ML20056B745
| ML20056B745 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 07/26/1971 |
| From: | Morris P US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Dienhart A NORTHERN STATES POWER CO. |
| References | |
| NUDOCS 9102080478 | |
| Download: ML20056B745 (6) | |
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1 JUL 2 81971
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Docket Es. 50-263
-Berthern States funer Caspear ATIB: Mr. Arther T. Disebert Vies President, Esgionertog 414 Nies11et Mall
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Gentlemma:
On May 12, 1971, you informed me that the flew 1adicaties for all four staan lines for the Monticelle Nueleer Generating Plant, Provistemet Operaties License Me. Dpt-12, was not se expected, and that as a result, the setpoints of the high fisw messors e W estemt to 140% of rated flow had been reduced from 122 paid (based en the flew assale calibraties curve) to 40 paid (based se extrapelaties of actual measurements).
Following telepheme teamersations with DEL sad Ceeplissee staff members, you su6mitted a second interim report sa July 2,1971, stating that additional testa had been approved and that the reassa for the amamely was not yet deterstmed. You alas stated that the setpetats of the high flew seneers had been adjusted to 43 paid and that the new setreint was justified by extrapolaties of measured data.
since the umasured pressure drey aereas the flew restrister is neck less than expected, and therefore the restrieter may met restrict flew to the extent assumed in the safety evolmation, the high fisw setpoint beoed en extrapelatism of measured data may met be ve114.
Beesose the reassa for the asemely la the performance of these esasere is not har===, we have caneladed that the operatism of the sensors.
should be tested at the Taeh=8*=1 Spedfications setpoint of 140% of rated ficer. Assurance is needed that the signal to initiate meia steam line isolaties would be generated at er below 140% of rated flow. Da the basis of the embaitted data, all four flow restrictors should be tested.
As soes as possible, submit your plane and the mothede you will see to eenduct the testa safely. If abenges to the Taeh=8aal specifteetiene are moeded for the conduet of the teste, list these limits that may U'
9102000478 710726 CF ADOCK 0500 63
Northera States Power Campany 1
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meed to be changed with the justificaties for the eheugs. As se disceseed with your I:;:::- ^M ises em July 7, is the Autoria perted i
until the tests have been performed the setpoints of the h @ fles sensors should est be set sheve previously tested leem1s.
When the tests have been ocupleted, and you have ametyeed the results, your plans for deteruimtes the esame of the mesastmas behaviar af es sensore ame far taking g re W remedial actimes should be
- W for our review, simmerely, i
Sriginal signed by Peter A. Neffl8 Peter A. Morris, Director Divisies of Ramster Licensing ec:
Mr. Gerald Charnoff i
Shaw, Pittman, Potts, Troubridge & Madden 910 17th Street, N. W.
Waak8 ;', D. C.
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Docket No. 50-263 4
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Northern tates Power Ceepany ATTN: Mr. Arthur T. Dianhart Yies ident, Engineering 414 Nieellet i
Minneapolis, en anota 55401 1
Gentlemen:
j On May 12, 1971, you ormed as that yhe flow indication for all four steam lines for the Mo$ticello Noelaat Generating plant, Provisiceal Operating License No. DPk 22, was a expected, and that as a reemit,
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had been reduced from 122 pshi (
ed on the flow nossle calibration curve) to 40 psid (based on ex apolation of actual measurements).
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a Following telephone convers ions th DEL and Compliance staff members, you submitted a second ist,sria repo em July 2, 1971, stating that additional tests had be approved a that the reason for the anomaly was not yet deter =iand.
From the data beitted on three of the four flow restrictors, it impossible to dekraise how the performance 6f the flow restrictor onpares with that expoeted from the calibrated i
orifices. You als9 stated that the setpoin' of the high flow sensors had been adjsstad to 43 paid. Tbs new setpo was justified by extrap-j olation of meas ed data.
Since, in the, performance of these sensors, the r for the anomaly is not knowp, we have concluded that the operation o) he sensors shouldbe)testedattheTechnicalspecificationsset t of 140% of rated fly. Assurance is needed that the signal to inihate main steam line isolation would be generated at or below 140% of ratM flow. On the basis of the submitted data, all four flow restrictors Nhould be tested.
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The potential inadequacy of the flow restrictor may be a significant safety consideration. The measured pressure drop across the floh terismechlessthanexpected,andthereforetherestrictormayahrestrie-t restrict flow to the extent assumed in the safety evaluaties. Sineex the reason for the anomaly is not known, the high flew setpoint based \\
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on estrapolation of measured data may not be id, the teste shes14
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j be performed on a timely basis.
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As soo's\\as possible, submit your plans the asthods you will use to conduct he tests scfely. If changes the Technical Specifications i
are moeded for the conduct of the t a list those limits that any~
i need to be anged with the justif tion for the change. ~As. es P l
untilthetes\\yourrepresentatigeenJuly7,intheinterimperiod,~'
discussed wit ts have been perio
, the setpoints of'the high: flow-i sensors should be set a previously tasted levels.
When the tests have een p lated, and you have analyzed the results, your plans for detershing the cause of the anomalous behavior of ^the i
sensors and for taking ny required remedial actions should be submitted for our review.
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Sincerely,
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l Yster A. Morris, Director l
Division of Reactor Licensing 4
1 cc: Mr. Gerald Charnoff Ihaw,Pittman,Fotts, Trowbridge & Madden 910 17th Street, N. W.
Washington, D. C.
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Docket me. 50-263
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Northezu States Feuer Coupemy j
ATTE: Mr. Arthur Ts Diesert
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414 micellet unit j
Minesepells, Minneesta 55401 1
i Gentia-aa:
On May 12 1971, you infonned es that' the flow Ladicetten for all four steam lines for the Honticelle Nuclear Generating Plant, Frevistemel Operating License No. DPR-22, was different them expected, and as a i
result, the setysists of the high flow sensors were reduced from l
122 paid (equivalent to 140% of rated flew based on the flew messle i
calibration curve) to 40 poid; 1,
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Following telephone cells,with DEL and Cany11asce staff, on July 2, 1
1971, you submitted a second interim report, stattag that additional I
tests were approved and'that the reases for the seems17 was not yet
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determined. h date (averagsd) submitted for three of the four flow i
restrictors show comaiderable divergence. Yee elas stated that the i
setpotats of the bish fisw sensors have been adjusted to 43 paid. h new setpoint was justified en extrapoistiam of measured data.
since we de meti know the reason for the essesty, we are of the opinion j
that the Technical specifications setpoint of 140% of rated flow be I
tested. We want the assurance that the a13 mal to initiate main steem isolation 1s generated below 140% of rated i' low. On the basis of the submitted data, all four flow restrictors abomid be tested.
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j N.an1 function of the flow restrictor may affect the health and safety of the public. Therefore, the required tests should be per -
j formed before the Monticelle plant generates say appreciable power.
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!j Myour eerliest osevenismos, we year plane and mothese you /
will'une for eseducting the test enfaly. If rettet from the O aisel' teettene to aseded der the duratism of the test.,41st 1,
those 1 shot may mood to be shooged usch the justifiaptism.'
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In the ported matti the teste have been perfeessed; the j
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the @ fles seneses should met be est aboom tested i
legale.
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He expect you will euhait year long remos plans en/how yes intend 1
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to espe with this anomaly se a timely beste.
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\\x Sincerelyi
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i Peter A. Morris, Director i
Division of Reactor Licensing 1,
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Mr. Gerald Charnoff
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