ML20070D811
| ML20070D811 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 02/15/1991 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20070D807 | List: |
| References | |
| NUDOCS 9103010211 | |
| Download: ML20070D811 (7) | |
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'o UNITED STATES g
' NUCLEAR REGULATORY COMMISSION e
- -t WASHINGTON, D. C 20555 49.....
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REAC(OR REGULATION RELATED TO AMENDMENT NO.136 TO PROVISIONAL OPERATit G LICENSE NO. DPR-?O CONSUMER! POWER COMPANY PALISADES PLANT DOCKET NO. 50-255
1.0 INTRODUCTION
CHANGE NO. 1 By letter dated November 2,1990, Consum". Power Company) (the licensee)
- equested amendment to the Technical Speu fications (TSs appended to Provisional Operating License No. OPR-20 fo,' the Palisades Plant. The proposed amendment would allow use of the Regulatory Guide 1.97 qualified neutron monitoring system which '- being installed during the 1990 refueling outage. Additionally, a change was proposed to the Design Features section to more accurately _ describe the fixed absorber rods.
CHANGE NO. 2 By letter dated June 13, 1990, and subsequently revised by letters dated November 9 and December 7,1990, and January 24, 1991, the licensee requested an amendment to revise TS-3.3.1.b., " Emergency Core Cooling System." The proposed amendment would reduce the required minimum boron solution level in the Safety injection Tanks (SIT) from _186 to 174 inches. Additionally, the maximum allowed tank level would be expanded from 198 to 200 inches. This change-effectively broadens the operating band at which SIT level-must be maintained from 12 to 26 inches.
Two related TS changes were also submitted.
First, a new surveillance requirement to-check the SIT high and low level alarms was proposed _to be included in TS table 4.1.2.
Secondly, the Bases section for TS 3.3.1 has been
-updated and two TS references have been added.
2.0 DISCUSSION CHANGE N0. 1 In 1988, the licensee performed a modification which upgraded the sensitivity-of the fission chambers used to detect neutron flux. Dur_ing the most recent refueling outage,-the licensee has completed its upgrade of the neutron monitoring system by certifying the system is ' Alified to the criteria of Regulatory Guide 1.97.
The changes in the r-oron monitoring system performed this outage involved using the existing f'ssion chambers, installing new-cables from the fission chambers through two new electric penetrations _to
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9103010211 910215 T'DR ADOCK 0500025S-.
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PDR-
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-2 preamplifiers (which were relocated to outside containment), and installing new cables-from the preamplifiers to the power sources in the control room.
Additionally, the neutron monitoring channel which supplies the alternate shutdown panel was modified. The alternate shutdown panel had previously received neutron monitoring indication from a dedicated, spare fission chamber. The new system supplies the panel through an optical isolator associatedwiththeleftchannel(NI-1/3)oftheRG1.97qualifiedinstrumen-tation.
Eight channels of instrumentation are provided to monitor the neutron flux. The nuclear instrumentation system consists of two start-up channels, two wide-range logarithmic channels and four powei range safety channels. The start-up and wide-range channels share high sensitivity fission chambers while the power ranges channels are completely independent (aach power range channels has a separate detector and power supply).
The rate-of-change of power is normally monitored at start-up by two source range monitors which sum inputs from two fission chambers and cover a range of approximately five decades (control room indication uses a scale from 1 to 3x10e5 cps). Tha two other channels are wide-range units which take signals from fission chambers and cover a range greater than ten decades, overlapping the start-up channels by approximately three decades (control room indication uses a scale from 1x10e-8 to 200% power).
The proposed Technical Specification changes, associated with the above modifications are as follows:
t
[_hanges A.-
In the third paragraph from the end of the Basis for Section 3.17, delete reference to the " start-up" range and replace it with
" source" range. Delete reference to the " log" range and replace it with reference to the " wide" range.
B.
In Table 3.17.1, change Item No. 3 from " Log Range" to
" Wide-Range".
C.
In Table 3.17.4, Item 7, change " Start-up" to " Source Range" and in footnote (d) to Ta'le 3.17.4, change " log range" to " wide range",
t D.-
In Table 3.25.1, -Item No. 7, change " Start-up" to " Source" and
"(N-001A)" to "(N-1/3C)".
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E.
In Table 3.25.1, Item 14, add " Neutron Monitor System Power" under the Function Column.
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F.
In Table 4.1.1, Item 2, under the Channel ')escription Column, delete the word " Logarithmic".
In Survei, lance Functional Column, add "C.
Calibrate".
In the Frequency Column, add "R" on the
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"C.
Calibrate" line.
In the Surveillance Method Column on the "a" line, delete "both wide-range readings" and insert " Channel indications".
Also in the Surveillance Method column, add "C.
Channel alignment through measurement / adjustment of internal test points".
G In Table 4.1.3, Item No.1 in the Channel Description Column change " Start-up" to " Source"; in the Surveillance Functions Column add "c. Calibrate"; in the Frequency Column, add "R" on the "c. Calibrate" line; and, in the Surveillance Method Column, add "C.
Channel alignment through measurement / adjustment of internal test points, H.
In Table 4.21.1, item No. 7 under the Channel Description column, change " Start-up" to " Source" and "(NI-001A)" to
"(NI-1/3C)".
In the surveillance Method Column, after "a.
Internal Test Signal" add, "(Performed under Table 4.1.3, Item 1.b)".
I.
In Section 5.3.2d, change the description of the mechanically fixed rods from "... mechanically fixed boron rods..."
-to"... mechanically fixed absorbers rods...".
' CHANGE NO. 2 The four safety injectian tanks are part of the safety injection system and are used to flood the core with borated water following a depressurization of the primary coolant system.
Three of the four tanks will provide sufficient coolant to recover the core following a Loss of Coolant Accident.
The tanks are
-connected to the Primary Coolant System cold legs through normally open-isolation valves._ _Two check valves prevent primary coolant from entering the tanks.
Current TS maintain the tanks pressurized to at least 200 psig, with a tank liquid level of at least 186 inches and a maximum level of 198 inches, and a boron conceatration from 1720 to 2000 ppm.
Injection will occur whenever the-primary. system pressure falls below the combined pressure of the static water head plus the tank gas pressure.
The licensee _ proposed the following: changes to the TS; Changes i
A.
Change Specification 3.3.1.b to read as follows:
"All four Safety Injection Tanks are operable and pressurized to-at least 200 psig with a tank liquid level of at least 174 inches
.and maximum level of 200 inches with'a boron concentration of at least 1720 ppm but not more than 2000 ppm."
B.
Change the fourth paragraph of Section 3.3 Basis _as-follows:
"The limits _for the Safety Injection Tank pressure-and volume assure the required amount of water _ injection during an accident
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and are based on values used-for the accident analyses (3, 4).
The minimum 174-inch level corresponds to a volume sof 1040
- f t3 and the maximum 200-inch level corresponds to a volume of 1176 ft3."
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4 C.
Add the following to
References:
"(3) FSAR, Section 14.17 (4) Letter,H.G.Shaw(ANF) tor.J.Gerling(CPCo)," Standard Review Plan Chapter 15, Disposition of Events Review for Changes to Technical Specification Limits on Palisades Safety Injection Tank Liquid Levels", April 11, 1990.
D.
Add Surveillance function "C."
To Item 13 on Table 4.1.2 to require performance, at least once per 18 months, of a functional check on the SIT high and low level alarms.
These changes are considered necessary to reduce the risk of TS violations made possible by periodic surveillance and correction of boron concentration. When sampling the SITS to verify boron concentration, it is necessary to drain the tanks sufficiently to obtain an accurate suple. During this evolution, TS Section 3.3.2.a is in effect and 1!mits the ncn-operability of one tank to one hour. Because a significant amount of water must be drained from the tank to obtain a representative sample, the possibility exists that proper level may not be restored within the one hour period.
This procedure places demands on the Operetions staff which would be minimized if the operating band of the tanks were broadened.
3.0 EVALUATION CHANGE No. 1 The changes to the neutron monitoring system enhance the reliability of the accuracy of the neutron monitoring function under accident conditions. The previous system has basically been upgraded to the more stringent requirements of Regulatory Guide 1.97.
The upgraded equipment performs the same function as the previously installed equipment, and maintains the same degree of redundancy.
For consistency with Standard Technical Specifications, the licensee has proposed to change the name of the most sensitive neutron monitoring range from " Start-up Range"- to " Source-Range". Similarly, the name of the
" Logarithmic Range" has been proposed to be renamed " Wide-Range". These designations are more consistent with standard industry phraseclogy, and more clearly describe the respective neutron monitoring ranges. Changes-A,B,C,0,F,G and H reflect the new terminology.
Changes D and H also correct the designaM on of the source range neutron monitor which provides indication for e~ ternate shutdown capability (N-001A is changed to NI-1/3C). The source of the signal to the alternate shutdown panel source range monitor has been modified. The previous signal (N-001A) originated from an older, dedicated fission chamber. Thenewsignal(NI-1/3C) is supplied through an optical isolator associated with the left channel of the new, RG 1.97 qualified instrumentation. The newer system.provides for-more accurate indication and improved reliability.
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Chcnge E provides additional information to the TS, to clearly delineate the neutron monitoring system power source. Changes F, G, and H either add additional surveillances to the TS, or clarify existing surveillances.
Change I is necessary to correct the TS description of the core's mechanically fixed rods. Fixed boron rods are no longer in use at Palisades. A conversion from boron to Gadolinia rods was completed in core reloads H, I and J.
- Also, with recent fuel cycles converting to reduced leakage designs, additional neutron absorbent rods are being utilized (e.g., stainless steel, Hafnium).
Because a variety of materials may be used, the term " fixed absorber rods" is considered appropriate to accommodate different core reload designs.
In sunnary, the proposed TS changes more clearly describe the function and operation of-the neutron monitoring system. Additionally, the changed description of the type of neutron absorbing rod in use at the Palisades Plant corrects an error in the Design Features TS section, which was overlooked at the time of the Core reload H submittal. These changes reflect the use of material or equipment which will perform the same functions as existing equipment, and are considered acceptable.
CHANGE NO.-2 Discussions were held with the licensee's Operations staff to assess the
- operational restrictions imposed by the current SIT level band. Operational data for the period from 11/88 to 9/90 indicates that the SITS were sampled 187 times. SIT sampling is required monthly by the TS. The increased sampling frequency (approximately 100. samples above the TS minimum) was required due to known inleakage into the SITS from the primary coolant system. This inleakage slowly lowered SIT boron concentration; therefore, additional monitoring of tank concentration was required in order to ensure the minimum TS levels for SIT boron concentration were maintained.
The SITS do not have tank recirculation capability;-therefore, a relatively large amount of tank water is required by procedure to be purged through the sample lines in' order to obtain a-representative sample (on the order of 1700 gallons per sample). This water volume necessitates that the TS
' Limiting Condition for Operation be entered each-time a tank is sampled.
Although the most appropriate deterrent in preventing unnecessary SIT sampling is ensuring the leak-tightness of the SIT boundary valves,-widening the operational water level band will assist in maintaining the tanks within their prescribed limits.
The licen ~ contracted with their fuel vendor to evaluate the effect of a slightly yeduced or increased total liquid volume in the SITS (174 and 202 inches, respectively, for minimum and maximum allowed SIT levels). The result of the fuel vendor's Standard Review Plan Chapter 15 disposition of -
events was that the large break loss of coolant transient is the only event which completely drains the SITS (thereby it is the only event which could be affected by the changes in SIT Nvel limits).
O o,
Data supplied by the licensee indicates that flow from the intact loop SITS, SIT lines, and cold legs keeps the downcomer full for about 30 seconds af ter the peak cladding temperature (PCT) for the transient is reached.
Reduction of the minimum SIT level to 174 inches causes the SITS to empty, in the worst case, approximately four seconds earlier than would have occurred with the previous tank limits. Downcomer level does not fall prior to the time the PCT is reached. Additionally, increasing the maximum SIT level to 202 inches has no impact on the large break LOCA analysis because the SIT flow time would be conservatively extended beyond the time in the limiting analysis. These conclusions apply to all break sizes contained in the February 1990 Palisades Large Break LOCA Analysis of record.
The following factors were also considered:
o The change in the upper SIT limit involves a relatively small increase in the maximum amount of water stored in the SITS (two inches of level);
therefore, the probability of overfilling, containment flooding, and malfunctions due to seismic events are not significantly increased.
The LOCA containment analysis, which conservatively does not take credit for SIT injection, shows tnat peak containment pressure stays below the design pressure.
A comparison of the SIT operating band volumes in use at several Combustion Engineering plants indicates similar volumes. Also, the Combustion Engineering Standard TS provides for an operating band of roughly the same volume as that proposed by Palisades (126 and 136 cubic feet, respectively).
The effect of the reduced minimum SIT inventory on the available suction source for Safety Injection during long term recirculation from the containment sump has been considered. The reduction (1885 gal) in required minimum inventory is a very small fraction of the total available-inventory (approx. 380,000 gal) considering the vast inventory contribution from the four SITS and the Safety Injection Refueling Water Tank; and, therefore, will have a negligible effect on the oper6 tion of the safety injection pumps or the containment-temperature and pressure response.
The boron concentration in the tanks will be unchanged and the slight reduction in total inventory will not have a significant effect on the sump boron concentration during the recirculation phase of the accident.
Additionally, this change will not significantly effect the time before hot leg injection is required to prevent precipitation of boron.
In sumary, the proposed changes to the Technical Specification limits on palisades SIT levels have been evaluated to ensure that adequate water is available for make-up to the primary coolant system.
The analysis shows that when the contents of the SITS are at the proposed lower level, and a large break LOCA occurs, the SITS do not empty until af ter the peak cladding temperature is reached and until after high and low pressure safety injection l
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are actuated. The addition of a surveillance requirement to perform a functional check on the S1T high and low level alarms institutes additional TS controls on ensuring that SIT level will be adequately measured and maintained. Additionally, the basis section has been updated and the TS Reference section appropriately expanded.
Therefore, these proposed TS changes are considered acceptable.
4.0 ENVIRONMENTAL CONSIDERATION
This amendment involves a change in a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and a change in a surveillance requirement.
The staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that this amendment involves no significant hazards consideration and there has been no public comment on such finding. Accordingly, this amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR Section 51.22(e)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of this amendment.
5.0 CONCLUSION
The staff has concluded, based on the considerations discussed above, that (1) there is reasonable assurance that the health and safety of the will not be endangered by operation in the proposed manner, and (2) public such activities will be conducted in compliance with the Commission's regulations, and the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
The staff trerefore concludes that the proposed changes are acceptable.
Principal Contributor:
Brian Holian Date:
February 15,'1991-l l
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