ML20056B663
| ML20056B663 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 10/19/1971 |
| From: | Grier B US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Wachter L NORTHERN STATES POWER CO. |
| Shared Package | |
| ML20056B654 | List: |
| References | |
| NUDOCS 9102070688 | |
| Download: ML20056B663 (2) | |
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October 19, 1971 l
-D-: 6:n ntaf@t M )i Northern States Power Company Docket No. 50-263 lj ATTN:
Mr. Leo Wachter, Vice President (j
Power Production and Systems f'
[i Operations 414 Nicollet Mall Minneapolis, Minnesota 55401 Gentlemen:
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$}l This letter refers to the inspections conducted by Messrs. Feierabend, Hunnicutt, Hyder, and Brunner of this office on July 20 and August 3,1971,
$i of activities at the Monticello Plant authorized by AEC License No. DPR.22, ji and to the discussion of our findings held by Mr. Feierabend with Messrs.
g' Larson, Clarity, Jacobson, and Eliason of your staff at the conclusion of the inspections.
f The areas examined during these inspections pertained to the unplanned J
release of gaseous radioactivity from the Monticello Plant which occurred j !
on July 14, 1971. This matter was reported to the Division of Reactor j
Licensing in your letter of July 23, 1971. The specific areas examined by our inspectors included the sequence of events during the occurrence, your evaluations of the radioactivity release paths and of the quantity f}
of radioactivity released, radiation protection activities iuring and subsequent to the occurrence, the cause of the occurrence, and the corrective action planned and impicmented. Within these areas the inspections consisted of examination of pertinent procedures and records, interviews with plant personnel, and observations by the inspectors.
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E No items of noncompliance with AEC requirements were identified within the scope of these inspections.
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1 With respect to the cause of the release of gaseous radioactivity, your letter of July 23, 1971, stated, "With the water lost from the air ejector off-gas loop seal, a direct path was established to vent off-gas from the 30 minute holdup line into the sump." Our inspections did not disclose any facts that would indicate a different.cause.
In this regard,
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we understand that the following corrective actioits have been taken:
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l Northern States Power Company October 19, 1971 l
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1.
A detailed supplemental procedure to the Operations Manual has been
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prepared. This procedure addresses itself to the reestablishment of normal operation of the air ejector system and the turbine steam seal system during recovery from a reactor isolation.
2.
The following control changes have been completed and tested to verify proper recovery from an isolated condition:
l a.
A control switch has been installed in the control room
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l which will allow the operators to isolate the off-gas line I
loop seal during high off-gas flow periods.
b.
The control switch, which is used to isolate the off-gas flow to the air ejectors, has been interlocked to also isolate the steam supply to the air ejectors.
3.
The duct penetration seals from the reactor building exhaust plenum to the reactor building have been repaired and tested.
We understand further that you will consider what additional action could be taken to assure that any release of radioactivity from the turbine building will be monitored. We plan to examine these matters during i
subsequent inspections.
With respect to the individuals who may have been exposed to airborne radioactivity during the occurrence, we have verified that you performed an evaluation of internal deposition based on special urine sampling and analysis and that the results of your evaluation showed no'above
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l normal activity.
j Ko reply to this letter is necessary; however, should you have any questions, I
we will be glad to discuss them with you.
l Sincerely yours,
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yce 11. Grier Regional Director
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