ML18066A170
| ML18066A170 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 06/04/1998 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML18066A169 | List: |
| References | |
| NUDOCS 9806100280 | |
| Download: ML18066A170 (4) | |
Text
WASHINGTON, D.C. 20555-0001
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~o UNITED STATES NUCLEAR REGULATORY COMMISSION SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO THE PUMP INSERVICE TESTING PROGRAM
1.0 INTRODUCTION
REQUEST FOR RELIEF NO. 11 CONSUMERS ENERGY COMPANY PALISADES NUCLEAR PLANT DOCKET NUMBER 50-255 The Code of Federal Regulations, 10 CFR 50.55a, requires that inservice testing (IST) of certain American Society of Mechanical Engineers (ASME) Code Class 1, 2, and 3 pumps and valves be performed in accordance with Section XI of the ASME Boiler and Pressure Vessel Code (the Code) and applicable addenda, except where alternatives have been authorized or relief has been requested by the licensee and granted by the Commission pursuant to Sections (a)(3)(i}, (a)(3)(ii}, or (f)(6)(i) of 10 CFR 50.55a. In proposing alternatives or requesting relief, the licensee must demonstrate that (1) the proposed alternatives provide an acceptable level of quality arid safety, (2) compliance would result in hardship or unusual difficulty witho.ut a compensating increase in the level of quality and safety, or (3) conformance is impractical for its facility. Section 50.55a authorizes the Commission to approve alternatives and to grant relief from ASME Code requirements upon making the necessary findings. Guidance related to the development and implementation of IST programs is given in Generic Letter (GL) 89-04, "Guidance on Developing Acceptable lnservice Testing Programs," issued April 3, 1989, and its Supplement 1 issued April 4, 1995. Additional guidance can be found in NUREG-1482, "Guidelines for lnservice Testing at Nuclear Power Plants," NUREG/CR-6396, "Examples, Clarifications, and Guidance on Preparing Requests for Relief from Pump and Valve lnservice Testing Requirements," and "Summary of Public Workshops Held in NRC Regions on Inspection Procedure 73756, 'lnservice Testing of Pumps and Valves,' and Answers to Panel Questions on lnservice Testing Issues," issued July 18, 1997.
The 1989 Edition of the ASME Code is the latest edition incorporated by reference in Paragraph (b) of Section 50.55a. Subsection IWV of the 1989 Edition, which provides the requirements for IST of valves, references Part 10 of the American National Standards lnstitute/ASME Operations and Maintenance Standards (OM-10) as the rules for IST of valves.
OM-10 replaces specific requirements in previous editions of Section XI, Subsection IWV, of the ASME Code. Subsection IWP of the 1989 Edition, which provides the requirements for IST of pumps, references Part 6 of the American National Standards lnstitute/ASME Operations and Maintenance Standards (OM-6) as the rules for IST of pumps. OM-6 replaces specific requirements in previous editions of Section XI, Subsection IWP of the ASME Code.
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PDR ADOCK 05000255 P
PDR ENCLOSURE
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In a letter dated April 21, 1998, Consumers Energy (licensee) submitted Pump Relief Request Number 11 for the Palisades Plant, third 10-year interval program for IST of pumps and valves.
The evaluation of this relief request is provided below. The Palisades Plant IST Program was developed to the 1989 Edition of ASME Section XI for the third 10-year interval that began August 21, 1995.
2.0 PUMP RELIEF REQUEST NUMBER 11 Relief is requested from OM-6, paragraph 4.6.1.2(a), which states that the full-scale range of each analog instrument shall not be greater than 3 times the reference v~lue. This request pertains to flow rate instrumentation for the charging pumps P-55B and C. The licensee has proposed to follow an alternative specified in NUREG-1482, Section 5.5.1, which states that the staff will grant relief when the combination of the range and accuracy yields a reading at least equivalent to the reading achieved from instruments that meet the Code requirements (i.e., up to
+/- 6 percent).
3.0 LICENSEE'S BASIS FOR REQUEST The licensee provided the following basis for the relief request:
These pumps return deionized and filtered reactor coolant to the Primary Coolant System (PCS) at a rate equal to the purification flowrate and the controlled bleed-off rate. Upon receiving*a safety injection signal, the pumps are started and discharge concentrated boric acid into the PCS.
Our [licensee's] instrument loop is calibrated to tolerances better than the 2% of full-scale required by OMa-1988 Part 6, Table 1. The combined
- range and accuracy of the loop yields a reading which is more accurate than the reading from an instrument that meets the Code range requirement. Therefore, this instrument meets the intent of the Code for the actual reading and would yield an acceptable level of quality and safety for the test results.
The flowrate reference value for both P-55B and P-55C is nominally 39.0 gpm (as of March 1998). The maximum allowable range based on this value is 0-117.0 gpm. Our proposed instrument loop has a range of 0-140 gpm which is 3.6 times this reference value. The Code requires an accuracy of +/-2% of full-scale which equates to +/-6% of the reference value
(+/-2.34 gpm). Our instrument loop has an accuracy of 1.5% of full-scale or
+/-5.4% of the reference value (+/-2.12 gpm). The equipment we are requesting relief for provides more accurate readings than would be provided if the minimum Code requirements for the full-scale range were satisfied.
3 This request is consistent with the NRC guidance in NUREG-1482, Section 5.5.1. In that response, the NRC states, "[W]hen the range of a permanently installed analog instrument is greater than 3 times the reference value but the accuracy of the instrument is more conservative than the Code, the staff will grant relief when the combination of the range and accuracy yields a reading at least equivalent to the reading achieved from instruments that meet the Code requirements (i.e., up to +/-6%)."
The combined range and accuracy of our instrument loop provides an overall uncertainty better than the minimum Code requirement.
Therefore, the intent of the Code is satisfied and the reading afforded by our instrument loop yields an acceptable level of quality and safety for testing.
4.0 PROPOSED ALTERNATE TESTING The licensee proposed the following alternative:
Palisades requests relief to use an analog instrument loop with a range that is 3.6 times the flowrate reference value. The instrument loop is permanently installed original plant equipment.
5.0 EVALUATION The licensee has proposed to use analog pump flow rate instrumentation that does not meet the range requirements of the Code. The instrument accuracy and range requirements of OM-6, paragraph 4.6, are to ensure that test measurements are sufficiently sensitive to changes in pump condition to allow detection of degradation. OM-6, paragraph 4.6, states that (1) accuracy for instruments used in the measurement of pressure shall be +/- 2 percent, and (2) full-scale range of analog instruments shall be 3 times the reference value or less. A range of greater than 3 times the reference value can be acceptable if the instrument is proportionately more accurate than required. As indicated in Section 5.5.1 of NUREG-1482, an alternative can be approved if the combination of range and accuracy yields a reading that is accurate to within +/- 6 percent of the reference value.
The licensee has proposed to follow the guidelines in NUREG-1482, Section 5.5.1, which states that the staff will grant relief when the combination of the range and accuracy yields a reading at least equivalent to the reading achieved from instruments that meet the Code requirements. For the instrument identified, the combination of range and accuracy yields a reading that is accurate to within +/- 6 percent of the reference value. The licensee's proposed alternative therefore provides an acceptable level of quality and safety for testing.
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6.0 CONCLUSION
The proposed alternative in Pump Relief Request Number 11 is authorized pursuant to 10 CFR 50.55a(a)(3)(i) based on the acceptable level of quality and safety provided by the alternative. The staff concludes that the relief request as evaluated by this safety evaluation will not compromise the operational readiness of the pumps to perform their safety functions. The staff has determined that authorization of the proposed alternative to the Code requirements pursuant to 10 CFR 50.55a is authorized by law and will not endanger life or property, or the common defense and security and is otherwise in the public interest, giving due consideration to the burden upon the licensee that could result if the requirements were imposed.
Principal Contributor: K. Dempsey Date:
June 4, 1998