ML20054K491
| ML20054K491 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 06/29/1982 |
| From: | Crutchfield D Office of Nuclear Reactor Regulation |
| To: | Fiedler P GENERAL PUBLIC UTILITIES CORP. |
| References | |
| TASK-15-06, TASK-15-6, TASK-RR LSO5-82-06-122, LSO5-82-6-122, NUDOCS 8207020251 | |
| Download: ML20054K491 (9) | |
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June 29, 1982
' Docket No. 50-219 LS05-82-06-122 Mr. P. B. Fiedler Vice President and Director - Oyster Creek Oyster Creek Nuclear Generating Station Post Office Box 388 Forked River, NJ 08731
Dear Mr. Fiedler:
SUBJECT:
OYSTER CREEK NUCLEAR GENERATING STATION, SEP TOPIC XV-16. RADIOLOGICAL CONSEQUENCES OF SMALL LINE BREAKS CARRYING PRIMARY COOLANT OUTSIDE CONTAINMENT General Public Utilities (GPU) letter dated November 4,1981, transmitted for our review your safety analysis report for SEP Topic XV-16, Radio-logical Consequences of Failure of Small Lines Carrying Primary Coolant Outside Containment. We have completed our review and have concluded that the potential exists for unacceptable doses at the exclusion area and low proulation zone for this postulated accident. The staff's evaluation (enclosed) provides a conservative analysis, based on infor-mation provided by the licensee, but using asumptions consistent with current licensing criteria.
4 These consequences are the direct result of a h!gh allowable core activity) leakage rate in combination with a high rate of letdown flow (750gpm through the reattor coolant demineralizers.
Consequently, the staff has recomended that the following alternatives be considered to restrict'the EAB3 and LPZ doses for the failure of small lines accidents:
1.
GPU perform an analysis to establish the maximum core leakage rate for dose equivalent I-131 that would lead to an EAB thyroid dose of 30 rem. Then, based on this core leakage rate, establish a reactor coolant dose equivalent I-131 activity limits (uC1/gm) for the desired reactor coolant demineralizer cleanup rate.
2 Control would then be placed on dose equivalent I-131 core leakage 9MT r e as indicated by reactor coolant activity sampling and cleanup gg 2.
GPU adopt the GE standard technical specifications for iodine monitoring and control and install flow restricting orifices
.inside the drywell in each of the instrument lines carryino reactor coolant to limit the coolant discharges to levels that omer)
......w nt..nat-cause-EAB-doses"in-excess"of 30 ret.
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Mr. P. Fiedler 3.
Any other procedures or modifications that will appropriately limit small line break doses to less than 30 rem at the EAB.
This evaluation will be a basic input to the integrated safety assessment, unless you identify changes needed to reflect the as-built conditions at your facility.
Sincerely, Dennis M. Crutchfield, Chief Operating Reactors Branch #5 Division of Licensing
Enclosure:
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Mr. P. B. Fiedler cc G. F. Trowbridge, Esquire Resident Inspector Shaw, Pittman, Potts and Trowbridge c/o U. S. NRC 1800 M Street, N. W.
Post Office Box 445 Washington, D. C.
20036 Forked River, New Jersey 08731 J. B. Lieberman, Esquire Commissioner Berlack, Israels & Lieberman New Jersey Department of Energy 26 Broadway 101 Commerce Street New York, New York 10004 Newark, New Jersey 07102 Ronald C. Haynes, Regional Administrator
. Nuclear Regulatory Commission, Region I 631 Park Avenue King of Prussia, Pennsylvania 19406 J.. Knubel BWR Licensing Manager GPU Nuclear 100 Interplace Parkway Parsippany, New Jersey 07954 Deputy Attorney General State of New Jersey Department of Law and Public Safety 36 West State Street - CN 112 Trenton, New Jersey 08625 Mayor Lacey Township 818 Lacey Road Fo.rked River, New Jersey 08731 U. S. Environmental Protection Agency Region II Office ATTN:
Regional Radiation Representative 26 Federal Plaza New York, New York 10007 Licensing Supervisor Oyster Creek Nuclear Generating Station
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Post Office Box 388 Forked River, New Jersey 08731 e
A
OYSTER CREEK SYSTEMATIC EVALUATION PROGRAM 1
XV-16 RADIOLOGICAL CONSEQUENCES OF FAILURE OF SMALL LINES CARRYING PRIMARY COOLANT OUTSIDE CONTAINMENT I.
INTRODUCTION Rupture of lines carrying primary coolant outside containment can allow primary coolant and the radioactivity contained therein to escape to the envi ronment.
SEP Topic XV-16 is intended to review the radiological conse-quences of such failures. The review of this topic encompassed those lines which carry primary coolant outside containment during power operation.
The scope included those' lines that are not normally expected to be open to the primary system but can be opened during power operation (i.e., reactor coolant sample lines,# instrument lines, etc. ).
II.
REVIEW CRITERION All small lines carrying primary coolant outside containment were reviewed t6 ensure that any release of radioactivity from their postulated failure was l
a small fraction of the 10 CFR Part 100 exposure guidelines.
Small fraction l
1s defined in the SRP to be no more. ran 10% of the 10 CFR Part 100 exposure guidelines.
III.
RELATED SAFETY TOPICS AND INTERFACES l
Lines which were excluded from this review included lines for which failure.
outside containment is not postulated, or lines for which interlocks prevent l
I l
. opening during power operation (e.g., the PWR residual heat removal lines).
The review also did not consider the release of radioisotopes from large pipes carrying primary system fluid prior to automatic isolation of such lines, (e.g., the main steam and feedwater lines of BWR). The consequences from failures in these lines are considered in SEP Topic XV-18, " Radiological Consequences of Main Steam Line Failure Outside Containment".
IV.
REVIEW GUIDELINES The review was conducted in accordance with SRP 15.6.2 and Regulatory Guide 1.11.
The licensee was requested to provide plant specific informa-tion such as the identification of lines covered by this Topic, the size of these lines, break locations and flow, etc.
The staff received the licensee's submittal for this SEP topic on November 10, 1981.
V.
EVALUATION In the submittal, the licensee indicated that a double-ended break of a one-inch instrument line, upstream of the outboard isolation valve, would be the most severe case of the small line rupture outside containment.
Altogether, there are 59 such lines at Oyster Creek which extend from the j
reactor vessel through the primary containment to instruments and gauges l
in the reactor building.
Because of a lack of inboard isolation valves, the
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discharge from the break would continue until the reactor vessel is e
, l depressurized and action can be taken to plug the leak. The estimate is that 196,000 pounds of primary coolant will be released outside the primary containment following the break.
The staff's review of the submittal indicates that Oyster Creek's primary coolant technical specification limit for iodine activity consists of a single shutdown value of 8 pCi/gm of gross iodine activity. This limit conflicts with the two-tier (equilibrium and spike) dose equivalent (D.E.)
I-131 limits found in the BWR standard technical specification (STS) and also with the Standard Review Plan (SRP) 15.6.2.
In order to evaluate Oyster Creek's primary coolant technical specification limit for iodine activity in accordance with SRP 15.6.2, the staff assumed that the shutdown limit of 8 pCi/gm gross activit.y was D.E.1-131 activity.
The assumptions used by the staff and the corresponding doses are provided in Tables 1 and 2.
Due to the very high doses derived from data reflecting the current Oyster Creek design, the staff has evaluated other cases which assumes the inclusion of a 1/4-inch flow restricting orifice in the instru-ment line inside containment and/or the adoption of the BWR standard technical specification D E.1-131 primary coolant activity limit of 0.2 pC1/gm (equilibrium) and 4 pCi/gm (spike).
These measures would limit I
the radiological consequences of this accident.
1 4-VI.
CONCLUSIONS The calculated thyroid and whole body doses (provided in Table 2) show that installing a 1/4-inch flow restricting orifice (in ach of the 59 instrument lines), in conjunction with adopting the BWR STS primary coolant activity limits, would limit the radiological consequences of this accident to levels which meet the acceptance criteria of SRP 15.6.2.
Without these dose reduc-tion measures, the 0-2 hour thyroid dose is found to be 12,000 rems, a value that is 400 times the guideline value.
t l
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TABLE 1 Assumptions Used in the Radiological Consequences of Instrument Line Break Outside Containment at Oyster Creek 1.
Reactor water volume 590,000 lbm 2.
RWCS cleanup rate 2.7x105 lbm/hr (760 gpm) 3.
Condensete demineralizer cleanup rate
-(carryover fraction x feedwater flow rate) 7.2x104 lbm/hr 4.
Ef fective cleanup rate (2. + 3.)
3.4x 105 lbm/hr 5.
lodine spiking factor 500 6.
Flash fraction 40%
7.
Fraction of flashed steam processed by 90% ef ficient SBGTS(l) 33%
0-2 hr, EAB 0-4 hr, LPZ 55%
8.
Duration of accident 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> 9.
X/Q values Ground level values
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0-2 hr, EAB 7.6x10-4 sec/m 3 0-4 hr, LPZ 6.5x10-5 sec/m3 Elevated release values (2) 3 0-2 hr, EAB 1.1x10-4 sec/m 5
3 0-4 hr, LPZ 4.2x10 7 sec/m3 4-8 hr, LPZ 9.1x10- sec/m (I)From figure 3.2 of licensee's submittal.
(2) Fumigation is assumed to persist for 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.
O
F TABLE I (Continued)
- 10. Case 1: Oyster Creek as designed (1)
Primary coolant concentration 8 Ci/gm gross taken as D.E. I-131
( 2)
No restricting orifice in lines (3)
Primary coolant discharged from break in 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> 120,000 lbm in 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> 196,000 lbm
- other parameters are same as Case 1 r
- 12. Case 3:
Installation of 1/4-inch restricting orifice in instrument line (1)
Primary coolant concentration 8 pCi/gm gross taken as D.E.1-131 (2)
Primary coolant discharged from break in 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> 13,200 lbm tn 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> 26,500 lbm
- 13. Case 4:
Inclusion of both 1/4-inch restricting orifice of Case 3 and BWR STS primary coolant activities of Case 2; the para-meters used are as same as Case 3 except for the.2 pCi/gm D.E.1-131 used for the primary coolant concentration
- The BWR STS primary coolant activities are.2 pCi/gm D.E.1-131 (equilibriur and 4 pCi/gn D.E.1-131 (spike).
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