ML19332C064

Provides Detailed Justification for 891109 Enforcement Discretion Request Re Containment Integrity Requirements & Associated Safety Analysis,Per NRC 891110 Request

ML19332C064
Person / Time
Site:	Millstone
Issue date:	11/14/1989
From:	Mroczka E NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
B13409, NUDOCS 8911220264
Download: ML19332C064 (5)

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7 November 14, 1989-Docket No. 50-336  !

i B13409 Re: Enforcement Discretion <

r U.S. Nuclear Regulatory Commission

-Attention: Document Control Desk Washington,;DC 20555 Gentlemen:

Millstone Nuclear Power Station, Unit No. 2 Enforcement Discretion

" Electrical Power Systems Ini a- letter dated November 9, 1989,II) Northeast Nuclear Energy Company ,

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"(NNECO) requested - that enforcement discretion be taken by the NRC Staff a _ regarding the requirements of Millstone Unit No. 2 Technical Specification Action Statement.3.8.2.2. Specifically, we proposed to position the contain-ment equipment hatch'so:that. it is capable of being-shut within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> of- an

-event' which resultsoin a loss of decay heat removal. -This action would be

,  ; undertaken rather than closing and sealing the containment equipment. hatch as '

required E to establish containment integrity in accordance with Technical Specification Action Statement 3.8.2.2. ,

The g Staff responded. to NNECO's. request in a letter dated November 10, 1989. In this: letter, the NRC Staff granted a one-time enforcement discre-l tion regarding- our containment integrity requirements due to the administra-

.tive inoperability- of: the emergency -diesel generators that occurred at 6:45 p.m. on November 9, 1989. This situation . developed as a result of a review of. calculations which- determined analytically. that the service water pump. discharge. strainers;could notibe qualified to appropriate seismic crite-ria. ' Specifically, the Staff granted relief from Millstone Unit No. 2 Techni-

. cal Specification 3.8.2.2, . '"A.C. Distribution--Shutdown," requirements to-

. establish containment integrity per Technical Specification 1.8.2 regarding closure and-sealing of the containment equipment hatch within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> from the

.(1) J. S.!Keenan letter to W. T. Russell, " Request for Enforcement Discretion," dated November 9, 1989.

(2) - W. T. Russell : letter to E. J. Mroczka, " Enforcement Discretion Regarding Containment Integrity During 'Inoperability of Diesel Generators," dated November 10, 1989.

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y U.S. Nuclear Regulatory Commission B13409/Page 2 November 14, 1989 loss of diesel operability. The NRC stipulated that this enforcem:nt discre-

. tion would remain in effect until 5 p.m. Tuesday, November 14, 1989, unless NNECO contacted the Staff and requested an extension with appropriate justifi-cation.

The purpose of this letter -is to submit, as an historical account, a more detailed justification for the enforcement discretion request and an associ-ated safety analysis.

Backaround and Basis At approximately 6:45 p.m. on November 9,1989, NNECO concluded that all three service water pump discharge strainers had been determined analytically to be, DRt qualified to the appropriate seismic criteria. As a result of this condition, both service water headers, hence both emergency diesel generators and both shutdown cooling loops, were declared inoperable.

Among the Technical Specification Limiting Conditions for Operation (LCOs) which cannot be satisfied in the condition described above is 3.8.2.2, "A.C.

Distribution--Shutdown." For all LCOs, which cannot be satisfied, action -l statements are being met except for Specification 3.8.2.2. As noted above, the action requirement for this LC0 requires establishing containment integ-rity within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. With the exception of the containment equipment hatch, all requirements for establishing containment integrity were met.

Our basis for deviating from this requirement in the case of the containment e quipment hatch results from our analysis of, and pregations for, loss of In our response to decay heat removal as required by Generic lette{4y8-17.

we committed to " implement Generic Letter 88-17, dated December 23, 1988, i procedures and administrative controls to reasonably assure containment i closure within 122 minutes following a loss of shutdown cooling." We maintain that our present condition, i.e., the seismic disqualification of our service water headers is no more limiting than a loss of shutdown cooling from a reduced inventory condition, for which the proposed positioning of the con-tainment equipment hatch has been reviewed and found acceptable. Explicit in

.our proposal is a commitment to not enter into reduced inventory operations i until the seismic condition of at least one service water header is restored.

(3) Generic Letter #88-17, " Loss of Decay Heat Removal."

(4) E. J. Mroczka letter to U.S. Nuclear Regulatory Commission, " Loss of Decay Heat Removal--GL 88-17," dated December 23, 1988.

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' November 14, 1989 #

p Justification for Enforcement Discretion Our request for enforcement discretion and the NRC Staff's approval of that request. was appropriate. First, Millstone Unit No. 2 Plant Operation and-Review Committee (PORC) and our Nuclear Review Board (NRB) have reviewed and concurred with the safety evaluation (see evaluation below) performed to

, support this request. In addition, the present situation could not have reasonably been avoided. NNEC0 had not concluded that the service water strainers were not seismically qualified until November 9,1989, the date we requested-enforcement discretion be granted.

On Septcmber 20,1989, the results of a quality assurance audit were published which called into question the method of ar,alysis used to resolve an as-found '

condition regarding the anchorage of the service water strainers. In an engineering response to the audit findings on October 23, 1989, a conclusion was reached that continued operability was justified, pending further evalua-tion of the strainer calculations. This evaluation was committed to be

- completed by November 22, 1989. During the evaluation NNECO identified two discrepancies with the original vendor's structural qualification of the strainers. ,

The discrepancies were:

o. The as-constructed configuration was not reconciled between the vendor's analysis and the architect / engineers' analysis.

o The input response spectra were not properly amplified to the appropriate building elevation at which the piping was supported.

NNEC0 determined that these discrepancies invalidated the seismic qualifica-

. tion of the strainers and declared the strainers inoperable on November 9,

' 1989.

L Safety Analysis l

It has been determined analytically that the service water pump discharge strainers are not qualified to the appropriate seismic criteria. Since

, service. water provides required flow to the shutdown cooling loops and both emergency diesel generators, these systems have been declared administratively inoperable. It should be noted that for all cor.ditions other than a seismic event, the service water strainers, and consequently the shutdown cooling loops and diesel generators, are operable and will be able to perform their function. In addition, since, other than the service water strainers, the reactor coolant system (RCS) boundary and all other safety equipment are seismically qualified, a seismically induced transient need not be postulated.

l Thus, the only event that needs consideration is the seismic event itself.

l l There are no specific direct impacts on any of the accidents analyzed in Chapter 14 of the Final Safety Analysis Report (FSAR). However, the 1

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U.S. Nuclear Regulatory Commission:

813409/Page 4 November 14, 1989 i

requirements. for safe shutdown following a seismk event could be affected.

Since the service water -strainers are not seismically qualified, they could fail during a seismic event. If the strainers were to fail, service water may-not be able to perform its function of providing cooling for the shutdown cooling systea, and the RCS may start to heat up. However, with the RCS F . vented through the pressurizer manway, no significant RCS pressurization would occur. There would be no core uncovery or fuel damage for several hours.

Since the containment hatch could be closed within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />, containment

' integrity would be established long before any fuel damage- would occur. Not specifically complying with the existing action statement has no 1mpact on the consequences of this event. For all other scenarios, the service water system will still perform its function, and thus this situaticn will have no impact f_ on the consequences of any other accident. ,

The allowance for an exception to containment integrity will not affect the performance of the containment. As discussed above, containment integrity '

will .be established when required prior- to any fuel failure. Thus, the containment integrity requirements for this scenario are met. There are no other impacts on the containment or any other safety system, and the contain-ment function will still be provided with no increase in off-site doses.

This scenario would allow a longer time for establishing containment integrity (closure of the equipment hatch). However, the containment function will still be performed, and there is no increase in the consequences of any acci-dents. Since there is no impact on any safety limits and there is no increase in the consequences of any accident, it is concluded that there is no reduc-tion in the margin of safety.

Conclusion NNECO is fully aware of the significance of the potential loss of service water due to seismically unqualified strainers. In our original review of this situation, two viable options existed for resolution. One option was to decouple the service water system trains, resulting in one train being fully L seismically qualified but making the other train physically inoperative for a 12- to 24-hour period while it was being decoupled. This would allow a quicker resolution- to the action statement requirement by being able to declare one diesel generator and one shutdown cooling loop operable. The other option was an expedited permanent repair to the strainers which would i l take longer, but, ultimately, no train would be required to be inoperative.

l- It was decided that the potential benefits gained from the interim repair did not warrant the risk associated with placing the plant in a further compro-

. mised position. We have expeditiously pursued a permanent repair to the pump

, discharge strainers which fully qualifies these to appropriate seismic crite-ria. This repair was completed the morning of November 14, 1989. NNEC0 has kept the Millstone Unit No. 2 NRC Resident Inspector fully apprised of the plant conditions and status of our repairs.

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U.S. Nuclear Regulatory Commission B13409/Page 5 November 14, 1989

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NNECO acknowledges that our request for enforcement discretion was granted by the Staff on November 10, 1989, allowing critical path outage work efforts to continue. This action prevents the loss of critical path time and enables resumption of Millstone Unit No. 2 operation at the earliest possible date.

.Thank you for your consideration and expeditious response to this situation, t No. further NRC action- is requested or required at this time.

We remain available to discuss- plant conditions or the information provided in this letter as necessary.

Very truly yours, -

NORTHEAST NUCLEAR ENERGY. COMPANY E . J. //

Seniv/Iroczka r Vice President cc: W. T. Russell, Region 1 Administrator G. S. Vissing, NRC Project Manager, Millstone Unit No. 2 W. J. Raymond, Senior Resident Inspector, Millstone Unit Nos.1, 2, and 3 P. Habighorst, Resident Inspector, Millstone Unit No. 2 i

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