically the three parts to violation 255/89026. Consumers Power Company response regarding the validity of the Instrumented Inspection Technique tests performed at Palisades will be forthcoming.

Consumers Power Company has concluded that all IIT testing performed at Palisades was in accordance with plant specific procedures and the NRC approved RAFA Topical Report 135 (P-A) which was approved by the NRC for licensing reference on November 7, 1985.

In addition, Consumers Power has determined that all affected systems are operable and fully capable of performing their intended safety functions.

The basis for ASME Section XI Hydrostatic Testing operability determinations OC0290-0254-NL04 9002260498 900206 PDR ADOCK 05000255 A OHS EIVRGY COMPANV Q PDC

Nuclear Regulatory Commission 2 Palisades Plant Response to IR 89026 February 6,' 1990 has been documented under Docket 50-255 License DPR Palisades Plant dated November 13, 1989.

It should be noted that Consumers Power Company intends to perform a hydrostatic test (or approved alternative test) on the main steam system following the steam generator replacement outage, currently scheduled for fall 1990. A hydrostatic test of the auxiliary feedwater system suction piping will be performed in the upcoming maintenance outage as post modification test requirement, per Section XI IWA-4400.

NOTICE OF VIOLATION 255/89026-lA Interim and post verification of channel sensitivity, considered a prerequisite for acoustic testing was neither performed nor required by the procedures.

The NRC has concluded that "The pencil-lead break check performed prior to testing is not considered an acceptable method of sensor calibration due to the fast rise/decay transient as opposed to the continuous signal procdure by a leak. Interim and post verification of channel sensitivity in considered essential in the evaluation of test data."

The pencil lead break technique uilized in the pre-test verification of the

• operability and sensitivity of the IIT Acoustic test equipment, as required by the IIT Acoustic test procedure, is considered an acceptable method for this application by ASTM Standard E-976, the Acoustic Emission Handbook and NUREG/CR-5134. In performing an independent review of the IIt Acoustic test method, Dr Marvin Ramstad, University of Denver, has concluded (See attached)

"My examination shows that the stanrlard lead break calibration technique used by RAFA along with reasonable sensor spacings does provide assurance that leaks (with acoustic strengths equivalent or greater than the levels of those examined in the laboratory, in plant development tests and in field tests to date) will be detected in the field. Current RAFA practice emphasizes a lead break on the pipe near the base of each acoustic waveguide. These breaks are carried out prior to the pressure test. RAFA used this data primarily to verify the particular channel at which the lead break was made. This approach checks the sound transmission of: 1) the adhesive from the pipe to the waveguide; ii) the adhesive between the waveguide and the sensor. It also checks the sensor and acoustic measurement system. In my opinion the data from these lead breaks also provides the information to check the sensitivity of the sensor to leaks located some distance form the sensor. By examining lead break calibration data I determined the amplitudes at the adjacent sensors and found them to be consistent with the values to be expected for reasonable sensor spacings."

In regard to interim post-test verifications of channel sensitivity, Dr Ramstad has stated that "since the acoustic test criticality depends on maintaining sensitivity throughout the whole test. I have examined RAFA approaches *towards assuring maintenance of sensitivity. Their approach has been three-fold: use of the response to ad.i acent sensors to normal changes in plant operating conditions; ii) use of simulated leak sources and OC0290-0254-NL04

Nuclear Regulatory Commission 3 Palisades Plant Response to IR 89026 February 6, 1990 iii) in some cases post~test lead breaks. These approaches are important due to the potential for the test conditions to disturb the sensitivity .

.There are at least three potential things that could happen: i) temperature rise resulting in loss of acoustic transmission due to an adhesive change or failure; ii) vibrations resulting in fracture of an adhesive bond; and iii) temperature effects on the sensors and/or preamplifiers. My finding indicate that the HAFA approaches are effective in finding extreme losses in sensitivity."* Additionally, RAFA performs comparative checks of all IIT Acoustic test equipment to ensure appropriate sensitivity exists both before and after testing.

Based upon the above, it is Consumers Power Company's belief that the Acoustic test procedure did include provisions for assuring that all prerequisites for a,given test have been met, thereby satisfying the requirements of 10 CFR 50, Appendix B, Criterion XI.

NOTICE OF VIOLATION (255/89026-lB)

The lack of a qualified, well designed relationship between background noise level and leak detection sensitivity did not permit evaluation of the suitability of environmental conditions encountered during the test.

During IIT Acoustic testing, changes in environmental conditions affect leak detection sensitivity in different ways, both negatively and positively.

Changes in ambient temperature during plant heat-up, which are most pronounced in the containment atmosphere, produce a negative affect on the order of a 1 to 2 db decrease in sensitivity. Changes in system temperature, which affects only the waveguide-system epoxy bond, produce a negative effect on the order of an approximately 5 db decrease in sensitivity. The change in system temperature does not affect the sensitivity of acoustic sensors since the waveguides are designed and utilized to off set the sensors from the system and dissipate the effects of increased temperature. Changes in system temperature affect leak detection sensitivity in a positive manner also.

Data contained in NUREG CR-5134 shows that as system temperature increases, acoustic signals from leakage increase. NUREG CR-5134 data also shows that acoustic signals from leakage increase with increases in system pressure.

IIT Acoustic test data has shown that during tests performed during plant heat-up, the background noise level actually decreases from that noted when the baseline data was acquired. All IIT Acoustic test equipment was installed, verified for operability and operated in accordance with the IIT Acoustic test procedure. Therefore, for IIT Acoustic testing, changes in environmental conditions, as a whole, actually enhance leak detection sensitivity rater .than degrade it.

During IIT Leak Testing (that utilizing Leak Measuring Devices (LMD's),

environmental conditions are not sub~ect to changes which would degrade the leak sensitivity of the Acoustic Leak Sensing Equipment (ALSE) used.

Acoustic sensors are attached to boundary valves on the test subsystems and verified for operability in accordance with the IIT test procedures. The test subsystem boundary is Sufficient ALSE background data is acquired at minimal differential pressure conditions to ensure that the detection of OC0290-0254-NL04

Nuclear Regulatory Commission 4 Palisades Plant Response to .IR 89026 Febru'ary 6, 1990 increased acoustic signals. Shortly thereafter, ALSE data is acquired at maximal differential pressure conditions when test pressure is achieved.

Comparison of this data is made to aid in the location of leakage through boundary valves at test pressure conditions. Therefore, for both types of IIT testing, the suitability of environmental conditions as they affect the relation ship between background noise levels and leak detection sensitivity has been addressed both in the IIT test procedures and in the methods used to perform the testing.

Based upon the above, it is Consumers Power Company's belief that the IIT test procedures did include provision for assuring that the tests were performed under suitable environmental conditions, thereby satisfying the requirements of 10 CFR 50, Appendix B, Criterion XI.

Notice of Violation 255/89026-lC The test procedures did not define the acceptance criteria and insufficient instrumentation was used.

Consumers Power Company does not agree that the test procedures did not define the test acceptance criteria. A visual examination, VT-2, as defined in ASME Section XI, Article IWA-5000, is required by RAFA Topical Report 135 (P-A) for IIT testing. This acceptance criteria was specified in Section 6.0 of each IIT test procedure and a VT-2 examination was performed as required by each IIT test procedure using Consumers Power Company VT-2 examiners. The VT-2 examin-ations or the completed IIT test results were reviewed by Authorized Inspectors from Factory Mutual Insurance Company.

Each IIT test procedure specified utilization of appropriate IIT test equipment to the level required by RAFA. Topical Report 135 (P-A). For those tests using the IIT Leak Testing method, at least 1 Leak Measuring Device was utilized to monitor each test boundary, and all test boundary valves were monitored with Acoustic Leak Sensing Equipment. For the test using the IIT Acoustic method, 5 Electro-Acoustic Ranging units and 148 acoustic sensors were utilized to monitor the test boundary. All IIT test equipment was installed and operated in accordance with the IIT test procedures.

Based upon the above, it is Consumers Power Company's belief that the IIT test procedure did incorporate acceptance limits and that adequate test instrument-ation was available and was used, thereb~r satisfying the requirements of 10 CFR 50, Appendix B, Criterion XI.

Li~~!<'(

- ~!>~ c Kenneth W Berry '

Director, Nuclear Licensing CC Administrator, Region III, USNRC NRC Resident Inspector - Palisades Attachment OC0290-0254-:NL04

ATTACHMENT 1 Consumers Power Company Palisades Plant Docket 50-255 HAMSTAD REPORT

• February 6, 1990

• OC0290-0254-NL04 7 Pages