ML20138G493
| ML20138G493 | |
| Person / Time | |
|---|---|
| Site: | Hope Creek  |
| Issue date: | 10/15/1985 |
| From: | Public Service Enterprise Group |
| To: | |
| Shared Package | |
| ML20138G467 | List: |
| References | |
| PSE-SE-Z-022, PSE-SE-Z-22, NUDOCS 8510250487 | |
| Download: ML20138G493 (6) | |
Text
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PUBLIC SERVICE ELECTRIC AND GAS COMPANY HOPE CREEK PROJECT SAFETY EVALUATION No. PSE-SE-2-022 TITLE:
SIMPLIFICATION OF TEST NUMBER 28E, RECIRCULATION SYSTEM CAVITATION Date:
1.0 PUR POS E The purpose of this Safety Evaluation is to document the results of the evaluation performed to ensure that the simplification of Test Number 28E, Recirculation System Cavitation, will not adversely affect reactor safety.
2.0 SCOPE The scope of this Safety Evaluation is the adequacy of Hope Creek's power ascension test program.
3.0 REFERENCES
1.
Regulatory Guide 1.68, Revision 2, August 1978 2.
Hope Creek Final Safety Analysis Report (FSAR)
Chapter 14 3.
General Electric Startup Test Specification 23A4137, Revision 0 4.0 DISCUSSION Regulatory Guide 1.68 (Revision 2, Augus t 1978), Appendix A,
paragraph 5.s requires that the recirculation flow control system be calibrated as necessary and its performance verified.
At conditions of high core flow and low reactor power, both the jet pumps and the recirculation pumps may cavitate due to inadequate subcooling at low feedwater flow.
The analytically determined cavitation region of the power / flow map (attached) is protected by cavitation interlocks which will run back recirculation pump speed at low power if the cavitation limit is exceeded (total feedwater flow less than 20% of rated flow).
Test Number 28E, Recirculation System Cavitation, verifies that no recirculation system cavitation will occur in the operable region of the power / flow map.
Currently, this PSE-SE-2-022 1 of 3 8510250487 851017 PDR ADOCK 05000354 A
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f test is planned to be performed at Test Condition 3 by lowering power at high recirculation flow until a
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recirculation pump runback occurs, or the plant is at approximately 18% power and no runback has occurred, or 4
1 there is indication of cavitation.
It is proposed that i
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the testing be simplified by performing the test as j
planned except for temporarily bypassing the recirculation runback feature by jumpering the contacts 2
in the recirculation pump speed limiter circuit that open when total feedwater flow is less than 20% such that an t
actual runback will not occur.
1 1
This is considered acceptable for the following reasons.
j The performance of the runback circuit is verified by i
j preoperational tests.
Confirmation that the recirculation runback logic actuates when the setpoint is j
reached will be provided by an annunciator.
No other recirculation pump runback logic feature will be affected by this temporary modification.
Power will be reduced in i
j a carefully controlled manner to minimize the possibility of reducing power below 19% (1% higher than in the
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current procedure) and to ensure that cavitation j
indication is identified when it first occurs.
1 Should a transient occur while performing this test which l
reduces feedwater flow below the cavitation interlock setpoint, plant safety will not be compromised.
This interlock is a cavitation avoidance feature for the recirculation pumps and jet pumps.
It is not a safety j
feature.
However, the test procedure will require that if such a transient occurs, the operator will be required
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to manually run back recirculation pump speed as s
j necessary to prevent cavitation and to maintain operation I
within the allowable region of the power / flow map.
j
5.0 CONCLUSION
a i
The simplification of the test of the recirculation i
system cavitation interlock discussed above can be I
i performed in a manner which does not adversely af fect any safety systems or the safe operation of the plant.
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i Consequently, an unreviewed safety question does not exist.
No changes to the plant Technical Specifications are required.
1 l
6.0 DOCUMENTS GENERATED l
None l
l PSE-SE-Z-022 2 of 3 a
o a
7.0 RECOMMENDATIONS Revision shall be made to the Hope Creek FSAR and Power Ascension Tes t Number 28E to reflect the test simplification described above.
8.0 ATTACHMENTS Hope Creek's Operation Power / Plow Map 9.0 SIGNATURES Originator f n M G. O m.R __
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PSE-SE-Z-022 3 of 3
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TEST NUMBER 28E - RECI RCULATION SYSTEM CAVITATION TEST SI MPLI FI CATION OBJ ECTI VE :
Regulatory Guide 1.68 ( Re v is ion 2,
August 1978), Appendix A, paragraph 5.s requires that the recirculation flow control system be calibrated as necessary and its performance verified.
At conditions of high flow and low power, both the jet pumps and the recirculation pumps may cavitate.
The analytically determined cavitation region of the power-flow map is protected by interlocks which will run back recirculation flows at low power if the cavitation limits are exceeded.
Test Number 28E, Recirculation System Cavitation, verifies that no recirculation system cavitation will occur in the operable region of the power-flow map.
Currently, this test is planned to be performed at Test Condition 3 by lowering power at high recirculation flow until a recirculation pump runback occurs, or the plant is at approximately 18% power and no runback has occurred, or there is indication of cavitation.
It is proposed that the testing be simplified by temporarily bypassing the cavitation interlock to prevent runback of the recirculation pumps.
DI SCUSSION :
Acceptable response of the system near the cavitation region is determined by analyzing test data and comparing to acceptance criteri7 which define the required system performance.
For the recirculation system cavitation test, the recirculation runback logic is required to be demonstrated to have settings adequate to prevent operation in areas of potential cavitation.
This may be demonstrated without requiring that recirculation runback occur by temporarily bypassing the runback logic during Test Number 28E.
Power can then be reduced to 19% (1% higher than in the current procedure), or to when cavitation indication is first identified, by inserting control rods.
The cavitation interlock logic can be monitored to ensure that it is actuated at the correct setpoint.
With appropriate placement of the jumper on the cavitation interlock, no other recirculation pump runback logic feature will be affected.
In addition, should a feedwater transient occur during the performance of this test, the operators can manually run back recirculation pump speed as necessary to prevent cavitation.
1
E l
k' CONCLUSION:
Cavitation interlock setpoints are designed to allow maximum operation in the power-flow map but are conservatively set to assure that no recirculation system cavitation occurs.
The proposed simplified testing will verify that cavitation does not occur at or above the cavitation interlock setpoint while eliminc. ting unnecessary core flow reductions during the test The proposed simplified testing will not adversely af fect any safety related systems or safe operation of the plant and does not involve an unreviewed safety question.
Therefore, Test Number 28E, Recirculation System Cavitation, can be simplified as stated above.
2
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