ML20215G094
| ML20215G094 | |
| Person / Time | |
|---|---|
| Site: | Hope Creek  |
| Issue date: | 12/18/1986 |
| From: | Corbin McNeil Public Service Enterprise Group |
| To: | Adensam E Office of Nuclear Reactor Regulation |
| References | |
| NLR-N86185, NUDOCS 8612240277 | |
| Download: ML20215G094 (11) | |
Text
,
Pubhc Service Electric and Gas Company C:rbin A. McNellt, Jr.
PublicService Electnc andGasCompany P.O. Box 236 Hancocks Bndge NJ C8038 609339-4800 Vice Present -
Nuclear December 18, 1986 NLR-N86185 Director of Nuclear Reactor Regulation United States Nuclear Regulatory Commission 7920 Norfolk Avenue Bethesda, Maryland 20814 Attention:
Ms. Elinor Adensam, Director Project Directorate #3 Division of BWR Licensing
Dear Ms. Adensam:
REQUEST FOR ADDITIONAL INFORMATION CONTAINMENT VENT / PURGE VALVE OPERATION HOPE CREEK GENERATING STATION DOCKET NO. 50-354 On November 26, 1986, a teleconference was held between the NRC (D. Wagner, U.
Cheh) and Public Service Electric and Gas Company (PSE&G) to discuss PSE&G's November 21, 1986 submittal regarding amendment of the Hope Creek containment vent / purge Technical Specification.
The discussion was focused on the Calculation of Doses Resulting from a LOCA While the Purge Valves are Open (Attachment 5 to Enclosure 2 of the November 21, 1986 submittal).
This submittal responds to the NRC request for additional information made during the subject teleconference, and revises PSE&G's application for amendment to the Hope Creek Technical Specifications (June 4, 1986 and November 21, 1986; C.
A.
McNeill, PSE&G, to E. Adensam, NRC).
The attached information, headlined as " ATTACHMENT 5",
revises the dose calculation to assume an initial iodine concentration of 4.0 pCi/gm dose equivalent I-131, addresses Mr. Cheh's request j
for more detail on the LOCA dose calculation method, and provides a qualitative description of how the total mass release was determined.
8612240277 861218 go!
t
Director of Nuclear 2
12-18-86 Reactor Regulation This attachment replaces the Attachment 5 of our submittal dated November 21, 1986.
In addition, revised page 3 of Enclosure 2 is attached to reflect the revision of Attachment 5, and replaces the page 3 of of our submittal dated November 21, 1986.
If there are any questions regarding this submittal do not hesitate to contact us.
Sincerely, I
Attachments C
D.
H. Wagner USNRC Licensing Project Manager R. W.
Borchardt USNRC Senior Resident Inspector
ATTACHnENT 5 CALCULATION OF DOSES FROM A LOCA WHILE THE PURGE VALVES ARE OPEN
_Assumotions:
Releases are assumed to be unfiltered from the con 1.
environment during the time that the valves are open.
Valves are assumed to close in five seconds.
2.
No fuel failure is assumed to occur.
3.
A pre-existing iodine spike which increases the I-131 equi limit) concentrationto4.'0pCi/gm(HCGSTech. Spec.3/4.4.5,shortterm 4.
is assumed to determine the coolant concentration.
The total activity released was calculated assuming that the mass 5.
released carried all of the dissolved iodine.
The drywell supply and exhaust purge valves are assumed 6.
open.
i 1
Offsite Dosest The Exclusion Area Boundary (EAB) doses were calculated as fol a
Dh=
MR DCFiCi X/Q BR t
i S._ _-- -.
ATTACHf1ENT.5 where:
O h = the total thyroid dose in rem, t
- the total mass released through the purge valves,1694 lbs MR DCFj= the thyroid dose conversion factor for isotope 1, from R. G. 1.109 Rev 1,
- the coolant concentration for isotope i in J1Ci/gm Ci 3
X/Q = the EAB atmospheric dispersion factor, 1.9 x 10-4 sec/m, and BR = the breathing rate, 3.47 x 10-4 m3 sec
/
The coolant concentrations were determined as follows:
- C o SF Ci i
where:
Cjo = the normal coolant concentration for isotope i, obtained from FSAR Table 11.2-3 injati/gm, and SF - the spiking factor (dimensionless).
The spiking factor was calculated assuming a 4.0 JiCi/gm I-131 dose equivalent
)
concentration as follows:
{ DCFj Cjo 1
4.0 J1Ci/gm - SF -
DCF -131 I
L 2-
1 ATTACHMENT 5 The calculation of the spiking factor and the resultant coolant concentrations is shown below:
4 l
Normal Thyroid DCF Spiked Concentration Concentration DCF x
Isotone futi/om)
(Rem /Ci)
Conc.
(uci/om)
I--131 1.85E-3 1.49E+6 2.76E+3 2.04E+0 I--132 1.10E-2 1.43E+4 1.57E+2 1.21E+1 I--133 7.50E-3 2.69E+5 2.02E+3 8.28E+0 I--134 1.35E-2 3.73E+3 5.04E+1 1.49E+1 I--135 7.50E-3 5.60E+4 4.20E+2 8.28E+0 Total 4.14E-2 5.40E+3 4.56E+1 1-131 Equivalent Conc.- 3.63E-3 pC1/gm Spiking Factor-1103.37 Using the above calculated concentrations, the resultant EAB thyroid doses calculated below:
Spiked Activity Thyroid Thyroid Concentration Released DCF Dose Isotone (mci /om)
(Ci)
(Rem /Ci)
(Rem)
I--131 2.04E+0 1.57 E+0 1.49E+6 1.54E-1 I--132 1.21E+1 9.33E+0 1.43E+4 8.79E-3 I--133 8.28E+0 6.36E+0 2.69E+5 1.13E-1 I--134 1.49E+1 1.14E+1 3.73E+3 2.31E-3 I--135 8.28E+0 6.36E+0 5.60E+4 2.35E-2 Total 4.56E+1 3.51E+1 3.02E-1 3.02 x 10~
Rem Resultant EAB thyroid dose
=
i L.
-3
ATTACHMENT 5 Control Room Doses:
To calculate the control room doses, an average release rate was determined as follows:
MRCi Rj =
T where:
- the release rate for isotope i in Ci/sec, and RJ T
- the valve closure time, 5 seconds.
.The calculated release rates are shown below:
Spiked Release Concentration Rate Isotone fuci/om)
(Ci/sec) 1--131 2.04E+0 3.14E-1 I--132 1.21E+1 1.87E+0 I--133 8.28E+0 1.27E+0 1--134 1.49E+1 2.29E+0 1--135 8.28E+0 1.27E+0 Total 4.56E+1 7.01E+0 The control room activity at any time is a function of the outside air concentration, the intake rate and the removal rate from the control room.
The outside air concentration is the product of the release rate with the control room atmospheric dispersion factor. The intake rate is the the sum of The the filtered pressurization flow and the unfiltered inleakage rate.
removal of radioactivity from the control room is due to radioactive decay, u
exfiltration and removal by the recirculation filters. These parameters can be expressed by the following differential equation: - -..
o ATTACHf1ENT 5 i - hDi j - (F+U)Aj - Fr Aj A
e dAj
[F(1-e) + U]
X/Qcr R
dt V
V where:
= the activity of isotope i in the control room in curies, Ai F
- the filtered air intake, 1000 cfm;
- the intake and recirculation charcoal filter efficiency, 0.99; e
U
- the unfiltered air inleakage, 10 cfm; Fr
- the recirculation flow, 3000 cfm; X/Qcr - the control room atmospheric dispersion factor, 4.39 x 10-5 sec/m3 ADi
- the decay constant for isotope i, obtained from the Table of Isotopes, 7th Edition; and 3
V
- the control room volume, 54,200 ft,
For simplicity, define fg as the equivalent unfiltered iodine intake flow as follows:
fr - F(1-e) + U 20 cfm Also define a total removal rate from the control room, hT as follows:
AT. ADi + F+U + Fre V
V ADi + 1.22 x 10-3 sec-1
-m-,
ATTACHMENT 5 The solution to the differential equation becomes:
For 0 < t S 5 sec, fl X/Qcr Rj - (1-e-AT )
t Aj(t) =
AT For t > 5 sec, the release rate has stopped, th'erefore Rj - 0, and Aj(t) - Aj(5)e-AT(t-5)
The dose rate at any time t in the control room is given by:
b (t) = )
DCFj BR Aj(t) th i
The total thyroid dose from the accident is:
oo b (t)dt Dth "
th 5
oo
[X/Qcrf Rj(1-e-AT )/AT]dt + Aj(5) e-AT(t-5)dt)
= BR - )
DCFj (
t l
i The above differential equations are solved below:
C.
ATTACHMENT 5 0-5 sec Outside Total Total Control Decay Thyroid Release Air Removal Integrated Room Constant DCF Rate Conc.
Rate Activities Thyroid Isotone (1/sec)
(Rem /Ci)
(Ci/sec) fuCi/cc)
(1/sec)
(Ci-sec)
Dose (Rem)
I--131 9.98E-7 1.49E+6 3.14E-1 1.38E-5 1.22E-3 5.31E-4 1.79E-4 I--132 8.43E-5 1.43E+4 1.87E+0 8.19E-5 1.31E-3 2.95E-3 9.55E-6 1--133 9.21E-6 2.69E+5 1.27E+0 5.58E-5 1.23E-3 2.14E-3 1.30E-4 I--134 2.20E-4 3.73E+3 2.29E+0 1.00E-4 1.44E-3 3.29E-3 2.77E-6 I--135 2.91E-5 5.60E+4 1.27E+0 5.58E-5 1.2SE-3 2.10E-3 2.66E-5 3.48E-4 Total
-4 3.48 x 10 Rem Resultant Control Room thyroid dose
=
Control Room Data Filtered Intake Rate 1000 cfm Unfiltered Inleakage 10 cfm Recirculation Flow 3000 cfm Filter Efficiency 99% percent Exhaust Flow 1010 cfm Control Room X/Q 4.39E-5 sec/m3 Control Room Volume 54200 ft3 Removal Rate (no decay) 1.22E-3 sec-I 3
Breathing Rate 3.47E-4 m /sec 4
4 L.
f i I
ATTACHMENT 5 l
DETERMINATION OF MASS RELEASED THROUGH PURGE VALVES FOLLOWING A LOCA As part of an analysis to determine the pressure which would exist in the ductwork outside of the purge isolation valves, it was necessary to determine the mass flux through the purge valves.
This analysis assumes that the ductwork blowout panels are func-tional so that back pressure is minimized and flow is maximized.
No credit was taken for back pressure due to room pressurization.
The mass flux thus determined was then used to calculate compart-ment pressurization and was used to determine the total activity released for the dose calculation.
)
The design basis LOCA pressure and temperature responses were provided by General Electric (GE) (NEDO-24579-1).
The valve flow coefficient versus disk angle was provided by the valve supplier.
The valve disk angle versus time was provided by the operability test conducted at Wyle Laboratory.
The valves were assumed to remain fully open for one second after the LOCA isolation setpoint was reached (2 psig at 0.044 sec) to allow for instrument response time and for the valves to begin moving after receiving a close signal.
The valves then stroke closed in four seconds.
Combining the flow coefficient versus angle with the angle versus time data yields a flow coefficient versus time.. The flow rate versus time was then determined assuming that the upstream reservoir (drywell) was saturated steam at the pressure provided by GE.
(Preliminary runs were made using air as the reservoir medium to be certain that the steam assumption yielded the most conservative results.)
The integral of the mass flow versus time curve then yields total mass released (1694 pounds).
j L.
f,
PE24/16
ENCLOSURE 2 mixing in the FRVS inlet ductwork, this will result in relative humidity at the FRVS filters of less than the design conditions.
Our evaluation also included the radiological dose assessment due to the LOCA mass blowdown through the CPCS duct blow-out panels.
Assuming that the releases are unfiltered from the drywell to the environment during the 5 second purge valve closure time, with the coolant concentrations based on a pre-existing iodine spike equal to the short term technical specification limit of 4 pCi/gm, it is estimated that the resultant thyroid dose at the site boundary is 0.30 Rem.
The control room thyroid dose is estimated to be 3.5 x 10-4 Rem.
These doses are well below the 10CFR100 and GDC19 dose criteria. summarizes this calculation.
Fur the rmo re, this assessment recognizes that the top of active fuel is not uncovered until approximately 25 seconds after the DBA LOCA (See HCGS FSAR Figure 6.3-20).
In order to minimize the probability that a LOCA could occur while the purge valves are open, a limit of 120 hours0.00139 days <br />0.0333 hours <br />1.984127e-4 weeks <br />4.566e-5 months <br /> /365 days for combined purging, inerting, and CPCS operation is included in the proposed Technical Specification revision.
Pressure control using the 2-inch bypass flowpath is not included in the 120 hours0.00139 days <br />0.0333 hours <br />1.984127e-4 weeks <br />4.566e-5 months <br /> /365 days limit.
Because HCGS utilizes a unique atmosphere recirculating Contai nmen t Prepurge Cleanup System (CPCS) to maintain offsite doses ALARA in lieu of purging through charcoal filters, an operational limit of 120 hours0.00139 days <br />0.0333 hours <br />1.984127e-4 weeks <br />4.566e-5 months <br /> /365 days for the vent / purge valves is necessary to allow HCGS operational flexibility similar to plants with 90-100 hours /365 days limitations.
Analyses based on CPCS flow rate, CPCS filter efficiency and drywell volume have determined that the CPCS will reduce the initial drywell equilibrium radiciodine concentration to a new, lower equilibrium concentration in approximately four hours.
Any additional CPCS operation will not significantly lower the containment atmosphere radiciodine concentrations while in operational conditions 1, 2,
and 3.
These analyses also show that operation of the CPCS in through the torus and out through the drywell does not reduce the time required for CPCS operation.
In addition, PSE&G's discussions with the NRC regarding consideration of CPCS operation in this mode indicated that PSE&G had discovered only one Mark I BWR plant that operated this way (be'ause it was their plant specific preference), and that the Hope C eek Operations staff prefers not to operate the CPCS in this made for reasons which include equipment considerations.
PSE&G concludes that operation of the Hope Creek CPCS will be in com71iance with BTP CSB 6-4 as presented in this submittal.
Had Hope Creek been designed without the benefit of a CPCS system, a 90-100 hour j
limit would permit about six inert /deinert cycles per year.
The additional four hours per deinert cycle for CPCS operation I
requires an additional 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> with the purge valves open.
This results in a limit of 120 hours0.00139 days <br />0.0333 hours <br />1.984127e-4 weeks <br />4.566e-5 months <br />.,
l
. -.