ML20196C576

Application for Amend to License DPR-65,revising Tech Specs Re Test Method for Control Room Air in-leakage.Fee Paid

ML20196C576
Person / Time
Site:	Millstone
Issue date:	02/09/1988
From:	Mroczka E NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
Shared Package
ML20196C577	List: B12820, Proposed Tech Spec 4.7.6.1.e.3 Re Test Method for Control Room Air in-leakage ML20196C576
References
B12820, TAC-67081, NUDOCS 8802160179
Download: ML20196C576 (6)

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NORTHEAST UTILITIES a.n.,o Orr,c.. . s.w.n sic..t. e.,an. Conn.ciieut 3 )SN'NIC((N P.O. BOX 270 H ARTFORD, CONN ECTICUT 06141-0270 k 1 J 7,[ [ [ C [,7 % (203) 665-5000 February 9, 1988 Docket No. 50-336 B12820 Re: 10CFR50.90, 50.91 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555 D ntlemen:

Millstone Nuclear Power Station. Unit No. 2 Proposed Revision to Technical Specifications Control Room Habitability Summary Pursuant to 10CFR50.90 and 50.91, Northeast Nuclear Energy Lompany (NNECO) hereby proposes to amend the Operating License No. DPR-65 for the Hillstone Nuclear Power Station, Unit No. 2, by incorporating the attached changes into the plant Technical Specifications. Current Technical Specifications require that the control room in-leakage be limited to 100 scfm at a delta pressure of 1/16" of water gauge. NNEC0 hereby proposes to delete the test method speci-fied in Technical Specification 4.7.6.1.e.3 and add the required testing configuration which will more accurately reflect an emergency situation. The proposed change would ensure that the control room air in-leakage is less than 100 scfm via the method currently specified in the Technical Specifications (i.e, measured flow using a test fan), gas dispersion test, or other approved method while in the recirculation mode.

NNEC0 requests this amendment be issued on an emergency basis in accordance with 10CFR50.91(a)(5). As discussed below, this request involves no signifi-cant hazards consideration and failure to act promptly would prevent timely entry into Mode 4 and subsequent resumption of operation upon completion of the current refueling outage. To allow entry into Mode 4, which is curren scheduled for February 12, 1988, NRCStaffactionisrequiredbythatdate.g (1) NNEC0 further notes that as an alternative to authorizing timely entry into Mode 4, the NRC Staff could consider the use of a temporary waiver to allow such entry prior to final action on the requested amendment. 0 0I i f

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1 V.S. Nuclear Regulatory Commission 812820/Page 2 February 9, 1988 Backaround In a letter dated August 3, 1987,(2) NNEC0 requested a change to the Millstone Unit No. 2 Technical Specifications that required the addition of a surveil-lance to verify that control room in-leakage be limited to less than 100 scfm at a delta pressure of 1/16" of water gauge. This request was in response to an identified open item referenced i No. 100 to DPR-65, dated June 19,1985.i3}he safety evaluation for Amendment In a letter dated September 25, 1987,(4) the NRC Staff issued Amendment No. 119 to Facility Operating License No. DPR-65. This effective date of this amendment was established as after entry into Mode 4 from the current refueling outage.

The proposed changes involve a modification to the specified test method to measure the control room air in-leakage at Millstone Unit No. 2. Extensive effort and excessive man-hour expenditures have been used at the facility to prepare the unit control room for the negative pressure test as prescribed by the current Technical Specifications. These efforts have resulted in several failed attempts to meet the current Technical Specification limit. NNEC0 believes that this method is a conservative method and not representative of emergency operating conditions.

After diligent and extensive efforts by NNECO to meet the specified Technical Specification limit, it has been concluded that the test method which was specified in the latest amendment (i.e., delta pressure of 1/16" of water gauge) is not the most realistic measurement of control room air in-leakage during emergency conditions. Since the Millstone Unit No. 2 design does not provide for a negative pressure in the control room envelope during emergency conditions but switches to a recirculation mode, testing under a negative pressure condition is not representative of system performance. NNEC0 now realizes that we unnecessarily penalized ourselves in our License Amendment Request dated August 12, 1987, by proposing an overly conservative surveil-lance requirement. The proposed change contained herein seeks to resolve that situation by allowing test conditions that more realistically reflect actual accident conditions.

(2) E. J. Mroczka letter to U.S. Nuclear Regulatory Connission, "Proposed Change to Technical Specifications Control Room Habitability," dated August 3, 1987.

(3) D. B. Osborne letter to J. F. Opeka, "NRC Amendment No.100 to Facility Operating License No. DPR-65," dated June 19, 1985.

(4) D. H. Jaffe letter to E. J. Mroczka, "NRC Amendment No.119 to Facility Operating License No. DPR-65," dated September 25, 1987.

! ,* U.S. Nuclear Regulatory Commission B12820/Page 3 i

February 9, 1988 NNEC0 proposes to test the system in its designed emergncy operating mode.

The testing method used will be tracer gas dispersion, fan pressurization or other technically acceptable methods.

Further, for the reasons discussed herein, NNEC0 requests, pursuant to 10CFR50.91(a)(5), that this amendment be issued on an emergency basis to permit timely resumption of Millstone Unit No. 2 operation. NNEC0 demon-strates below that this revision presents no significant hazards considera-tion. The need to request the amendment on an emergency basis could not have been reasonably avoided. Finally, prompt restart of Millstone Unit No. 2 is particularly critical in view of potential power generation shortfalls in the Northeast region during the remainder of the winter. For these reasons, issuance of the requested amendments on an emergency basis is warranted.

Description of Chanae The proposed changes to the Technical Specifications are provided in Attach-ment 1. The proposed changes will eliminate the reference to conduct the test using a delta pressure of 1/16" of water gauge and explicitly specify that the control room air-conditioning system be in the recirculation / filtration mode of operation.

Specific changes would be as follows:

Page 3/4 7-17, Section 4.7.6.1.e.3: Remove "at a A P of 1/16" of water gauge" and add "with the control room air-conditioning system in the recirculation / filtration mode."

The proposed changes do not change the requirements of the 100 scfm control room air in-leakage limits approved by License Amendment No. 119. However, it allows for NNECO to accurately measure the in-leakage rate in an environment that more realistically resembles the actual postulated accident conditions.

Emeraency License Amendment Pursuant to 10CFR50.91(a)(5), NNEC0 requests NRC approval of the License Amendment described herein on an emergency basis. Emergency authorization is required to permit timely entry into Mode 4, which may occur as soon as February 12, 1988.

o Justification for Emeraency Amendment Issuance of the requested amendment on an emergency basis is appropriate.

First, the amendment involves no significant hazards consideration (see discussion below). In addition, the present situation could not j (5) The use of this method to calculate the control room in-leakage has been approved on Perry Nuclear Power Plants, Units 1 and 2, Docket Nos. 50-440, 50-441. Reference NRC Letter dated November 13, 1984.

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,o UcS. Nuclear Regulatory Commission B12820/Page 4 February 9, 1988 reasonably have been avoided. This is the first opportunity for the current situation to have occurred and thus be discovered. Since Amend-ment No.119 was issued on September 25, 1987, and this is the first refueling outage since that date, this has been NNECO's first opportunity to accurately measure the control room air in-leakage to meet the new surveillance requirements. of Specification 4.7.6.1.e.3. In the process of conducting this test, NNEC0 has realized that this surveillance requirement is unnecessarily restrictive in light of the actual design and operation of the control room emergency ventilation system at Millstone Unit No. 2.

Further, the emergency situation is particularly significant at this time because of potential power shortages in the Northeast during the rest of the winter. There is a compelling need for Millstone Unit No. 2 to return to power cperation as soon as possible.

Safety Assessment The proposed change to Section 3/4.7.6 revises an 18-month surveillance requirement (4.7.6.1.e.3) that specifies a limit on the allowable air in-leakage (100 scfm) into the Millstone Unit No. 2 control room at a specific differential pressure delta pressure (1/16" of water gauge). This proposed change deletes the specific requirement to perform the test at 1/16" of water gcuge. Delta pressure adds the requirement to perform the test with the control room air-conditioning system operating in the filtration / recirculation mode.

The surveillance requirement to test for air in-leakage into the control room was added in response to Amendment No. 100 to DPR-65 to ensure the validity of assumptions made in the control room habitability analysis performed for Millstone Unit No. 2. The surveillance requirement, as it now exists, would verify that the accident analysis assumptions are valid. However, after further consideration, NNEC0 has concluded that this method (i.e., performing the test at a delta pressure of 1/16" of water gauge) is conservative and that there are other valid techniques for verifying analysis assumptions.

The control room is maintained at or near atmospheric pressure during normal operation. Adjacent areas are maintained at a negative pressure with respect to the control room to prevent in-leakage. In the event that airborne radio-activity is detected outside the control room, the control room air-conditioning system is automatically switched to the isolation / recirculation mode. Since the control room is at or near atmospheric pressure when the isolation mode is initiated, in-leakage of unfiltered air should be insig-nificant. The only air in-leakage that would be expected would be due to localized pressure differences between inside and outside the ductwork due to the recirculating fans that would be operating in the recirculation mode.

Joints in the ductwork have been sealed to minimize this in-leakage. However, since the proposed change discussed herein would ensure operation of the recirculation fans during the test, any such in-leakage wou?.i be evaluated, i This proposed change will allow use of the gas dispersion method, fan pressur-ization method, or other acceptable methods which have proven to be practical, reliable means of determining leakage rates from control rooms similar to

o o U.S. Nuclear Regulatory Commission B12820/Page 5 February 9, 1988 ,

l Millstone Unit No. 2. The gas dispersion method (or other technically accept- j able methods) will demonstrate the validity of assumptions used in the control I room habitability analysis when testing the system in the recirculation mode l without applying the 1/16" delta pressure of water gauge during the test. In addition, the proposed change will accommodate testing that is consistent with the actual ventilation system design as described in Section 9.9.10.3.2 of the Final Safety Analysis Report. The octual design of the system does not provide for a negative pressure condition in the control room envelope during emergency conditions. The ventilation system is switched to a recirculation / filtration mode at the onset of an emergency condition.

NNEC0 has reviewed the proposed change pursuant to 10CFR50.92 and has deter-mined that it does not constitute a Significant Hazards Consideration in that this change would not:

1. Involve a significant increase in the probability or consequences of an accident previously evaluated. Although the proposed change would result in a less conservative test, the test results would still demonstrate the validity of the accident analysis assumptions. The proposed change would yield a test that more realistically reflects the actual circumstances while providing a fully valid verification of analysis assumptions. The test as previously intended (i.e., with the delta pressure of 1/16" of water gauge) is technically acceptable. However, this test method has proven to be extremely difficult to meet. Nonetheless, either method provides verification that the accident analysis assumptions are valid.

Therefore, there is no change to the probability or consequences of the control room habitability analysis (the only analysis affected by this change).

2. Create the possibility of a new or different kind of accident from any accident previously evaluated. The proposed change allows alternative tests to be performed that fully validate the control room habitability analysis assumptions. Since this change continues to ensure the validity of assumptions in existing analyses, the potential for new or different kinds of accidents is not created.

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3. Involve a significant reduction in the margin of safety. The proposed change allows testing methods that are less conservative than that intended by the current Technical Specifications because the current Technical Specifications are unnecessarily restrictive. The alternative tests allowed by this proposed change fully validate the accident analysis assumptions and, therefore, there is no significant decrease in the margin of safety associated with this change.

With respect to the proposed Technical Specification change, our review of the given examples in 51 FR 7750, March 6,1986, of amendments that are considered not likely to involve a significant hazards consideration, NNEC0 has deter-mined that Exansple (vi) is most applicable, in that "a change which either may result in some increase to the probability or consequences of a previously-analyzed accident or may reduce in some way a safety margin, but where the results of the change are clearly within all acceptable criteria with respect to the system or component specified in the Standard Review Plan; e.g., a change resulting from the application of a small refinement of a previously used calculational model or design method."

7 U.S. Nuclear Regulatory Commission B12820/Page 6 February 9, 1988 The Millstone Unit No. 2 Nuclear Review Board has reviewed and approved the attached proposed revisions.

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

Pursuant to the requirements of 10CFR170.12(c), enclosed with this amendment request is the application fee of $150.

NNEC0 respectfully requests that this License Amendment Request be issued prior to entry into Mode 4, currently scheduled to occur on February 12, 1988.

As an alternative, the NRC Staff may wish to consider the use of a temporary waiver to allow entry into Mode 4 as scheduled prior to final action on the requested amendment.

Thank you in advance for your prompt attention to this matter. Please feel free to contact us if you have any questions.

Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY E.7 Kroczka/

Selfior Vice President cc: Mr. Kevin McCarthy, Director Radiation Control Unit Department of Environmental Protection Hartford, Connecticut 06116 W. T. Russell, Region I Administrator D. H. Jaffe, NRC Project Manager, Millstone Unit No. 2 W. J. Raymond, Senior Resident Inspector, Millstone Unit Nos.1, 2, and 3 STATE OF CONNECTICUT)

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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 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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Notary Public

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