ML19339B326
| ML19339B326 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 10/24/1980 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Counsil W NORTHEAST NUCLEAR ENERGY CO. |
| References | |
| NUDOCS 8011060746 | |
| Download: ML19339B326 (1) | |
Text
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tec UNITED STATES y, ",., (
g NUCLEAR REGULATORY COMMISSION E
REGION I
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8 631 PARK AVENUE
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KINO cP PRUSSIA, PENNsYt.VANIA 19406 S
Docket Nos. 50-245
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50-336 50-423
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Northeast Nuclear-Energy Company ATTN:
Mr. W. G. Counsil
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Senior Vice President - Nuclear Engineering and Operations P. O. Box 270 Hartford, Connecticut 06101 Gentlemen:
The enclosed IE Information Notice No. 80-37, " Containment Cooler Leaks and Reactor Cavity Flooding at Indian Point Unit 2,"
is for narded to you for information.
No written response is required.
If you desire additional information regarding this matter, please contact this office. '
Sincerely, e
ce H. Grier Director
Enclosures:
1.
IE Information Notice No. 80-37 2.
List of Recently Issued IE Information Notices CONTACT:
E. G. Greenman (215-337-5257) cc w/encis:
E. J. Mroczka, Station Superintendent D. G. Diedrick, Manager of Quality Assurance J. R. Himmelwright, Licensing Safeguards Engineer K. W. Gray, Supervisor of Construction Quality Assurance H. R. Nims, Director of Nuclear Projects 8011060746 h
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- p es SSINS No.
6835 Accession No.:
8008220249 UNITED STATES IN 80-37 NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555
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October 24, 1980 IE Information Notice No. 80-37:
CONTAINMENT COOLER LEAKS AND REACTOR CAVITY FLOODING AT INDIAN POINT UNIT 2 Discription of Circumstances:
This Notice contains information regarding multiple service water leaks into containment with resulting damage to reactor instrumentation and potential damage to the reactor pressure vessel.
Upon containment entry on October 17, 1980 at Indian Point Unit 2, to repair a malfunctioning power range nuclear detector, it was discovered that a significant amount of water was collected (approximately 100,000 gal) on the containment floor, in the containment sumps, and in the avity under the reactor pressure vessel (RPV). This collected water probably caused the detector malfunction, and the water in the cavity under the RPV is beif eved to have been deep enough to, wet several feet of the pressure vessel lower head, causing an unanalyzed thermal stress condition of potential safety significance.
This condition resulted from the following combination of conditions:
(1) Both cor.tainment sump pumps were inoperable, one due to blown fuses from an unknown cause and the other due to binding of its controlling float; (2) The two containment sump level indicating lights which would indicate increasing sater level over the water level range present in the containment were stuck (on) and may have been for several days, leaving the operator with no operable ir.strumentation to measure water level in the containment; (3) The moisture level indicators in the containment did not indicate high noisture levels, apparently because they are designed to detect pressurized hot water or steam leaks (i.e., a LOCA), and are not sensitive to the lower airborne moisture levels 2
resulting from relatively small cold water leaks; (4) The hold-up tanks which ultimately receive water pumped from the containment sump also receive Unit 1 process water, lab drain water, etc.
These other water sources masked the effect of cessation of water flows from the Unit 2 sump; (5) There were significant, multiple service water leaks from the containment fan cooling units directly onto the containment floor.
These coolers have a history of such leakage, which cannot be detected by supply inventory losses since the supply system (service water system) is not a closed system; (6) The two submersible pumps in the cavity under the Reactor Pressure Vessel were ineffective since they pump onto the con-tainment floor for ultimate removal by the (inoperable) containment sump pumps.
There is no water level instrumentation in the cavity under the RPV, nor was there any indication outside the containment when these pumps are running.
The licensee has installed redundant sump level annunciated alarms in the control room and has installed an annunciated alarm in the control room to indicate if either submersible pump in the reactor cavity activates.
The ifcensee has also repaired the service water leaks, installed guide bushings on the sump pump control floats to prevent their binding, and has repaired the containment sump water level indicators.
j j
s IN 80-37 October 24, 1980 Page 2 of 2 The ifcensee plans in the longer term to replace the containment fan unit cooling cofis.
It is anticipated that results of a continuing NRC investigation into this incident will result in issuance of an IE Bulletin and/or an NRR Generic Letter in the near future which will recommend or require specific licensee and applicant actions.
In the interim, we recommend ' hat all ifcensees ascertain that the potential does not exist for undetected water accumulation in the contzinment.
This Information Notice is provided to inform licensees of a possibly significant matter.
No written response to this Information Notice is required.
IE Information Notice No. 80-37 October 24, 1980 RECENTLY ISSUED IE INFORMATION NOTICES Information Subject Date Issued to Notice No.
Issued 80-36 Failure of Steam 10/10/80 All holders of a Generator Support power reactor Bolting OL or CP 80-35 Leaking and Dislodged 10/10/80 All holders of a Iodine-125 Implant Category G or G1 Seeds i'edical License 80-34 Baron Dilution of 9/26/80 All holders of a Reactor Coolant During PWR Power Reactor OL Steam Generator Decontamination 80-33 Determinatien of 9/15/80 All holders of Teletherapy Timer a teletherapy Accuracy license 80-32 Clarification of 9/12/d0 All holders of Certain Requirements an NRC or Agreement for Exclusive-use State License Shipments of Radioactive Materials 80-31 Maloperation of Gould-8/27/80 All holders of Brown Boveri 480V-Type a power reactor K-6005 and K-Don 6005 OL or CP Circuit Breakers 80-30 Potential for Unaccept-8/27/80 All holders of able Interaction a BWR power reactor Between the Control OL or CP Rod Drive Scram Function and Non-essential Control Air at Certain BWR Facilities 80-29 Broken Studs on 8/7/80 All holders of Terry Turbine a power reactor Steam Inlet Flange OL or CP Supplement Notification of 7/29/80 All holders of a to 80-06 Significant Events power reactor OL at Operating Power and near term OL Reactor Facilities applicants
.