Bulletin 80-24: Prevention of Damage Due to Water Leakage Inside Containment (October 17, 1980 Indian Point 2 Event)
SSINS No.: 6820
Accession No.:
8008220270
IEB 80-24
UNITED STATES
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555
November 21, 1980
IE Bulletin No. 80-24: PREVENTION OF DAMAGE DUE TO WATER LEAKAGE INSIDE
CONTAINMENT (OCTOBER 17, 1980 INDIAN POINT 2 EVENT)
Description of Circumstances:
On October 24, 1980 IE Information Notice No. 80-37 described an event that
occurred at the Indian Point Unit 2 (IP-2) facility. On October 17, 1980,
upon containment entry for repair to a nuclear instrument, it was discovered
that several inches of water had accumulated on the containment floor
without the operators' knowledge. This accumulation was later determined to
have amounted to over 100,000 gallons which flooded the reactor vessel pit
and wetted the lower nine feet of the reactor vessel while the reactor was
at operating temperature.
The flooded condition resulted from the following combination of conditions:
(1) There were significant multiple service water leaks from piping and fan
coolers onto the containment floor. This system had a history of leakage;
(2) Both containment sump pumps were inoperable, one due to blown fuses and
the other due to binding of its float switch; (3) The significance of two
containment sump level indicating lights which indicated that the water
level was continuously above the pump-down level was not recognized by the
operators; (4) There was no high water level alarm and the range of sump
level indicating lights failed to indicate the overflowing sump level; (5)
The moisture level indicators for the containment atmosphere did not
indicate high moisture levels, apparently due to an error in calibration
and/or ranging which made them insensitive to the moisture levels resulting
from relatively small cold water leaks; (6) The hold-up tanks which
ultimately receive water pumped from the containment sump also received
water from other sources (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; (7) The fan cooler condensate wier level measuring instruments
were not properly calibrated; (8) There was no water level instrumentation
in the reactor vessel pit and the pumps were ineffective since they
discharge to the containment floor for ultimate removal by the containment
sump pumps.
This Bulletin is issued to enable the NRC staff to formulate requirements
for long term generic corrective actions which will be the subject(s) of
future NRC actions. The bulletin requires short term actions which will
preclude IP-2 type events at other plants in the interim before the longer
term generic actions are accomplished.
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IEB 80-24
November 21, 1980
Page 2 of 3
Actions to be Taken by Licensees:
1. Provide a summary description of all open* cooling water systems
present inside containment. Your description of the cooling water
systems must include: (a) Mode of operation during routine reactor
operation and in response to a LOCA; (b) Source of water and typical
chemical content of water; (c) Materials used in piping and coolers;
(d) Experience with system leakage; (e) History and type of repairs to
coolers and piping systems (i.e., replacement, weld, braze, etc.); (f)
Provisions for isolating portions of the system inside containment in
the event of leakage including vulnerability of those isolation
provisions to single failure; (g) Provisions for testing isolation
valves in accordance with Appendix J to 10 CFR 50 (h) Instrumentation
(pressure, dew point, flow, radiation detection, etc.) and procedures
in place to detect leakage; and (i) Provisions to detect radioactive
contamination in service water discharge from containment.
2. For plants with open cooling water systems inside containment take the
following actions:
a. Verify existence or provide redundant means of detecting and
promptly alerting control room operators of a significant
accumulation of water in containment (including the reactor vessel
pit if present).
b. Verify existence or provide positive means for control room
operators to determine flow from containment sump(s) used to
collect and remove water from containment.
c. Verify or establish at least monthly surveillance procedures, with
appropriate operating limitations, to assure plant operators have
at least two methods of determining water level in each location
where water may accumulate. The surveillance procedures shall
assure that at least one method to remove water from each such
location is available during power operation. In the event either
the detection or removal systems become inoperable it is
recommended that continued power operation be limited to seven
days and added surveillance measures be instituted.
d. Review leakage detection systems and procedures and provide or
verify ability to promptly detect water leakage in containment,
and to isolate the leaking components or system. Periodic
containment entry to inspect
* An Open system utilizes an indefinite volume, such as a river, so that
leakage from the system could not be detected by inventory decrease. In
addition, a direct radioactive pathway might exist to outside
containment in the event of a LOCA simultaneous with a system leak
inside containment. A closed system utilizes a fixed, monitored volume
such that leakage from the system could be detected from inventory
decrease and a second boundary exists to prevent loss of containment
integrity as a result of a system leak inside containment.
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IEB 80-24
November 21, 1980
Page 3 of 3
for leakage should be considered.
e. Beginning within 10 days of the date of this bulletin, whenever
the reactor is operating and until the measures described in (a)
through (d) above are implemented, conduct interim surveillance
measures. The measures shall include where practical (considering
containment atmosphere and ALARA considerations) a periodic
containment inspection or remote visual surveillance to check for
water leakage. If containment entry is impractical during
operation, perform a containment inspection for water leakage at
the first plant shutdown for any reason subsequent to receipt of
this bulletin.
f. Establish procedures to notify the NRC of any service water system
leaks within containment via a special licensee event report (24
hours with written report in 14 days) as a degradation of a
containment boundary.
3. For plants with closed cooling water systems inside containment provide
a summary of experiences with cooling water system leakage into
containment.
4. Provide a written report, signed under oath or affirmation, under the
provisions of Section 182a of the Atomic Energy Act of 1954, in
response to the above items within 45 days of the date of this
bulletin. Include in your report where applicable, your schedule for
completing the actions in response to items 2 (a) through (d). Your
response should be sent to the Director of the appropriate Regional
Office with a copy forwarded to the Director, NRC, Office of Inspection
and Enforcement, Washington, D.C. 20555.
If you desire additional information regarding this matter please contact
the appropriate IE Regional Office.
Approved by GAO, B180225 (ROO72); clearance expires November 30, 1980.
Approval was given under a blanket clearance specifically for identified
generic problems.
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