ML17298B441

Forwards Probabilistic Assessment of Uncontrolled Deboration Event W/Control Room Fire for Palo Verde Nuclear Generating Station, Per Commitment to Perform PRA of Alternate Shutdown Capability

ML17298B441
Person / Time
Site:	Palo Verde
Issue date:	10/31/1984
From:	Van Brunt E ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	Knighton G Office of Nuclear Reactor Regulation
Shared Package
ML17298B442	List: ML17298B441
References
ANPP-31013WFQ-T, NUDOCS 8411020243
Download: ML17298B441 (7)

Text

REOULATORYOFORMATION DISTRIBUTION SYSTEM (RIDE)

ACCESSION NBR:8411020243 DOC ~ DATEt 84/10/31 NOTARIZED: YES DOCKET FACIL:STN 50-528 Pa'lo Vetde, Nuclear Stations Unit ii Arizona Publi 05000528 STN 50 529 Palo Verde Nuclear Stations Unit 2F Ar izona Pub)i 05000529 STN-50-530 Palo Verde Nuclear Stations Unit 3F Arizona Publi 05000530 AUTH',NAME, AUTHOR AFFILIATION

,VAN BRONTFE.ED Arizona Public Service Co.

RECIP ~ NAME RECIPIENT AFFILIATION KNIGHTONFG ~ H ~

Licensing Branch 3

SUBJECT:

Forwards "Probabilistic Assessment of Uncontrolled Deborat-ion EVent Ii/Control Room Fire for Palo Verde Nucleat Generatin9, Stations" per commitment'o perform PRA of alternate shutdown capability'ISTRIBUTION CODE:

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I Arizona Public Service Company Director of Nuclear Reactor Regulation Attention:

Mr. George W. Knighton, Chief Licensing Branch No. 3 Division of Licensing U.S. Nuclear Regulatory Commission Washington, D.C.

20555 October 31, 1984 ANPP-31013 WFQ/TFQ

Subject:

Palo Verde Nuclear Generating Station (PVNGS)

Units 1, 2 and 3

Alternate Shutdown Capability Probabilistic Risk Assessment Docket Nos. STN-50-528/529/530 File:

84-056-026.

G.1.01.10

Reference:

Letter from T.M. Novak, NRC, to E.E.Van Brunt, Jr.,

APS dated July 30, 1984

Dear Mr. Knighton:

As discussed in the reference letter, we had committed to perform a

probabilistic risk assessment (PRA) of the PVNGS alternate shutdown capability to provide further confidence that a source range neutron flux monitor is not necessary to perform and control the required plant functions given a control room fire, per the requirements of

10CFR50, Appendix R.

A summary of this PRA is provided for your use.

This assessment estimates the probability of an uncontrolled boron dilution event while the plant is operated from outside the control room.

The probability of operator error in detecting and terminating the event is determined for three methods of detection; boron

sampling, source range neutron flux monitor, and both sampling and the neutron monitor.

The results of the assessment are summarized below:

Case Detection Method Frequency of an Extended Boron Dilution Event Boron Sampling Source Range Neutron Flux Monitor Boron Sampling and Source Range Neutron Flux Monitor 1.3X10

/Reactor Yr.

2.1X10 6 /Reactor Yr.

6.25X10

/Reactor Yr.

84ii020243 84i03i PDR ADOCK 05000528 PDR

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George M. Knighton

$Lternate Shutdown Capability Probabilisitc Risk Assessment ANPP 31013 Page 2

The results of the PRA indicate that for this event, boron sampling is a better method than the source range neutron flux monitor for detecting an uncontrolled boron dilution event.

This can be attributed to the limited usefulness of the monitor given the large initial shutdown margin present when assuming an all-rods-in SCRAM.

Mhen comparing boron sampling in conjunction to the source range neutron flux monitor, to boron sampling only, there is a very small decrease in the frequency of the event.

This assessment confirms that a source range neutron flux monitor is not necessary for the PVNGS alternate shutdown capability.

This is based on the very low frequency of an extended boron dilution event using boron sampling for detection of the event, 1.3X10 per reactor year, which js very small compared to the NRC proposed safety goal of 1X10 per reactor year.

1 Please contact me if you have any questions on this matter.

EEVBJr/TFQ/no Attachment Very truly yours P.F V~

E.E.

Van Brunt, Jr.

APS Vice President Nuclear Production ANPP Project Director CC:

T.M. Novak (NRC) w/a L.S. Rubenstein (NRC) w/a E.A. Licitra w/a A.C. Gehr w/a R.P.

Zimmerman w/a

October 31, 1984 ANPP-31013 STATE OF ARIZONA

)

)

sate COUNTY OF MARICOPA)

I, Edwin E.

Van Brunt, Jr.,

represent that I am Vice President, Nuclear Production of Arizona Public Service

Company, that the foregoing document has been signed by me on behalf of Arizona Public Service Company with full authority to do so, that I have read such document and know its

contents, and that to the best of my knowledge and belief, the statements made therein are true.

Edwin E. Van Brunt, Jr.

Sworn to before me thle~+/

day of S'.

My Commission Expires:

My Commission Expires Aprii 6, 1987

, 1984.

Notary Public

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