ML18053A332

Application for Amend to License DPR-20,changing Tech Specs to Update Low Temp Overpressure Protection Requirements

ML18053A332
Person / Time
Site:	Palisades
Issue date:	04/12/1988
From:	Hoffman D CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:
Shared Package
ML18053A306	List: ML18053A304 ML18053A308 ML18053A332
References
NUDOCS 8804250194
Download: ML18053A332 (6)

Text

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• 1 CONSUMERS POWER COMPANY Docket 50-255 Request for Change to the Technical Specifications License DPR-20 For the reasons hereinafter set forth, it is requested that the Technical Specifications contained in the Provisional Operating License DPR-20, Docket 50-255, issued to Consumers Power Company on October 16, 1972* for the Palisades Plant be changed as described in Section I below:

I. Changes A. Section 3.1.lh is revised to ensure an energy addition to the PCS I will not occur when forced circulation is initiated at low PCS I temperatures (see page changes). I I

B. The last paragraph in the Basis for section 3.1 is revised to I explain why precautions against a PCS energy addition are only I required at low temperatures (see page changes). I I

C. S~ction 3 .1. 2a has been revised to restrict heatup rate limitaticms I at low temperatures (see page changes). I I

D. Proposed Section 3.l.2b has been revised to restrict cooldown rates I at low temperatures (see page changes). I I

E. Section 3.1;2c has been revised to include the heatup and cooldown I rate restrictions as proposed in Section.3.l.2a and b (see page I changes). I I

F. Section 3.1.2d has been revised to restrict the pressurizer heatup I rate (se~ page changes). I I

G. Two paragraphs have been proposed at the end of the Basis for I Section 3.1.2 to explain limitations placed on heatup and cooldown I rates (see page changes). I I

H. Figures 3-1 and 3-3, the pressure/temperature limits for heatup I and hydro, have been revised to allow higher pressures at a given I temperature. Figure 3-2, pressure/temperature limits for I cdoldown has been revised in format only to maintain consistency I with the format of Figures 3-1 and 3-3 (see page changes). I I

I. Section 3.1.8 is completely revised to change PORV setpoints, I increase the temperature range.where LTOP is applicable and I provide an alternate method of venting the PCS (see page changes). I I

J. Section 3.3.2g is revised to enhance protection against core damage I if a loss of coolant accident would occur while the reactor is I subcri!tical; and>i at the same time, ft ensures that Appendix G I

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2 heatup and cooldown limits will not be exceeded while requiring one I HPSI pump to be operable above 350°F, two HPSI pumps to be operable -I above 460°F, and a dedicated operator if the PORV's are not operable I above 385°F and less than 430°F. In addition, a choice of method of I insuring HPSI inoperability is allowed to permit pump testing (see I page changes). I I

K. The last paragraph of the Basis for section 3.3 is deleted and four I paragraphs added to include the basis for HPSI operability require- I ments in certain PCS temperature ranges, for the requirement to have I 1

a d edicated operator and for the exceptions to the requirements of I Section 3.0.3 (see page changes). /

I L. Section 4.1.lc has been added to provide a surveillance requirement I when open PORV pilot valves are used as an alternative to venting I the PCS (see page changes). I I

M. Sections 4.6.la and b have been combined as Section 4.6.la and a I new Section 4.6.lb has been added to ensure both HPSI pumps are I inoperable when the PCS temperature is less than 300°F (see page I changes). I I

II. Discussion The above proposed Technical Specifications changes will provide Low Temperature Overpressure Protection (LTOP), enhance protection against core damage resulting from a subcritical loss of coolant accident (LOCA), and prevent the 10CFRSO Appendix G heatup and cooldown pressure limits from being exceeded. Above 430°F, the pressurizer safety valves provide overpressure protection. Three conditions are recognized which could cause the primary coolant system (PCS) pressure to exceed the 10CFR50 Appendix G limits. They are:

1. A mass addition caused by the start of a high pressure safety injection (HPSI) pump,

2. A mass addition resulting from a charging/letdown imbalance,

3. An energy addition caused by the initiation of forced circulation when the steam generator temperature is greater than the cold leg temperature of the PCS.

A mass addition by a HPSI pump and the concurrent pressure increase is I limited in proposed section 3.3.2g by the requirement for both HPSI I pumps to be inoperable when the PCS temperature is less than 300°F I unless the reactor head is removed and by requiring that only one HPSI I pump be operable when the PCS temperature is equal to or more than I 350°F and is less than 430°F. I I

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The setpoints of the Power Operated Relief Valves (PORVs), as required I

- -- by proposed -sections 3; 1. 8a and 3 .1. 8b, have been shown by analysis I (References 1, 2 & 3) to be low enough to prevent the pressure increase I resulting from the maximum possible charging/letdown imbalance (three I charging pumps operating and letdown isolated) plus a one pump HPSI from I causing the PCS pressure to exceed 10CFR50 Appendix G heatup and I cooldown pressure limits. I I

Analysis (Reference 4) has been completed which shows that the maximum I possible charging/letdown imbalance plus inadvertent HPSI operation I will not cause the 10CFRSO Appendix G pressure limits to be exceeded I when the PCS temperature is greater than 385°F, a bubble is formed in /

the pressurizer, the actual pressurizer liquid level is less than 60%, I and a dedicated operator takes mitigatory action within 2.9 minutes. I Proposed section 3.1.8c allows the PORVs to be inoperable when these I conditions exist. Forming a bubble of appropriate size and rendering I the PORVs inoperable facilitates operation by increasing the size of I the operating pressure/temperature window. Proposed Section 3.3.2 I requires a dedicated operator. I I

ACTION steps "a" and "b" of Section 3.1.8 are similar to the Standard I Technical Specifications except the option of venting the PCS by opening I the pilot valves and block valves for both PORVs has been added. I Analysis (Reference 1) has been completed which shows that if a single PORV is open at 310 psia, a charging/letdown imbalance will not cause the 10CFR50 Appendix G pressure limits to be exceeded.

The proposed requirement in Section 3.1.lh for the steam generator temperature to be less than or equal to the PCS cold leg temperature before a primary coolant pump is started to initiate forced circulation, unless the PCS cold leg temperature is more than 450°F, eliminates the possibility of a low temperature energy addition caused by the initiation I of forced circulation. Above 450°F, an energy addition to the PCS resulting from the initiation of forced circulation will not cause the 10CFR50 Appendix G pressure limits to be exceeded because the PCS safety valves provide adequate overpressure protection.

Proposed Sections 3.1.2a, b, and c. are necessary to restrict heatup and cooldown rates to those rates for which the pressure limits of 10CFR50 I Appendix G, as illustrated in Figures 3-1, 3-2 and 3-3 of Section 3 .1. 2, are above the maximum pressures which could result from a possible transient. Proposed Section 3.l.2d restricts the pressurizer heatup rate to maintain the PCS within the analyzed conditions (Reference 2).

_Proposed ch?nges to the heatup and hydro pressure/temperature limits in I Figures 3-1 and 3-3 of Section 3.1.2 are the result of the deletion of I non-required conservatisms. The proposed limits were derived using Reg I Guide 1.99 draft Revision 2 correlations and remain in compliance with I Appendix G of 10CFR50. The proposed changes have been informally I reviewed by the NRC staff and are the basis for administrative LTOP I and low temperature ECCS requirements as described in our January 20,. I 1988 and January 22, 1988 submittals. Reference 5 contains the analysis I which determines pressure and temperature limits. I OC0288-0039-NL02

4 The proposed changes in Sections 4.1.lc, 4.6.lb and in the basis for Section 4.6 align the Surveillance Requirements with the proposed Limiting Conditions for Operation.

Therefore, through a combination of PORV setpoints, equipment operability requir~ments, and restrictions on the primary/secondary temperature relationship when initiating forced circulation in the PCS, the proposed Technical Specifications prevent the pressure limits of the 10CFR50 Appendix G curves from being exceeded.

References

1. EA-PAL-85-101 "Calculation of PCS Pressure Increase From Adding I 133 gpm (3 charging pumps) Before the PORVs Open," November 4, 1987. I I

2. EA-PAL-LTOP-880119 "Calculation of Required PORV Capacity to maintain /

the PCS Below Appendix G", January 20, 1988. I I

3. EA-PAL-LTOP-880120 Rev A - "PORV Flow Capacity at Expected LTOP /

Conditions" February 15, 1988. I I

4. EA-PAL-LTOP-880121 - "Calculation of Time for Operator to Act for l HPSI and Bubble" January 20, 1988. I I

5. EA.:.RBJ-RWS-"Palisades Reactor Pressure Vessel Temperature Limits /

Determination", April 4, 1988. /

I III. Analysis of No Significant Hazards Consideration Consumers Power Company finds that activities associated with this change request involve no significant hazards, and, accordingly, a no significant hazards determination per 10CFR50.92(c) is justified. The following evaluation supports that finding.

Evaluation

1. Involve a significant increase in the probability or consequences an accident previously evaluated LTOP prevents the PCS pressure from exceeding 10CFR50. Appendix G pressure/temperature limits. Three recognized conditions could cause those limits to be exceeded. Two involve mass additions i.e.,

an inadvertent HPSI pump start and/or a charging/letdown imbalance.

The third involves an energy addition - i.e., the initiation of forced PCS circulation when the steam generator temperature is greater than the PCS temperature.

This proposed Technical Specification change prevents those conditions from causing Appendix G limits to be exceeded by:

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1. Requiring both HPSI pumps to be inoperable below 300°F, I requiring one HPSI pump to be inoperable below 430°F, and I

2. Requiring the PORVs to be operable (unless T > 385°F~ actual pressurizer level is less than 60%, and a deH~~ated operator is used) up to 430°F, and

3. Requiring the steam generator temperature to be equal to or less than the PCS temperature when forced PCS circulation is initiated unless the PCS temperature is high enough to allow the PCS safety valves to provide overpressure protection.

The PORV setpoint has been lowered and the temperature range over I which the PORV's provide protection has been extended. Therefore, I overall the probability of exceeding allowable pressures is *j decreased. The LOCA during heatup or cooldown has not been I evaluated nor has the NRC reviewed it using specific NRC guidance. I Thus, the proposed change does not increase the probability or I consequence of a previously evaluated accident. However, the. I proposed change does insure at least one HPSI pump available at I temperatures above 350°F to insure adequate heat removal. I

2. Create the possibility of a new or different kind of accident from any accident previously evaluated The proposed changes slightly raise the heatup pressure limits, I significantly lower the pressure relief setting, extend LTOP to I higher temperatures and add precautionary operator monitor measures I during heatup and cooldown. None of these changes create a new or I different kind of accident from that previously evaluated for LTOP. I I

There has been no LOCA evaluated for plant conditions during heatup. I or cooldown, thus, no change to previous evaluations. The proposed I change is to insure LOCA protection equipment operability and revise I LTOP setpoints. Maintaining LOCA equipment operable over an I extended plant operating mode could change the probability of a I low temperature overpressure accident but does not create the I possibil~ty of a new or different kind of accident. /.

3. Involve a significant reduction in a margin of safety The margin of safety is the difference between the stress at which the PCS pressure boundary could fail and the stress permitted by 10CFRSO Appendix G. This change does not change the stress allowed by 10CFRSO Appendix G and ensures that the stress allowed by .10CFRSO Appendix G will not be exceeded. Therefore, it does not involve a reduction in.a margin of safety.

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6 IV. Conclusion

• • The Palisades Plant Review Committee has reviewed this Technical Specification Change Request and has determined that this change does not involve an unrevi.ewed safety question and therefore involves no significant hazards consideration. This change has also been reviewed under the cognizance of the Nuclear Safety Board. A copy of this Technical Specification Change Request has been sent to the State of Michigan official designated to receive such Amendments to the Operating License.

CONSUMERS POWER COMPANY By~ David P Hoffman, i Nuclear Operations Sworn and subscribed to before me this 12th day of April 1988.

Elaine E Buehr r, otary Public Jackson County, Michigan My commission expires October 31, 1989 OC0288-0039-NL02