ML19319A871

Notifies That Overpressure Protection Sys Does Not Meet NRC Criteria.Requests Addl Info & Proposed Mods Re Electrical Circuit & Logic Diagram of Overpressure Protection Sys

ML19319A871
Person / Time
Site:	Oconee
Issue date:	11/10/1977
From:	Schwencer A Office of Nuclear Reactor Regulation
To:	Parker W DUKE POWER CO.
References
NUDOCS 7912191055
Download: ML19319A871 (4)

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- g We have~ completed a preliminary. review of the overpressure protection system for Oconee 1, 2 and 3..We.have.found that the system currently installed does not meet allithe. criteria. established by the NRC.

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Your system maintains'a gas blanket or bubble in the pressurizer at all times, in confunction~with'a singla low pressure setpoint relief valve.

This design has certain advantages over..other concepts because failure 7

of an operator to manually enah"e the low-pressure setpoint of the reitef valve does.not totally defeat protection against a pressure transient; We have concluded thatyour system adequately accosmodates all postulated overpressure transients with the exception of an inadvertent: initiation of safety. injection by the high pressure injection (HPI) pump.

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Based on your analyses, we have. identified high pressure injection as the limiting mass addition overpressure transient.. Operation of the 191 pump, which is capable of delivering flow against full system operating pressure, fs required whenever a reactor coolant pump.;is in operation. Since the

. discharge of the HPI pump is.fsolated from the reactor coolant system by '

a. single fajection v41ve, afsin51e error or. equipment failure could open the injection valve and; initiate.a pressure increase inside the reactor 4,.4. _

' coolant system pressere boundaryt(RCSPE)..;1f. failure of the' single low

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setpoint pouer operstad relief.value is-then assumed as the single failure

'l' fo11 cuing initiation of the eventaour analysis shows that operator i

action would be requiredytthin.five minutes to maintain the~ RCSPB pressure below Appendix E limits..This. is/niet inaccordance with MRC criteria which does not allow credit for operator intervention for ten minutes..

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,.,D Since'your system'does notifully: satisfy our established criteria,%; %^% S

L we request that you propose system modifications that will provide n T+ w overpressure protection in fullconformance with.NRC criteria, and that

you provide a valbe-inpact assessment on schedule and cost to make all.

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'It.is also our position that ta assure. proper alignment of the

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-overpressure protection system during. plant emidown, an enabling.

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alam must be provided which monitors the y a enabling switch and 7~~

c the position of the isolation valve. upstream ut the power. operated relief valve:(PORV) W 4*.w.L,.R a.

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g Your pnvious submittals"do not. provide adequate electrical. circuit and logic diagrams of the overpressure. protection system to permit -

U a thorough review. ;Please pmvide,thesfollowing:

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.17RCS oe rpressure protection system diagram..-

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5. : Annunciator system schematic.

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7 6.[0virpmssure~ protection, control disp 15y an~. layout?

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In addition to the items discussed above, we have identified several concems mlated to PORY maintenance and HPI testing for the currently pmposed system. (IfJthe relief; valve requires maintenance the upstream isolation valve would need to be. closed thereby mmoving the single '..~~

. relief valve from service'.- Therefore we request _.that you propose Technical.5pecifications which^ stipulate that when the reactor vessel..

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temperature is belopthe miniansLvSlut.fDr which the vessel;Can be' [.

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-period.ef' time only ifat(1) charging. pumps are out of service' and' all'HPI injection valves lare closed.and power.r-md, or (2) the..,y i.3 L l

' vessel heed is removed.#.Regarding HPI testing, we request that tho' S g' PPI valve be allawed to be cycled.only if al1~ HPL ounps are out of -

service, or vessel tempenture is.above.the minimum value for which-the vessel can be fully pressurizede or;the reactor vessel head is?

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, Daystem enabling temperature and the FORY setpoint..In addition,

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?you shocid propose specifications related to. system testing.- --

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These maintenance and testing restrictions should'be examined to'

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assure compatibility with present Technical Specification requirements regarding the operability and periodic testing of ECC and emergency J

boration systems. Also, since.the impact of the proposed Technical;,

- e Specifications will,be considered.by.us_in.detamining the

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acceptability of the pnposed overpressure mitigating system. you ashould provide a thorough evaluation of.the effect of these maintenance-

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and testing requirements on the, susceptibility of the reactor coolant system to a pressure transiente,c..c ~,.,..n-

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You should provide the above requested infomation and the proposed Technical Specifications within 4E. days of receipt of this letter.

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For the interim period prior to installation of a system which meets all the NRC criteria, you should. continue to use the ovegrotection

' measures of your installed system._ We realize that although your

. overpressure mitigating system.does. not meet the NRC criteria, it

,will provide adequate protection.for tha.dnterim period.

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A. Schwencer Chief Operating Reactors Branch #1

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See next page

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~y-Duke:PowerlCompany.

4-November 10, 1977

. cc:- JMr. William L. Porter '

-Duke' Power Comoany-

.P. 0.1 Box 2178 ~

-422: South Church Street Charlotte, North' Carolina 28242 J. Michael McGarry,.III, Esquire DeBevoise &~Liberman-

.700 Shoreham Building 805-15th Street,'NW.,-

Washington, D.C.

20005 Oconee' Public 1.ibrary 201. South Spring Street'

=Walhalla, South Carolina 29691 O

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