ML20248F927

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Application for Amend to License DPR-61,changing Tech Spec Section 3.11.B Re Containment Integrity During Containment Air Recirculation Fan Motor HX Cleaning Activities
ML20248F927
Person / Time
Site: Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png
Issue date: 03/31/1989
From: Mroczka E
CONNECTICUT YANKEE ATOMIC POWER CO., NORTHEAST UTILITIES
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20248F931 List:
References
B13201, TAC-72024, NUDOCS 8904130261
Download: ML20248F927 (10)
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March 31, 1989 Docket No. 50-213 B13201 Re: 10CFR50.90 and 50.91 U.S. Nuclear Regulatory Commission Attention: Document Control Desk i Washington, DC 20555 Gentlemen:

i Haddam Neck Plant Proposed Revision to Technical Specifications Containment Integrity During Containment Air Recirculation Fan Motor Heat Exchanaer Cleanina Activities Pursuant to 10CFR50.9C and 50.91, Connecticut Yankee Atomic Power Company  !

(CYAPCO) hereby proposes to amend Operating License DPR-61 by incorporating the changes identified in Attachment 1 into the Technical Specifications for the Haddam Neck Plant.

Specifically, the proposed change to Technical Specification Section 3.11.8 will prorlde an expansion of the one-time relaxation of containment integrity l specifications, issued as License Amendment No.112, to allow the four con-tainment air recirculation (CAR) fan motor heat exchangers to be cleaned or replaced while at power (see Figure 1). Each CAR fan motor heat exchanger is comprised of two cooling coils (see Figure 2).

Backaround In a letter dated February 10, 1989,II) CYAPC0 proposed to amend Operating License DPR-61 by incorporating certain changes into the Technical Specifica-tions for the Haddam Neck Plant. Specifically, the proposed changes would allow a one-time relaxation of containment integrity specifications to allow the service water side of the four CAR fan g t exchangers to be cleaned while at power. In a letter dated March 7, 1989, the NRC Staff issued Amendment No. 112, approving CYAPC0's license amendment request.

l (1) E. J. Mroczka letter to the U.S. Nuclear Regulatory Commission,

" Containment Integrity During CAR Fan Hect Exchanger Cleaning Activities," dated February 10, 1989.

(2) A. B. Wang letter to E. J. Mroczka, " Issuance of Amendment (TAC 1 No. 72024)," dated March 7, 1989.

AM 8904130261 890331

{DR ADOCK 05000213 Ig PDC

U.S. Nuclear Regulatory Commission B13201/Page 2 March 31, 1989 Following receipt of the license amendment, CYAPC0 -initiated the process of cleaning each CAR fan heat exchanger as described in the February 10, 1989 letter. Upon opening the heat exchangers, we confirmed our expectations and found that there was a buildup of material that restricted service water flow through the exchangers. However, the fouling mechanism was somewhat different than anticipated in that rather than providing localized tube plugging, there was a uniform buildup over the whole heat exchanger. The cleaning process has successfully removed the material.

In addition to the CAR fan heat exchangers, there is a smaller motor heat exchanger for each of the four CAR fans (two cooling coils per fan motor heat exchanger). Because of the fouling mechanism identified, CYAPC0 has concluded it would be necessary to clean these heat exchangers as well. CYAPC0 has performed a reevaluation of the service water system and concluded that with the CAR heat exchangers cleaned, Haddam. Neck Plant operation is acceptable with a service water temperature up to 75'F. CYAPC0 has determined that to operate above 75'F, the CAR fan motor heat exchangers would have to be cleaned or replaced as well . In recent discussions with the NRC Staff, CYAPC0 discussed our plans and rationale for inspection of the . fan motor heat exchangers to correct any fouling that may be present.

Description of Prorosed Chana9 The purpose of the change to Section 3.11.B (including the bases) of the Technical Specifications is to permit CAR fan motor heat exchanger cleaning /

replacement during power operatien. The service water piping (containment boundary) for each CAR fan motor heat exchanger may be impacted for up to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> at a time to install or remove threaded pipe caps and test the newly established containment boundary during power operation. During this short time, compensatory measures will be taken to provide an alternate containment barrier. If the service water piping is not restored to the original configu-ration or isolated by leak-tested valves or threaded pipe caps within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, the proposed specification requires the plant to be in HOT STANDBY within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTOOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />. The total of 64 hours7.407407e-4 days <br />0.0178 hours <br />1.058201e-4 weeks <br />2.4352e-5 months <br /> established in License Amendment No. ?.12 for cleaning the CAR heat exchangers will remain as an absolute limit for servicing both the CAR heat exchangers and the fan motor heat exchangers. If the 4-hour limit is exceeded, the total time that containment integrity is relaxed is to be counted towards the 64 hours7.407407e-4 days <br />0.0178 hours <br />1.058201e-4 weeks <br />2.4352e-5 months <br />. This is a one-time change which is applicable only during the remainder of Cycle 15 to allow the sequential cleaning of each CAR fan motor heat exchanger.

The service water piping itself inside containment constitutes the containment barrier. That is, there are no service water valves inside containment which are credited as being containment isolation valves as specified in 1-0CFR50, Appendix A, General Design Criterion 57. The NRC Staff has accepted this configuration using seismic qualification of piping inside containment as the

U.S. Nuclear Regulatory Commissioil B13201/Page 3 March 31, 1989 basis for this position.(3) In order to clean the CAR fan motor heat exchang-ers the service water piping pressure boundary inside containment may be impacted resulting in containment integrity being technically

. relaxed. z4) thus Description of Cleanina Activities In order to physically clean / replace each CAR fan motor heat exchanger, the i following sequence will be utilized:

1. A CAR unit will be removed from service for a period not to exceed 7 days in accordance with existing administrative controls. The Haddam Neck Plant Technical Specifications will be met throughout these evolutions since they require that only three CAR units be operable while the reactor is critical.
2. The appropriate service water supply to the motor cooler will be isolated by closing manual valve SW-V-771A, 772A, 773A, or 7/4A. i
3. The corresponding service water return from the motor cooler will be isolated by closing manual valve SW-V-7718, 772B, 7738, or 774B.
4. The corresponding service water return isolation ball valve SW-V-264, 266, 268, or 270 will be closed.
5. The corresponding CAR fan motor cooler will be drained by utilizing the drain connections on the motor cooler. This step results in the relaxa-tion of containment integrity.
6. The flexible hose will be disconnected at the first threaded connection.

The manual isolation valves closed in Steps 2 and 3 will be leak tested.

A pipe cap will be installed on the piping at the inlet and outlet motor cooler service water valves. These caps will be tested for leak tight-ness if the corresponding manual valves are not leak tight.

(3) The D. M. Crutchfield letter to W. G. Counsil, dated May 7, 1982, concluded that an exemption from Appendix J testing for Penetrations P-51 through P-58, service water to and fro,n the CAR unit is not required because isolation valves in closed systems inside containment which do not rupture as a result of a LOCA do not require Type C testing.

(4) In a strict regulatory sense, containment M egrity is being relaxed and that is the reason for this license amendment request. However, the compensatory measures described herein are designed to ensure that a redefined containment boundary will adequately prevent a radioacti.ve '

release in the unlikely event of a design basis accident concurrent with this cleaning evolution.

U.S. Nuclear Regulatory Commission B13201/Page 4 March 31, 1989 i

7. The service water side of the CAR motor cooler will be cleaned or the units replaced as necessary.
8. After cleaning or replacement, the pipe caps will be removed and the flexible hose . reinstalled.
9. The motor cooler service water supply and return valves will be opened to fill and pressurize the piping. Each reconnected joint will be inspected for leakage. No leakage is acceptable at normal service water system pressure. This step reestablishes containment integrity.
10. The service water return manual ball valve will be opened returning the CAR fan to service.

During the above sequence of operations, the existing seismic integrity of the affected service water supply and return piping inside containment will not be degraded.

Significant Hazards Consideration i

In accordance with 10CFR50.92, CYAPC0 has reviewed the attached proposed change and has . concluded that it does not involve a significant hazards ,

consideration. The basis for this conclusion is that the three criteria of.  !

10CFR50.92(c) are not compromised. The proposed change does not involve a '

significant haards consideration because the change would not:

1. Involve a significant increase in the probability or consequences of an accident oreviously evaluated. This Technical Specification change is I bounded by the evaluation submitted in CYAPC0's letter dated N: uary 10, 1989, and approved by the NRC Staff in Amendment No. 112. The tt tal time restriction of 64 hours7.407407e-4 days <br />0.0178 hours <br />1.058201e-4 weeks <br />2.4352e-5 months <br /> for having the service water system opan enve- 3 lopes this proposed change as well. CYAPC0 is not requesting an addi- I tional 64 hours7.407407e-4 days <br />0.0178 hours <br />1.058201e-4 weeks <br />2.4352e-5 months <br />, but proposes to perform the work allowed by this license i amendment under the original 64-hour restriction approved in Amendment No. 112. Therefore, the 10CFR50.92 evaluation described in CYAPCO's February 30, 1989, license amendment request bounds this proposed change  !

as well.

1 In the process of cleaning / replacing the CAR fan motor cooling coils, the CAR units will be removed from service one at a time. A design basis accident (DBA) LOCA or steam line rupture coincident with a failure of i one of the three operable CAR units could result in insufficient cooling l of containment. Thus, containment design pressure and/or temperature l could potentially be exceeded. However, the Haddam Neck Plant Technical i Specifications require that only three CAR units be operable whenever the reactor is critical, and current administrative controls allow a fourth l

CAR unit to be removed from service for up to 7 days. Since the unavail-ability of the CAR system due to the cleaning process is equivalent to the unavailability already permitted by the administrative controls, the

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U.S. Nuclear Regulatory Commission B13201/Page 5 March 31, 1989 3 I

proposed configuration is allowed by existing administrative controls and is equivalent to the existing Technical Specifications. In addition, the evaluations confirm that four service water pumps and three operable CAR units are adequate to meet all service water cooling requirements, including containment cooling with service water temperature less than 75'F. Therefore, the consequences of a DBA will not be significantly increased by the removal of a single CAR unit from service for cleaning.

By opening up the service water piping inside containment, containment integrity will be technically relaxed. If a DBA LOCA were to occur coincident with a loss of containment, the allowable off-site dose could be exceeded absent compensatory measures. To ensure that an adequate containment will be in place at all times during the CAR cooling coil cleaning activities, special precautions will be implemented as compensa-tory measures. During the time the service water piping is open, the supply and return lines from the fan motor coolers will be isolated by manual isolation valves (see Figures 1 and 2). Also, the service water supply line isolation valve will be open to maintain service water pressure in that line greater +han projected peak accident pressure inside containment (Pa). As an additional precaution, threaded caps will be placed on the ends of the open CAR fan motor cooler supply and return lines. This will offer additional protection in the unlikely event that off-site power is lost and one emergency diesel generator fails to start.

In this case, only one service water pump can be assumed to be operating,  ;

and it cannot be assured that service water pressure would remain above I Pa. Therefore, the compensatory measures will ensure that no significant increase in radiological consequences following an accident will occur as a result of this change. During the allowable time that the service water piping may be open, the containment barrier will be the manual isolation valves, the piping caps, the water pressure in the service water piping, and the seismic integrity of the service water piping i inside containment.

The proposed change would not affect the probability of a DBA LOCA or a steam line rupture. As stated earlier, administrative controls currently l allow a single CAR unit to be removed from service for up to 7 days.

I Therefore, the probability of failing the CAR fan system will not be significantly affected.

l The special procedure regarding isolation of service water supply to the l CAR fan motor heat exchanger unit will not impact service water system availability to other components.

The purpose of the proposed change is to clean / replace the CAR fan rotor heat exchangers. In so doing, service water flow through the heat j exchanger will increase. This increase in heat removal capacity is necessary to restore the CAR unit performance to that assumed in the updated Final Safety Analysis Report for the design service water j i

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U.S. Nuclear Regulatory Commission B13201/Page 6 March 31, 1989 temperature. The net effect of the change will be to improve CAR unit-cooling system performance, specifically by ensuring proper fan motor cooling.

2. Create the possibility of a new or different kind of accident from any pmiousiv evaluates!. The possibility for an accident or malfunction of a different type than any evaluated previously in the Final Safety Analysis Report is not created since the change and/or failure modes associated with the change do not modify the plant response to the point where it can be considered a new design basis accident. There are no new failure modes associated with the proposed change which could represent a new unanalyzed accident.

In addition, our plant-specific Probabilistic Safety Study was utilized to gain additional insight regarding this criterion of the no significant hazards consideration determination.

The compensatory measures, combined with the short duration of contain-ment integrity relaxation, result in an increase in the probability of failure of containment isolation of 7 x 10 5 when averaged over a year.

This low probability, coupled with the low probability of accidents resulting in a release of significant radioactivity into the containment, is judged to be negligible and need not be considered for this mainte-nance evolution. The basis for this determination is that containment isolation failure in tha current configuration has some finite probabil-ity, and the incremental increase resulting from the propo. sed change would be insignificantly small.

In addition, a qualitative assessment of the core melt frequency risk associated with a seismic event and a loss of containment integrity during the 64-hour period was performed. Using the Millstone Unit No. 3 seismic hazard curves and the seismic experience data base on inherent seismic capacity of ANSI B31.1 nonseismically supported piping, it may be shown that the probability of pipe rupture during the 64-hour period as a result of a seismic initiating event is of the same order of magnitude as the probability of a core melt accident (nonseismic) concurrent with loss of containment integrity reported above.

The pr%osed change does not create a new unanalyzed event based on compensatory measures which will be in effect. As described above, the proposed change does not increase tne probability of an accident to the point where it should be considered within the design basis of the plant.

3. Invol.ve a significant reducticn in a marain of safety. The proposed change does not impact the consequences of an accident on the fuel or reactor coolant system protective boundaries. The impacts on containment integrity and off-site public dose are sufficiently low as to be consid-ered beyond the design basis of the plant.

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1 U.S. Nuclear Regulatory Commission J B13201/Page 7 1 March 31, 1989 l

The proposed change will allow the opening of the service water piping i inside containment for relatively short periods of time. This piping j serves as the containment boundary. The relaxation of containment 4 integrity does not represent a significant reduction in the cargin of I safety. As noted above, the compensatory measures which will be imple- J mented provide reasonable assurance that the containment boundary will be j maintained and that the allowable off-site dose limit will not be j exceeded. i Basec' on the above discussion, the proposed change will not decrease the 4 margin of safety because of: {

a. The compensatory measures to maintain the containment boundary,
b. The relatively short duration when the service water pipir.g inside containment is open.
c. The unavailability of the CAR fan units is bounded by that allowed by both the Technical Specifications and existing administrative control s .

Moreover, the Commission has provided guidance concerning the application of standards in 10CFR50.92 by providing certain axamples (March 6, 1986, 51FR7751) of amendments that are considered not likely to involve a signifi-l cant hazards consideration. Although the proposed change herein is not

  • enveloped by a specific example, the proposed change would not involve a significant increase in the probability or consequences of an accident previ-ously analyzed. As stated earlier, the proposed change, coupled with the compensatory measures, will ensure that no significant increase in conse-quences following an accident will occur as a result of this proposed change.

In addition, the change does not create a new unanalyzed event based on compensatory measures which will be taken and associated probabilistic consid-erations. The change does not increase the probability of an accident to the point where it should be considered within the design basis. Finally, the crapensatory measures will provide assurance that the containment boundary I will be maintained and that the allowsble off-site dose limit will not be I exceeded. Based on this and the fact that the service water piping inside i containment will be open for a relatively short duration, the margin of safety l is not significantly decreased. 7 Based upon the information contained in this submittal and the environmental l

assessment for the Haddam Neck Plant, there are no significant radiological or nonradiological impacts associated with the proposed action, and the proposed license amendment will not have a significant effect on the quality of the human environment.

The Haddam Neck Plant Nuclear Review Board has reviewed and approved the attached proposed ravisions and concurs with the above determinations.

i U.S. Nu lear P.egulatory Commission ,

B13201/Page 8 l March 31,.1989 In accordance with 10CFR50.91(b), CYAPC0 is providing the State of Connecticut with a copy of this amendment.

-We trust ycu find this information satisfactory for issuance of the requested amendment. CYAPC0 requests review and issuance of this proposed license amendment as soon as possible and no later than May 30, 1989 in order to allow the cleaning of the CAR fan motor heat exchangers prior to the service water  ;

temperature exceeding 75*F. 1 i

Very truly yours, '

CONNECTICUT YANKEE ATOMIC POWER COMPANY OAfd E. J'Atroczka #

e<J Senior Vice President cc: W. T. Russell, Region I Administrator .

A. B. Wang, NRC Project Manager, Haddam Neck Plant 1 J. T. Shediosky, Senior Resident Inspector, Haddam Neck Plant Mr. Kevin McCarthy Director, Radiation Control Unit  !

Department of Environmental Protection Hartford, CT 06116 STATE OF CONNECTICUT)

) ss. Berlin COUNTY OF HARTFORD )

Then personally appeared before me, E. J. Mroczka, who being duly sworn, did state that he is Senior Vice President of Connecticut Yankee Atomic Power Company, a Licensee herein, that he is authorized to execute and file the foregoing information in the name and on behalf of the Licensees herein, and that the statements contained in said information are true and correct to the best of his knowledge and belief.

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