ML20024G597

Forwards Annual Rept of Primary Coolant Leakage to Drywell for License DPR-22

ML20024G597
Person / Time
Site:	Monticello
Issue date:	03/20/1974
From:	James Keppler NORTHERN STATES POWER CO.
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
References
NUDOCS 9102130445
Download: ML20024G597 (4)

Text

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MSP NORTHERN 8 TATE 5 POWER COMPANY MINN E A POLIS. MIN N E SOTA 95408

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March 20, 1974

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-a Mr. J F O' Leary 3

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p U S Atomic Energy Commission Washington, DC 20545 q

Dear Mr. O' Leary:

FONTICLLIA NUCLEAR GENERATING PIMI Docket No. 50-263 License No. DPR-22 Annual Report of Primary Coolant Lenkage to Drywell This report is submitted in accordance with Section 6.7.C of Appendix A, Technical Specifications, of the Provisional Operating License for the Monticello Nuc1 car Generating Plant.

It is a summary of coolant to drywell leakage rate measurements for the period of January 1 through December 31, 1973.

Drywell leakage is broadly classified as being from identified or unidenti-fled sources.

Identified leakage is piped from the recirculation pump seals, valve stem leak-offs, reactor vessel flange leak-off, bulkhead and bellows drains, and vent cooler drains to the drywell closed radwaste sump. All other leakage is collected in the drywell open radwaste sump and classified as unidentified leakage. Drywell leakage is calculated daily using flow integrators installed in the pump discharge line of each sump. Accuracy of measurement is better than + 37..

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Table I is a summary of drywell coolant leakage measurements for 1973. As l

noted in the Tabic, all leakage remained well below the Technical Specification Limits of 5 GPM for unidentified Icakage and 25 GPM for total leakage.

In our " Report of Performance of the Reactor Coolant Leakage System," which j

was submitted to the Directorate of Licensing on December 28, 1972, we de-scribed an improved system for giving rapid indication of increases in drywell coolant leakage. This system was installed in October 1973, and is currently in use. It performs as expected and earlier concerns about speed of response in leakage detection have been fully resolved. 'Ihis system is independent of and in addition to all other installed equipment. Drywell identified and unidentified l

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NOR's.iERN CTATEO POWER COMPANY Mr. J F O' Leary March 20. 1974 luakage is calculated periodically by the computer and printed out in the control room.

Leak rates in excess of preset limits print out as alarms.

The major components of the system are

a. Displacement type level transmitter mounted in a stilling well from the top of each drywell sump

b. Recorders in the control room to continuously conitor sump level

c. Input to plant process computer to calculate leak rate and generate alarms The system provides the following functions

a. Alarms on unidentified leakage in excess of a preset limit (now sct at 2.5 GPM) with a delay of 1.iinute or less

b. Alarms on identified leakage in excess of a preset limit (now set at 5 GPM) with a delay of I minute or less

c. Provides graphic indication in the Control Room of drywell leakage trends This system provides a timely method of detecting leakage from the reactor coolant boundary and no further modifications for this function l

are considered necessary.

Yours truly,

~

L 0 Mayer, PE Director of Nuclear Support Services i

tom /DMM/1h cc: J G Kepplet G Charnoff Minnesota Pollution Controi Agency Attn:

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l Table I Sumry of Coolant Leakage to Drvvell-1973 Leakage from Known Sources (GPM)

Leakage from Unknown Sources (GPM)

Total Leakage (CPM)

Month Highest Lwest g

Highest Invest M

Highest Iowest A_vg Remarks l

JAN 1.66 1.04 1.34 0.91 0.25 0.59 2.28 1.51 1.93 FEB 1.55 0.99 1.28 0.81 0.42 0.59 2.30 1.54 1.86

' MAR 1.38 0.55 1.01 0.70 0.16 0.47 1.95 0.71 1.48 Annual Outage 3/4/73 - 5/14/73 APR NAY 1.22 0.04 1.00 0.27 0

0.05 2.24 0.04 1.06 JUN 1.30 0.12 1.03 0.38 0

0.20 1.68 0.12 1.23 JUL 1.30 0.52 1.22 0.50 0.12 0.28 1.79 0.72 1.50 AUG 1.78 0.01 1.23 1.13 0

0.09 2.91 0.01 1.32 SEP 1.56 0.11 1.29 0.35 0

0.11 1.79 0.11 1.40 OCT 2.77

0. D 1.99 0.32 0

0.06 2.80 0.13 2.05 NOV 2.90 0.13 2.01 0.75 0

0.23 3.28 0.13 2.24 l

DEC 2.46 1.46 1.77 0.39 0.2k 0.33 2.84 1.71 2.10 i

YEAR 2.90 0.01 1.38 1.13 0.0 0.27 3.28 0.01 1.65 (22.6*)

(5.4*)

(13.1*)

(6.6*)

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• Percentage of Technical Specification Limit.

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AEC DI

'IQUTION FOR PART 50 DOCEET MA9

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CONTROL NO:

24k4 FILE:,,,,,,

FROM DATE OF DOC DATE REC'D LTR MEMO RPT OTHER Northern States Power Con.pany Minneapolis, Minnesota

!. O. Mayer 3-20-74 3-25-74 X

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ORIG CC OTHER SENT AEC PDR XXX J. F. O' Leary 40 CLASS UNCLASS PROP INFO INPUT NO C1S REC'D DOCKET NO:

XXX 40 50-263 DESCRIPTION:

ENCLOSURES:

Ltr furn info rc coolant to drywell leakage Attaclaent: Table I-Sunn.ary of Coolant Leakage ra te mea surements.. 1-1-73 thru 12-31-7 3...

to Drywell 1973 trans the following'...

IACKN06'LEDGEu

$0No.tarauuvE PLANT NAME: MONTICELLO (40 cys att rec'd)

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(1)(2)(10) NATIONAL LAB'S 1-PDR-SAN /LA/NY

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