ML19340C845
| ML19340C845 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 10/24/1980 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| References | |
| NUDOCS 8012170700 | |
| Download: ML19340C845 (1) | |
Text
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UNITED STATES
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NUCLEAR REGULATORY COMMISSION g
r REGION V 8
o 1990 N. CALIFORNIA BOULEVARD d
SUITE 202, WALNUT CREEK PLAZA 4e,,a WALNUT CREEK, CALIFORNIA 94596 I
h Decket fic. 50-312 Sacramento Municipal Utility District P. O. Box 1583D Sacramento, California 95813 Attention:. Mr. John J. Mattimoe i
Assistant General Manager Gentlemen:
This Inforr:ation Notice is being forwarded to you for information. No written response to tnis Information Notice is required.
If you have any questions related to the subject, please contact this office.
Sincerely, f
$[pDmM[b-,
l R. H. Engelken Director j
Enclosures:
1.
IE Information
!!otice ilo. 80-37 2.
List of Recently Issued Information flotices cc w/ enclosures:
R. J. Rodriguez, SMUD L. G. Schwieger, SMUD b
801217o 70 0
SSINS I!o.: 6835 Accession No.:
8008220249 UflITED STATES Ifl 80-37 NUCLEAR REGULATORY COMMISSIO!1 0FFICE OF IrlSPECTION AND ErlFORCEMEtiT bb MASHINGT0!!, D.C.
20555 t_Af October 24, 1980 IE Information Motice flo. 80-37:
C0!! TAI!l4ENT COOLER LEAKS AND REACTOR CAVITY FLOODING AT INDIAN POINT UNIT 2 Discriotion of Circumstances:
This flotice contains information regarding multiple service water leaks into containment with resul ting 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 rep;1r a malfunctioning power range nuclear detector, it was discovered that a Mgnificant amount of water was collected (approximately 100,000 gal) on the containment floor, in the containment sumps, 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 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 containment 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 Mghts 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 instrumentation to measure water level in the containment; (3) The moisture level indicators in the containment did not indicate high roisture 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 l
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 Peactor 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 I
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 l
licensee has also repaired the service water leaks, installed guide bushings l
on the sump pump control floats to prevent their binding, and has repaired the containment sump water level indicators.
IN 80-37 October 24, 1980 Page 2 of 2 The licensee plans in the loncer tarn to reolace the containment fan unit cooling coils.
It is anticirated that results of a centinuins NRC investication into this incident will result in issuance of an IE Eulletin and/or an NRR Generic Letter in the near future which vill recorrend or recuire specific licensees and acolicant actions.
In the interin, we reconnend that all licensee ascertain that the potential does not exist for undetected water accumulation in the containment.
This Information Notice is orovided to inforn licensees of a possibly significat natter.
No written resocnse to this Infornation Notice is required.
6
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IN 80-37 October 24, 1980 RECEriTLY ISSUED IE IrlFORMATI0tl MOTICES Information Date of flotice !!o.
Subject Issue Issued to 80-36 railure of steam 10/10/80 All nuclear power-generator support bolting reactor facilities holding OLs or cps 30-35 Leaking and dislodged 10/10/80 All categories G and Iodine-124 implant seeds G1 medical licensees 80-34 Boron dilution of reactor 9/26/S0 All oressurized water coolant during steam reactor facilities generator decontamination holding power reactor OLs 80-33 Determination of teletherapy 9/15/80 All teletherapy tirer accuracy (G3) licensees 80-32 Clarification of certain 8/12/80 All URC and agreement requirements for Exclu-state licensees sive-use shipments of radioactive materials 80-31 Maloperation of Gould-8/27/80 All light water reactor-Drewn Boveri Type 480 facilities holding OLs volt type K-600S and or cps K-00! 6005 circuit i
breakers 80-30 Fotential for unaccept-8/19/80 All boiling water reactor able interaction between facilities holding power the control rod drive scran reactor OLs or cps.
function and non-essential control air at certain GE BWR facilities i
j 80-29 Broken studs on Terry 8/7/80 All light water reactor turbine steam inlet facilities holding i
flange power reactor OLs or cps *
)
Supplement to flotification of 7/29/80 All holders of reactor 80-06 significant events at and near-term OL operating power reactor applicants facilities 80-28 _
Prompt reporting of 6/13/80 All applicants for and required information holders of nuclear power to flRC reactor cps' i
- Operating Licenses or Construction Permits L