ML20058N269

Application for Amends to Licenses DPR-53 & DPR-69,revising Tech Specs Re Low Temp Overpressure Protection

ML20058N269
Person / Time
Site:	Calvert Cliffs
Issue date:	08/13/1990
From:	Creel G BALTIMORE GAS & ELECTRIC CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20058N273	List: ML20058N269 ML20058N274
References
NUDOCS 9008140009
Download: ML20058N269 (10)

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.lL BALTIMORE GAS AND ELECTRIC CHARLES CENTER e P.O. BOX 1475 o BALTIMORE. MARYLAND 21203 1475 0: enoc c.cacet August 13,1990  !

. Vict PasseDtNT Nucitan catmew 0 01) #4 0* e al t U.S. Nuclear Regulatory Commission

' Washington, DC 20555 NITENTION: Document Control Desk SUBJECI': Calvert Cliffs Nuclear Power Plant Unit Nos.1 & 2; Docket Nos. 50-317 & 50-318 License Amendment Request Low Temperature Overpressure Protection ,

(LTOP) j

REFERENCES:

(a) Ixtter from Mr. D. G. Mcdonald, Jr. (NRC) to Mr. G. C. Creel ]

(BG&E), dated July 24,1990, Issuance of Amendment No.145 (TAC .

l No. 76130)

(b) letter from Mr. G. C. Creel (BG&E) to NRC Document Control  !

Desk, ' dated July 18, 1990, Request for Emergency License Amendment  :

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(c) Ixtter from Mr. G. C. Creel (BG&E) to NRC Document Control Desk' dated May 14, 1990, Request for Technical Specification Change (d)- Letter from Mr.'O. C. Creel (BG&E) to NRC Document Control Desk dated October 27,1989, Request for Av.,endment Gentlemen: .

By letter dated July 24,1990 (Reference a), the Nuclear Regulatory Commission issued Amendment J No.145 to Facility Operating License DPR 53 for Calvert Cliffs Unit 1. The amendment consisted  ;

of changes to the Technical Specifications proposed by Baltimore Gas and Electric (BG&E)

L Company's application dated May 14,1990 (Reference c), as modified by letter dated July 18,1990 -

(Reference b).

Amendment No.145 replaced the existing 0-10 cffective full power year (EFPY) and 10-40 EFPY  :

~ heatup and cooldown cuives with 0-12 EFPY heatup and cooldown curves based on Regulatory =

Guide 1.99, Revision 2. In addition, new controls were implemented to establish adequate low temperature overpressure protection (LTOP). These included: (1) adjustments to the LTOP mitigating system; i.e., the power operated relief valve (PORV) pressure lift setting and enable l

changes to reactor coolant pump (RCP) controls; (3) changes to clarify high  :

1 temperature; pressure safety m (2) jection (HPSI) operability requirements; and (4) modifications to IIPSI controls. ,

9008140009 900813 DR ADOCK0500g7 L

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Document Control Desk August 13,1990 Page 2 The RCP controls, unlike the other controls proposed in Reference (b), were temporary and only valid for the current low decay heat condition (60 days shutdown). These controls were put in place on an emergency basis to allow a continuation of the Unit 1 outage while analyses were completed for long term RCP controls. Continuation of the outage was achieved when early on July 27,1990, reactor coolant system (RCS) integrity was established and a reactor coolant loop was made operable in accordance with Technical Specification 3.4.1.3. This allowed one train of the Saltwater System to be taken out-of service for maintenance. His maintenance is currently proceeding.

The analysis of long-term requirements for the control of RCP starts has been completed, ne results indicate that only modest adjustments to the current controls are required to still be effective in the mitigation of energy addition events when low temperature overpressure protection is required. Accordingly, the purpose of this letter is to describe the methods and results of the final I analyses and to propose changes to:

o the heatup and cooldown curves and rates; o the PORVlift setting; and I o the RCP start controls.

These changes must be implemented prior to entry into MODE 2,which is currently scheduled for  !

September 18,1990. Therefore, we request that you approve these changes before that date. l Another purpose of this letter is to notify you that our response to Nuclear Regulatory Commission (NRC) Oeneric Ixtter 8811, submitted to you by letter dated October 27,1989 (Reference d), will i require modification in view of our overall re-evaluation of LTOP. Our response included a request for new 16 EFPY heatup and cooldown curves based on new methods developed by ABB Combustion Engineering Nuclear Power (C E). Whe. as the methodology proposed by C-E will not be affected, changes will be necessary in the proposed plant specific administrative controls related to LTOP.

Attachment (1) provides the proposed markup of the technical specifications affected by this amendment request. Attachment (2)is a revised LTOP system description.

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1. SUMMANY A. APPROACH The RCP start controls implemented by Reference (a) only apply to current Unit 1 '

conditions with a low decay heat load. New analyses have been performed for the higher decay heat loads that exist shortly after (i.e. 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> or more) a reactor shutdown. The results demonstrate that new RCP start controls, in conjunction with revised pressure temperature limits and an increased PORV setpoint, will prevent

• challenges to the PORV for planned RCP starts under these conditions. A single PORV will adequately mitigate energy addition transients that may occur if the RCPs are started in response to a loss of decay heat removal when decay heat loads are high and letdown is isolated.

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Document Control Desk August 13,1990 Page 3 B. HEATUP AND COOLDOWN CURVES AMD RATES The proposed change to the Technical Specifications will revise the existing 0-12 EFPY heatup and cooldown curves and rates. The existing 012 EFPY heatup and cooldown curves and rates are based on the calculation of a family of P-T limit cun'es that comprise the basis of References (b) and (c), as apprc,ved by NRC in Reference ,

(a). Each of the P-T limit curves within this " family of curves" is associated with a unique heatup and cooldown rate. We have gone back to that data and have selected new 012 EFPY curves that correspond to lows heatup and cooldown rates. With a ,

lower allowable rate of temperature change, the corresponding maximum allowable pressures are increased as reaccted in a shift upward in the P T limit (heatup and curves. De effect of the selection of these lower rates, then, is greater cooldown)l flexibility with higher allowable Appendix G pressures.

operationa The above changes permit the low temperature PORV pressure lift setpoint to be increased to accommodate higher decay heat values in the RCP start transient  !

analyses (corresponding to approximately 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> following reactor shutdown). The 1 low temperature PORV pressure lift setpoint is based on protecting the most limiting pressure of the applicable heatup and cooldown Apyndix G curves. This occurs during a cooldown at a temperature of 700F. Throug1 the selection process discussed above, the minimum allowable Appe.. dix 3 pressure has increased by 39.6 l psi. Consequently, the pressure limit which the PORV must protect when Qc RCS is below the MPT enable temperature has been increased by the same amount. .

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Specifically, the maximum allowable pressurizer pressure (not including pressure - J instrument uncertainty) when in MPT enable has increased from 424.5 psia to 4M 1 1 psia.

The maximum allowable heatup rate of 600F/hr, for an RCS temperature of 700F to  ;

3050F, has been reduced to 400F/hr and will be applicable for temperatures of 700F to 3130F, The maximum allowable heatup rate of 100F/hr will now be applicable for

• 3140F to 3270F rather than the previous temperature range of 3050F to 3270F. The maximum allowable cooldown rate for less than 1700F hu been changed from 200F L to 100F/hr.

I t Revised Technical Specification Figures 3-4.2a and 3 4.2b (heatup and cooldown  ;

curves) have been conservatively devcioped in accordance with the requirements of 10 CFR 50 Appendix G, as supplemented by Appendix G to Section III of the ASME Boiler and Pressure Vessel Code,1986 Edition. The adjusted RTNDTvalues used in their development have been consen>atively calculated using the methodology i p provided in Regulatory Guide 1.99 Revision 2, and are based upon the peak neutron Quence experienced by the reactor beltline region through a period of 12 Effective Full Power Years.

C. LTOP CONTROLS i i

ne low temperature PORV pressure lift setpoint is based on protecting the most restrictive pressure of both the heatup and cooldown curves. The most restrictive pressure limitation is for the 100F/hr cooldown at 700F in the RCS. With the P T limits being revised as presiously described, the maximum allowable pressurizer l pressure (not including pressure mstrument uncertainty) when in MPT enable has increased from 424.5 to 464.1 psia. A setpoint of 430 psia, which includes L

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requirements necessary for the protection of 464.1 psia, was selected.- [ NOTE:L It should be pointed out that the existing PORV lift setting in Technical Specification -  ;

3.4.9.3 is f 424.5 psia. his value represents the P T limit, without instrument ,

1 ' uncertainties. The actual PORV setpoint in the plant, with uncertainties accounted  !

for, is 384.4 psia. Henceforth, the actual PORV setting will be shown in the technical ,

specifications for clarity (430 psia).]

The LTOP enable temperature was developed using the guidance found in NRC Standard Review Plan 5.2.2, Revision 2. The enable temperature was originally ..

developed with the 12 EFPY P-T limits proposed in Reference (c) [and approved in Reference (a)]. The enable temperature was cehrlated uting specific heatup transients with changing thermal rates to reduce he r 7 plied thermal stress. The selection of the more restrictive heatup and cooldown rates and the resulting allowable pressure limits as described chove do not impact the LTOP enable E temperature. Therefore, the LTOP enable temperature remains unchanged, j D. h CP START CRITERIA 1 Modifications n+e v. the plant heatup and cooldown curves and associated rates permit raising the PSRV setpoint. The higher PORV setpoint provides additional l margin to accommodate possible pressurization transients after starting two (2) l reactor coolant pumps. The thermal hydraulic analysis of RCP start transients has been upgraded to more accuratel conditions within the pressurizer.y, buthave Calculations conservatively, also statisticallysimulate combined thermodyn ,

instrumentation uncertainties, providing additional margin in assumed initial  !

conditions for transient analysis. These improvements provide a set of operating i conditions which permit normal RCP starts without challenging the PORV. t ,

The plant conditions which must be satisfied for RCP starts are as follows:

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indicated initial pressurizer pressure less than or equal to 290 psia. This is a '

decrease of 10 psi from the current limit of 300 psia.-

3 indicated initial pressurizer level less than or equal to 170 inches. This is an L increase of 5 inches from the current limit of 165 inches.

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indicated steam generator secondary temperature no more than 300F higher than indicated RCS temperature. This is no change from the current limit.

L L . E. RCP STARTTRANSIENT ANALYSIS 1,

l Initial conditions for pressurizer pressure, pressurizer level, and steam generator to-L RCS

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delta-T are determined by statistical combination of instrumentation uncertainties. The statistical analysis provides at least a 95% confidence that 95% of the instrumentation uncertainty combinations are bounded. The methodology used a root-sum-square combination of instrument uncertainties, combined with 6cnsitivity L coefficients based on partial derivatives of peak pressure with respect to initial 1- pressurizer pressure and level, and steam generator - to - RCS delta T.

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y ~ Pressurizer insurge was calculated for limiting decay heat loads and steam generator . l to-RCS delta T. Analysis includes energy addition from two RCPs. , letdown is- 5 assumed to be isolated, and no credit is taken for sensible heat absorption by the RCS o component metal mass except as described below.T Limiting, insurge results are input

? to the pressurizer model described below.

Prior to the calculations described in our July 18,1990 submittal [ Reference (b)],

LTOP calculations of the RCS pressure rise for the LTOP energy addition transiccts (starting of RCPs) consisted of a calculation of the pressure change resultir,g from an adiabatic compression of the pressurizer steam space. Because an adiabstic process was assumed, no credit was taken for heat transfer mechanisms that wouk act to ,

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reduce the pressure rise following an insurge (i.e., condensation of steam on the L pressurizer walls as a result of wall heat transfer). l t

p For this analysis, a si:nple computer model of the pressurizer was developed to more accurately calculate the transient pressure response as a function of time. The model 1

- consists of three regions where Region 1 is the steam space, Region 2 is the initial 3

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saturated liquid volume, and Region 3 is the subcooled liquid region at the bottom of the pressunzer which is formed as a result of the transient insurge. The state conditions that can exist for each region are: saturated cc su xtheated steam in : <

Region 1, saturated or subcooled water in Region 2, and subcoo'ed water in Region 3.

Mass and energy transfer between Regions 1 and 2 is assumed to occur only as the result of liquid vaporization and/or steam condensation. Mass and energy transport into or out of the pressurizer is assumed to occur only as the result of surge flow, ,

oressurizer heater input, and wall heat transfer for this analysis. No credit is taken for condensation of steam on the liquid steam interface, or for the mixing of, or transfer - .t of heat between the initially saturated liquid and the colder insurge liquid. Heat '  ;

transfer is assumed to occur radially through the wall. No credit is taken for heat ~'

conduction to other structures.

F. MASS ADDITION TRANSIENTS The changes in PORV setpoints and pressure temperature limits do not affect the q existing mass addition transient controls. ,

L G. OUALITY VERIFICATION l

L As in the development of Reference (b), ABB Combustion Engineering Nuclear Power (CE) was consulted extensively during this analysis effort. Calculations performed by BG&E and CE were closely coordinated to ensure the analytical' approach and methods used were appropriate. The consultation end analysis by CE c provide aJded assurance that the analyses presented here are accurate.

II. REOUEST FOR LICENW AMENDMENT The Baltimore Gas and Electric Company hereby requests an amendment to Operating License DPR 53 for Calvert Cliffs Unit I with the submittal of the proposed Technical  :

Specifications in Attachment (1). These changes are required prior to entry into MODE 2, L

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i STARTUP. ' Unit _1 is currently scheduled to enter MODE 2 on September 18,1990;. a therefore we request approval of these changes before that date.

A.. DESCRIPTION OF CHANOES ,

1. Heatup and Cooldown Curves and Ratp1

a. Change Technical Specification Limiting Condition for Operation (LCO) 3.4.9.1.a (p. 3/4 4 23), maximum allowable heatup rates,~ as-follows:

Maximum Allowable Heatun Rate RCS Temocrature (FROM) 600 Fin any hour period- 700F to 3050F  !

100 Fin any hour period 3050F to 3270F l 600 Fin any hour period 2 3270F -  ;

(TO) 400 Fin any hour period 70oF to 3130F 100 Fin any hour period 3140F to 3270F 600 Fin any hour period > 3270F

b. Change Technical Specification LCO 3.4.9.1.b (p. 3/4 4-23) to limit ,

the cooldown rate to 10 F per hour when RCS temperature is below I 170oF The current limit is 200F per hour cooldown rate.

c. Replace old Technical Specification Figures 3.4 2a and 3.4-2b (pp. 3/4 4-24 and 4-24a),' RCS Pressure-Temperature- Limits, with new

. Technical Specification Figures 3.4-2a and 3.4 2b.

2. LTOP Controls 6

a. Change the PORV lift setting of Technical Specification 'LCO 3.4.9.3.a.1 and 2 (p. 3/4 4-26a) from "1424.5 psia" to "A 430 psia."

b. For references to the MPT enable temperature, where the wording-J "below 3270F" occurs, change it to "3270F or less." This is an editorial change for consistency with other references to MPT enable i

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, temperature; i.e., ?s 3270F," and more properly reflects its meaning." -  ;

' Affected Technical Specifications are:

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3.1.2.1- 3/41-8 [

3.1.23 3/4110 #

Table 33 3 3/4 3-11 4.5.2 3/45-4  :>

3.53 3/45-6 1 Bases 3/4.4.9 B3/44-8 i Bases 3/4.5.2 B 3/4 5 2

3. RCP Start Criteria ,

a. Change the RCP sta.t controls in footnote ("*) to ' the .i

- APPLICABILITY of Technical Specification 3.4.13 (p. 3/4-2a) as .

follows:

FROM .IQ l

Pressurizer water level-  :

$ 165 inches- . $ 170 inches Pressurizer pressure . s 300 psia 5290 psia

b. Add a' footnote (") to the , APPLICABILITY of Technical i

~ Specification 3.4.1.2 (p. 3/4 4-2) to provide RCP start controls; consistent with those existing in Technical Specification 3.4.13.

c. Also in footnote ("') to Technical Specification 3.4.13 delete the. -

requirement to measure pressurizer pressure " ... by plant computer or equivalent precision instrument,". and the restriction on entry into MODE 2. These requirements were part of the temporary RCP 1 controls established by Reference (a) and are no longer needed.: t

-Normal control room panel indication of pressurizer pressure is - i L

sufficient for implementation of the newly proposed controls. The- .

new controls are also valid for higher decay heat loads, therefore the restriction from entry in MODE 2 can be removed.

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4. 73 Bases  ;

I Revise Technical Specificatic4 Bases 3/4.4.1, Coolant Imops and Coolant L Circulation and Bases 3/e' J ), Pressure / Temperature Limits, to be consistent

. with the above changes.

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B. DETERMINATION 'OF NO SIGNIFICANT HAZARDS

' Rese pro msed changes have been evaluated against the standards in 10 CFR 50.92

- and have men determined to involve no significant hazards considerations, in that i operation of the facility in accordance with the proposed amendment would not: ,

(i) ' involve a significant increase in the probability or consequences of an accident pn viouslyevaluated;or

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De existing Unit 1 ~2 EFPY P T limits (approved by Reference a) were-conservatively developed in accordance with the fracture 'oughness - . .

requirements of 10 CFR 50,- Appendix G, as supplemented by the ASME Code Section III, Appendix G. The reactor vessel material Adjusted RTNDT values are based on the conservative methodology provided in Regulatory Guide- 1.99, Revision 2. This amendment will not change the P T limit calculations that are the basis for the existing heatup and cooldown curves;  !

L however, a neve combination of heatup and cooldown curves and associated rates has been selected from this set of limits.' This new selection, which features lower heatup and cooldown rates, permits the Appendix G allowable -

pressure to be increased for corresponding temperatures, thereby increasing the region of allowable operations with reactor coolant pumps. This  ;

additional operational flexibility minimizes x the potential for pressure -

transients that could challenge the P T limits during normal plant startup and shutdown evolutions. The new heatup and cooldown curves and associated ,

t limits continue to provide conservative administrative restrictions on reactor coolant system pressure to minimize material sta.sses in the RCS due to normal operating transients, thus minimizing the IRelihood of a rapidly propagating fracture due to pressure transients at low temperature. Because -

these new heatup and cooldown curves and rates are based on the same P-T ,

y limits approved in Reference (a), this proposed amendment does not involve L an increase in the probability or consequences of accident previously evaluated.

O Consistent with the selection of new heatup and cooldown curves and rates, . .

the LTOP controls are being changed by increasing the PORV lift setting to ,

430 psia. The MPT enable temperature of 3270Fis not being changed. The ,

new PORV setpoint is based on protecting the most restrictive pressure of both the heatup and cooldown curves; i.e., a 100F per hour cooldown at 700F

> RCS temperature. Since the basis for the selection of the PORV setpoint has not chaaged, the PORV would provide the same degree of protection in mitigating postulated LTOP transients with the new setting as tbat provided by the present LTOP system. Therefore, this change does not increase the l F - probability or consequences of accidents previously evaluated. 3 The lower heatup and cooldown rates and the increased PORV lift setting  !

provides additional margin to accommodate postulated pressurization from energy addition transients. New calculations have been performed that more precisely predict the response to such transients. From these calculations, a revised set of RCP start controls have been selected that will permit planned RCP starts during normal operational activities without challenging the

PORV For the postulated start of 2 RCPs during recovery from a loss of 1

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- August 13,1990 1 Page 9 l decay heat removal, the PORVs may be required to respond in cases where decay heat load is high if operator actions are either not taken or are ineffective. A single POR / has been determined to be capable of ,

adequately mitigating this trarulent. Because these RCP controls now credit -

the function of the PORV to migitate certain energy addition transients, this ^

is considered a slight incr<,ase in the consequences of these transients.

However, because the remits of the analysis remain well within the conservative acceptance limits of 10 CFR 50 Appendix 0, this increase is r.ot significant.

(ii) create the possibility of a new or different type of accident from any accident previously evaluated a

The changes to the heatup and cooldown curves and rates, PORV lift-setting, and the RCP controls do not represent a significant change in the configuration or operation of the plant. Specifically, no new hardware is .

being added to the plant as part of the proposed change, no' existing equipment is being modified, nor are any significantly different types of l operations being introduced. Therefore, the proposed amendment would not  :

create the possibility of a new or different kind of accident from those previously evaluated.

(iii) involve a significant reduction in the margin ofsafety This change will ensure that the margin of safety is maintained with respect to an energy addition event in that there are no postulated events that could challenge the Appendix G curves. The changes to the controls placed on the variables for a planned RCP start are mmor in nature and provide. an additional margin of safety. The changes to.the heatup and cooldown curves / rates and the PORV lift setting ensure that the margin safety is - ,

maintained by protecting the Appendix G limits for all postulated transients.

The changes made in the manner of reference to the MPT enable temperature are editorial. The MPT enable temperature is 3270F; therefore, ,

all references to the LTOP temperature region should be "at 3270F and less,"

or equivalent. Since this is consistent with other existing references to MPT enable temperature, this change does not constitute a significant hazards ,

consideration.

t C.. SAFETY COMMITTEE REVIEW  :

This proposed change to the Technical Specifications and our determination of significant hazards have been reviewed by our Plant Operations and Safety Review- l Committee.and Off Site Safety Review Committee, and they have concluded that  :

implementation of these changes will not result in an undue risk to the health and L safetyof the public.

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, Very trulyyours v -

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STATE OF MARYIANu :

bwb4) hImb,: TO WIT:

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-o () l I hereby certify that on th: /d day of >M//oS . .J9ff bejore me, the ubscriber, .

a Notary Public of the State of Maryland v in and for /</>////>d;/' // _ >

personally appeared George C. Crect, being duly sworn, and sfates that he is Vice Pd:sident of the

~ Baltimore Gas and Electric Company, a corporation of the State of Maryland; that he provides the foregoing response for the purposes therein set forth; that the statements made are true and correct to the best of his knowledge, information, and belief; and that he was authorized to provide the response on behalf of said Corporation.

WITNESS my Hand and Notarial Scal: dv///N u

'$/g&iy Public &

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My Commission Expires: /M////>h//df #4M

Date / ,

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Attachments: (1) Proposed Technical Specification Changes (2) . LTOP System Description '

l l: cc: D. A. Brune, Esquire J. E. Silberg, Esquire R. A. Capra, NRC D. G. Mcdonald, Jr., NRC T. T, *"artin, NRC L E. , .alson, NRC R. I. M. .:an, DNR 1-i l

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