ML20090H193

Proposed Changes to Tech Specs to Reduce Primary Containment Atmosphere from 5% 0-2 to 4% 0-2

ML20090H193
Person / Time
Site:	Oyster Creek
Issue date:	07/19/1984
From:	GENERAL PUBLIC UTILITIES CORP.
To:
Shared Package
ML20090H181	List: ML20090H177 ML20090H186 ML20090H193
References
NUDOCS 8407260172
Download: ML20090H193 (5)

Text

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b. Two of the fourteen' suppression chamber - drywell vacuum breakers may

-be inoperable provided that they are secured in the closed position.

c. One position alarm circuit for each operable vacuum breaker may be inoperable for up to 15 days provided that each operable suppression chamber - drywell vacuum breaker _with one defective alarm circuit'is physically verified to be closed immediately and daily during this

. period.

6. Af ter completion of the startup test program and demonstration of plant

-electrical output .the primary containment. atmosphere shall be reduced to less than 5.0% 02 with nitrogen gas within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and less than 44, 02 with nitrogen gas within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> after the reactor mode selector

- switch is placed. in the run mode. Primary containment deinerting may commence 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> prior ta a scheduled shutdown.

7. - If specifications 3.5.A.l.a. b,.c(1) and 3.5.A.2 through 3.5.A.5 cannot be met, reactor shutdown.shall be initiated and the reactor shall be in

. the cold shutdown-condition within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.-

2 8. ShockSuppressors.(Snubbers)

a. During all modes of operation except cold shutdown and refuel, all safety related snubbers listed in Table 3.5.1 shall be operable except as noted 3.5.A.8.b, c and d below.

b. From and after the time that a snubber is determined to be inoperable, continued reactor operation is permissible only during the succeeding i- '72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> unless the snubber is sooner made operable or replaced.

- c. If ~ the requirements of 3.5.A.8.a and 3.5.A.8.b cannot be met, an

--orderly shutdown shall'be initiated and the reactor shall be in a cold shutdown condition within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

d. If a snubber is determined to be -inoperable while the reactor is in

.the shutdown or refuel mode, the snubber shall be made operable or

, 4 replaced prior to reactor'startup.

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e. Snubbers may be added to safety related systems without prior License Amendment to Table 3.5.1 provided that a revision to Table 3.5.1 is E Qcun;. included with the next License Amendment request.

9. .Drywell-Suppression Chamber Differential Pressure

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% !a. Differential pressure between the drywell and suppression chamber shall.be maintained within the acceptable operating range shown on J1 1 835 Figure 3.5-1 within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after the reactor mode selector switch is 7o :placed in the run mode. - The differential pressure may be reduced to less than the range shown on~ Figure 3.5-1 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> prior to a

-! gj$a.n.L scheduled shutdown. The differential pressure may be decreased to

, ,_ -less than the required value for.a maximum of four hours during L

' --required operability testing of the drywell-pressure suppression chamber vacuum breakers.

{ Amendment - No. ( 2A , 2$ , 30 -

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3.5-5 The capacity of the fourteen suppression chamber to drywell vacuum relief ,

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valves is sized to limit _the external pressure of the drywell during

. 1 .. post-accident drywell cooling operations to the design limit of 2 psi.

_Theyareijz9j0)-on:the' basis of the15Bodega In Amendment Bay pressure of the Oyster Creek FDSAR, suppressionSection tests. IW1 T .

II the. area of 2920 sq. in.-is stated as the minimum area for flow of non-condensible gases from the suppression chamber to the drywell. To

- achieve ~this requirement, at least 12 of the 14 vacuum breaker valves (18" diameter) must be operable.

Each suppression chamber drywell . vacuum breaker is fitted with a redundant pair of limit switches to provide fail safe signals to panel ,

mounted indicators in'the' Reactor Building and-alarms in the Control Room when the. disks _are open more than 0.1" at any point along the seal

surface of the disk. These switches are capable of transmitting the disk closed-to-open signal with 0.01" movement of the switch plunger.

? , Continued reactor. operation with failed components is justified because "of the redundancy of components and circuits and, most importantly, the accessibility of the valve lever arm and position reference external to the. valve.~ The' fail-safe feature of the alarm circuits assures operator

. attention if a line fault occurs.

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Conservativs' estimates of'the hydrogen produced, consistent with the' core cooling system provided, show.that the hydrogen air mixture resul_ ting from a. loss-of-coolant' accident is considerably below the flammability

,Slimit and hence it cannot burn, and inerting would not be needed.

- However, inerting of the primary containment was included in the proposed design and operation. The 5% oxygen limit is the oxygen concentration n11mit stated by the American Gas Assocjgtion for hydrogen-oxygen mixtures

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lbelow which combustion will not occur Pl. The 4% oxygen limit was established by analysis of the' Generation and Mi jgqLion of Combustible -

Gas Mixtures in Inerted BWR Mark I Containments. 21

. To pr'eclude_the possibility of starting up the reactor and operating a long period of time with a significant leak in the primary system, leak ,

checks must be made when the pySt m js at or near rated temperature and

'dressure. It has been shown iW1 9t10J that an acceptable margin with 1 respect to flammability-exists without containment inerting. Inerting x the primary containment.provides additional margin to that already considered acceptable. . Therefore, permitting access to the drywell for

-the purpose of. leak checking would

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O AmendmentL No FIA,

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f 3.5-6 not reduce the margin of safety below that considered adequate and is judged prudent in terms of the added plant safety offered by the opportunity for leak inspection. The 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> time to provide inerting is l judged to be a reasonable time to perform the operation and establish the required 02 limit.

Snubbers are designed to prevent restrained pipe motion under dynamic loads as might occur during an earthquake or severe transient, while allowing normal thermal motion during startup and shutdown. The consequence of an inoperable snubber is an increase in the probability of structural damage to piping as a result of a seismic or other event initiating dynamic loads. It is, therefore, required that all snubbers required to protect the primary coolant system or any other safety system or component be operable during reactor operation.

All safety related hydraulic snubbers are visually inspected for overall integrity and operability. The inspection will include verification of proper orientation, adequate hydraulic fluid level and proper attachment of snubber to piping and structures.

Examination of defective snubbers at reactor facilities and material tests performed at several laboratories (Reference 11) has shcwn that millable gum polyurethane deteriorates rapidly under_the temperature and moisture conditions present in many snubber locations. Although molded polyurethane exhibits greater resistance to these conditions, it also may be unsuitable for application in the higher temperature environments.

Data are not currently available to define precisely an upper temperature limit for the molded polyurethane. Lab tests and in-plant experience indicate that seal materials are available, primarily ethylene propylene compounds, which should give satisfactory performance under the most severe conditions expected in reactor installations.

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Because snubbar protection is required only during low probability events, a period of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> is allowed for repairs or replacements. In case a shutdown is required, the allowance of 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> to reach a cold shutdown condition will permit an orderly shutdown consistent with standard operating procedures. Since plant startup should not commence with knowingly defective safety related equipment, Specification 3.5.A.8.d prohibits startup with inoperable snubbers.

Secondary containment (5) is designed to minimize any ground level release of radioactive materials which might result from a serious accident. The reactor building provides secondary containment during reactor operation when the drywell is sealed and in service and provides primary containment when the reactor is shutdown and the drywell is open, as during refueling. Because the secondary containment is an integral part of the overall containment system, it is required at all times that primary containment is required. Moreover, secondary Amendment No. 18,

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3.5-7 containment.is required during fuel handling operations and whenever

. work,is being performed on the reactor or its connected systems in the reactor building since their operation could result in inadvertent release of radioactive material.

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The standby gas treatment system (6) filters and exhausts the reactor building atmosphere to the stack during secondary containment

" . isolation conditions, with a minimum release of radioactive materials from the reactor building to the environs.

Two separate: filter tra' ins _are provided each having 100% capacity.(6)

~If one filter. train becomes inoperable, there is no immediate threat to secondary containment and reactor operation may continue while Lrepairs are being made. 'Since the test interval for this system is one month.(Specification 4.5), the time cut-of-service allowance of 7 days is'. based on considerations presented in the Bases in Specification 3.2 for a one-out-of-two system.

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References:

-(l) FDSAR, Volume I, Section V-1

'(2).~ FDSAR, Volume I, Section V-1.4.1 (3) FDSAR, Volume I, Section V-1.7

-(4) Licensing Application, Amendment 11, Question I.II-25 (5) FDSAR, Volume I, Section V-2 (6) 'FDSAR, Volume I, Section V-2.4

-(7)- Licensing Application, Amendment 42

-(8) _ Licensing Application, Amendment 32, Question 3

.(9)' Robbins, C. H., " Tests on a Full Scale 1/48 Segment of the Humboldt Bay Pressure Suppression Containment,"'

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GEAP-3596,1 November 17, 1960.

' 4 .(10) Bodega Bay Preliminary Hazards Summary Report,

_ Appendix 1, Docket 50-205, December 28, 1962.~

, w3 (ll)- Report H. R. Erickson, Bergen-Paterson-to K. R.

+ Goller, NRC,.0ctober 7,-1974. .

Subject:

Hydraulic

-Shock Sway Arrestors.

.(12)~, General: Electric NEDO-22155 " Generation and Mitigation

. of Combustible ~ Gas Mixtures in Inerted BWR Mark I t _ Containments June 1982.

. , . In conjunction with the Mark I Containment. Short Term Program,' a plant unique analysis was performed on August 2, 1976, which demonstrated a

. factor;of safety of at least two for the weakest element in the-y^~ suppression chamber support system. -The maintenance of a i drywell-suppression chamber differential pressure within the range shown

.on Figure.3.5-1 with a, suppression chamber water level corresponding to a downcomer submergence range of 3.0 to 5.3 feet will assure the integrity; of the suppression chamber when subjected to post-LOCA suppression pool hydrodynamic. forces, s

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, 4.5.10 After the containment oxygen concentration has been reduced to meet the

. specification. initially, the containment atmosphere is maintained above t ,

atmospheric pressure by the primary containment inerting system. This system supplies nitrogen makeup to the containment so that the very slight leakage from the containment is replaced by nitrogen, further reducing the oxygen concentration. In addition, the oxygen concentration is continuously recorded and high oxygen concentration is annunciated. l Therefore,-a weekly check of oxygen concentration is adequate. This i system also provides capability for detemining if there is gross leakage

? from the containment.  ;

The drywell exterior was coated with Firebar D prior to concrete pouring 1 du' ring construction. The Firebar D separated the drywell steel plate from the concrete. After installation, the drywell liner was heated and

-expanded to compress the Firebar D to supply a gap between the steel drywell and the concrete. The gap prevents contact of the drywell wall with the concrete which might cause excessive local stresses during drywell expansion in a loss-of-coolant accident. The surveillance program is being conducted to demonstrate that the Firebar D will maintain its integrity and not deteriorate throughout plant life. The, csur'veillance frequgnqy is adequate to detect any deterioration tendency of the material.; (8)

The operability of the instrument line flow check valves are demonstrated

.to assure isolation capability for excess flow and to assure the operability of the instrument sensor when required.

Because of the large volume and themal capacity of the suppression pool,

- the volume.and temperature normally changes very slowly and monitoring -

these parameters-daily is sufficient.to establish any temperature trends. By requiring the suppression pool temperature to be continually rronitored and also observed during periods of significant heat addition,

the temperature trends will be closely followed so that appropriate action can be-taken. The requirement for an external visual . examination following any event whera potentially high loadings could occur provides assurance.that no-significant-damage was encountered. Particular  ;

attention si.ould be focused on structural' discontinuities in the vicinity

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'of the relief valve discharge since these are expected to be the points of highest stress.

Amendment:No.

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