ML20116E658
| ML20116E658 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 05/18/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20116D885 | List:
|
| References | |
| FOIA-96-237 NUDOCS 9608060076 | |
| Download: ML20116E658 (8) | |
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UNITED STATES
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ENCLOSURE 1 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATING TO TECHNICAL SPECIFICATION CHANGES FOR LOW TEMPERATURE OVERPRESSURE PROTECTION BALTIMORE GAS AND ELECTRIC COMPANY CALVERT CLIFFS NUCLEAR POWER PLANT, UNIT 1 DOCKET NO. 50-317
1.0 INTRODUCTION
By letter dated May 14, 1990, the Baltimore Gas and Electric Company (the l
licensee) proposed to amend the Technical Specificatioes of the Calvert Cliffs
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Nuclear Power Plant Unit 1.
In its submittal, the licensee provided Technical l
Specification changes to support Appendix G heatup and cooldown Pressure /
Temperature curves applicable to the Unit I reactor vessel for a period up to 12 effective full power years (EFPY). The changes include revised heatup i
rates, a change in the Power Operated Relief Valve (PORY) pressure setpoint for Low Temperature Overpressure Protection (LTOP), a change in the LTOP enable
, prature, a sE11fication to Reactor Coolant Pump (RCP) controls when in LTOP
' conditions, a modification to High Pressure Safety Injection (HPSI) pump controls when in LTOP conditions, and changes to the bases for the affected Limiting Conditions for Operation (LCOs) to justify the changes. The staff evaluation included a review of the Calvert Cliffs Unit 1 LTOP system descrip-tion provided as Attachment I to the licensee's letter dated May 14, 1990.
To evaluate the proposed changes, the staff used the following NRC Regulations and guidance:
10 CFR Part 50.36(c)(2); Regulatory Guide 1.99, Revision 2 (final); Standard Review Plan (SRP) Section 5.2.2, Revision 2; and Generic Letter 88-11.
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2.0 EVALUATION New 12 EFPY P/T heatup and cooldown curves have been developed to replace the J
existing 10 - 40 EFPY heatup and cooldown curves in the Calvert Cliffs Unit 1 l
Technical Specifications. To accommodate the more restrictive pressure /
l temperature Ifmits resulting from consideration of Regulatory Guide 1.99, l
Revision 2, a new LTOP setpoint, a new enable temperature, and new heatup rates l
are proposed for the Calvert C11ffs Unit 1 Technical Specifications. Revised i
LTOP setpoints and the heatup rates were chosen to prevent violation of the Appendix G pressure / temperature limits should a RCS pressure transient occur during low temperature operations.
In order to accomplish this, the LTOP l
pressure setpoint will be lowered, the enable temperature will be increased,
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and in general, heatup will be slowed, i.e., the rates reduced, for specified i
RCS temperature ranges.
l LTOP is provided by the PORVs on the pressurizer. These PORVs are set to open f
at a pressure low enough to prevent violation of the Appendix G heatup and cooldown curves should a RCS pressure transient occur during low temperature i
operations. The licensec, in Attachment I to its May 14, 1990 amendment l
request, discussed the results of analyses of the most limiting overpressure transients used in detemining the PORY setpoint for LTOP. The PORY setpoint
- tiimit has been set by two design criteria. These are the limiting transients l
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for mass addition and energy addition.
i Peak pressures resulting from mass addition-transients were calculated by the licensee to detemine the effect of inadvertent actuation of combinations of HSPI pumps and charging pumps. The design basis event assuming a water solid RCS is an inadvertent High Pressure Safety Injection (HPSI) actuation with l
concurrent charging pump injection. Based on an assumed single failure of one i
PORY and the remaining PORV discharging against a backpressure of 115 psia, the calculated RCS pressure for a total mass input of 470 gpm would be 424.5 i
psia (as measured in the pressurizer).
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3 The limiting energy addition transient is the startup of a reactor coolant pump while steam generator secondary temperature is greater than the primary coolant temperature. A reactor coolant pump startup in one loop with a steam generator primary to secondary temperature difference of less than 150 F and a bubble in the pressurizer was modeled by the licensee using the RETRAN computer code and calculated results demonstrated that the peak pressure would be less than the PORY lift setpoint. Current Calvert Cliffs Technical Specifications specify conditions under which a reactor coolant pump may not be started, which include conditions corresponding to LTOP. To be within the limiting condition, the pressurizer indicated water level is administratively controlled to maintain an adequate steam bubble for mitigating the energy addition transient and the startup of a RCP is restricted to when the secondary temperature is less than 150 F above the RCS temperature. Revisions to numerical values in the applicable Technical Specifications have been proposed to be consistent with the assumptions in the reanalysis of the coolant pump startup transient.
In addition to the PORY setpoint change, the LTOP enable temperature is raised from 275'F to 327"F. This change is a result of following the guidance provided in the Standard Review Plan (SRP) 5.2.2, Revision 2.
The SRP I
c::nsiders the enable temperature as the water temperature corresponding to a metal temperature at the reactor vessel beltline that is controlling in the TAppendix G calculation.
l Below 327'F, the anticipated low temperature overpressurization transients may be adequately mitigated by the automatic action of the pressurizer PORVs or by l
allowing sufficient time for operator response. Based on the results of the most limiting LTOP transient, the licensee proposed Technical Specification PORY setpoint is less than or equal to 424.5 psia when RCS average temperature is less than or equal to 327"F. The licensee proposed PORY setpoint and enable temperature changes in proposed Technical Specification 3.4.9.3, the heatup rates identified by proposed Technical Specification 3.4.9.1 and the associated bases section reflect the above discussed LTOP considerations. The staff finds 3
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that they are based on approved Regulatory guidance, are reasonably conservative and are acceptable.
l The new LTOP limits and supporting analyses require that other Technical Specifications be revised to reflect the analysis assumptions.
These are the I
specifications related to HPSI pump operability and reactor coolant pump l
controls (discussed earlier under energy addition limits). 'The PORY setpoint of 424.5 psia was based on an analysis of a mass addition transient from a j
total mass input of 470 gpm. This mass input considers one HPSI pump injecting at 350 gpm combined with a charging pump injecting at 45 gpm and accounting for system expansion due to decay heat. To meet the limiting condition, over-pressurization will be precluded for temperatures below 327'F by disabling two I
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.HPSI pumps, placing the third in pull-to-lock, and by throttling the third pump i
to 350 gpm flow when it is used to add mass to the RCS.
i The licensee provided its updated pressure / temperature curves in proposed Technical Specification Figure 3.4-2a (for heatup) and Figure 3.4-2b (for l
cooldown). The necessary adjustments of LTOP controls are as follows:
Technical Specification 3.4.9.1, " REACTOR COOLANT SYSTEM PRESSURE / TEMPERATURE LIMITS." provides LCOs for acceptable heatup and cooldown rates based on an
.,Jverage RCS temperature limit (T,yg). The maximum heatup rate in LCO 3.4.9.1.a l
has been lowered from 100*F in any one hour period to a proposed rate of 60*F per hour with T,y, in the range 70*F to 305'F and greater than or equal to 327'F and 10*F per hour with T,y, in the range 305'F to 327*F. The pressure /
l temperature limit change also requires a change in the ACTION statement which consists of a lowering of the cooldown pmssure limit from 500 psia to 300 psia. The same change in the cooldown pressure limit is proposed in the ACTION statement in Technical Specification 3.4.9.2, " PRESSURIZER." These changes are necessary as a result of the new pressum/ temperature limit curves for 12 EFPY and the supporting Appendix G analysis. They are acceptable based on the use of approved NRC guidance in the Regulatory Guide 1.99, Revision 2 methodology.
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l Technical Specification 3.4.9.3, "0VERPRESSURE PROTECTION SYSTEMS." identifies j
the overpressure protection requirements to be met to ensure that Appendix G l
limits are maintained. The LCO is revised to identify the proposed PORV lift point setting of 424.5 psia, the LTOP enable temperature of 327T, the over-presatire requirements for HPSI pump operability and flow rate limitation, and l
other LTOP controls. Technical Specification 3.4.9.3.a is further revised to require system vents equivalent to the number of PORVs not available. The l
controls of the proposed Technical Specification are not applicable if a system vent area equal to or greater than eight square inches exists. Eight i
square inches is a flow area which can provide protection from the inadvertent injection from any combination of operable pumps and therefore the protection requirements in the LCO are not required. ACTION STATEMENT changes are proposed to decrease the time to restore an inoperable PORV to OPERABLE status from 7 days to 5 days and to increase the time pemitted to vent the RCS from 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> to 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. This change is proposed to establish a more practicable time for cooldown and depressurization (based on pa:;t operational experience).
Since the proposed change does not increase the total time a PORY could be out of service (7 days) before a vent is established in the RCS, the proposal is acceptable.
Proposed Technical Specifications 3.4.9.3.b and 3.4.9.3.c and ACTION STATEMENTS d and e are added to specify the disabling of two HPSI pumps and to prevent the automatic alignment of HPSI pump flow to the RCS.
Proposed Technical Specification 3.4.9.3.d and ACTION STATEMENT f are added to limit the HPSI flow to less than or equal to 350 gpm in accordance with analyzed conditions and to provide appropriate actions if the specified flow is exceeded while pump suction is aligned to the Refueling Water Tank and a RCS vent less than or equal to 2.6 square inches exists.
The proposed changes as identified in the licensee's amendment request are acceptable based on the supporting analysis and staff review discussed above.
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6 Surveillance Requirement 4.4.9.3.3 is added to verify the conditions in the proposed LCO for Technical Specification 3.4.9.3 and is acceptable. Since the current Surveillance Requirement 4.5.3.2 dealing with ECCS subsystems would be redundant if 4.4.9.3.3 is adopted, the proposed deletion of 4.5.3.2 is acceptable.
Technical Specification 3.4.1.3, " COOLANT LOOPS AND COOLANT RECIRCULATION -
SHUTDOWN " concerns reactor coolant pump controls. To accommodate the LTOP conditions for Modes 4 and 5, a footnote appended to the APPLICABILITY of the LCO is revised to require that a reactor coolant pump not be started when a RCS cold leg temperature is less than or equal to 327 F unless (1) the pressurizer indicated water level is less than 170 inches and (2) the secondary water temperature of each steam generator is less than 150"F above the RCS temperature. These changes reflect the analysis assumptions for the limiting energy addition transient discussed above and are acceptable.
Technical Specifications 3.1.2, "B0 RATION SYSTEMS " concerns the use of a HPSI pump to provide a source of boron injection in Modes 5 and 6.
To provide protection against overpressurization from inadvertent HPSI injection while borating, a footnote to LCOs 3.1.2.1 and 3.1.2.3 is proposed to define an operable pump as being in pull-to-lock and states that HPSI pump manual use is in accordance eith approved procedures under the restrictions of Specification 3.4.9.3.d.
This is the same as a footnote to Item a. of LCO 3.5.3, "ECCS SUBSYSTEMS," which was approved by Amendment No.14J +.o Facility Operating L' cense No. DPR-53 for the Calvert Cliffs Units No.1, March 6,1990, and is acceptable since it is consistent with the assumptions in the LTOP analysis provided in this amendment request. Amendment No.140 also approved a change to Technical Specification Table 3.3-3 related to manual operation of the HPSI pump. Further clarification is proposed in the current amendment request to allow an operating temperature band between 350 F to 327"F for disabling the pumps. This additional clarification is to define the previously reviewed and accepted range and is acceptable since it is basically administrative in nature.
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7 Technical Specification 3.5.3, "ECCS SUBS (STEMS," will be modified to identify the new LTOP enable temperature of 327*F in LCO 3.5.3.a.
A footnote is proposed to the Surveillance Requirement 4.5.2, " EMERGENCY CORE COOLING SYSTEMS " to allow full flow testing of a HPSI pump at RCS temperatures less than or equal to 327 F as long as the HPSI pump is recirculating RCS Water.
The proposed footnote is acceptable since it limits the mass addition from a HPSI pump to analyzed limits.
3.0 CONCLUSION
Based on the staff evaluation in Section 2.0 above, the staff concludes that the licensee proposed changes to Technical Specification LCOs 3.4.9.1, 3.4.9.3, 3.4.1.3, 3.1.2, and 3.5.3, Surveillance Requirements 4.4.9.3.3 and 4.5.2, Table 3.3-3, and their associated bases are acceptable to support the Appendix G pressure / temperature limits applicable for a period up to 12 EFPY, The staff has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (2) such activities will be conducted in compliance with the Commission's regulations, and issuance of this amendment will not be inimical to the common defense and security or to
'Tthe health and safety of the public.
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i ENCLOSURE 2 j
SYSTEMATIC ASSESSMENT OF LICENSEE PERFORMANCE FACILITY NAME Calvert Cliffs Unit 1 1
StMIARY OF REVIEW l
Baltimore Gas and Electric Company, the licensee of Calvert Cliffs Unit I, has i
submitted an application to update P/T limits applicable for the period of 12
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EFPY and associated changes of Technical Specifications. The Reactor Systems Branch (SRXB) has reviewed the proposed chances within the SRX8 review scope and concludes that the licensee proposed changes are acceptable. The review was perforined in the period March through May 1990.
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NARRATIVE DISCUSSION OF LICENSEE PERFORMANCE - SAFETY ASSESSMENT / QUALITY I
- W RIFICATION The Itcensee showed a general understanding of the technical issues from a safety standpoint and used acceptable approaches to resolve them.
AUTHOR:
M. A. McCoy I
DATE:
5/17/90 l
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