ML19339C002
| ML19339C002 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 10/27/1980 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Oprea G HOUSTON LIGHTING & POWER CO. |
| References | |
| NUDOCS 8011170031 | |
| Download: ML19339C002 (1) | |
Text
_
~/fc
- <c, UNITED STATES NUCLEAR REGULATORY COMMISSION
^
- ~ ;, 71 q
k
N -
E' REGION IV
/ !
s 2
.; 4 /
. 611 RYAN PLAZA DRIVE. SUITE 1000
, ="
ARLINGTON, TEXAS 76011 In Reply Refer To:
RIV Docket Nos. 50-498/IE Information Notice No. 80-37 50-499/IE Information Notice No. 80-37 Houston Lighting & Power Company ATTN:
Mr. G. W. Oprea, Jr.
Executive Vice President Post Office Box 1700 Houston, Texas 77001 Gentlemen:
This IE Information Notice is provided as an early notification of a possibly significant matter.
It is expected that recipients will review the information for possible applicability to their facilities.
No specific action or response is requested at this time.
If further NRC evaluations so indicate, an IE Circular or Bulletin will be issued to recommend or request specific licensee actions.
If you have questions regarding this matter, please contact the Director of the appropriate NRC Regional Office.
Sincerely,
\\
dicC ' xAvw oJ.arl V. Seyfrit Director
Enclosures:
1.
IE Informaton Notice No. 80-37 2.
List of Recently Issued IE Information Notices senno CFA
SSINS No.:
6835 Accession No.:
8008220249 NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 IE Information Notice No. 80-37 Date:
October 24, 1980 Page 1 of 2 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 iloor, in the containment sunps, and in the cavity under the reactor pressure vessel (RPV). This collected water probably caused the detector malfunction, and the water in the cavity under the RPV is believed to have been deep enough to we: 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 containment sump pumps were inoperable, one due to blown fuses from an unkncwn cause and the other due to binding of its controlling float; (2) The two containment sump level indicating lights which would indicate increasing water: 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 inst::umentation to measure water level in the containment; (3) The moisture levei indicators in the containment did not indicate high moisture 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 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.
a
IE Information Notice October 24, 1980 No. 37 Page 2 of 2 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 licensee 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.
The licensee plans in the' longer term to replace the containment fan unit cooling coils.
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 licensees and applicant actions.
In the interim, we recommend that all licensee ascertain that the potential does not exist for undetected water accumulation in the containment.
This Information Notice is provided to inform licensees of a possibly significanc matter.
No written response to this Information Notice is required.
i a
I t
1
IE Information. No. 80-37 October 24, 1980 LISTING OF RECENTLY. ISSUED IE INFORMATION NOTICES Info rmation Subject Date Issued To Notice No.
Issued 80-30 Potential for Unaccept-8/19/80 All boiling water reactor able Interaction Between facilities holding power the Control Rod Drive Scram reactor Operating Licenses Function and Non-Essential (0Ls) or Construction Control Air at Certain GE BWR Permits (cps)
Facilities 80-31 Maloperation of Gould-8/27/80 All light water reactor Brown Boveri Type 480 facil. ties holding volt type K-600S and Operating Licenses or and K-DON 600S circuit Construction Permits breakers (cps) 80-32 Clarification of certain 8/12/80 All NRC and agreement requirements.for Exclu-state licensees sive-use shipments of radioactive materials 80-33 Determination of Tele-9/15/80 All teletherapy therapy Timer Accuracy (G3) licensees l
80-34 Boron Dilution of Reactor 9/26/80 All Pressurized 1
Coolant During Steam Water Reactor Generator Decontamination Facilities holding power reactor Operating Licenses (OLs) 80-35 Leaking and Dislodged 10/10/80 All categories G and l,
Iodine-124 Implant Seeds
.G1 medical licensaes 80-36 Failure of Steam 10/10/80 All nuclear power Generator Support Bolting reactor facilities holding Operating Licensees (OLs) or Construction Permits (cps)
Enclosure
>