ML20125B628
| ML20125B628 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 12/04/1992 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20125B627 | List: |
| References | |
| NUDOCS 9212100089 | |
| Download: ML20125B628 (4) | |
Text
-.
-- ~. - - -.
63 itEC UNITED STATES
~
I NUCLEAR REGULATORY COMMISSION o
g a
W ASHINGTON, D, C, 20555
\\.....,/
i SAFETY EVALVATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION l
RELATED TO AMENDMENT NO. 160 i
TO FACILITY OPERATING LICENSE NO. DPR-16 l
GPU NUCLEAR CORPORATION AND JERSEY CENTRAL POWER & LIGHT COMPANY 0YSTER CREEK NUCLEAR GENERATING STATION DOCKET NO. 50-219
1.0 INTRODUCTION
4 By letter dated February 19, 1992, GPU Nuclear Corporation, (GPUN, the licensee), proposed to delete the auto-start logic from the containment spray system (CSS).
The licensee's reason for deleting the auto-start logic was based on a commitment made to the NRC in Licensee Event Report (LER) #86-023 as well as an overall concern of inadvertent spray actuation.
In that LER, i
the licensee described the discovery of a single failure mode of the CSS as a result of a power supply failure. Their corrective action for the deficiency l
included deletion of the auto-start signal for CSS.
The licensee also proposed to delete those technical specifications (TS) and bases which would become obsolete due to the deletion of the auto-start logic.
The TS changes include:
revisions to TS bases sections 3.1, " Protective Instrumentation," and 3.4, " Emergency Cooling," deletion of the Instrumentation Requirements of Table 3.1.1-Section E, " Containment Spray,"
deletion of the Containment Spray System from Table 4.1.2, "Minimurt Test Frequencies for Trip Systems," and, deletion of the surveillance requirement of TS 4.4.C.2 for auto-start actuation test of the CSS.
2.0 EVALVATION Presently, the logic for the CSS at Oyster Creek automatically actuates on low-low reactor water level coincident with high drywell pressure in a "one-out of two twice" logic. The inputs which complete the logic. assure that the automatic logic will function for an event which causes a loss-of-coolant accident (LOCA) large enough to decrease reactor water level below the low-low setpoint and sufficient blowdown to raise drywell pressure to the high setpoint value.
l l
However, it was recognized at the time of the Systematic Evaluation Program (SEP) review that some classes of small diameter pipe breaks (small break LOCA) do not automatically actuate the CSS. Small break LOCAs would not reduce the reactor vessel level sufficiently to reach the low-low level and l
i 9212100089 921204 PDR ADOCK 05000219 P
-. - = - -
e i
7 i
actuate the CSS if operation of the feedwater system continued post LOCA.
This zone of manual actuation was described in a GPUN submittat (ref. 1).
That submittal was reviewed by the staff and reported on in a safety evaluation report (ref. 2).
The February 19, 1992, GPUN submittal was reviewed by the staff and documented in the subsequent staff safety evaluation.
The st&ff concluded that the analyses submitted by the licensee, have satisfactorily demonstrated the adequacy of the containment functioral design. As part of this evaluation, the staff concluded that the two fuadamental aspects of this submittal which will change the design are acceptable.
l The first obvious change was that there was a portion of the pipe break l
classes where manual actuation was necessary, the small breaks in the main steam line. The staff had approved many,al actuation for main steam line 4
breaks up to and including 2.0 sq.ft., with 2.0 sq.ft. being the largest break -
size that can blowdown without initiating the automatic spray system..The 0.75 sq.ft, main steam line break produces the highest drywell temperature.
For larger pipe breaks (greater than 2.0 sq.ft.), the CSS would receive an i
auto-start signal.
Secondly, the acceptance of manual starting of the CSS, the staff had previously accepted a 10 minute manual initiation of the containment sprays.
For purposes of this evaluation, the staff has not reevaluated the bases for these two critical assumptions which have been previously accepted by the staff in reference 2.
The licensee has requested that the acceptable zone for manual activation be expanded to include the entire spectrum of possible pipe breaks.
In other words, the automatic actuation signal for the sprays would be removed.
Therefore, the sprays would be manually actuated for all accident events requiring containment spray, GPUN had submitted results from their analysis -
which indicated that the elimination of the automatic spray start signal will not have an effect on the Oyster Creek Environmental Qualification (EQ) temperature profile or the containment design basis. The-coctainment design basis and EQ temperature profile were not affected by this change due to the small main steam line breaks (0.01 and 0.75 sq.ft.) never being sufficiently i
large enough to blowdown reactor water level below the low-low setpoint and i
actuate the containment spray (ref. 1). Therefore, automatic CSS wos never given credit for in past safety analysis and the assumption made'for CSS was that the sprays were manually started in 10 minutes.
The licensee stated that a 0.75 sq.ft main steam line break produces the highest calculated temperature within the drywell. The staff had performed confirmatory analysis for the main ' steam line break, including 0.01 and 0.75 sq. ft main steam line pipe breaks and concluded that GPUN's calculations were acceptable' (ref. 2).
Therefore, the analysis submitted by GPUN in reference 1 and approved by the staff in reference 2 bounds the maximum calculated temperature profile used for the EQ temperature profile since the small pipe break classes are not affected by this change to the CSS.
e m ~
w e
w rm--n
,w
i
. A To support the elimination of the automatic signal, a series of analyses were conducted by the licensee. These analyses focused on the large break LOCA 4
since that was the region that would be most affected by the elimination of the automatic signal to CSS. The large break considered was the bounding double ended guillotine break area of 6.2 sq.ft, of a recirculation loop.
Comparative analyses were performed considering the presence of the automatic signal and a parallel case considering manual actuation.
A comparison of the two cases for the double ended break case is provided below.
CASE 1 CASE 2 PARAMETER AUTOMATIC SPRAY 1 MANUAL SPRAYS AT 10 MIN i
Drywell Pressure, psig 38.4 at 5 sec 38.4 at 5 sec Torus Pressure, psig 26.6 at 99 sec 27.0 at 612 see-Orywell Vapor Temperature, 'F 282.7 at 5 sec 282.7 at 5 sec i
Torus Liquid Temperature, F 158.8 at 10,890 see 159.4 at 10,530 sec l
The data from GPUN's. analysis shows that there is almost no effect on the i
maximum containment parameter values when the automatic CSS logic is eliminated.
A 0.1 sq.ft. recirculation line break was also evaluated in a similar fashion.
The results of this comparative analysis is provided below.
CASE 3 CASE 4 PARAMETER AUTOMATIC SPRAYS MANUAL SPRAYS AT 10 MIN-l Orywell Pressure, psig 20.6 at 351 sec 20.8 at 355 sec Torus Pressure, psig 19.0 at 413 sec 19.2 at 598 sec
'F 259.8 at 351 sec 260,1 at 430 sec Orywell Vapor Temperature,'F i
Torus Liquid Temperature, 153.2-at 18,310-sec 153.2 at 18,270 sec As can be seen, the peak values are only slightly higher due to the elimination of the CSS automatic start logic. Manual actuation of the sprays 2
shows that the drywell and_ torus-pressure peak values are greater. However, a
the peak pressure increases are only 0.2 psi. These differences are-considered to-be minor.
The important consideration is that the peak values are within the design pressure iimits for both the drywell and torus.
It_is important to-note that the sprays were not credited for any design-basis accident (DBA) transients in confirmatory analysis made by the staff in reference 2. -Also, the Emergency Operating Procedures (E0Ps) which are currently in place at Oyster Creek do contain criteria for the start of the CSS. The licensee stated that the E0Ps currently contain sufficient criteria for the operator to determine when to start the CSS and no change to that criteria is required for manual activation of CSS as a result of a postulated large pipe break LOCA. The E0Ps currently require starting the CSS on high torus pressure (12 psig) or before reaching 281'F in the drywell and within the Drywell Spray Initiation Limit, or high concentrations of hydrogen and -
i 4
1 4
' Based on the above findings, the staff finds that the licensee's proposed change is acceptable.
In addition, the staff finds the revision to the TS and bases accaptable since they are necessary to properly reflect this change in the TS.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the New Jersey State official was notified of the proposed issuance of the amendment.
The State official had to comments.
4.0 [NVIRONMENTAL CONSIDERATION Pursuant to 10 CFR 51.21, 51.32, and 51.35, an environmental assessment and finding of no significant impact have been prepared and published in the Federal Egoister on October 14, 1992 (57 FR 47125). Accordingly, based upon the environmental assessment, the staff has determined that the issuance of the amendment will not have a significant effect on the quality of the human environment.
5.0 CONCLUSION
The Commission has concluded, based on the considerations c:: cussed above, that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such e
activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimica; to the common defense and security or to the health and safety of the public.
6.0 REFERENCES
1.
Letter from GPUN to the staff titled "0yster Creek Containment Temperature Profile for Environmental Qualification of Equipment," dated November 1, 1980.
2.
Staff SER titled Evaluation Report on Containment Pressure and Heat Removal Capability, SEP TOPIC VI-3 and Mass and Energy Release for Possible Pipe Break Inside Containment, SEP TOPIC VI-2.D for the Oyster Creek Nuclear Power Plant.
Principal Contributors:
A. D'Angelo, K. Bristow Date:
December 4,1992 i
l l