ML19345C445
| ML19345C445 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 11/21/1980 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Oprea G HOUSTON LIGHTING & POWER CO. |
| References | |
| NUDOCS 8012050018 | |
| Download: ML19345C445 (1) | |
Text
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ARLINGTON, TEXAS 76011 19E0 Nfff 28 IM.I 08 In Reply Refer To:
November 21, 1980 RIV Docket Nos. 50-498/IEy BuU,e'tigidts. 80-24 ne,
50-499/IE Bullstin No. 80-24 Houston Lighting & Power Company ATTN: Mr. G. W. Oprea, Jr.
Executive Vice President Post Office Box 1700 Houston, Texas 77001 Gentlemen:
Enclosed is IE Bulletin No. 80-24 which is transmitted for information with ragard to your nisclear power facilities.
Should you have any questions regarding this bulletin, please contact this office.
Sincerely, g? f L
gKarl V. Sd frit s-Director
Enclosure:
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8008220270 UNITED STATES OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 IE Bulletin No. 80-24 November 21, 1980 Page 1 of 3 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 hsw 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 containmenr.. 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.
4,.
IE Bulletin No. 80 November-21, 1980 Page 2 of 3 Actions ' to be Taken - by -Licer.sse-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 vulner-ability'of those isolation provisions.to single failure; (g) Provisions for j
testing isolation-valves in accordance with Appendix J to 10 CFR 50 L
(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.
i 2.
For plants with open cooling water systems inside containment take the following actions:
7 Verify existence.or provide redundant means of detecting and promptly a.
alerting control room operators of a significant accumulation of water j
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.
s.
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 l
water may accumulate. -The surveillance procedures shall assure that at i
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 l
operation be limited to seven days'and added surveillance measures be instituted.
t
- d. Review leakage detection systems and procedures and provide or. verify i.
ability to promptly detect water leakage in containment, and to isolate the leaking components or system.
Periodic-containment entry to inspect for leakage should be considered.
i
" 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 i
1 direct radioactive pathway might exist to outside containment in the event of
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a LOCA simultaneous with a. system leak inside cent 4inment.
A closed system utilizes a fixed, monitored volume such that leakage from the system conid L
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.
IE Bulletin No. 80-24 November 21, 1980 Page 3 of 3 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 considerationr) a periodic containment inspection or remote visual surveillance to cneck 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 subseqLent to receipt of this bulletin.
f.
Establish procedures to notify the NRC of any service water systen leaks within containment via a special licensee event report (24 haurs with written report in 14 days) as a degradation of a containment boundary.
3.
For plants with closed cooling water systems inside contain.7.?nt provide a summary of experiences with cooling water system leakage inte containment.
4.
Provide a written report, signed under oath or affirmation, under the provi-sions of Section 182a of the Atomic Er.ergy 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 (R0072); clearance expires November 30, 1980.
Approval was given under a blanket clearance specifically for identified generic problems.
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