L-88-420, Requests Discretionary Enforcement to Permit Plant to Cooldown Below 275 F When Required
| ML17347A845 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 09/16/1988 |
| From: | Conway W FLORIDA POWER & LIGHT CO. |
| To: | Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| L-88-420, NUDOCS 8810070012 | |
| Download: ML17347A845 (5) | |
Text
PIMRIBUTlON DEMONSTRATION.
SYSTEM REGULATORY. INFORMATION DISTRIBUTION SYSTEM (RIDS)
ACCESSION NBR:8810070012 DOC.DATE: 88/09/16 NOTARIZED: NO FACIL:50-250 Turkey Point Plant, Unit 3, Florida Power and Light C 05000250 50-251 Turkey Point Plant, Unit 4,.Florida Power and Light C 05000251 AUTH.NAME AUTHOR AFFILIATION CONWAY,W.F-Florida Power' Light Co.
RECIP.NAME RECIPIENT AFFILIATION GRACE,J.N.
Region 2, Ofc of the Director
SUBJECT:
Requests discretionary enforcement to enable continued operation w/COMS not fully meeting Tech Spec basis.
DISTRIBUTION CODE:
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TITLE: General (50 Dkt)-Insp Rept/Notice of Violation Response NOTES:
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1 RECIPIENT ID CODE/NAME EDISON,G DEDRO NRR/DLPQ/PEB 11 NRR/DOEA DIR 11 NRR/DREP/RPB 10 NRR/PMAS/ILRB12 OE~IrIEBERMAN,J REG FILE+
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P OX 14600, 'UPlO a=acH. t-" ea-'cs.c>>""o SEPTEMBER 1 6 1988 L-88-420 Dr. Z. Nelson Grace Regional Administrator, Region II U. S. Nuclear Regulatory Commission 101 Marietta St.,
N.W., Suite 2900
- Atlanta, GA 30323 Gentlemen:
Re:
Turkey Point Units 3 and 4
Docket Nos.
50-250 and 50-251 Request for Discretionary Enforcement to Enable Continued Operation With Cold Overpressure Mitigation S stem Not Full Meetin Technical S ecification Basis It was recently identified that a discrepancy existed between the actual values for Pressurizer Power Operated Relief Valves (PORV) stroke times and the values for PORV stroke time used in determination of Cold Overpressure Mitigation System (COMS) setpoints.
The COMS is designed to mitigate mass input and heat input induced pressure transients during cold shutdown conditions and during heatup and cooldown transients.
The system was designed to provide overpressure protection for the following cases:
1)
The inadvertent start of two charging pumps with a loss of letdown; or 2) the start of a High Pressure Safety Injection (HPSI) pump and its injection into a water solid RCS; or 3) the start of an. idle'eactor Coolant Pump (RCP) with the secondary water temperature of the steam generators 50'F above the RCS cold *leg temperature.
Cases N2 and N3 are stated in the basis for the Technical Specifications of Turkey Points Units 3 and 4, Section 3.15.
All cases are addressed in the original generic Westinghouse presssure transient analysis.
33100700i2 330916 Fan ADOCK 0. 0002S0 PD(:
Dr.'. Nelson Grace L-88-420 Page two In the generic Westinghouse pressure transient analysis and in the NRC Safety Evaluation Report (SER) issued on March 14, 1980, the stroke times for the PORVs were specified as 2.0 seconds for the mass input case and 3.0 seconds for the heat input case.
Actual PORV stroke time test results vary from below 2.0 seconds to a
maximum of 6.41 seconds.
'ince the current situation has the potential to be outside the Technical Specification design basis during cold shutdown conditions when COMS is required, FPL has examined the potential safety issues that arise from the degraded PORV stroke times.
Case 41 - Inadvertent start of two charging pumps with a loss of letdown.
A reanalysis of this case shows that for the case of two charging pumps starting with a loss of letdown and a six second stroke time, the overshoot value is 18 psi, which"can be readily accommodated by the COMS.
This case is the most. probable mass input transient and the PORV stroke times would have'o degrade to greater than 10.0 seconds before the pressure excursions would approach 10 CFR 50 Appendix G limits.
To prevent a third charging pump from being
- operated, procedures will be revised to tag open one of the three charging pump breakers when the RCS temperature is below 285'F.
Case 42 - Spurious start of one HPSI pump.
The case of a spurious HPSI pump start is the limiting injection transient.
Although this case with the degraded PORV stroke times has not been evaluated to date, the possibility of this event is remote.
Administrative controls are in effect at Turkey Point that prevent the possibility of a
mass input transient caused by a
spurious HPSI pump start.
In addition to those procedures already in place, the plant procedures will be revised to require a bubble in the pressurizer with RCS temperature greater than 200'F in order to minimize the time when the RCS is operated in a solid condition.
These factors combine to give reasonable assurance that a
COMS event resulting from a spurious HPSI pump start will not occur at Turkey Point.
Case 43 -
Inadvertent starting of a
RCP with a
temperature differential between the secondary system and the RCS of 50'F.
Current operating procedures specify a
maximum differential temperature of 10'F in order to start an RCP.
Using a
maximum temperature differential of 20'F, the PORV stroke times would have to degrade to greater than 10.0 seconds before the limits of 10 CFR 50 Appendix G would be approached.
Dr. J. Nelson Grace L-88-420 Page three In summary, the analyses assure that the 10 CFR 50 Appendix G
limits will be met as long as the following procedure restrictions are implemented prior to the next unit cooldown below 275 F.
1)
The HPSI system is isolated from the RCS at temperatures less than 380'F.
This is a current requirement of Technical Specification 3.15.
2)
A maximum of 2
charging pumps may be running for RCS temperatures less than 285'F.
3)
The pressurizer bubble would be maintained for RCS temperatures greater than 200'F.
4)
At RCS temperatures less than 200'F, with no RCP running, a
RCP may not. be started unless steam generator secondary water temperature is less than 20 F above the RCS temperature.
Based on the above analysis and the implementation of the described procedural restrictions, the PORVs can be considered as operable.
and able to function and mitigate a cold overpressure transient at the tested PORV stroke times.
FPL thus requests discretionary enforcement to permit Turkey Point Units 3 and 4 to cooldown below 275'F when required.
This request is only through the next refueling outage for each unit.
Accordingly, a long term resolution to this issue will be developed prior to restart from the next scheduled refueling outage for each unit.
Should there be any questions on this information, please contact us
~
Very truly yours, W. F.
Conw Senior Vice President Nuclear WFC/SDF/gp cc:
Document Control Desk, USNRC Dr.
G.
E. Edison, Project Manager,