B13834, Application for Amend 47 to License NPF-49,modifying Tech Spec 4.6.4.2.b.4, Electric Hydrogen Recombiners, to Provide Variable Acceptance Criteria for Flow Testing Containment Pressures

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Application for Amend 47 to License NPF-49,modifying Tech Spec 4.6.4.2.b.4, Electric Hydrogen Recombiners, to Provide Variable Acceptance Criteria for Flow Testing Containment Pressures
ML20079A999
Person / Time
Site: Millstone Dominion icon.png
Issue date: 06/06/1991
From: Mroczka E
NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20079B000 List:
References
B13834, NUDOCS 9106120193
Download: ML20079A999 (6)
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T U.C.[w.CUI[,Y.! P O BOY 270 k 2., e .ON.C((j,,,. HARTf OFtD. CONNECilCUT 0014 Mc70 E .A .~.s a ea w n (20386% S/C June 6, 1991 Docket No. 50 421 1111011 Re: 10CfR50.90 1

U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555

Gentlemen:

Millstone Nuclear Power Station, Unit No. 3 Proposed Revision to Technical Specifications Hydcoaen Recombiners Pursuant to 10CFR50.90, Northeast Nuclear Energy Company (NNECO) hereby proposes to amend its operating license, NPF 49, by incorporating the changes identified in Attachment 1 into the Technical Specifications of Millstone Unit No. 3.

!!rckaround inaletterdatedMarch2,1990,N the NRC Staff issued Amendment No. 47 to NNECO for Millstone tJnit No. 3. This amendment was issued in response to a license amendment request submitted by NNECO on November 2,1989 and later supplemented on December 1, 1989. Amendment No. 47, in part, modified Techni-cal Specification 4.6.4.2.b.4.. " Electric. Hydrogen Recombiners," to provide variable acceptance criteria for flow testing at different containment pres-sures. Specifically, the amendment added an acceptance curve to the Technical

' Specifications for flow rate through the hydrogen recombiners.

t Since the issuance of Amendment No. 47, new technical information has been received from the blower manufacturer, M 0 Pneumatics, which indicates that l the flow versus containment pressure curve should be replaced by a series of I equations for increased accuracy. These ecuations use actual inlet pressure, temperature, and pressure rise across the )1owers to predict the blower flow rate. Thus, a considerably more accurate flow acceptance determination can be (1)- d. H. Jaffe letter to E. J. Mroczka, Issuance of Amendment, dated March 2, 1990.

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~U.S. Nuclear Regulatory Commission B13834/Page 2 June 6, 1991 i

made. Therefore, in a letter dated January 18,1991,(2) f4!4ECO submitted an amendment request which would revise the surveillance requirements for the hydrogen recombiners based upon new technical information received from the 3 olower manufacturer.

On March 26, 1991, as a part of the 18 month surveillance test, a functional test of the Millstone Unit No. 3 hydrogen recombiner (A) was performed using the acceptance criterie included in Technical Specification 4.6.4.2.b.4 (License Amendment No. 47). The test results indicated that the hydrogen recombiner was capable of delivering a flow rate of approximately 74.5 scfm at a containment pressure of 14.77 psia. This represents a failure to meet the acceptance criteria of Technical Specification figure 3.6-2 which is a pres-sure dependent flow curve by approxifrately 2 scfm.

On March 29, 1991, when the same test was repeated, the hydrogen recte biner (A) passed the acceptante criteria of Technical Specificaticn fig-ure 3.6-2. The hydrogen recombiner (B) f ailai the technical specification flow rate by only 2 percent when it was tested on April 2, 1991. Based on these test results, NNEC6 could not verify the operability of both the hydrogen recombiners using the acceptance criteria included in figure 3.6 2.

Therefore, on April 2,1991, N!4ECO informed the Staff of the current situation and NNECO's plan to request that the NRC Staff procega license amendment on an energency basis, in a I 4 and supplemented by a letter dated April 8,1991,gtt)er dated April 5, ;1991 UNEC0 proposed that the following footnote be added to Technical Specification figure 3.6 2:

"Until September 30, 1991, a flow rate of 72.4 scfm or greater at a pressure of 14.5 to 14.8 psia is acceptable in lieu of the values indi-cated by figure 3.6-2."

14NECO, in that letter, also requested that pursuant to 10CFR50.91(a)(5), the proposed technical specification change be approved on an emergency basis.

Emergency authorization was requested to permit timely resumption of Millstone Unit No. 3 operation from the third refueling outage. The ORC granted a Temporary Waiver of Compliance from the requirement of leck tical (2) E J. Mrotzka letter to the U.S. Nuclear Regulatory Commission, " Proposed Revision to Technical Specification--Hydrogen Recombiners," dated January 18, 1991.

(3) E. J. Mroczka letter to the U.S. fluclear Regulatory Commission, " Proposed Revision to Technical Specification Hydrogen Recombiners," Request for Authorization and Approval, dated April 5, 1991.

(4) E. J. Mroczka letter to the U.S. Nuclear Regulatory Commission, " Proposed Revision to Technical Specifications Hydrogen Recombiners, Request for Emergency Authorization and Approval," dated April 8, 199'.

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' U.S. Nuclear Regulatory Commission B13834/page 3 June 6, 1991 Specification 4.6.4.2.b.4 on April 9,1991 to allow Millstone Unit No. 3 to resumepoweropgrgtionfollowingthethirdrefuelingoutage. Subsequently, on

April 22, 1991, the NRC issued the requested amendment. The purpose of this letter is to propose a change to Technical Specification Sec-tion 4.6.4.2.b.4 as the footnote to figure 3.6 2 is only applicable until September 30, 1991. Therefore, NNEC0 heraby proposes to amend its operating license, NPF-49, by incorporating the chy m s identified in Attachment 1 into the Technical Specifications of Hillstc% bnit No. 3.
  • Descrintion of the Prpposed Ch10 M S  !

The surveillance requirement, 4.6.4. ' o.4, for the hydrogen recombiner is proposed to be modified. Specifically the description of the gas temperature (Section 4.6.4.2.b.4) and the flow rate have been separated. A new Sec-tion 4.6.4.2.b.5 for flow rate verification has been proposed. Verification of these acceptance criteria (Section 4.6.4.2.b.4 and 4.6.4.2.b.5) will be performed concurrently. The existing surveillance requirement requires 1 testing with a fiow rate above the limit specified in figure 3.0 2. Fig-ure 3.5 2 was developed ustra generic information for this type of blower. As stated earlier, since the issuance of Amendment No. 47, new technical informa-tion was received from the blower nanuf acturer which indicates that the flow versus containment pressure curve should be replaced by a series of equations for increased accuracy. Them equations use actual temperature and pressure to calculate the recombiner fiow, The equations are too complex to be includ-l ed in the body of the technical specifications, however, these equations will be incorporated into the revised surveillance procedure. The equations provided by the blower manufacturer are the basis for the test method provided in Attachment 2 ard are the basis for the proposed new Section 4.6.4.2.b.5.

This proposed new Section 4.6.4./ t 5 would require that the 18 month func-tional test for the hydrogen r~ Yainers be performed using containment air which will verify that a flow rate of at least 41.52 scfm at a containment i

pressure of 12.47 psia and 130'F could be obtained. This flow rate included in the technical specification is the required design flow rate 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> af ter i

a loss of coolant accident (1.0CA) which will maintain the hydrogen concentra-tion inside containment at a safe level (telow 4 percent). This method of '

testing ensures a performance ievel for the hydrogen recombiners which meets the requirement of the desigr, bisis analysis. The analysis has included the effect of containment ;rassure, temperature, and relative humidity on blower performance and hydrog;;n concentration. However, the flow rate included in Tech 61 cal Specification 4.6.4.2.b.5 does not include instrument error. The '

crror margin due to insuument error will be incorporated in the surveillance

  • procedure rather than the technical specifications. 1he amount of instrument <

l error varies significantly over the operating flow and pressure range of the cystem. The variability of this error makes it difficult to place error (5) D. H. Jaffe letter to E. J. Hroczka, " Issuance of Amendment (TAC No. 79628)," dated April 22, 1991.

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~U.S. Nuclear Regulatory Commission 813834/Page 4 June 6, 1991 margin in the acceptance criteria without becoming overly conservative.

Revisions are also being proposed to Bases Section 4.6.2.4 to reflect these changes. In addition, the Technical Specification index would then be revised to reflect deletion of figure 3.6-2. The appropriate changes to the Hillstone l Unit No. 3 Final Safety Analysis Report will be made within six months once  !

the Staff issues the license amendment. I Safety Assess.Mul Since issuance of Amendment No. 47, new technical information has been received from the blower manufacturer, H D Pneumatics, which indicates that the flow versus containment pressure curve should be replaced by a series of equations. These equations use actual inlet pressure, temperature, and pressure rise across the blowers to predict the blower flow rate. Thus, a considerably more accurate flow acceptance determination can be made. The calculation of the acceptance criteria requires a complex calculation. The listing of the calculational details in the technical specifications would be inappropriate. As an alternative, the minimum flow performance of the recombiner blowers under post-LOCA conditions 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after the event has been r.tated in the technical specifications. The ability of the blowers to ,

deliver this flow rate will be confirmed by measuring the performance of the blowers and calculating the expected post-LOCA performance using the equa. '

tions. The acceptance method will confirm that no unacceptable level of I degradation has occurred in the blower performance. The accuracy range of flow measurement instrumentation has been incorporated into the acceptance .

criteria. This method of documenting acceptable blower performance will be incorporated into the revised surveillance procedure.

1 Changes to Section 4.6.4.2.b.4 provide a clarification of the surveillance and do not reduce the effectiveness of the technical specifications. The proposed

, new Section 4.6.4.2.b.5 does not modify any safety system components or their method of operation. The changes only modify the calculation method used to verify acceptable performance. The revised acceptance criteria is based on the required system performance as determined by the accident analysis, it c%tinues to verify that the system can perform its design function.

The proposed changes to the surveillance requirement will ensure a performance level of hydrogen recombiners which will keep the containment hydrogen concen-tration below 4 percent when placed in service within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of a LOCA.

Therefore, it is concluded that the LOCA and its consequences as analyzed remain valid.

Sianificant Hazards Consideration NNECO has reviewed the proposed changes in accordance with 10CFR50.92 and concluded that the char.ges do not involve a significant hazards consideration.

The basis for this conclusion is that the three criteria of 10CfR50.92(c) are

U.S. Nuclear Regulatory Commission B13834/Page 5 June 6, 1991 not compromised. The proposed changes do not involve a significant hazards consideration because the changes would not:

1. Involve a significant increase in the probability or consequences of an accident previously analyzed.

The new proposed Section ( 6.4.2.b.5 will contiaue to verify the capabil-ity of the hydrogen recombiner to meet design basis analysis assumptions, lhe appropriate plant procedures are in place to ensure that the hydrogen recom)iners are placed in service within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of a LOCA. Therefore, it is concluded that the LOCA and its consequences as analyzed remain valid. Since no physical modifications are propo.ed, the probability of a LOCA is not affected. The surveillance requirement related to verifi-cation of the gas temperature (Section 4.6.4.2.b.4) has been separated from the flow rate verification and this change does not reduce the effectiveness of the technical specifications. The change to the Techni-cal Specification Index has no impact on the consequences or the proba-bility of an accident previously analyzed.

2. Create the possibility of a new or different kind of cccident from any previously analyzed, i

The proposed changes to Sections 4.6.4.2.b.4 and 4.6.4.2.b.5 and the Technical Specification Index do not impact the plant response to a LOCA.  !

Since there are no changes in the way the plant is operated, the poten-tial for an unanalyzed accident is not created, and no new failure modes are introduced.

3. Inycive a significant reduction in the margin of safety.

The p"/sosed changes do not increase the consequences of any accidents as the I;dogen concentration is maintained below 4 percent. Also, none of the protective boundaries are affected. The performance level of the hydrogen recombiner:. assured by the proposed surveillance requirements along with the appropriate plant procedures maintain the margin of safety as defined in the existing and proposed technical specifications.

Moreover, the Commission has provided guidance concerning the application of standards in 10CFR50.92 by providing certain examples (March 6, 1986, SlFR7751) of amendments that are considered not likely to involve a signifi-cant hazards consideration. Although the proposed changes are not enveloped by a specific example, the changes would not involve a significant increase in the probability or consequences of an accident previously analyzed. The t proposed surveillance requirement will ensure a performance level of the hydrogen recombiners which meets the requirements of the design basis analy-sis.

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1 U.S. Nuclear Regulatory Commission BUS 34/Page 6 June 6, 1991 Based upon the information contained in this submittal and the environmental assessment for Hillstone Unit No. 3, 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 Millstone Unit No. 3 Nuclear Review Board has reviewed end approved the proposed changes and has concurred with the above determinations.

S h.ca the applicability of the footnote to Technical Specification Fig- '

ure 3.6-2 expires on or before September 30, 1991, NNECO hereoy requests the NRC Staff process and issue this proposed amendment by September 30, 1991, to be effectlve upon issuance.

Should the Staff request any additional information to process this request, NNE00 remains available to promptly provide such information.

In accordance with 10CFR50.91(b), we are providing the State of Connecticut with a copy of this proposed amendment.

Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY Tf^Y' l

E. J. M czka v Senior Vice President cc: T. T. Martin, Region 1 Administrator D. H. Jaffe, NRC Project Manager, Hillstone Unit Nos. I and 3 W. J. Raymond, Senior Resident inspector, Millstone Unit Nos.1, 2, and 3 Mr. Kevin McCarthy Director, Radiation Control Unit y Department of Environmental Protection Hartford, Connecticut 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 Northeast Nuclear Energy Company, a Licensee herein, that he is authorized to execute and fite the foregoing information in the name and on behalf of the Licensee herein, and that the statements contained in said information are true and correct to the best of his knowledge and belief. a , ,,

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