ML20141H825
| ML20141H825 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 07/30/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20141H828 | List: |
| References | |
| NUDOCS 9708010213 | |
| Download: ML20141H825 (3) | |
Text
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l CONTAINMENT SYSTEMS l
BASES 3/4.6.3 CONTAINMENT ISOLATION VALVES The OPERABILITY of the containment isolation valves ensures that the containment atmosphere will be isolated from the outside environment in the event of a release of radioactive material to the containment atmosphere or pressurization of the containment and is consistent with the requirements of General Design Criteria 54 through 57 of Appendix A to 10 CFR Part 50.
Containment isolation within the time limits specified for these isolation valves designed to close automatically ensures that the release of radioactive material to the environment will be consistent with the assumptions used in the analyses for a LOCA.
FSAR Table 6.2-65 lists all containment isolation valves. The addition of deletion of any containment isolation valve shall be made in accordance with Section 50.59 of 10CFR50 and approved by the Plant Operation Review Committee.
3/4.6.4 COMBUSTIBLE GAS CONTROL l
Hydrogen Monitors are provided to detect high hydrogen concentration conditions that represent a potential for containment breach from a hydrogen explosion.
Containment hydrogen concentration is also important in verifying l
the adequacy of mitigating actions.
The requirement to perform a hydrogen sensor calibration at least every 92 days is based upon vendor recommendations a
to maintain sensor calibration. This calibration consists of a two point j
calibration, utilizing gas containing approximately one percent hydrogen gas for one of the calibration points, and gas containing approximately four
{
percent hydrogen gas for the other calibration point.
The OPERABILITY of the equipment and systems required for the detection and control of hydrogen gas ensures that this equipment will be available to maintain the hydrogen concentration within containment below its flammable i-limit during post-LOCA conditions.
Either recombiner unit or the Mechanical i
Vacuum Pumps are capable of controlling the expected hydrogen generation associated with: (1) zirconium-water reactions, (2) radiolytic decomposition of water, and (3) corrosion of metals within containment. These Hydrogen Control Systems are consistent with the recommendations of Regulatory Guide 1.7, " Control of Combustible Gas Concentrations in Containment Following a LOCA," March 1971.
The Post-LOCA performance of the hydrogen recombiner blowers is based on a series of equations supplied by the blower manufacturer. These equations are also the basis of the acceptance criteria used in the surveillance procedure.
The required performance was based on starting containment conditions before the LOCA of 10.59 psia (total pressure),120*F and 100%
relative humidiy.
The surveillance procedure shall use the following methods to verify acceptable blower flow rate:
j NILLSTONE - UNIT 3 B 3/4 6-3 Amendment No. 17,77,142 0490 9700010213 970730 PDR ADOCK 05000423 P
PM i
CONTAINMENT SYSTEMS BASES
]
3/4.6.4 COMBUSTIBLE GAS CONTROL (Continued) 1 i
1.
Definitions and constants j
i CFM = cubic feet per minute RPM = revolutions per minute Blower RPM = 3550
]
Blower ft*/ revolution =.028 ft' 4
i Standard CFM = gas volume converted to conditions of 68'F and 14.7 psia.
2.
-Measure and record the following information:
1 Pcontainment--Average of 3LMS*P934, 935, 936, and 937 (psia)
Pout--From 3HCS-PIIA or B (psia) l Tc--Containment temperature (*F)
Pin--Measure with a new inlet gauge or calculate from Equation 3a below j
(psia) 4 l
scfm measured--See Procedure / Form 3613A.3-1 AP,--From Table 2 (psi) 1 i
A--As found Slip Constant
\\
Accuracy--Instrument accuracy range from Table 1.
3.
Calculate as found slip constant (A) f a.
Pin - Pcontainment - AP, f
b.
scfm A
3550 -
measured ccuracy M,Tc + 460 i-0.028
- 0.95
, Pin 528 A=
' ' Eggi,14.7 '
- 14.7' I. ' El, Tc + 460 ' %
,, Pin
, Pin 528 i
4 i
MILLSTONE - UNIT 3 8 3/4 6-3a Amendment No. Q, 142 0645 6
- - _ ~.... -. _.. - - -
i (
CONTAINMENT SYSTEMS BASES 3/4.6.4 COMBUSTIBLE GAS CONTROL (Continued) 4.
Calculate expected postaccident flow rate usir.g A calculated in Step 3.
a.
Slip RPM
- A * (4.937)%
- 1.218 b.
Actual Inlet CFM l
ACFM
.028 (3550 - Slip RPM) t c.
Standard CFM scfm = ACFM 0.725 d.
Postaccident scfm Minimum - scfm
- 0.95 e.
Acceptance Flow Rate l
j Postaccident scfm minimum 2 41.52 scfm.
Table 1 Accuracy Range (Ref. 2) scfm (measured)
Accuracy Ranae 40 to 50 5.8 scfm 50 to 80 4.7 scfm Table 2 Inlet Piping Loss (Ref. 1) scfm Heasured AP, (psi)
(Unadiusted) 30
.21 40
.31 50
.52 60
.73 70
.98 80 1.28
References:
1.
Calculation 90-RPS-722GM, " Flow Acce 3HCS*RBNR 1A/B Blowers 3HCS* CIA /B." ptance Criteria for 2.
Calculation PA 90-LOE-0132GE, " Hydrogen Recombiner Flow Error Analysis.
The acceptance flow rate is the required flow rate at the worst case containment conditions 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after the LOCA.
The analysis assumes the recombiners are started no later than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after the accident.
The 18-month surveillance shall verify the gas temperature and blower flow rate concurrently.
MILLSTONE - UNIT 3 B 3/4 6-3b Amendment No. p. 142 0490
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