ML20101D279
| ML20101D279 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 12/03/1984 |
| From: | Lee O PUBLIC SERVICE CO. OF COLORADO |
| To: | Johnson E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| RTR-NUREG-0737, TASK-3.D.3.4, TASK-TM P-84511, NUDOCS 8412240003 | |
| Download: ML20101D279 (4) | |
Text
PUBLIC SERVICE COMPANY OF COLORADO P. O. 8 0 X 840
- DENVER, COLORADO 80201 December 3, 1984 Oscan n.x.zm Fort St. Vrain vic e m.,om Unit No. 1 P-84511 Regional Administrator Region IV Nuclear Regulatory Commission DEC 141984 611 Ryan Plaza Drive, Suite 1000 lp Arlington, Texas 76011 Attention: Mr. Eric H. Johnson DOCKET N0: 50-267
SUBJECT:
NUREG-0737, Item III.D.3.4
REFERENCE:
PSC Letter, Warembourg to Eisenhut, dated 3/30/84 (P-84101)
Dear Mr. Johnson:
This letter is to inform you of the status of the Three-Room Complex HVAC Filter installation committed to by Public Service -Campany in the above Reference.
Installation of the new HEPA filter and charcoal adsorber was completed on October 1, 1984. At this time the filter is considere1 operational;
- however, subsequent testing has shown that the instrumentation provided and installed with the filter unit is not adequate for testing in accordance with ANSI N510-1980 and Regulattry Guide 1.52, Revision 2,
March, 1978.
The flow instrumentation, necessary for testing, will be installed in a timely manner depending on material availability.
In response to a
recent telephone conversation between Mr. Philip Wagner, NRC Region IV, and Mr. M. H. Holmes, Public Service Company, concerning electric air heaters in the Three-Room Complex HVAC Filter System, Public Service Company has concluded that heaters are not needed to control or reduce the relative humidity of the incoming air before it reaches the filter system for the following reasons:
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.1.) The filter system is available.to support plant operations during accident conditions, but has not been relied upon during or
-following either of the Design Basis Accidents.(DBA). Reference FSAR Sections 14.10, 14.11, 11.2.2.6, and Appendix C,
Design Criterion 11.
There is no source of moisture associated with either DBA.
Therefore, relative humidity greater than 70 percent, which would adversely affect filter efficiency, is not postulated to occur during a d. sign basis accident condition at Fort St. Vrain.
2.) Since the primary coolant does not contain appreciable levels of moisture, the only potential accidents at FSV which result in the release of radioactivity and high humidity conditions are those in which significant quantities of secondary coolant are released to atmosphere.
LC0 4.3,8 of the FSV Technical Specifications limits secondary coolant activity concentrations to 0.009 uCi/cc of I-131 and. 6.8 uCi/cc of tritium.
These limits were established to limit the exclusion area boundary dose to less than suggested limits in the event of the accident involving simultaneous loss of outside electric power, main turbine trip and failure of one diesel generator to start (FSAR Sec 10.3.2).
As stated in the basis for LC0 4.3.8,..about 52,000 gallens of water would be vented to the atmosphere as steam.
In this accident, less than 3 curies of I-131 would be released.
Since the activity is released outside the reactor and turbine buildings, the reactor building exhaust stack gas activity monitors would most likely not detect sufficient levels of activity to trip and cause the Control Room HVAC system to assume the recirculation mode with minimum makeup. Since Control Room air is not supplied through the emergency makeup filter, electric air heaters on this filter would not affect the consequences of
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this accident.
In the event of a secondary coolant pipe rupture inside the turbine building with radioactivity in the secondary coolant, the turbine building atmosphere would contain high humidity and radioactivity. Since the reactor building exhaust stack gas activity monitors would not sense the radioactivity in the turbine building, the Control Room HVAC system would remain in the normal operating mode, obtaining makeup air from outside the turbine building with no makeup air passing through the emergency makeup filter.
This is desireable since makeup air to the Control Room will consist of fresh air from outside and not high temperature, high humidity, radioactive air from within the turbine building.
In this situation electric air heaters on Control Room HVAC filters are unwarranted since makeup air will not contain high levels of humidity.
Presently, secondary coolant levels of I-131 and tritium are only a small fraction of the levels permitted by LC0 4.3.8.
e 3;) The emergency makeup air is taken from the enclosed, heated turbine building. This greatly reduces the relative humidity during._ cold months when space heating is required. During the i
remainder of the time, meteorological data indicates that the l
relative humidity of air to the filter system is very rarely j
greater than 60 percent. Section 4.1 of ANSI N509-1980 states, l
" Heaters are required for units' having adsorbers if the relative humidity of air to the adsorber is potentially greater than 70 percent for sufficient time -to cause iodine release to exceed guidelines."
4.). Filter test.results associated with two similar filter systems without heaters (reactor building exhaust and the onsite Technical Support Center) have been acceptalle when tested in accordance with ANSI NGIO-1980 and Regulatory Guide 1.52, Revision 2, March, 1978.
5.) The amount of iodine expected to be released during a FSV radiation release accident or DBA is minimal.
In Design Basis Accident No. 2, which involves the release of all primary coolant circulating iodines and 0.57% of all plateout iodine, only 10 Curies of I-131, 12 Curies of I-133, and 71 Curies of all other iocines are expected to be released to the atmosphere (FSAR Table 14.11-3).
Therefore, a proposed Technical Specification change which will meet the requirements of NUREG-0737, Item III.D.3.4 and be consistent with the design of the Three-Room Complex HVAC Filter installation, will be submitted within thirty days following the installation and testing of required flow instrumentation.
If you have any questions or comments concerning this matter, please contact Mr. M. H. Holmes at (303) 571-8409.
Very truly yours,
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- 0. R. Lee, Vice President Electric Production ORL/DLF/kss
h UNITED STATES OF AMERICA NUCLEAR REGULATORY C0t941SSION In the Matter
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Public Service Company of Colorado Docket No. 50-267 Fort St. Vrain Unit No.1 AFFIDAVIT 0.
R. Lee, being duly sworn, hereby deposes and says that he is Vice President of Public Service Company of Colorado; that he is duly authorized to ' sign and file with the Nuclear Regulatory Commission the attached response concerning NUREG-0737, Item III.D.3.4; that _he is familiar with the' content thereof; and that'the matters set forth therein are true and correct to the best of his knowledge, information and belief.
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- 0. R. Lee Vice President STATE OF h
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COUNTY OF-A. W
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Subscribed and sworn to before me, a Notary Public on this M day of Aru,.J.v /
, 1984.
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N6tary Public&-
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My commission expires ch w # / r
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