ML19319E227
| ML19319E227 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 08/08/1977 |
| From: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| Shared Package | |
| ML19319E208 | List: |
| References | |
| NUDOCS 8003310734 | |
| Download: ML19319E227 (6) | |
Text
r%
N N.
]
em s
(
) fli:J:lLIL )
\\
SACRAMENTO MUNICIPAI. UTILr f DISTRICT O 6201 S Street Box 15830, Sacramento, California 95813; (916) 452 3211 August 8, 1977 1
Director of Regulatory Operations ATTN:
Mr. R. H. Engelken NRC Operations Office, Region V 1990 North California Boulevard Walnut Creek Plaza, Suite 202 Walnut Creek, California 94596
Reference:
NRC Inspection Results of Inspection 77-9 Gentlemen:
(
j In reply to your inspection conducted by R. T. Dodds and H. L.
Canter on May 31, June 1 and June 20-23, 1977, we offer the following explanations and corrective actio'ns which will assure full compliance with NRC requirements.
Appendix B of your letter states:
"With respect to the detection of leaks in the reactor coolant system, Section 4.2.3.7 of the Final Safety Analysis Report states, in part, ' Changes in the reactor coolant leakage rate in the Reactor Building may cause changes in the control room indication of the Reactor Building atmosphere particulate and gas radioactivi ties... '
" Contrary to the above, it was found during the inspection that the Reactor Building atmosphere particulate and gas monitors had their high range alarms activated.
The particulate monitor was Indicating above full scale and the gaseous monitor was 5 cpm) decade range. These conditions Indicating in the upper (10 rendered the monitors ineffective as one of the means to detect changes in the reactor coolant leakage rate."
SMUD REPLY TO DEVIATION A
/'- sh e
)
Sustained full power operation at Rancho Seco has slowly increased
+
'N the contained radioactivity within the' Reactor Building.
- 8003310 $
~.
Mr. R. H. Engelken Page 2 August 8, 1977 The radioactivity increase was recognized by the operations personnel who have brought the problem to.the Plant Review Committee. The Committee recognized the' problem of:high' radioactivity within the Reactor Building and concluded that purging to maintain a low level should.not be permitted. The Reactor Building should be sealed andl purged only when entry is required. The de, cision was based on safety to.the general public in that radioactivity decay in the building is better than. radioactivity decay in the environment.
In other words, a'ny decay In'the Reactor Building is that much less radioactivity released offsite, which Is In agreement with the PRC interpretation of "as low as practical." At the time of the PRC review the particulate and gaseous monitors were high but not offscale.
The Reactor Building Radiation monitors have been observed to be cyclic and are dependent on the use of process equipment within the Reactor Build-Ing.
The monitors, ~ depending on the operations activities, vary approximately
. one decade.. A check of the recording chart Indicates that prior to the NRC 4
Inspection,- the monitor was on scale but during inspector's observation the monitor was-at the high side of the cycle. At the time of the audit, Radiation Monitors R-15001A and R-15ColB were considered inoperable and not capable of detecting reactor coolant leakage as specified in Technical Specification 3.1.6.
FacIIIty pers'onnel understood by Interpretation that the Reactor Building Area Monitors R-15025, R-15026 and R-15027 were included in the Technical Specification 3.1.6 and.FSAR Section 4.2.3.7 Specifically, the i.
FSAR states:
}
" Leakage of reactor coolant into the Reactor Building during reactor operation will be detected by one or a combination of the following methods.
A.
Sump and Tank Levels...
B.
Reactor Coolant System inventory...
C.
Radioactivity
)
" Changes in the reactor coolant leakage rate in the Reactor Building
[
may cause changes in the control room Indication of the Reactor Building atmosphere particulate and gas radioactivities and of the l
. Reactor Building radiation monitors."
{
' All sump and tank levels were in service and all systems to measure the reactor coolant system inventory were operable. Therefore since the leadin statenant ' requires only "one or a combination of the above," the requirement has been complied with.
The Technical-Specification 3.1.6.7 requi res :
"During' power operation, two' reactor coolant leak detection systems 1
of different. operating principles shall. be in operation, with one of the two systens sensitive to radioactivity. The systems sensi-tive to radioactivity may be out-of-service for 48. hours provided two'other means are available-to detect l ea kage.
O '
I'
v Q Mr. R. H. Engelken Page 3 August 8, 1977 The bases, page 3-14, also qualify this requirement and include:
"8.
Radioactivity - Changes in the reactor ecolant leakage rate in the Reactor Building may cause changes 5 the control. room Indication of the Reactor Building atmosphere particulates and gas radioactivities and of the Reactor Building radiation mon i to rs. "
The ' interpretation concerns the extent and qualification of the monitors.
SMUD believes that any one of the Reactor Building monitors will qualify as a leak detector and offers the following calculations to qualify the Reactor Building Area Monitors as part of the specification.
Assumptions:
1.
Primary coolant activity levels released are those used in the FSAR response and can be seen in the 100-day column of Table 140-4 for 1% defective fuel and Table 140-8 for 0.1% defective fuel.
2.
Reactor Building free air space is:
1.98 x 108 ft3 4
8 3
Reactor primary coolant volume is 3 31 x 10 cc, 4.
Dose equivalent curies (Xe-133) = Ag EXe-133
,p Where Ag = Total activity in curies E
Dose Ecu! valent Curies Isotope Xe-133 1% Defective Fuel 0.1% Defective Fuel
~2 Kr 85 6.18 x 10 192 14.2 Kr 85m 2.21 1,242 79 1 Kr 87 13.17~
4,000 258.1 Kr 88 25.6 25,440 1,612.8 Xe 131m 2.025 1,610 105.3 89.500 5,800 Xe 133 Xe 133m 2.88 2,970 189.5 Xe 135 3.26 6,040 386.6 Xe 135m 6.55 2,170 142.1
.Xe'138 5.19 960 62 3 1 131 7.16 8,320 543.4 I 132 26.1 45,600 1,378.1
.I 133 8.15 11,320' 722.9 I 134.
29.4
-5,350 314.'
i 135 26.8' 18,620 I.198-Totals.
223,334 12,807 I
4-w-+*-
w
-qmp-
'4 g4=9
=-siepy w
n-t1-M'ex--
T-
=
1 Mr. R. H. Engelken Page 4 August 8, 1977 Reactor Building Dose Rates:
1% Oefective Fuel
.1 gpm leak rate D r. -
5 mrem /hr/MeV-Ci/cc) (0.081 MeV) (223,334CI)(4.73xlppg{n)
(mrem /hr), (9.12x10 9
(3 31xiod cc) (6.99xio " cc) 3 37 mr/hr Assuming.this semi-infinite dose rate is further adjusted due to the heavy concrete' shielding wall It is attached to, the value most ilkely to be encountered would be:
= (3.37) (1/2)
= 1.7 mr/hr following the first minute of release this value would in turn increase by 1.7 mrem /hr for each additional minute of release.
t 0.1% Defective Fuel - 1 gpm leak rate 5
6 Dr = (9.12x10 ) (0.081) (12,807) (4.73x10 )
(3.31x10*) (6 99xto.")
= 0.193 Adjusting for concrete wall (0.193) (1/2)
= 0.1 mr/hr Coneluston Assuming that the operator would become aware of the leakage at the time the radiation monitor " Alert" alarm sounds, the response time for the three Reactor Building area monitors would be:
R-15025 R-15026 R-15027
. Monitor Monitor Monitor Alert Alarm Point Settings
- 10 mr/hr 100 mr/hr 100 mr/hr Existing Readings **
I mr/hr 6 mr/hr 8 mr/hr 1% Defective Fuel Responsa Times 6 minu'tes 60 minutes 60 minutes 0.1% Defective Fuel. Response Times 90 minutes 990 minutes 990 minutes
[
- Rancho Seco Process Standards
, =.\\j
- As of August 2,1977 at 1800 hours0.0208 days <br />0.5 hours <br />0.00298 weeks <br />6.849e-4 months <br />.
t i
/'"'N R. H..Engelken Page 5 August 8, 1977 s_-
if on the other hand, other parameters discussed in the FSAR Indicate the' likelihood of a leak and the area radiation instruments are being used to confirm this condition, then 5-10 minutes and 1-2 hours would f
8 be required from initiation of the 1% and 0.1% defective fuel leakage, respectively, until a distinctly noticeable change in the log rate meter readings would occur.
f The FSAR, " Answers to questions," 4A.6, and the Technical Speci fica-tions Section 316 Bases state the response times for the gaseous j
radiation monitor (R-150018) are:
i Coolant.' Activity Response Time f
1% defective fuel 67 seconds 0.1% defective fuel 5.3 minutes The airborne particulate radiation monitor response time is dependent upon the speed of filter paper aavance which, during normal operation, I
will be the slow speed. Thus, assuming either 0.1 percent defective i
fuel and a 1 gpm leak or expected corrosion product activity and a
,.{'
I spm leak, the response time will be about I to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.
This time d, -
period is associated with filter tape movement from the point of j
particle deposition to the detector.
If leakage is indicated by d
another leak detection nethod, the filter paper can be manually advanced
_,/
to verify that a substantial leak has occurred.
By stopping the fliter tape advance mechanism, an integrated sample can be taken over a short period of time (e.g.,5 minutes) for a quick evaluation of pq r
the situation.
i<
Response Time j
i Excluding Filter 1
Coolant Activity Advance 1
1% defective fuel 40 seconds sI g
0.1% defective fuel 41 seconds No defective fuel, 18 minutes corrosion prcducts only.
The radiation monitoring system depends entirely upon reactor coolant activity in order to provide reactor coolant leakage rate detection capability.
~
~
a
- j g
f i
\\j
.i
i I
i Mr. R. H. Engelkan.
Page 6 August 8, 1977 It is therefore concluded that the area monitors would respond more slowly than the Reactor Building gas monitor, but more quickly than the particulate monitor and most certainly provide a reasonable backup to these two Instruments.
Respectfully submitted,
~
. %h J. J. Mattimoe Assistant General Manager and Chief Engineer JJM:RWC: Jim j
t cc:
4th Floor Files 3rd Floor Files i
D. G. Raasch R. J. Rodriguez.
@ - RS a
I s
i e
1 4
i l
l 1
I e
i s
)
y
.-,r.._,,,
,,,.,,,,, _,. _,,..,..