ML20137S084
| ML20137S084 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 02/07/1986 |
| From: | NRC |
| To: | |
| Shared Package | |
| ML20137S001 | List: |
| References | |
| NUDOCS 8602130570 | |
| Download: ML20137S084 (2) | |
Text
(IricYosure 0 PUBLIC SERVICE COMPANY OF COLORADO FT. ST. VRAIN NUCLEAR POWER PLANT DOCKET NO. 50-267 CONFIRMATORY ACTION 2
'5ER OF PCRV STRUCTURAL INTEGRITY The licensee assessed the leak tightness and structural integrity of the PCRV during the heatup which could occur following the extended loss of forced circu ation (LOFC) resulting from a high energy line break (HELB) from 35 per-cent of rated power (Ref. 1). The assessment took into consideration the cold reheat helium interspace leak. PCRV penetrations and seals, and other portions of the'PCRV where leakage could be a concern. The licensee's assessment was evaluated by the Oak Ridge National Laboratory (0RNL) (Ref. 2) and reviewed by the NRC staff. This SER reflects the conc 16sions resulting from the review of the licensee's analysis and the evaluation by the ORNL.
In assessing the potential for leakage, the licensee postulated a very con-f.-
servative scenario by the following:
1)
The reactor was assumed to be pressurized hence increasing the pressure differential and hence the leakage.
2)
The circulator shafts are delayed in being sealed thus increasing
the leakage.
3)
By assuming that the total inventory of the primary coolant radio-activity is at the design level of 30.000 curies.
It is estimated that actually the primary coolant radioactivity will be of the order of 300 curies and at 35 percent power, about 105 curies.
The Technical Specifications LCO 4.2.7 and 4.2.9 limit the amount of leakage of helium through all the primary closure seals in steam generator penetrations to 1.4 curies per day. The licensee demonstrated that the radioactivity in leakage is appropriately limited by means of activity detector installed in the exhaust line of the air ejector which monitors the radioactive noble gas activity in the line.
The Technical Specification limits also the total helium leakage through all primary closure seals in any penetration group I through VIII to 400 pounds per day at a differential pressure of 10 psi in the absence of an interspace gas leak pathway to the reheat steam system or 700 pounds per day with an inter-space gas leak pathway to the reheat steam system.
The licensee demonstrated that at the depressurized condition the upper lim *t on the reheat path leak rate would be between 1.2 percent and.2.4 percent which is lower than 3.8 percent at 5 psi corresponding to the 400 pounds per day at 10 psi. Additionally, the licensee controls the 700 lb./ day limit on the steam generator penetrations having a reheat steam line leakage path by monitoring the differential pressure between the penetration and the reheat steam ifne.
In view of the above we conclude that this licensee has demonstrated that the regulatory requirements regarding structural integrity of the PCRV are met.
OIOH,Ich Ob 7
e
E References :
1.
Letter from R. F. Walker of Public Service Company of Colorado to H. N. Berkow of NRC, dated December 10. 1985.
2.
Letter from S. J. Ball of Oak Ridge National Laboratory to Ken L. Hietner of NRC dated December 23, 1985 (transmitting Enclosure 7).
Reviewer:
R. Lipinski l
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