ML20072T189
| ML20072T189 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 04/05/1991 |
| From: | Debarba E, Mroczka E NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20072T193 | List: |
| References | |
| B13794, NUDOCS 9104180010 | |
| Download: ML20072T189 (10) | |
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,. o eou,o HM f FORD CONNECTICUT ($1410270 L t a ;"C.;;'i CPlX'.L;"i aowt-tao April 5,1991 Docket No. 50 423 B13794 Re: 10CFR50.90 10CFR50.91 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington DC 20555
References:
(1) E. J. Mroczka letter to the U. S. Nuclear Regulatory Commission, Proposed Revision to Technical Specifications Hydrogen Recombiner, dated January 18, 1991.
(2) E. J. Mroczka lotter to the U. S. Nuclear Regulatory Commission, Proposed Revision to Technical Specifications - Hydrogen Recombiners Request for Emergency Authorization and Approval, dated April 3, 1991.
Gentlemen:
Millstone Nuclear Power Station, Unit No. 3 Proposed Revision to Technical Specifications Hydrogen Recombiners Reauest for Emergency Authorization and Acoroval in a letter dated January 18, 1991 (Reference [1]), Northeast Nuclear Energy Company S!NECO) proposed to amend Operating License NPF-49 by revising the Millstone Unit No. 3 Technical Specifications regarding the surveillance requirements for the hydrogen recombiners. In a latter dated April 3,1991, NNECO requested that the NRC staff process the above-referenced one nEV Mc
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! .U. S. Nuclear Regulatory Commission B13794/Page 2 April 5,1991 license amendment request on an emergency basis in accordance with 10CFR50.91(a)(5). Based on the discussion with the staff on April 4, 1991, NNECO hereby proposes to modify the license amendment request (Reference [1]) and requests staff approval of the license amendment request described herein on an emergancy basis.
As discussed below, this request involves no significant hazards consideration. and failure to act promptly would prevent start up of the plant from the present refueling outage. Plant start up (i.e., criticality) is currently scheduled for April 8, 1991.
Alternatively, it is requested that a temporary waiver of compilance from Technical Specification Section 4.6.4.2.b.4 be granted until the staff acts on the emergency amendment. The justification for emergency authorization and approval is provided below. This amendment request supersedes in its entirety the previously submitted requests (References (1) and (2]).
Descriotion of the Prooosed Changes The surveillance requirement, 4.6.4.2.b.4, for the hydrogen recombiner is proposed to be modified. The existing surveillance requirement requires testing with a flow rate above the limit specified in Figure 3.6 2. Instead, the proposed change would require that the 18-month functional test for the hydrogen recombiners be performed using containment air at a flow rate of at least 70 scfm at a containment pressure less than or equal to 15 psia and greater than or equal to 55' F. This flow rate includes instrument inaccuracy and humidity effects inside containment, The Technical Specification index would then be revised to reflect deletion of Figure 3.6 2.
Background
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 criterion included in Section 4.6,4.2.b.4 (License Amendment No. 47). The test results indicate that the hydrogen recombiner is capable of delivering a
.U. S. Nuclear Regulatory Commission B13794/Page 3 April 5,1991 flow rate of approximately 74.5 scfm at a containment pressure of 14.77 psla. This represents a failure to meet the acceptance criterion of Technical Specification Figure 3.6-2 by approximately 2 sofm. On March 29, 1991, when the same test was repeated, the hydrogen recombiner (A) passed the acceptance criterion of Technical Specification Figure 3.6-2. The blower delivered a minimum flow rate of 74.3 scfm at a containment pressure of 14.5 psia, while the acceptance criterion was 74 scim. On March 31, 1991, the same functional test was performed on the redundant hydrogen recombiner (B) to verify its operability. The test data indicated that the hydrogen recombiner (B) failed to meet the acceptance criterion of Technical Specification Figure 3.6-2, giving a flow rate of approximately 72.5 sofm against an acceptance criterion of 76.5 scfm at a containment pressure of 14.8 psia. On April 2,1991, NNECO performed the same test on hydrogen recombiner (B). The test results indicate that the hydrogen recombiner (B) is capable of delivering a flow rate of approximately 72.8 scfm at 14.725 psia whereas the required flow rate is 75 sofm.
Based on these test results, NNECO could not verify the operability of both the hydrogen recombiners using the acceptance criterion included in Technical Specification Figure 3.6 2. Therefore, on April 2,1991, NNECO informed the staff of the current situation and our plan to request that the NRC staff process a license amendment on an emergency basis.
Since the issuance of Amendment No. 47, new technical information has been received from the blower manufacturer, M-D Pneumatics, which indicates that the information .used to generate Technical Specification Figure 3.6 2 was not appropriate and was overly conservative. This has resulted in the recent test failures on March 26, 31, and April 2,1991. Figure 3.6 2 was developed using generic information for this type of blower. Using the proposed acceptance criterion, the blower performance is acceptable as the measured flow rate exceeds 70 sofm. This ensures a performance level for hydrogen recombiners in an accident condition which will maintain hydrogen levels below 4 percent. The proposed acceptance criterion simplifies
.U. S. Nuclear Regulatory Commission l B13794/Page 4 April 5,1991 the surveillance requirement by eliminating the need to have a figure to determine operability.
Safety Assessment The hydrogen recombiner flow requirements for the functional testing are being modified to a flow rate of 70 sofm at a containment pressure less than or equal to 15 psia at greater than or equal to 55 F rather than a variable flow rate as depicted on Figure 3.6 2. By actual testing and use of the proposed surveillance criterion, it has been domonstrated that the expected performance of the hydrogen recombiner in an accident condition would be over the required flow rate of 40.5 sofm to maintain hydrogen levels below 4 percent. This ensures a performance level of hydrogen recombiners which meets the requirement of the design basis analysis.
Justification for Emeraencv License Amendment Recuest Pursuant to 10CFR50.91(a)(5), NNECO hereby requests NRC staff approval of the license amendment described herein on an emergency basis. Emergency approval is appropriate because "an emergency situation exists, in that failure to act in a timely way would result in... prevention of... increase in a wer output up to the plant's licensed power level," the situation could not have been avoided, and because the proposed amendment does not involve a-significant hazards consideration (SHC).
Presently Millstone Unit No. 3 is in Mode 5 because the plant was shutdown for a refueling outage on February 2,1991. Emergency authorization is required to permit timely resumption of operation (i.e., criticality) which is currently scheduled for April 8, 1991. Since the hydrogen recombiners failed the 18 month functional test on March 26, 1991, NNECO has been diligently working to restore the inoperable hydrogen recombiner to operable status. As described in the Background section, several tests were conducted without success. NNECO could not have reasonably anticipated the recent test failures that occurred on March 26, 31, and April 2, 1991. In summary, therefore, l
.U. S. Nuclear Regulatory Commission B13794/Page 5 April 5,1991 emergency approval is warranted for this license amendment since an unavoidable emergency has resulted that will prevent the start-up of the plarq from the present refueling outage.
Alternatively, NNECO hereby requests that a temporary waiver of compliance from current Technical Specification Section 4.6.4.2.b.4 requirements be granted until the staff acts and issues the proposed amendment. Further, the requested emergency authorization is appropriate because this amendment request does not involve an SHC. The proposed method of testing ensures a performance level for hydrogen recombiners which meets the requirement of the design basis accident analysis.
Temocrarv Walver of Comollance NNECO hereby requests a temporary waiver of compliance from Technical Specification Section 4.6.4.2.b.4 until the license amendment proposed herein is issued by the NRC staff. In support of this request, NNECO provides the following information:
- Requirements for Which a Waiver is Requested NNECO is requesting, if necessary, a waiver from Technical Specification 4.6.4.2.b.4 (regarding recombiner system functional test using containment atmospheric air) until an emergency license amendment, as described herein, can be issued.
Discussion of Circumstances Surrounding the Situation /Need for Prompt Action /Why the Situation Could Not Be Avoided As discussed in the Background section, NNECO could not have reasonably anticipated the recent test failures that occurred on March 26, 31, and April 2,1991.
- Discussion of Compensatory Action The hydrogen recombiner system is not normally in operation. The design basis analysis shows that containment hydrogen concentration remains below 4
i L .U. S. Nuclear Regulatory Commission I B13794/Page 6' April 5,1991 percent during a loss-of coolant accident (LOCA) if the recombiners are started within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of the accident.
The results of the test performed per the proposed surveillance requirement have confirmed that no unacceptable level of degradation has occurred in the blower performance. This ensures a performance level of hydrogen recombiners which meets the requirements of the design basis analysis. Therefore, there are no additional compensatory actions required during the time frame this waiver of compliance would be in effect.
- Safety Significance and Potential Consequences of Request The purpose of this letter is to allow Millstone Unit No. 3 to continue power ascension from the current Mode 5 to Mode
- 1. There are no adverse safety impacts since the existing equipment capabilities ensure that the safety function of the recombiners will be fulfilled.
- Discussion Justifying the Duration of the Request The temporary waiver of compliance is being requested, if necessary, from the time period from April 8,1991, until the license amendment request submitted herein is processed and issued. Issuance of the requested amendment would allow the 18-month surveillance test to be conducted utilizing the new acceptance criterion. Had this new surveillance criterion been used on March 26, 31, or April 2, 1991, when the surveillance was performed, we would have passed the surveillance.
Basis for the No SHC Determination The requested temporary waiver of compliance does not constitute an SHC for the reasons documented below.
- Basis for No irreversible Environmental Consequences The proposed waiver of compliance has no environmental impact since the waiver simply allows Millstone Unit No. 3
. U. S. Nuclear Regulatory Commission B13794/Page 7 April 5,1991 to continue power ascension to Mode 1 while the NRC
. processes a license amendment for the hydrogen recombiner 18-month surveillance requirement. Protective boundaries are not directly affected in that postaccident containment response capabilities remain unchanged.
Significant Hazards Consideration i
NNECO has reviewed the proposed changes in accordance with 10CFR50.92 and concluded that the changes do 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 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 proposed changes to Section 4.6.4.2.b.4 will continue to verify the capability of the hydrogen recombiners to meet design basis analysis assumptions. The appropriate plant procedures are in place to ensure that the hydrogen recombiners 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 proposed, there is no impact on the probability of failure. Therefore, probability of a LOCA is not affected.
- 2. Create the possibility of a new or different kind of accident from any previously analyzed.
The proposed changes do not impact the plant response to a LOCA. Since there are no changes in the way the plant is operated, the potential for an unanalyzed accident is not created, and no new failure modes are introduced.
- 3. Involve a significant reduction in the margin of safety.
. U, S. Nuclear Regulatory Commission B13794/Page 8 April 5,1991 The proposed changes do not increase the consequences of any accidents, Also, none of the protective boundaries are adversely affected. The performance level of the hydrogen recombiners 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, 51FR7751) of amendments that are considered not likely to involve a significant 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 proposed surveillance requirement will ensure a performance level of the hydrogen recombiners which meets the requirements of the design basis accident analysis.
Based upon the information contained in this submittal and the environmental assessment for Millstone Unit No. 3, there are no 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 and approved the proposed changes and has concurred with the above -
determinations.
Conclusion NNECO has concluded that it is appropriate and necessary that this license amendraent request be processed on an emergency basis for the following reasons:
- The amendment request is needed to permit the start-up and continued operation of the plant.
The license amendment does not constitute an SHC.
, U. S. Nuclear Regulatory Commission l B13794/Page 9 April 5,1991
- NNECO made every effort to process this request in a timely manner to avoid this situation.
We also wish to emphasize our conclusion that this proposed amendment involves no undue safety risk nor irreversible environmental consequences. We are therefore requesting this action to allow the start up and continued operation of the plant, an action which is in the best interest of the health and safety of the public, our customers, and our shareholders, in accordance with 10CFR50.91(b), NNECO will provide the State of Connecticut with a copy of this request via electronic mall to ensure their awareness of this request.
We believe the above information provides a complete basis for approval of the requested amendment. We will continue to keep you informed on matters relevant to this request including the schedule for mode ascension and restart of the unit.
Should the staff request any additional information to process this request, NNECO remains available to promptly provide such information.
Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY For: E. J. Mroczka Senior Vice President M AOds By: E. A. DeBarba Vice President 1
.U. S. Nuclear Regulatory Commission Ill3794/Page 10 April 5,1991 cc: T. T. Martin, Region i Administrator D. H. Jaffe, NRC Project Manager, Millstone Unit Nos.1 and 3 W. J. Raymond, Senior Resident inspector, Millstone Unit Nos.1, 2, and 3 Mr. Kevin McCarthy, Director Radiation Control Unit Department of Environmental Protection Hartford CT 06106 STATE OF CONNECTICUT)
) ss. Berlin COUNTY OF HARTFORD )
Then personally appeared before me, E. A. DeBarba, who being duly sworn, did state that he is Vice President of Northeast Nuclear Energy Company, a Licensee herein, that he is authorized to execute and file 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, t>.ssaJ_ $.bU1rs Y Notary Pypfic MyCm'$n 0;'tx thrch 31,003
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