ML20207S442

Application for Amends to Licenses DPR-71 & DPR-62,changing Tech Specs to Provide More Reliable Indications of Jet Pump Performance.Fee Paid

ML20207S442
Person / Time
Site:	Brunswick
Issue date:	03/13/1987
From:	Cutter A CAROLINA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20207S443	List: ML20207S442 ML20207S444
References
NLS-86-225, NUDOCS 8703190459
Download: ML20207S442 (5)

Text

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.y CD&L Carolina Power & Light Company SERIAL: NLS-86-225 MAR 131987 10CFR50.90 United States Nuclear Regulatory Commission ATTENTION: Document Control Desk Washington, DC 20555 BRUNSWICK STEAM ELECTRIC PLANT, UNIT NOS.1 AND 2 DOCKET NOS. 50-325 & 50-324/ LICENSE NOS. DPR-71 & DPR-62 1 i

REQUEST FOR LICENSE AMENDMENT i JET PUMP SURVEILLANCE REQUIREMENTS Gentlemen:

SUMMARY

In accordance with the Code of Federal Regulations, Title 10, Parts 50.90 and 2.101, Carolina Power & Light Company (CP&L) hereby requests a revision to the Technical Specifications (TS) for the Brunswick Steam Electric Plant, Unit Nos. I and 2. The proposed amendment changes TS Section 3/4.4.1.2 to provide more reliable indications of jet pump performance.

DISCUSSION There have been two occurrences of BWR/3 jet pump hold down beam failures during plant operation which have caused jet pump mixer displacement. In both cases, significant recirculation system performance degradation occurred prior to beam failure (there have not been any failures in BWR/4 beams). In response to these failures, General Electric (GE) investigated the occurrences and performed structural tests of both BWR/3 and BWR/4 beams. GE released its findings in Service Information Letter No. 330, Supplement 1 (SIL 330). SIL 330 discusses the differences between the failure mechanics of the BWR/3 and BWR/4 beam designs and the corresponding effects on jet pump performance monitoring. The letter recommends that licensees with BWR/4 jet pump beam designs modify their surveillance requirements to provide more reliable indications of jet pump performance to preclude this type of failure. Thus, the purpose of the proposed amendment to TS 3/4.4.1.2," Jet Pumps,"is to revise the surveillance requirements to provide more reliable indications of jet pump performance, following the guidance as discussed in SIL 330 as applicable. This will be accomplished by providing new test criteria and by using deviations from established pump relationships as an indication of potential problems, as opposed to deviations from analytical evaluations as is currently used. The proposed changes are described in more detail below.

1. Surveillance Requirements - Applicability The monitoring instrumentation used for surveillance testing of jet pumps is designed to provide performance data while the recirculation pumps are operating at medium to high speeds. However, recirculation pumps are required to be at minimum speed until af ter the mode switch is placed in the Run position (about 10 to gEC'D u)lCMECW 411 Fayettevine Street

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.Documint Control Desk MAR 131987 NLS-86-225 / Page 2 12 percent rated thermal power). Recirculation pump speed is not increased until

ignificantly after the switch to Run (Operational Condition 1). Surveillance testing currently required during Startup/ Hot Shutdown (Operational Condition 2) has demonstrated that there is too much scatter in the data obtained to make an effective determination of jet pump performance. Reliable data has been obtained below the current limit of 25 percent of rated thermal power, but only after recirculation pump speed has been increased. Therefore, the proposed change removes the requirement for jet pump surveillance in Operational Condition 2.

2. Surveillance Requirements - Simultaneous Criteria The current surveillance requirements (TS 4.4.1.2) include the requirement to monitor three criteria and require the unit to be in at least Hot Shutdown within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> if all three conditions occur simultaneously. Consequently, only one of the three criteria needs to be monitored and passed to satisfy the surveillance requirement. The concern is that such a procedure inherently depends on testing only one criterion instead of all three. The proposed change replaces the simultaneous criteria with a two-out-of-three logic which necessitates the testing of at least two criteria. This change will increase the capabilities of the plant to detect any equipment problems as soon as possible and thereby improve the effectiveness of the surveillance program.

3. Surveillance Requirements - Items a and b Several alternatives for monitoring jet pump performance are discussed in SIL 330, however, GE recommends monitoring less sensitive instruments, specifically those instruments which provide an indication of recirculation pump flow / speed ratio or jet pump loop flow / speed ratio, and incorporating more restrictive tolerances (5 percent). This allows surveillance of more easily monitored conditions without compromising the ability to detect problems.

a. Item a Surveillance Requirement 4.4.1.2.a currently monitors recirculation pump flow / speed ratio, but has a greater acceptable deviation from established characteristics than is recommended by SIL 330. The proposed change revises the surveillance requirement to include a 5 percent deviation; this is a more restrictive condition than currently allowed.

b. Item b The proposed change replaces the current Surveillance Requirement 4.4.1.2.b with the second criterion recommended in SIL 330 to be monitored, which is jet pump loop flow / speed ratio. The current requirement is not as sensitive to performance degradation, and significant time is needed to analyze the data; the proposed requirement will provide a better indication, in less time and, therefore, will increase the effectiveness of the jet pump surveillance program.

4. Surveillance Requirements - Item c in addition to the two operating characteristics described above, SIL 330 recommends that a third criterion be measured to determine jet pump operability.

SIL 330 recommends that each individual jet pump diffuser to lower plenum differential pressure (D/P) percent deviation from average loop D/P be measured

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. Documint Control Desk j , NLS-86-225 / Page 3 MAR 131987 and evaluated against an established deviation. However, it has been determined, consistent with the findings of the SIL, that this test is only reliable at high recirculation pump speeds. The proposed revision to Surveillance Requirement 4.4.1.2.c meets the intent of the GE recommended test while at the same time making the test more accurate at the lower recirculation pump speeds applicable during the test. The proposed surveillance requirement indicates pump inoperability if the diffuser-to-lower plenum differential pressure reading on any individual jet pump varies by more than 10 percent from that jet pump's established operating characteristics. The proposed requirement will provide a more accurate indication of jet pump operability than is currently available by Surveillance Requirement 4.4.1.2.c and therefore, will increase the effectiveness of the jet pump surveillance program.

5. Bases The proposed revision to Bases 3/4.4.1 adds a section to explain the methods required to establish the actual acceptance criteria in the proposed surveillances.

The current jet pump surveillance requirements monitor operating relationships which are based upon deviations from analytical solutions. The proposed TS, as recommended by SIL 330, uses deviations from established relationships as an indication of potential problems as opposed to deviations from analytical evaluations. Instrument inaccuracies, instrument readability, jet pump efficiencies, and unequal flow may cause actual flow / speed relationships to vary significantly from analytical results. Thus, the proposed method of analyzing acceptance criteria based upon established data provides a more accurate means of detecting jet pump problems while eliminating the false indications inherent in analytical evaluations.

Data to provide the established operating characteristics for the proposed surveillance requirements is currently being compiled. Once the requested amendment has been approved and issued, the data compiled up to that date will serve as the baseline data to determine the established operating characteristics. As new data is collected, it will be incorporated to refine the operating characteristics of these pumps. The established values for Items 4.4.1.2.a and 4.4.1.2.b will be determined using a linear regression best fit line through the data compiled. Since the criteria for item 4.4.1.2.c is based on the jet pump differential pressure to jet pump loop differential pressure ratio, the

established value will be the average ratio from the data. For each of the three criteria, i the width of the established range will be found by evaluating the acceptable error possible in the data based on instrument loop tolerance, indicator readability, and indicator " float."

The above method of evaluating the test data will result in a more reliable and accurate indication of jet pump performance and will increase the effectiveness of the jet pump surveillance program.

SIGNIFICANT HAZARDS ANALYSIS The Commission has provided standards for determining whether a significant hazards consideration exists (10 CFR 50.92(c)). A proposed amendment to an operating license for a facility involves no significant hazards consideration if operation of the facility in (1) involve a si accordance with the proposed amendment would not:the probability (2) create or theconsequences of a possibility of a new or different kind of accident from any accident previously evaluated; or (3) involve a significant reduction in a margin of safety.

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' . Docum:nt Control Desk NLS-86-225 / Page 4 MAR 131987

1. - Surveillance Requirements - Applicability Carolina Power & Light Company has determined that the requested change per 10 CFR 50.92 does not involve a significant hazards consideration for the following reasons. (1) The proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated because jet pumps themselves have no moving parts or operating controls. Flow through the jet pumps and their resulting function of providing the driving flow within the core is controlled solely by the operation and control of the recirculation pumps.

Therefore, the deletion of the requirement for jet pump operability in Operational Condition 2 does not effect the function, operation, or accident analyses of any plant system. (2) The proposed change does not create the possibility of a new or different kind of accident from any accident previously evaluated for the same reasons as discussed in item (1) above. (3) Although the proposed change may slightly reduce a safety margin, the results of the change are within acceptable criteria with respect to the safe operation of the plant as specified in the Standard Review Plan. Surveillance testing during Operational Condition 2 does not provide a determination of jet pump operability. The monitoring instrumentation that is available for determining operability _ is not designed to be used at the low recirculation pump speeds mandatory by procedure during Operational Condition 2.

However, jet pump operability can be determined with a high degree of confidence after the recirculation pump speeds are increased following the mode change to Operational Condition 1 (Run) and still maintain the current requirement of performing the surveillance prior to exceeding 25 percent of rated thermal power.

As testing in Operational Condition 2 cannot verify operability, and since the requirement to demonstrate jet pump operability prior to exceeding 25 percent of rated thermal power is not changed, the intent of the TS has not been changed.

2. Surveillance Requirements - Simultaneous Criteria Carolina Power & Light Company has determined that the requested change per 10 CFR 50.92 provides for additional surveillance of the jet pumps, a more restrictive condition, and as such: (1) does not involve a significant increase in the probability or consequences of an accident previously evaluated; (2) does not create the possibility of a new or different kind of accident from any accident previously evaluated; or (3) does not involve a significant reduction in a margin of safety. The current TS requires simultaneous occurrence of the three surveillance criteria to establish jet pump inoperability, thereby resulting in the possibility of testing only one criteria (assuming the normal condition of the first test passing satisfactorily).

By requiring a two-out-of-three condition, at least two of the criteria will be tested every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> during Operational Condition 1.

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! 3. Surveillance Requirements - Items a, b, and c Carolina Power & Light Company has determined that the requested changes per 10 CFR 50.92 provide for more comprehensive, reliable, and effective testing for determining the operability of the jet pumps to a high level of confidence and,

therefore

(1) do not involve a significant increase in the probability or

consequences of an accident previously evaluated; (2) do not create the possibility

of a new or different kind of accident from any accident previously evaluated; or i (3) do not involve a significant reduction in a margin of safety.

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, . Document Control Desk NLS-86-225 / Page 5 MAR 131987

4. Bases Carolina Power & Light Company has determined that the requested change merely explains the methods required to establish the actual acceptance criteria in the proposed surveillance requirements and, therefore, for the same reasons discussed above: (1) does not involve a significant increase in the probability or consequences of an accident previously evaluated; (2) does not create the possibility of a new or different kind of accident from any accident previously evaluated; or (3) does not involve a significant reduction in a margin of safety.

The changes presented by this TS amendment follow the recommendations or the intent of the recommendations provided by SIL 330. The purpose of the TS amendment and the intent of SIL 330 is to provide more reliable indications of jet pump performance to preclude failure and thereby increases the effectiveness of the jet pump surveillance program. Therefore, the proposed TS amendment will increase the margin of safety.

Based on the above, CP&L has determined that the proposed amendment meets the criteria of 10 CFR 50.92(c) and, therefore, does not involve a significant hazards consideration.

ADMINISTRATIVE INFORMATION The proposed Brunswick-1 and Brunswick-2 TS pages are provided in Enclosures 1 and 2.

Carolina Power & Light Company has evaluated this request in accordance with the provisions of 10 CFR 170.12 and has determined that a license amendment application fee is required. A check for $150 is enclosed in payment of this fee.

Should you have any questions concerning this submittal, please contact Mr. Sherwood R.

Zimmerman at (919) 836-6242.

Yours very truly

[

(b$/'k A. B. utter - Vice Pre dent Nuclear Engineering & Licensing ABC/ MAT /bmc (3976 MAT)

Enclosures i

cc: Mr. W. H. Rutand (NRC-BNP)

Dr. J. Nelson Grace (NRC-RII)

! Mr. E. Sylvester (NRC)

Mr. Dayne H. Brown i

A. B. Cutter, having been first duly sworn, did depose and say that the information

1. contained herein is true and correct to the best of his information, knowledge and belief; and the sources of his information are officers, employees, contractors, and agents . . , , ,

Carolina Power & Light Company. RA

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