ML17298A491

Requests Rev to 830517 Response Re Source Range Flux Monitor for Remote Shutdown Panel to Include Direct Capacity for Monitoring Source Range Flux Per App R to 10CFR50

ML17298A491
Person / Time
Site:	Palo Verde
Issue date:	07/28/1983
From:	Knighton G Office of Nuclear Reactor Regulation
To:	Van Brunt E ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
References
NUDOCS 8308050571
Download: ML17298A491 (10)

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JUL 28 >983 Docket Nos.:

50-528, 50-529 and 50-530 Mr. E.

E.

Van Brunt, Jr.

Vice President - Nuclear Projects Arizona Public Service Company Post Office Box 21666 Phoenix, Arizona 85036 DISTRIBUT~

ocument Control 50-"528/529/530

, ti NRC PDR L PDR NSIC PRC System LB¹3.Reading EALicitra JLee

Attorney, OELD ACRS (16)

Jordan, IE Taylor, IE TMNovak OParr

Subject:

Source Range Flux Monitor for Palo Verde Remote Shutdown Panel By letter dated Hay 17. 1983, you responded to our request to add two additional instruments to the Remote Shutdown Panel for Palo Verde for direct indication of process variables.

In your response, you state that as requested a direct indication of the reactor coolant loop cold;l~'eg temperature will be added to the Remote Shutdown Panel and you commit to complete installation of tgjs instrument by the end of the first refueling for Unit 1 and prior to fuel 1ioad for Units 2 and 3.

You also provide justification for interim operation of Unit 1 until the instrument is installed.

Based on our evaluation of your submittal, we find this commitment to be acceptable.

In your response, you also state that the source range neutron flux monitor requested by us is not needed since Ireactivityj can be controlled without direct indication of. neutron source range flux.

lie have'reviewed your response and conclude that it does not meet the staff position with regard to monitoring source range flux as shown in Enclosure

1. Therefore",.

we (request:that you revise your response to include a direct capability for monitoring source range flux from the ';Remote-- ShutdownPanel.

Please advise us as to when you plan to respond to this request.

If you have any questions regarding the request, you should contact Hanny Licitra, the Licensing Project Manager.

Sincerely,

~igina1 signed by George I. Knight~~

Enclosure:

Staff Position

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8URN 8/0805057'30728 PDR ADOCK 05000528 D

F PDR NRC FORM 318 (10-80) NRCM 0240 George M. Knighton, Chief Licensing Branch No.

3 Division of Licensing DL'LB¹3 EALicitra/y OParr 7l@/83 7/58/83 OFFIClAL RECORD COPY P.L.t.P.G........

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Palo Verde Mr. E.

E.

Van Brunt, Jr.

Vice President, Nuclear Projects Arizona Public Service Company P. 0.

Box 21666 Phoenix, Arizona 85036 CC:

Arthur C. Gehr, Esq.

Snell 5 Wilmer 3100 Valley Center Phoenix, Arizona 85073 Charles S. Pierson Assistant Attorney General 200 State Capitol 1700 West Washington Phoenix, Arizona 85007 Charles R. Kocher, Esq., Assistant Counsel James A. Boeletto, Esq.

Southern California Edison Company P. 0.

Box 800

Rosemead, California 91770 I!'. Marqaret Walker Deputy l3!rector of Energy Programs Economic Planning and Development Office 1700 West Washington Phoenix, Arizona 85007 Mr.. Rand L. Greenfield Assistant Attorney General Bataan Memorial Building Santa Fe, New Mexico 87503 Regional Adminstr ator-Region V

U. S. Nuclear Regulatory'Commission 1450 Maria Lane Suite 210 Walnut Creek, California 94596 Kenneth Berl'in, Esq.

Winston 5 Strawn Suite 500 2550 M Street, N.

W; Washington, D.

C.

20037 Lynne Bernabei Government Accountability Project of the Institute for Policy Studies 1901 gue Street, N.

W.

Washington, D;

C.

20009 Resident Inspector Palo Verde/NPS U. S. Nuclear Regulatory Commission P. 0.

Box 21324 Phoenix, Arizona 85001 Ms. Patricia Lee Hourihan 6413 S. 26th Street Phoeni.x-., Arizona 85040-

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Enclosure Staff Position Section III.L.1 of Appendix R to 10 )FR 60 requires that alternative shutdown capability shall.

be able to achieve and maintain subcritical reactivity conditions in the reactor.

Section III.L.2 of Appendix R'o 10 CFR 50 requires provision 'for direct readings of the process variables necessary to perform and control the reactor shutdown function.

Among the process variables which are to be monitored are:

source range flux, reactor coolant temperature, and steam generator pressure.

These three have been controversial so we have set forth our basis for concluding that they are necessary in order to meet Section, III'.Lof Appendix R.

Source Ran e Flux Monitoring of core flux provides a direct indicati5n of the reactor shutdown condition.

The monitoring of other pr'ocess variables. would, provide an inferred answer only.

Nth regard to the fission process, changes in neutron flux provides the quickest means of. assessing;.reactor criticality conditions.

Dilution events caused by the postulated. spurious operation of valves could result in power excursion which would. not'e readily detected by interPreting the changes in other process variables (such as reactor coolant temperature or pressure).

Periodic sampling of the reactor coolant for boron concentration is considered inadequate for determining "real-time" boron requirements.

Additionally, should the operators fail to detect; a.

loss of negative reactivity in a timely manner, the capability to prevent a criticality is indeterminate since components needed for such actions may be unavailable due to fire.

Thus, the provision for post fire soUrce range flux monitoring is necessary to meet Section III.L.2 of Appendix R.

Reactor Coolant Tem eratures The reactor coolant temperatures, in con)unction with the reactor coolant system

{RCS) pressure, are essential parameters necessary for plant cooldown and control and,

hence, conformance with Section III.L.2 of Appendix R; The plant control elements which rely on accurate reactor coolant temperature indication are natural circulation, subcooling and pressurized thermal shock concerns.

(1)

Natural Circulation:

In the natural circulation mode of operation, the hot leg temperature, cold leg temperature and the difference between the hot leg and cold leg temperatures.

(TH - T), provide indication by which natural circulation conditions can be determined.

In order to verify that natural circulation has been established, normal plant procedures require the operator to use cold leg temperature Tr..- It. has been su gested that the saturation temperature correspo6ding to the secondary side steam generator pressure T

. will approximate TC.

The staff sugges e

sat'

(2)

(3)

(4) acknowledges that such a condition can exist if natural circulation is occurring; however, the converse cannot be assumed.

Cooldown is usually achieved by the operator controlling the steam generator pressure and auxiliary feedwater flow to the steam generators.

Due to the inherent lag in response between the secondary and primary side, T cannot be inferred from T Natural circulation is normally deteFmined by knowing T, T.%serving that T and T are constant or decreasing.

and by moL'to/'ing (T -T ).

Sincf normal control room procedures require the use of T in con i ing natural circulation, emergency procedures should not dfviate: from this practice.

Thus. the provision for post fire cold leg temperature, T

wide range indication is necessary for meeting Section III.L.2 of Appefdix R.

U er Vessel Voidin:

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Subcoolin The bulk fluid temperature TH provides a reliable indication of the egree of RCS subcooling when used in conjunction with the RCS.

pressure.

TH is also used as a means of ver ifying natural circulation.

It has been suggested that exit core thermocouples.

(ECTs) provide temperature indications equivalent to T.

ECT readings provide.'local temperature conditions above the core, Ld can give representative equivalent T< provided the individual ECTs are Iudiciously selected..

since ECT readings are dependent not* only upon radial positioning; but also local flow rates past the ECTs.

Thus',, the provision-for wide range ECTs is-an acceptable alternate; to wide range T loop RTDs for meeting Section III.L.2 of, Appendix R, provided; that The'Ticensee demonstrates that their selection of* ECTs, will result; in averaged temperature readings representative of T.

Also, the licensees should demonstrate that under= conditions where the reactor vessel upper head.....

void is expanding thus, bringin9 higher temperature fluid into the.nUtl~t-"

plenum and hot legs, the EITs give

a. conservative indication of outlet-plenum temperature.

Pressurizhd Thermal Shock and A

endix G Considerations:

Tr, in con-junction with the RCS pressure, provides a direct indicatiott of the plant condition relative to the plant's pressure/temperature limits as it pertains to the Pressurized Thermal Shock considerations and the low temperature overpressure protection as outlined in Appendix G of 10 CFR 50.

Due to the collective effect of the steam generator con-ditions (i.e., feedwater flow and steam generator pressure) on the primary coolant temperatures, and the inherent lag beteen the secondary and primary sides conditions especially during transient conditions, T

may not be accurately inferred from the secondary side steam cknditions.

Steam Generator Pressure During non-power modes of operation, "control" is effected principally by adjusting secondary system parameters (the parameter usually specified by procedures is pressure) to compensate for variances in primary system

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performance.

Naintenance of level in the steam generators may not be sufficient in itself to control the heat removal rate and thereby maintain a "hot standby" or "hot shutdown" mode, or translate from "hot, shutdown" mode to "cold shutdown" mode.

Improper pressure control may cause an imbalance in heat:.removal whish.could result in excessive depressurization, the result of which could be generation of an undesired bubble. fn the primary system (e.g.,

upper head, for all PMRs, or candy cane, for. BEW designs) or rapid cooldown and,potential for violation of vessel pressure/temperature li 't For the monitoring of secondary system heat, removal, two secondary system parameters should be known:

level (inventory), and pressure.

provisions for post fire steam generator pressure and level monitoring are necessary for meeting Section III.L.2of Appendix R.

Instrumentation GuidelinesSection III.L.6 requires that, "Shutdown systems. installed to. ensure post-fire: shutdown capability need not be designed to meet seismic Category I criteria, single failure criteria, or other design'basis accident criteria, except where for required for other reasons',

e.g.,

because of interface with or impact on existing safety systems, or because of adverse valve actions; due to fire damage.."

Thus, the'onitors f'r the above listed para-meters. need not be "safety grade" in order to meet the requirements of Appendix. R.

Section III.G.3 requires that, "Alternate or dedicated shutdown capability and its associated circuits. independent of cables, systems or componen s

in the area, room or zone under consideration, shall be provided;"

For a postulated fire, an electrically independent monitoring capability for the above listed parameters should be provided outside the control room.

Based on the above, the revised list of instrumentation needed for PMRs is:

a) pressurizer pressure and. level, b) reactor coolant hot leg temperature or exit core thermocoup es, an cold leg temperature, c) steam generator pressure and level (wide range),

d) source range flux monitor, e

diagnostic instrumentation for shutdown systems, and.

f) level indication for all tanks used (e.g..

CST).

The instrumentation needed for BWRs is unchanged.

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