ML20002C675
| ML20002C675 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 05/02/1973 |
| From: | Sewell R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Oleary J US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 8101100698 | |
| Download: ML20002C675 (3) | |
Text
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TO Mr. John F. O' Leary, Director Re: Docket No 50-155 Directorate of Licensing License No DPR-6 US Atomic Energy Co==ission Washington, DC 20545
Dear Mr. O' Leary:
By letter dated September 1, 1972, Consumers Pcwer Company reported that recent test measurements indicated the Big Rock Point Plant off-gas holdup time to be approximately 16 minutes as opposed to the design holdup limit of 30 minutes. At that time, we stated that an internal inspection of the holdup pipe would be conducted during the next refueling outage and, until that time, the release rates would be based on a holdup time as determined by the monthly tests.
The internal inspection of the pipe was conducted during the recently compi ted refueling outage and showed that the pipe was in-stalled according to the design specifications and it is free of ob-structions and/or water pockets. This verifies the theory that the decrease in holdup time from that of the original design is due to stratification of the gases. This stratification would appear to be in existence because of the gas density differences (ie, xenon density is about 70 times the density of hydrogen). Other measurements taken during plant operation show that the reduced holdup time is not due to excessive air inleakage.
As a result of the slightly higher decay energy of the shorter-lived species of noble gases and daughter products (16 minutes holdup time versus 30 minutes holdup time), the corresponding calculated site boundary dose also changes. The factor by which previously calculated site boundary doses are to be adjusted are:
Equilibrium Mixture - 1.2 Diffusion Mixture
- 1.4 (Recoil mixtures of nuclides are either not observed or are insignificant relative to equilibrium re diffusion mixture contributions.)
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/f NC The difference in calculated dose between 30 minutes and 16 minutes delay time decreases as a function of distance from the point of release. Thus, the calculated dose to any population area remains essentially unchanged.
The controlling species of particulate and halogen releases are unchanged by a reduction in holdup time.
s Since the 16-minute holdup time has been verified to exist with the corresponding off-gas flow rate of 10 cfm and monthly tests over the past six months indicate it is not changing, these monthly tests have been discontinued. If a change in off-gas flow rate indicates a possible reduction in holdup time, additional tests will be conducted. Since the off-gas flow rate has averaged approximately 10 cfm since initial plant operation, all previous off-gas release rates will be adjusted to reflect the 16-minute holdup time. The ad-justed numbers will be included in the next semiannual report (No 18).
Yours very truly, 0
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.J4. u RES/mel Ralph E. Sewell Nuclear Licensing Administrator CC: BHGrier, USAEC l
2935
AEC DISTRIBUTION FOR PART 50 D00.CT rdERIAL
( m P03ARY FORM)
CONTROL NO:
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'. :FE.2C DATE OF DOC:
DATE REC'D LTR MEMO RPr OniEn Consumers Power Company, Ja.ekson, Michigan 49201 Ralph B. Sewell 5-2-73 5-4-73 X
203 ORIG CC OTHER SEIG AEC PD3 x
Mr. O'Jpary
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(UgeRo? INFO INPUT No crS REC'D DOCS 2 NO:
39 50-155 JEScaIPTION:
ENCLOSgEES:
Ltr re their 9-1-72 ltr.... furnishing info re the internal. inspection of the holdup pipe....
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