ML20029A716
| ML20029A716 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 02/22/1991 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20029A714 | List: |
| References | |
| NUDOCS 9103040109 | |
| Download: ML20029A716 (4) | |
Text
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ENCLOSURE SAFETY EVALUAT10tl I.Y_THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AN It4 SERVICE TESTING PROGRAft RELIEF RE0t!r$T FOR PEACH BOTTOM AT0!i10 POWIR STATION, Ull1T$ 2 AND 3 DOCKET 1105, 50-277 At:0 00-278 INTRODUCTION The Code of federal Reg 11ations,10 CFR 50.55a(g), requires that inservice testing (IST) of ASitt C)de Cless 1, 2, and 3 pumps and valves be performed in accordance with Section XI of the ASME Boiler and pressure Vessel Code and applicable addenda, except where specific written relief has been req (uested by the licensee and granted by tbc Comission pursuant to 10 CFR 50.55a a)(3)(i),
(a)(3)(i ), or (g)(6)(i),
in requesting relief, the licentce must demonstrate that: (1 the proposed alternatives provide an acceptable level of quality and safety; 2) compliance would rtsult in hardship or unusual difficulty without a compensating increase in the level of quality and safety; or (3) conformance with certain requirements of the applicable Code edition and addenda is impractical for its facility.
The Regulation,10 CFR 50.50a(a)(3)(i), (a)(3)(ii), and (g)(6)(i), authorizes the Comnission to grant relief from these requirements upon making the necessary findings. The NRC staff's findings with respect to IST progran Relief Request GpRR 3 are presented in this safety evaluation.
The IST program associated with this safety evaluation covers the second ten-year inspection interval. The second ten-year interval for Units 2 and 3 commenced July 6, 1984 and December 13, 1984, respectively.
The licensee's program was submitted in a letter dated June 29, 1988, which was amended by a letter dat u September 11, 1990. The staff issued its safety evaluation related to the licensee's IST program for the $ccond ten-year inspection interval in a letter dated January 17, 1991. Relief Request 0pRR-3 was submitted in a letter dated December 10, 1990, which withdrew the Relief Request 50-FRR-1 from the IST program.
The program is based on the requirements of Section XI of the ASME Code, 1980 Edition through the Winter 1981-Addenda.
EVALUATION IST Program Relief Request GPRR-3 has been reviewed b assistance of its contractor, EGt.G Idaho, Inc. (EG&G)y the staff with the The granting of relief is based upon the fulfillment of any commitments nede by the licensee in its basis for each relief request and the alternative proposed testing.
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2-The relief request was evaluated utilizing the criteria and guidance contained in the Code of federal Pegulations 10 CFR 50.55a and Generic Letter 89-04, " Guidance on Developing Acceptable Inservice Testing Programs."
The licensee's basis for requesting relief froni the Code testing requirements and the staff's evaluation of that request is summarized below for the submitted relief request.
Pelief Request No. GPRR 3 Relief Pecuest.
The licensee has requested relief from the instrument accurecy and allowable rance requirements of Section x1, Paragraphs !WP 4110 and -4120, for the diesel fuel oil transfer, emergency service weter, emergency servict water booster, and emergency cooling water punps.
The licensee has proposed to use ultrasonic flow instrumentation, which is accurate to within 45% of reading, to measure pump flow rates.
Licensee's Lasis for tecuesting Rtlief.
PECo proposes to neasure flow using ultrasonic flow instrumentation that is calibrated to an accuracy within 451 of-reading instead of the Code required +2% of full-scale. Although this~
equipment does not trect the Code requirements exactly, it meets the intent of the Code by ensuring that data collected during inservice testing is measured to the degree of accuracy specified in Articles IWP t.110 and JWrdl?0.
Because the Code does not address digital instruments and of-tading accuracy limits, a conversion of full-scale accuracy to of reading accuracy is r.ecessary to compare the ultrasonic instrument accuracy to the accuracy specified in the Code. Also, because the Ultrasonic flow transducers are capable of measuring flow our the entire range of the instrument (0 to 40 fcct/second), e percentage of full-scale accuracy would te meaningless when measuring low flow rates associated with small diameter pipes. To enfure that the most accurate data is collected during inservice testing, the technicians are provided guidance through the vendor manuals to select the transducer that is best suited for the pipe where flow is being neasured.
For instruments to be in conpliance with ASME Section X1 Subsection !WP, two requiretrents must be satisfied.
Thefirstrequirement(specifiedin IWP-4110, Table IWP-4110-1) states that flow instrumentation must be accurate to within +21 of the full-scale value; the second requirement (saccified in IWP-4120)statesthat"thefull-scaleranceofeachinstrumentsiellbethree l
times the reference value or less.*
PEco s interpretation of these requirements allows for establishing a maximum of-reading error of +61 that would be acceptable per the Code.
Magnetic flow meters, which provide greater accuracylsmically qualified were considered.
However, because the magnetic flow meters are not se they are not suitable for use in the required applications.
Also,installatIonof these metert would require significant piping modifications.
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3-The licensee censiders that the ultrasonic flow instrunants provide the necessary accuracy for pump performance trending purposes and to detect pump degradation. Also, the licensee considers that it meets the intent of the code since the ultrasonic flow instrument is accurate to within 46f of-reading, i
Although the existing method of measuring flow is acceptable (i.i., measuring change in tar,k level as e function of time), ultrasonic flow measurement provides more accurate data.
ALTEttiATE TESTit$.
Use ultrasonic flow instrumentation, which is cccurate to w'Whin y of-reading, for measuring IST flow data.
Evaluation.
Section XI, paragraph IWM110 requires the use of flow instrumentr' ion with an accuracy of +2% of full-scale end 10p-4120 requires that the instrument full scale range ~be equal to or less than three times the reference value. The worst case combination of these two requirements coulo result in an instrument that is only accurate to 46'I at the reference value with higher inaccuracies for readings belew the reference value.
It is possible to use instrumentation whose accurary does not meet the Section XI accuracy requiren.cnts but still is able to previde eceivalent or better indication accuracy at the reference value thar is allowed by the Code.
Ultrasonic flow instruments are generally digitt.1 or multi-rarge instruments that cover a broad range of flow rates whose accuracy is not based on the full-scale range but rather on the indicated value.
Use of instrumet ation with an accuracy of +5'i of the indicated value shculd be a reasonable altern6tive to the Code even thoue the Code accuracy requirement is not met.
It would be a hardship without a compensating ircrease in the level of cuality and safety to require the licensee to purebtte instruu ntation that meets the Code accuracy and range requiremr.nts since installation of such replacement instrumentation would recuire breaking the pressure boundary and such replacement instrumentation would not be significantly more accurate at and below the reference value than the instruments the licensee has proposed l
to use to measure IST data for these pumps.
The Section XI full-scale range requirements are not appropriate for digital or multi-range instruments whose accuracy and readability is not a function of the instrument full-scale range.
These instruments are capable of reading over a broad range without diminishing their indication readability or reading accuracy. Pulti-range instruments either automatically switch or can be penually switched to the range that results in a reading that is closest to being in the center of the scale.
Ree,uiring the licensee to use a single range analop instrument would be a hard:. hip without a compensating increase in the level of quality and safety.
l The licensee's proposal should provide a reasonable alternative to the Code requirements; however, since the purpose of the Code is to monitor pump operational readiness and detect dcgradation, the licensee should strive to obtain the most accurate IST test data possible.
Therefore, when replacing this instrunentation, if the use of ultrasonic flow metering is retained, the licensee should purchase instrurentation with improved accuracy and, if l
possible, meet tie Code accuracy requirements.
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4 C0t4CLUS10H Based on the review of the licensee's IST relief request, the staff concludes that the relief request as evaluated by this SE will provide reasonable assurance of the operational readiness of the sumps to perform their safety related functions. The staff has determined 11at granting relief, pursuant to 10 CFR 50.55a(a)(3)(ii) is authorized by law and will not endanger life or property, or the common defense and security and is otherwise in the public interest.
Based on the determination that conpliance with the Code requirements would be a hardship without providing a compensating increase in the level of quality and safety, relief is granted from the Code accuracy and range requirements as requested.
IST program Relief Request GPPR-3 for peach Bottom Atomic power Station, Units 2 and 3, provided by a submittal dated December 10, 1990, is acceptable for implementation, 3
New or revised relief requests contained in any subsequent revisions should not be impicmented without prior approval by NRC, unless they are relief requests meeting the positions in Generic Letter 89-04, Attachment 1.
Principal Contributt.r:
E. Sullivan, Jr.
Dated:
Februc y 22, 1991 4
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