ML20151R766

Proposed Tech Specs Re Jet Pump Flow Indication,Reflecting Operation W/Failed Jet Pump Instrument Line

ML20151R766
Person / Time
Site:	Quad Cities
Issue date:	01/28/1986
From:	COMMONWEALTH EDISON CO.
To:
Shared Package
ML20151R762	List: ML20151R756 ML20151R766
References
NUDOCS 8602060226
Download: ML20151R766 (8)

Text

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ATTACHMENT 1 PROPOSED CHANGES TO DPR-29 TECHNICAL SPECIFICATIONS 8602060226 PDR 860128ADOCK05000P]4 1202K

QUAD-CITIES OPR-29 G. Jet Pumps G. Jet Pumps

1. Whenever the reactor is in the 1. Whenever there is recirculation flow Startup/Het Otandty or cur. ::dec. :11 with the reacter in the Startup/ Hot jet pumps shall be intact, and all Standby or Run modes, jet pump operating jet pumps shall be operable. integrity and operability shall be If it is determined that a jet puen is checked daily by verifying that the inoperable. an orderly shutdown shall be following two conditions do not occur initiated and the reactor shall be in a simultaneously:

cold shutdown condition within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

a. The rectreulation pump flow differs

2. Flow indication from 19 of the 20 jet l by more than 10% from the pungs shall be verified prior to established speed-flow initiation of reactor startup from a characteristics.

cold shutdown condition.

b. The indicated total core flow is

3. The indicated core flow is the sun of more than 10% greater than the core the flow indication from 19 jet pumps flow value derived from established plus the flow from Jet Pump number 8 power-core flow relationships.

added in a second time to compensate for loss of flow indication from Jet Pump 2. Additionally, when operating with one number 7. If flow indication failure recirculation pump with the equalizer occurs for three or more jet pumps, valves closed, the dtffuser to lower innediate corrective action shall be plenum differential pressure shall be taken. If flow indication for all but checked daily, and the differential two jet pumps cannot be obtained within pressure of any jet pump in the idle 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. an orderly shutdown shall be loop shall not vary by more than 10%

initiated and the reactor shall be in a from established patterns.

cold shutdown condition within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

- 3. The baseline data required to evaluate the conditions in Specifications 4.6.G.1 and a.6.G.2 will be acquired each operating cycle.

H. Recirculation Pump Flow Mtsmatch H. Rectrculation Pump Flow Misnatch

1. Whenever both recirculation pumps are in Recirculation pumps speed shall be checked operation.. pump speeds shall be daily for mismatch, maintained within 10% of each other when power level is greater than 80% and

.within 15% of each other when power level is less than 80%.

2. If Specification 3.6.H.1 cannot me met, one recirculation pump shall be tripped.

3. The reactor shall not be operated with one recirculation loop out of service for mere than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. With the reactor operating if one recirculation loop is out of service the plant shall be placed in a hot shutdown condition 3.6/4.6-5 Amendpunt No.

QUAD-CETIES DPR-29 G. Jet Pumps l Fa11Lre of a jet pump nozzle assembly holddown mechanism, nozzle assembly, and/or riser increases the cross-sectional flow area for blowdown following the postulated design-basis double-ended recirculation line break. Therefore, if a failure occurs, repairs must be made to assure the validity of the calculated consecuences.

The following factors form the basis for the surveillance requirements:

1. A break in a jet pump decreases the flow resistance characteristic of the external piping loop causing the recirculation pump to operate at a higher flow condition when compared to previous operation.

2. The change in flow rate of the failed jet pump produces a change in the indicated flow rate of that pupp relative to the other pumps in that loop.

Comparison of the data with a normal relationship or pattern provides the indication necessary to detect a failed jet pump.

3. The jet pump flow deviation pattern derived from the diffuser to lower plenum differential pressure readings will be used to further evaluate jet pump operability in the event that the jet pumps fail the tests in sections 4.6.G.1 and 2.

Agreement of indicated core flow with established power-core flow relationships provides the most assurance that recirculation flow is hot bypassing the core through inactive or broken jet pumps. This bypass flow is reverse with respect to norpul jet flow. .The indicated total core flow is a summation of the flow indications from 19 jet pumps plus the flow from Jet Pump number 8 added in a second time to compensate for loss of flow indication f rom Jet Pump number 7. The total core flow measuring instrumentation sums reverse jet pump flow as though it were forward flow. Thus, the indicated flow is higher than actual core flow by at least twice the norwul flow through any backflowing pump. Reactivity inventory is known to a high degree of confidence so that even if a jet pump failure occurred during a shutdown period subsequent power ascension would promptly demonstrate abnormul control rod withdrawal for any power-flow operating map point.

A nozzle-riser system failure could also generate the coincident f ailure of a jet pump body; however, the converse is not true. The lack of any substantial stress in the jet pump body makes failure impossible without an initial nozzle riser system failure.

H. Recirculation Pump Flow Mismatch The LPCI loop selection logic is described in the SAR Section 6.2.4.2.5. For some limited low probability accidents with the recirculation loop operating with large speed differences, it is possible for the logic to select the wrong loop for injection. For these limited conditions, the core spray itself is adequate to prevent fuel temperatures from exceeding allowable Itmits. However, to limit the probabiltty even further, a procedural itettation has been placed on the allowable variation in speed between the recirculation pungs.

The licensee's analyses indicate that above 80% power the loop select logic could not be expected to function at a speed differential of 15%. Below 80% power, the loop select logic would not be expected to function at a speed differential of 20%. This specification provides a margin of 5% in pump speed differential before a problem could artse. If the reactor is sperating on one pump, the loop select legis trips that pump before making the loop selection.

ECCS performance during reactor operation with one rectreulation loop out of service has not been analyzed. Therefore, sustained reactor operation under such conditions is not permitted.

3.6/4.6 13 knendment No.

ATTACHMENT 2 Safety Evaluation The proposed Technical Specification Amendments, (1) change from 20 to 19 the number of jet pumps from which flow indication shall be verified prior to Reactor startups from cold conditions on Unit One, and (2) change

, from 20 to 19 the number of jet pumps used as input to the indicated core flow on Unit One. Subsequent additional flow indication failures will now require immediate corrective action after three instead of two flow in-dication failures to take into account the existing Jet Pump number 7 loss of flow indication. If the number of flow indication failures cannot be reduced to two (Jet Fump number 7 and one additional loss of flow indica-tion) within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, then the Reactor shall be in a cold shutdown con-dition within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. This maintains the required action levels con-sistent with the current number of operable jet pump flow instrument lines.

The proposed Technical Specification change does not represent a significant change in acceptance criteria or safety margins. This change is being initiated as a result of considerations that continuing Unit One operation without flow indication from all 20 jet pumps is not within strict compliance of current Technical Specifications.

Unit One has been operated with one jet pump instrument line in-operable since November 17, 1972, when the Jet Pump number 7 DP instrument line failed. Operation in this manaer has been satisfactory and both the ability to accurately monitor total core flow and to demonstrate jet pump integrity has been adequately maintained.

Operation in t,his fashion has not been detrimental to the core measurement system accuracy. The sensing line on Jet Pump number 7 is inoperable but the jet pump itself is completely operable. Jet Pump number 7 receives drive flow from the same riser as Jet Pump number 8. Thus, the two jet pumps should have equivalent flows. Base data taken prior to the sensing line failure shows the ratio of Jet Pump number 7 to number 8 flows to be 1.0057. This demonstrates that the pumps have flows that are equal within the accuracy of the instrumentation. The milliamp flow signal of Jet Pump number 8 has been supplied to the core flow summer to represent Jet

{

1 Pump number 7 flow, giving a total core flow based on 20 inputs. It is pescible to e=pley thic same method of supplying cubetitute jet pump flev signals to the core flow summer to have a valid indication of total core flow even in the event of multiple jet pump flow sensing line failures.

Hence, the proposed changes to the Technical Specifications are conserva-

~t ive with regards to the impact on the core flow measurement avstem.

In addition to the surveillance on individual jet pump flows, there are a variety of acceptable means for verifying jet pump integrity. The methods available include the following comparisons:

1. Recirculation pump speed to recirculation loop flow (Technical Specification requirement).

2. Core flow to core power and flow control line (Technical Specification requirement).

3. Core flow to core plate DP.

4. Core flow to recirculation drive flow.

5. Recirculation pump speed to jet pump loop flow.

The ability of these methods to detect jet pump failure has not been jeopardized by the loss of Jet Pump number 7 flow indication since the capability of the core measurement system has been maintained. The proposed Technical Specification neither alters the jet pump integrity surveillance methods used nor their ability to detect jet pump failure.

The Jet Pump number 7 instrument line provides an additional leakage path from the jet pump to the annulus region. The instrument line is a 0.25 inch line and would allow insignificant leakage during the design basis LOCA compared to the capacity of the available core cooling systems. The leakage from the sensing line is also insignificant with respect to the design leakage assumed for jet pumps during normal operations and during LPCI operation. Jet pump flow indication line failures have been observed at other G.E. plant locations and G.E. has not identified any need to address the effect on LOCA analysis when considering operation with loss of a jet pump flow sensing line.

From the above discussion, it is concluded that continued operation of Quad-Cities Unit One with loss of Jet Pump number 7 flow indication is acceptable under the provisions of the proposed change to the Technical Specifications. Core measurement system accuracy is unchanged, the ability to determine jet pump integrity and operability has not been affected, and operation of the plant with a failed jet pump sensing line poses no threat to the health and safety of the public.

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ATTACHMENT 3 l

Significant Hazards Consideration I

Commonwealth Edison Company proposes to amend Provisional Operating License DPR-29 to change the number of jet pumps required to have flow indication prior to Reactor startup, and the number of jet pumps used as input to the indicated core flow.

The proposed Technical Specification change does not represent a significant change in acceptance criteria or safety margins. This change is being initiated as a result of considerations that continuing Unit One operation without flow indication from all 20 jet pumps is not within strict compliance of current Technical Specifications.

In addressing Reactor operation with a failed jet pump instrument line, three items of concern are identified. These are the core flow measurement system accuracy, jet pump integrity surveillance capability, and the affect on LOCA analysis.

Quad-Cities Unit One has operated since October 17, 1972, with the DP instrumentation on Jet Pump number 7 inoperable. Based on data taken prior to the instrument line failure of Jet Pump number 7, the jet pump flows of number 7 and number 8 are equal within the accuracy of the instrumentation. During this time period, core flow measurement system accuracy has been maintained by supplying the flow signal of Jet Pump number 8 into the core flow summer to represent Jet Pump number 7 flow giving a total core flow based on 20 inputs. Core flow calculated by this method is within the accuracy achieved by summing the inputs from all 20 jet pumps provided Jet Pump number 7 and number 8 are operating normally.

There are a number of acceptable methods for verifying jet pump integrity during operation in addition to the surveillance on individual jet pump flows. These include the following comparisons:

1. Recirculation pump speed to recirculation loop flow (Technical Specification requirement).

2. Core flow to core power and flow control line (Technical Specification requirement).

3. Core flow to core plate DP.

4. Core flow to recirculation drive flow.

5. Recirculation pump speed to jet pump loop flow.

In considering the effect on LOCA analysis, the broken instrument line provides an additional leakage path from the jet pump to the annulus region. The instrument line is a 0.25 inch line and leakage through this line during the design basis LOCA is insignificant when compared to the available core cooling capacity and design leakage attributed to jet pumps under normal and LOCA conditions. LOCA sensitivity studies have indicated that an increase in leakage on the l order of that associated with a failed jet pump instrument line has no effect on LOCA safety limits or their calculations.

Based on the preceding discussion, the Station concludes that the changes incorporated in the proposed amendment will not; (1) involve a significant increase in the probability of occurrence of an accident previously evaluated or; (2) create the possibility for a new or different kind of accident from any accident previously evaluated or; (3) involve a significant reduction in the margin of safety. Therefore, based on the criteria established in 10 CFR 50.92, the proposed changes do not constitute a significant hazards consideration.

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