ML20055H759
| ML20055H759 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 07/24/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20055H758 | List: |
| References | |
| NUDOCS 9007300022 | |
| Download: ML20055H759 (14) | |
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UNITED STATES 4
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.f NUCLEAR REGULATORY COMMISSION 1
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SAFETY. EVALUATION.BY-THE.0FFICE.0F-NUCLEAR. REACTOR. REGULATION
- RELATED.TO. AMENDMENT.NO.145.T0 FACILITY.0PERATING. LICENSE NO..DPR. (3, i
BALTIMORE: GAS AND. ELECTRIC COMPANY CALVERT. CLIFFS. NUCLEAR. POWER. PLANT.. UNIT 1
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DOCKET.NO. 50-317
1.0 INTRODUCTION
_By letter dated May 14, 1990, as modified on July 18, 1990, the Baltimore I
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Gas and Electric Company (the licensee) proposed to amend the Technical Specifi-cations of the Calvert Cliffs Nuclear Power Plant, Unit 1.
In its submittal,
'the licensee provided Technical Specification changes to su
' Appendix G, heatup and cooldown Pressure / Temperature (P/T) pport 10 CFR Part 50, limits applicable to the Unit 1. reactor vessel for a period up to 12 effective full power years (EFPY).
The proposed P/T limits were developed based on Regulatory Guide (RG) 1.99, Revision 2.
The proposed revision provides up-to-date P/T limits-for-the operation of' the reactor coolant system during heatup, cooldown, criticality,.
and inservice hydrostatic testing.
In addition, the proposed changes included
- revised heatup rates, a change in the Power Operate 1 Relief Valve-(PORV)
.-pressure setpoint for Low-Temperature Overpressure Protection (LTOP), a change
'intheLTOP_enabletemperature,amodificationtodeactorCoolantPump-(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 l
'LTOP. system description provided as in the licensee's letter dated May 14, l h and updated in the July 18, 1990, submittal.
To evaluate-the P/T limits and supporting changes, the staff used the following NRC regulations and guidance: Appendices G and' H to 10 CFR' Part 50; the American Society of Testing Materials (ASTM) Standards and the American Society -
ofMechanical-Engineers (ASME) Code,whicharereferencedinAppendicesGandH; 10 CFR Part 50.36(c)(2); RG 1.99, Rev. 2; Standard Review Plan (SRP)
' Sections 5.2.2 and 5.3.2; and Generic Letter 88-11.
Each licensee authorized to operate a nuclear power reactor is required by 10 CFR 50.36 to provide Technical Sp(ecifications for'the operation of theIn particula 4
plant.
operation be included in the Technical Specifications. The P/T limits are.
among the' limiting conditions of operation in the Technical Specifications for P
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2-all commercial nuclear plants in the United States. Appendices G and H of 10 CFR Part 50 describe specific requirements for fracture toughness and reactor vessel material surveillance that must be considered in setting P/T limits. An acceptable method for constructing the P/T limits is described in SRP Section 5.3.2.
Appendix G of 10 CFR Part 50 specifies fracture toughness and testing requirements for reactor vessel materials in accordance with the ASME '.: ode and, in particular, that the beltline materials in the surveillance capsules be tested in accordance with Appendix H of 10 CFR Part 50. Appendix H, in turn, refers to ASTM Standards.
These tests define the extent of ',essel embrittlement at the time of capsule withdrawal in terms of the increase in reference temperature. Appendix G also requires the licensee to predict the effects of neutron irradiation on vessel embrittlement by calculating the adjusted reference temperature (ART) and Charpy upper shelf energy (USE).
Generic Letter 88-11 requested that licensees and permittees use the methods in RG 1.99, Revision 2, to predict the effect of neutron irradiation on reactor vessel materials. This guide defines the ART as the sum of unirradiated
. reference temperature, the increase in reference temperature resulting from neutron irradiation, and a margin to account for uncertainties in the prediction method.
Appendix H of 10 CFR Part 50 requires that the licensee establish a surveillance program to periodically withdraw surveillance capsules from the reactor vessel.
Appendix-H refers to the ASTM Standards which, in turn, require that the capsules be installed in the vessel before initial plant startup and that they contain test specimens made from plate, weld, and heat-affected-zone (HAZ) materials of the reactor beltline.
LTOP is provided by-the PORVs on the pressurizer. These PORVs are set at a pressure low enough-to prevent violation of the 10 CFR 50 Ap during heatup and cooldown should a reactor coolant system (pendix G P/T limits RCS) pressure transient occur during low temperature operations. The potential for overpres-surization of the RCS can be minimized by a combination of administrative procedures and operator action. However, because operator action cannot always be assumed, and because possible equipment malfunctions must be considered, additional controls must be in place to ensure adequate protection exists for
.all postulated events.
.The two major concerns for LTOP protection are the mass addition and energy
. addition transients. The proposed amendment provides restrictions on the use of high pressure safety injection (HPSI) pumps to provide protection for mass addition transients. Restrictions are also imposed on the starting and use of the reactor coolant pumps (RCP) to provide protection for energy addition transients.
The licensee's July 18, 1990, submittal addressed concerns related to the assumptions used for the opening time for the presscrizer PORVs when performing the analysis for the LTOP protection portion, of the amendment rreuest. The licensee performed additional analysis and confirmatory testing to assure that the opening time assumed for the Calvert Cliffs, Unit 1 I
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- PORVs'was adequate to support the initial amendment request. The results of-the additionel. analysis.and confirmatory tests indicated that no changes were
. required to the initial amendment request-in relation to the opening time of the PORVS. However, as the result of resolving the PORV concern, the licensee performed a re-evaluation of the previous LTOP mass addition and energy addition _ transient analyses. As the result-of this effort,
- non-conservative assumptions and errors were identified.
-2.0 Changes.to.the Initial Amendment Request The licensee's July 18, 1990 submittal modified those portions of the initial amendment request pertaining to the LTOP controls for the HPSI and RCPs.
The results of the re-evaluation of the mass addition transient analysis resulted in changes to total limiting flow and the maximum allowed HPSI pump flow. The initial submittal did not consider critical flow effects which-limit the capability of the PORVs to relieve pressure during a mass addition transient and result in a change to the allowable HPSI pump flow.'
In addition, higher decay heat loads were considered during the re-analysis which resulted in an; increase in the reactor coolant expansion following a loss of shutdown cooling. Subsequently, the HPSI flow must also be reduced'by a corresponding amount. The licensee also based the' decay heat load on a minimum time-to cooldown to an LTOP condition from a previously assumed 2 days to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.
As a result of.these more conservative assumptions (critical flow considerations, higher decay heat loads, and shorter cooldown time), the total flow changed from-470 gpm to 380 gpm and the maximum allowed HPSI pump flow from 350 gpm to
- 210-gpm.
The results of the re-evaluation of the energy addition transient resulted in-changes to the secondary-to-primary delta T and pressurizer level.
In addition, a limit on pressurizer pressure (not previously proposed) is imposad. These limits are required prior to the starting of an RCP. The chanr,es were the result of errors identified during the re-evaluation relating to inputs to a RETRAN computer calculation for pressurizer level. A nor-conservative level value was used; non-conservative steam generator heat transfer coefficients identified;-and a non-conservative value for thermal expansion of the reactor coolant, due to decay heat loads, had been used.
-The.new, more restrictive RCP start criteria resulting from the re-evaluation, correcting the problems identified above, resulted in:
changing the initial
- pressurizer level from'170 inches to 165 inches; secondary-to-primary temperature from less than 150*F to less than or equal to 30'F; and adding a requirement for the-pressurizer pressure to less than or equal to 300 psia.
- These more restrictive RCP start criteria are temporary restrictions and are only valid for the current shutdown condition and do not allow entry into MODE 2 until the restrictions have been revised. This re: :riction from entry into MODE 2 is included in proposed TS 3.4.1.3 as a footr. 'e on the applicability.
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The supplemental information provided in the licensee's July 18, 1990 submittal' is included in our evaluation of the proposed changes to the LTOP as detailed in Section 4.0 of this SE. The information provided in tLe supplement z
h superseded portions of the initial proposed TS changes relative to LTOP as i
l noticed in the Federal Register on May 30, 1990 (55 FR 21962). We have L:
addressed the licensee's request to handle this amendment, as the result of the re-evaluation and its impact on the restart of the unit, as an emergency in L
Section 5.0.of this SE. We have also made a Final ~ Determination of No Significant E
Hazards Consideration in Section 7.0 of this SE regarding proposed TS changes l
related to LTOP which were revised after the initial notice.
3.0 EVALUATION.. APPENDIX.G.HEATUP.AND COOLDOWN P/T. LIMITS The staff evaluated the effect of neutron irradiation embrittlement on each beltline material in the Calvert Cliffs I reactor vessel. The amount of irradiation embrittlement was calculated in accordance with RG 1.99, Rev. 2.
The staff has determined that the material with the highest ART at 12 EFPY was i
the intermediate shell weld with 0.21% copper (Cu), 0.87% nickel (Ni), and an
. initial'RT of 04 ndt The licensee has removed one surveillance capsule from Calvert Cliffs 1.
The results from capsule 263 were published in a Battelle-Columbus Laboratories report. All surveillance. capsules contained Charpy impact specimens and l
tensile specimens made from base metal, weld metal, and HAZ metal.
For the limiting beltline material, the intermediate shell weld, the staff calculated the ART to be 222.3'F at 1/4T (T-= reactor vessel beltline thickness)and of 1.15E19 n/cm{62.5'F for 3/4T at 12 EFP{.- The staff used a neutron flue at 1/4T and 4.08E18 n/cm at 3/4T. The ART was determined by Section~1 of RG 1.99, Rev. 2, because only one surveillance capsule has been removed from the reactor vessel.
The licensee used the method in RG 1.99, Rev. 2, to calculate an ART of 222'F at 12 EFPY at 1/4T for the same limiting weld metal. The staff judges that a difference of 0.3'F between the licensee's ART of 222*F and the staff's ART of 222.3*F.is-acceptable. Substituting the ART of 222.3*F into equations in SRP 5.3.2, the staff verified that the proposed P/T limits for heatup, cooldown, and inservice hydrostatic test meet the beltline material requirements in Appendix G of 10 CFR Part 50.
-In. addition to beltline materials, Appendix G of 10 CFR Part 50 also imposes P/T _ limits based on the reference temperature for the reactor vessel closure flange materials.Section IV.2 of Appendix G states that when the pressure exceeds 20% of the preservice system hydrostatic test pressure', the temperature of the-closure flange regions highly stressed by the bolt preload must exceed the reference temperature of the material in those regions by at least 120*F for normal operation and by 90*F for hydrostatic pressure tests and leak tests.
Based on the-flange reference temperature of -10 F, the staff has determined that the proposed P/T limits satisfy Section IV.2 of Appendix G.
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'Section IV.B of Appendix G requires that the predicted Charpy USE at end of life be above 50 ft-lb. The unirradiated USE for lower shell course plate D-7207-1 was 77 ft-lb. Using Figure 2 of RG 1.99, Rev. 2, the staff determined that the EOL USE would be 52.7 ft-lb. This is greater than 50 ft-lb and, j
therefore, is acceptable.
The staff has determined that the proposed P/T limits for the reactor coolant system for heatu), cooldown, inservice hydrostatic test, leak test, and criticality are valid throug i 12 EFPY because the limits conform to the requirements of Appendices G and H of 10 CFR Part 50.
The licensee's submittal also satisfies Generic Letter 88-11 because the licensee used the method in RG 1.99, Revision 2, to calculate the ART.
Hence, the proposed P/T limits may be incorporated into the Calvert Cliffs 1 Technical Specifications.
4.0 EVALUATION;.LTOP A new LTOP setpoint, a new enable temperature, and new heatup rates are proposed for the Calvert Cliffs Unit 1 Technical Specifications to accommodate the more restrictive P/T limits.
Revised LTOP setpoints and the heatup rates were chosen to prevent violation of the Appendix G P/T limits should an RCS pressure transient occur during low temperature operations.
In order to accomplish this, the LTOP pressure setpoint will be lowered, the enable temperature will-l be increased, and in general, heatup will be slowed, i.c., the rates reduced, for specified RCS temperature ranges.
LTOP is provided by the PORVs on the pressurizer. 'These PORVs are set to open at a pressure low enough to prevent violation of the Appendix G heatup and cooldown curves should an RCS pressure transient occur during low temperature operations. The licensee's submittal provided the results of analyses of the.
most limiting. overpressure transierits used in determining the PORV setpoint for LTOP. The PORV'setpoint limit has been set by two design criteria. These are the limiting transients for mass addition and energy addition.
Peak. pressures resulting from mass addition transients were calculated by the licensee to determine 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 HPSI actuation with concurrent charging pump-injection.
Based on an assumed single failure of one PORV and the remaining PORY discharging against a backpressure of 115 psia, the calculated RCS pressure for a total l-mass input of 380 gpm would be 424.5 psia (as measured in the pressurizer).
The limiting energy addition transient ir
. startup of an RCP while steam generator secondary temperature is greate.han the primary coolant temperature.
An RCP. startup in one loop with a steam generator primary to secondary tempera-ture difference of less than or equal to 30*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 an RCP may not be started, which include conditions corresponding to LTOP. To be within the limiting condition, the pressurizer indicated water m
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' level is administrative 1y contro11eo to mainta'in an adequate steam bubble for
> mitigating the energy addition transient and the startup of an RCP is restricted
'to when the secondary temperature is-less than or equal to 30'F above the RCS temperature and the initial pressurizer pressure is less than or equal to 300
)sia.
Revisions to numerical values in the applicable Technical Specifications lave been proposed to be consistent with the assumptions in the reanalysis of the coolant pump startup transient.
In addition to the PORV setpoint change, the LTOP enable temperature is raised j
from 275'F to 327'F. This change is a result of following the guidance provided in SRP 5.2.2, Revision 2.
The SRP considers the enable temperatere as the water temperature corresponding to a metal temperature at _ the reactor vessel beltline that is controlling in the Appendix G calculation.
.Below 327'F, the anticipated low temperature overpressurization transients may be adequately mitigated by the automatic action of the pressurizer PORVs or by 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 that they are based on approved regulatory guidance, are reasonably conservative i
and are acceptable.
The new LTOP limits and supporting analyses require that other Technical i
Specifications be revised to reflect the analysis assumptions. These are the specifications related to HPSI pump o earlier under energy addition limits)perability and RCP controls (discussed The PORV setpoint of 424.5 psia was based on an analysis of a mass addition transient from a total mass input of 380 gpm. This mass input considers one HPSI pump injecting at 210 gpm combined with a charging pump injecting at 45 gpm and accounting for system expansion given the current low level of core decay heat. To meet the limiting condition, overpressurization will be precluded for temperatures-below 327'F by disabling two HPSI pumps, placing the third in pull-to-lock, and by throttling the third pump to 210 gpm flow when it is used to add mass to the RCS.
Technical Specification 3.4.9.3, "0VERPRESSURE PROTECTION SYSTEMS," identifies the overpressure protection requirements to be met to ensure that Appendix G limits are maintained. The LCO is revised to identify the proposed PORY lift point setting of 424.5 psia, the LTOP enable temperature of 327'F, the over-pressure requirements for HPSI pump operability and flow rate limitation, and 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 l,
vent area equal to or greater than eight square inches exists. Eight square i
inches is a flow area which can provide protection from the inadvertent injec-tion from any combination of operable pumps and therefore the protection re-L quirements in the LC0 are not required. ACTION STATEMENT changes are proposed to decrease the time to restore an inoperable PORY to OPERABLE status from l:
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- m 7 days to 5 days and to increase the time permitted 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 past operational experience). Since the proposed change decreases the total time a PORV could be out of service before a vent is established in the RCS from 7 days 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> to 7 days, 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 HPS! pumps and to prevent the automatic alignment of HPSI pump flow to the RCS, In addition, 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 210 gpm in accordance with the 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. These proposed changes are acceptable based on the supporting analysis.
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 RCP 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 an RCP not be started when an RCS cold leg temperature is less
.thanorequalto327'Funless(1)thepressurizerindicatedwaterlevelisless-than or equal to 165 inches, (2) the secondary water temperature of each steam generator is less than or equal to 30'F above the RCS temperature,-and (3) the pressurizer pressure is less than or equal to 300 psia by plant computer indication or equivalent precision instrument. The footnote also specifies that the restrictions are only valid for the current shutdown condition and that entry into Mode 2 will nit occur until the restrictions have been revised.
These changes reflect the analjsis assumptions for the limiting energy addition transient discussed above and ace acceptable.
Technical Specification 3.1.2, "BMATION SYSTEMS," concerns the use of a HPSI pump to provide a source of. boron infection in Modes 5 and 6.
To provide pro-tection 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 with 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.140 to Facility Operating License No. DPR-53 for the Calvert Cliffs Unit 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 amendmant 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. This change is acceptable since it provides additional guidance to assure conformance to the Technical Specification requirements.
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Technical Specification 3.5.3, "ECCS SUBSYSTEMS," will be modified to' identify the new LTOP enable temperature of 327'F in LC0 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, l
Based on our evaluation, the staff has determined 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.
5.0 STATEMENT OF EMERGENCY CIRCUMSTANCES The licensee's July 18, 1990 submittal requested that the amendmenc, 'is modified, be approved on.an emergency basis. The licensee has schedu od outage activities which include extensive pipe replacement, repairs, an4 maintenance work on the salt water service system (SWSS). The current p' ant conditions require that both trains of the SWSS be available to remove deuy heat. An alternate source of decay heat removal is necessary to allow the 3WSS train to be taken out of service.so that the pipe replacement, repairs, and maintenance can be performed. The alternate source of decay heat removal-is a reactor coolant system (RCS) loop.which requires the unit to operate in Mode 3 or 4 to allow an RCS Loop steam generator to remove decay heat. The current-plant condition, Mode 5 with the RCS-vented (pressurizer manway removed), does not allow use of this alternative decay heat removal source. The'LTOP protection
.pru ided by this amendment is needed to secure the RCS and operate the unit at v
temperatures and pressures' necessary for an operable RCS loop and-to remove decay heat via its steam generator. This alternate decay heat removal source will permit the removal-from-service of the SWSS train. Each day's delay in the issuance of this amendment will result in a corresponding day's delay in the startup of the unit.
10 CFR 50.91(a)(5) provides the necessary requirements for issuing an amendment when the Commission finds that an emergency situation exists and failure to act in a timely way would result in derating or shutdown of a
-nuclear plant or in prevention of either resumption of operation or of increase in power output up to the plant's licensed power level. The Commission expects its licensees'to: apply for license amendments in a timely fashion; not abuse the emergency provisions by failing to make a timely application of the amendment and thus itself creating the emergency; provide an explanation as to why the emergency situation occurred; and why it could not have been avoided.
The licensee indicated that the circumstances leading to this emergency request could not have reasr,nably been foreseen. The initial amendment request was submitted on Ny 14, 1990, and adequate time was available to pre-notice and issue the amendment under normal circumstances. An NRC Information Notice No. 69-32, " Surveillance Testing of Low Temperature Overpressure Protection Systems," was issued on March 6,1989, which identified
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' problem::.in testing.PORVs and potential times : ssumed in analyses for LTOP
. protection. The licensee had performed. reviews of LTOP issues and concerns between October 1989 and April 1990, however, this effr,rt primarily focused on
.the initial LTOP design and restoration of the LTOP system to its initial design requirements. The licensee's efforts related tc the information notice resulted in the licensee performing additional analysis and confirmatory testing to assure that the unit 1 PORV opening times 4ssumed in the initia' amendment request were adequate. The results of the effort indicated that no changes were necessary in relation to the PORY timing issue. Had factors unrelated to the PORY issue not arisen (discovery of non-conservative
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assumptions and errors in input to the computer calculations), the amendment as initial.ly requested would have been issued.
In flay 1990, the'latter part of the licensee's effort related to the-information notice and resolution of other LTOP issues, the licensee identified non-conservative.
assumptions used in performing its LTOP analysis and errors in the input to the RETRAN computer calculations.
The licensee informed the staff in late June 1990 of potential non-conservatisms and errors in the analysis. As a result, the licensee requested that the issuance of'the amendment be held pending resolution.
The licensee enlisted the assistance of Combus; ion Engineering to confirm the results of its.re-evaluation of the mass addition and energy addition transient analyses performed to support the LTOP portion of the amendment request and the
. licensee promptly submitted its July 18 submittal after completing the necessary analyses.
The staff finds that the licensee has acted in good faith and made a timely application.+or revising portions of the LTOP related TS after discovering
.and evaluating the deficiencies in its LTOP analysis and errors in its calculations.
Further, the staff finds that the amendment is needed to allow completion of activities during the current outage that are required for startup.
Corrective actions are being taken to preclude recurrence of this type of f
emergency. The licensee is assessing.the circumstances and root causes leading to the emergency situation to assure improved process and administrative. controls are being put in place.
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Based on-the above, the Commission has determined that the licensee has not abused the emergency provisions of 10 CFR 50.91(a)(5); failure for the Commission to act on the licensee's request would result in a delay in the resumption of power. operation of the unit; and therefore, the request should be processed under the emergency provision of 10 CFR 50.91(a)(5).
6.0
SUMMARY
The staff has concluded, based on the discussions included in Sections 3.0-and 4.0 above, that the proposed Technical Specifications supporting the new 12 EFPY P/T limits and the LTOP controls are acceptable.
Further, based on the discussion in Section 5.0, a determination has been made that the licensee has acted in good faith and justified the need for emergency action, i
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7.0 FINAL DETERMINATION OF NO SIGNIFICANT_ HAZARDS CONSIDERATION The propo' sed changes'to the Calvert Cliffs, Unit 1. Technical Specifications as-initially requested by letter-dated May 14, 1990,.and noticed in the Federal Register on May 30, 1990, (55 FR 21962), were grouped as follows:
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Change 1:
Changes proposed to the heatup and cooldown curves Change 2:
Changes proposed to adjust the'LTOP controls Change 3:
Changes proposed to modify the RCP controls Change 4:
Changes proposed to clarify HPSI operability i
Change-5: Changes proposed to modify HPSI pump controls As noted in Section 2.0 of this SE, the July 18, 1990 submittal only modified 1
certain TS change requests associated with proposed changes to Change 2 (changes proposed to adjust LTOP controls) and Change 3 (changes proposed to modify HPSI controls).
Specifically, for Change 2, the submittal revised the
. TS 3.4.1.3 footnote on applicability for Modes 4 and 5.
This changed the pressurizer water level to less than or equal to 165 inches, the secondary water temperature of each-steam generator to less than or equal to 30'F above the RCS' temperature, and added a requirement for. pressurizer pressure of less than or equal to 300 psia by plant computer, indication or equivalent precision instrument. The footnote further indicated that-the restrictions are only.
valid for the current shutdown condition an( that entry into Mode 2 will not occur until the restrictions have been revised.1The associated TS bases pages
.were updated to reflect these proposed changes.
The ' submittal modifications related to Change 3 revised TS 3.4.9.3.d and f which i
specified that the HPSI flow shall be limited to equal to or less than 210 gpm.
Section f also. indicates that, if the' flow is exceeded while suction is aligned to:the RWT-and an RCS vent of less than 2.6. square inches exists, immediate action must be taken to reduce flow to less than or equal to 210 gpm.
t The associated TS bases pages were updated to reflect these proposed changes.
Because,these changes were not encompassed by the Federal Register notice published on May 30, 1990 and the changes were needed to prevent delay in
-startup of'the Unit, the' licensee requested that the portions of the proposed amadment which were modified by its, July 18, 1990 submittal be approved on an emergency basis. The details relating to the circumstances leading to the changes and request for emergency action by the staff are detailed in Section 5.0 above.
Since no comments have been received on the initial notice, the 1
- staff's final determination in relation to significant hazards consideration addresses only those proposed ~ changes that are impacted by the July submittal (Changes -2' and 3) and are the subject of the emergency request.
The Comission has provided standards for determining whether a significant
' hazardsconsiderationexists(10CFR50.92(c)). A proposed amendment to an J
- operating license for a facility involves no significant hazards consideration if operation of the facility in accordance with the proposed amendment would 1
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(1) involve a significant increase-in the probability or consequences or an accident previously evaluated; or (2) create the 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.
The following evaluation addresses the three standards in relation to Change 2 and 3.
First Standard - Involve a significant increase in the probability or consequences of an accident previously evaluated.
- Change 2 - LTOP Controls-The PORV pressure setpoint and enable temperature have been adjusted based on the current 12 EFPY analysis and have been selected in accordance with 10 CFR
- Part 50, Appendix G,-including applicable NRC, staff guidance.
LTOP controls are not required if adequate venting is available.
It has been determined, and reflected in the TS, that additional LTOP protection is not required if a vent of 8 square inches is available.
The analysis' performed conservatively assumed only one PORV available and the requirement to have a vent. equivalent to an out-of-service PORV when LTOP
. pro ection is needed provides assurance against'a single failure during a t
postulated LTOP transient. More conservative restrictions have been imposed on the amount of time that a PORV can be out of service before a vent is opened in
- the RCS.. Increased depressurization time also provides assurance that adequate
. time is available for operators to make the transition from water solid to vented conditions which minimizes the likelihood of an LTOP transient occurring.
- The limiting of,the available mass addition sources.by throttling the operable HPSI pump provides assurance that the Appendix G limits will not be exceeded while maintaining a HPSI-pump available for required uses. The safety-related function'of the throttled HPSI pump for other design basis events was evaluated and a determination made that the proposed throttled value provides, with margin, sufficient flow to mitigate the postulated design basis events.
Change 3 - RCP Controls The-limiting transient for an LTOP energy addition transient is a spurious start of an RCP with the isolation of letdown. Controllable variables are the
-pressurizer pressure, pressurizer level, and energy addition from hot steam.
generator limits. Lnnits for these variables have been established, including:
the pressurizer pre.. ure; pressurizer level; and the secondary-to-primary delta T which includes consideration of associated uncertainties. The analysis performed assumed a start of two RCPs, with the proposed limits in place, and demonstrated that a PORV would not be required to open to mitigate the transient.
The restrictions imposed are valid only for the current shutdown conditions and the proposed TS assures that entry into Mode 2 will not be allowed until the restrictions have been revised. This is consistent with the assumptions used in the analysis and assures safe operation. Therefore, the-results of the analysis satisfy the requirements of 10 CFR Part 50, Appendix G.
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Thus, we have concluded that the changes 2 and 3 as modified by the July 18, 1990 submittal, do not involve a significant increase in the probability or consequences of previously evaluated accidents.
Second Standard - Create the possibility of a new or different kind of accident-from. any accident previously evaluated.
Change 2 - LTOP Controls The changes in pressure and-temperature setpoints are consistent with the requirements of the 10 CFR Part 50, Appendix G curves. The out-of-service-times of the PORVs, the vent sizes, depressurization time, and throttling the HPSI flow do not represent a significant change in the existing configuration of the unit. The. proposed changes reflect adjustments based-on the current 12 EFPY analyses.. No new hardware is being added to the unit nor is existing equipment being modified.- The longer cooldown will lessen the likelihood of an unforeseen situation.
Finally, no different types of operations are being l
introduced.
Change 3.- RCP Controls No new type of accident is created by altering the RCP start criteria in the TS.
No new hardware is being added to the unit as a result of this proposed change, no existing equipment is being modified, nor are any different types of operations being introduced.
RCPs are now normally, by procedure, started while e bubble
'is-in the pressurizer._ This requirement is now included-in the proposed TS.
The' restrictions imposed are valid only for the current shutdown conditions
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and the proposed TS assures that entry into Mode 2 will not be' allowed until the restrictions have been revised. 'This is, consistent with the assumptions used in the< analysis and assures safe opertion.
Thus; we have concluded 'that changes 2 and 3 as modified by the July 18, 1990 submittal, do not create the possibility of a new or different kinc' J accident-from an accident previously evaluated.
Third Standard - Involve a significant reduction in the margin of safety.
Change.2 - LTOP Controls The proposed changes do not involve a significant reduction in the margin of safety. The pressure and temperature setpoints were determined in accordance with 10 CFR 50, Appendix.G.
The established vent size was conservatively chosen to relieve flow fror, any poss'ible combination, beyond which LTOP is not required, was conservatively chosen to relieve flow from any possible combination of pumps. The margin of safety for PORVs is established by requiring 1
an equivalent amount of vent capacity when on PORV is out-of-service.
The PORV out-of-service time is reduced which increases the safety margin.
Increased cooldown time also lessens the likelihood of transients occurring which require LTOP protection.
Change 3.
.RCP. Controls The proposed changes ensure that the margin of safety is maintained. The starting of an RCP while water solid is no longer permitted by the TS. Adequate y
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operator response time is assured given a steam bubble in the pressurizer.
The controls placed on the variables, including new controls on the system pressure,. provide an additional margin of safety. The restrictions imposed are t
valid only for'the current shutdown conditions and the proposed TS assures that entry into Mode 2 will not be allowed until the restrictions have been revised.
The-is consistent with the assumptions used in the analysis and assures safe operation.
'Thus; we have concluded that the changes 2 and 3 as modified by thE July 18, 1990 submittal, do not involve a significant reduction in a margin of safety.
Based on the foregoing, the Commission has concluded that the standards of i
10 CFR 50.92 are satisfied. Therefore,-the Commission has made a final L
determination that the proposed amendment does not involve a significant hazards-l<
consideration' for changes 2 and 3, as modified by the July 18, 1990 submittal.
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8.0 STATE CONSULTATION
The appropriate representative of the State of Maryland was notified of this
-amendment. The state of Maryland had no comments.
9.0 ENVIRONMENTAL' CONSIDERATION This amendment involves a change to a requirement with respect to the installation or use of the facilities' components located within-the restricted areas as defined in 10 CFR Part 20 and to a surveillance requirement. The-staff has determined that this amendment involves no l
l significant increase in the amounts, and no significant change in the types, of ar.y effluents that may be released offsite and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has-previously issued a proposed finding and final determination that this amendment involves no significant hazards consideration and there has been no public cumment on such finding. Accordingly, this amendment meets'the y
eligibility criteria for categorical exclusion set forth in 10 CFR Sec 51.22(c)(9).
Pursuant to 10 CFR 51.22(b) no environmental imract statement or environmental assessment need be prepared in connection with the issuance of this amendment, t
10.0 CONCLUSION
l We have concluded, based on the considerations discussed above, that:
(1) the l
amendment:will not (a) significantly, increase the probability or consequences L
'of accidents previously evaluated, (b) create the possibility of a new or different kind of accident from any accident previously evaluated, or (c)
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significantly reduce a margin of safety, and therefore, the amendment does not involve significant hazards consideration; (2) there is reasonable assurance L
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that the health'and safety of the public will not be endangered by operation in-the proposed inanner; and (3) such activities will be conducted in compliance with the Comission's regulations and the issuance 'of-this amendment will not be. inimical to the comon defense and security or to the health.and safety of'
.the public.
Dated: - July 24,1990-PRINCIPAL CONTRIBUTORS:-
T'. Tsao:
M;' McCoy
,D. Mcdonald-w 4
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