ML20235M652
| ML20235M652 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 02/10/1989 |
| From: | Whittier G Maine Yankee |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| RTR-REGGD-01.097, RTR-REGGD-1.097 GDW-89-47, MN-89-15, NUDOCS 8902280349 | |
| Download: ML20235M652 (7) | |
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RELIABLE ELECTRICITY FOA MAINE S!NCE 1972 -
- EDISON DRIVE. AUGUSTA, MAINE 04330. (2d7) 622 4868
-February 10, 1989-MN-89-15' GDH-89-47 0
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. UNITED STATES' NUCLEAR REGULATORY' COMMISSION Document Control Desk-m Washington, D. Cs 20_555
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References:
(a)t?Licens'e No. DPR-36.(Docket No. 50-309) 1
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(b)' USNRC Letter to MYAPCo dated November 15, 1988.- Emergency
- Response Capability - Conformance to. Regulatory Guide-1.97,
' Revision ~3 (TAC 51103).
- (c) MYAPCo'Letterjto USNRC dated February 28, 1985 _(MN-85-43)
(d) :MYAPCo Letter to USNRC dated. April 18.-1988 (MN-88-41)-
- (e) :MYAPCo Letter to USNRC dated April'29, 1988 (MN-88-49) y
-(f) MYAPCo Letter to USNRC dated September 19, 1988._ (MN-88-94) a
Subject:
- Conformance:to' Regulatory Guide (R.G.) 1.97 Rev.~3 y
. Gentl emen:' -
- Please find enclosed-Maine Yankee's responses to the open items. identified
.in Reference (b). The enclosure also contains a clarification describing-
- Maine' Yankee's conformance to recommendations for instrumentation to monitor T
component cooling water flow (described in Reference [f]);iand justification'
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..for a deviation.in the recommended accur'acy range of certain accident-
. moni toring1 instrumentation..
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.Please. contact us if you have any ' questions.
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.Very truly yours, MAINE YANKEE
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G.'D. Whittier, Manager Nuclear Engineering.and Licensing GDH/bjp-I w
Enclosure m,
c: Mr. Richard H. Hessman Mr'. H1111am T. Russell
-m4 Mr.. Patrick M. ' Sears Mr. Cornelius'F. Holden-00b g i IO918L-SDE.
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t FAINE YANKEE RESPONSE TO OPEN ITEMS IN CONFORMANCE TO REGULATORY GUIDE 1.97, REV. 3 (TAC 51103) j Open Item 1:
Accumulator level and pressure - the licensee should designate either level or pressure as the key variable and provide environmentally qualified instrumentation for that variable (Section 3.3.10).
Maine Yankee Resoonse 1:
The Staff has determined, in Reference (b), the range of the SIT pressure instrumentation to be acceptable.
Therefore, the instrumentation utilized
, to monitor SIT pressure satisfies the intent of the Regulatory Guide 1.97, Rev. 3, except for the recommendation on environmental qualification.
As stated previously, the Safety Injection Tanks (SITS) level and pressure instrumentation are not required to function in a harsh environment, so the environmental qualification requirements of 10 CFR 50.49 are not applicable, and these instruments should not have to be environmentally qualified.
It is our understanding based on discussion with NRC staff that the necessity for EQ requirements for this instrumentation is under NRC generic review.
Please inform us if our interpretation of the requirements of 10 CFR 50.49 is incorrect.
Quen Item 2t Pressurizer heater status - the licensee should provide the recommended current instrumentation (Section 3.3.15).
hiainq Yankee Resoonse 2:
The Technical Evaluation Report (EGG-NTA-7083), enclosed in Reference b, concluded that "A means of monitoring pressurizer heater current in the control room should be provided" (p. 12).
Heater current is presently displayed on the plant computer point #286.
This instrumentation will indicate the operability of the pressurizer heaters when the power source is offsite power.
Heater breaker status and diesel kilowatt meter provide q
an indication of the pressurizer heater operability when power is supplied by the emergency diesel generators.
Thus, existing instrumentation satisfies the staff's recommendations for indications of pressurizer heater status operability.
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Containment atmosphere temperature - the licensee should provide the recommended range for this instrumentation (Section 3.3.21).
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MailleYankee M3ine Yankee Response 3:
One channel of the existing 30-150*F temperature monitors will be expanded to 40-400*F.
This range change will require the installation of a new transmitter that will satisfy the R.G. 1.97, Rev. 3 recommendations for a Category 3 in:,trument.
The new transmitter will be installed by the end of the 1990 refueling outage.
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Ooen Item 4:
Containment sump water temperature - the licensee should provide the recommended instrumentation or identify alternate instrumentation that provides the same information and satisfies the regulatory guide (Section 3.3.22).
Maine Yankee Response 4:
Existing instrumentation, with indication on the main control board, monitors the RHR heat exchanger outlet temperature for both trains.
Maine Yankee proposes to install a Category 3 instrument to monitor RHR heat exchanger inlet temperatures for each train to provide for an indication of temperature change across the heat exchanger.
Maine Yankee will install this instrumentation by the end of the 1990 refueling outage, provided that we receive NRC written approval of our proposal by June 30, 1989.
Onen Item 5:
Vent from steam generator safety relief valves - the licensee should
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provide the recommended instrumentation for this variable to monitor any radioactive releases from this point.
Maine Yankee RespJnse 5:
The main steam line monitors (RM-901A,B,C), are utilized to detect a I
release of radioactive materials from the steam generator (S/G) safety relief valves (SRV) or the atmospheric steam dump valves (ASD).
The six safety relief valves located in each main steam line are set to open at successively higher steam pressures between 985 psig and 1035 psig.
Normal system pressure at full power is 835 psig.
Flow rates have been established for the SRV and th The instrument range of the MSL monitor instruments is 10 p ASD valves.7 mR/hr. Using the equivalent
' to 10 l
noble gas release rate, Q (uCi/sec), established for each of the six I
safety relief valves and atmospheric steam dump valve setpoints and the flow rate (cm3/sec) for each, the quantity of activity per unit volume released (uCi/cc) can be calculated as follows:
uCi/cc - 0 (uCi/secl F (cm3/sec) t 0918L-SDE
MaineYankee
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The instrumentation installed to detect the release of radioactive materials from the S/G safety relief valves or the atmospheric steam dump valves has an equivalent range from 3.6E-4 uCi/cm3 to 6.4E5 uCi/cm3 which exceeds the recomn. ended range of R. G. 1.97.
.Clarificaijsn of the Technical Evaluation Reogr_t You also asked, in Reference (b), to comment on the contents of the Technical Evaluation Report (TER), identifying any incorrect assumptions or commitments.
The following information updates Section 3.3.25 of the TER.
Section 3.3.25 of the TER is based on Maine Yankee's letters of April 8 and April 29, 1988 (References [d] and [e]) and states:
"3.3.25 honent Coolina Water Flow to Engineered Safety Futures (ESF)
System Components Regulatory Guide 1.97 recommends Category 2 instrumentation for this variable with a range of 0 to 110 percent of design flow.
The licensee is upgrading alternate instrumentation to Category 2 requirements.
The alternate instrumentation consists of the following for each of the two component cooling water subsystems.
Surge tank level pump motor current temperature alarms for each individual cooling load.
A decrease in the surge tank level (displayed on demand) would indicate leakage or a break in the cooling water subsystem. A pump flow curve j
shows that the pump motor current would decrease if system blockage occurred on the discharge side of the pump or if pump suction was lost.
A high temperature alarm on any component would indicate the possibility of inadequate system operation.
He find the upgraded alternate instrumentation to be a viable and acceptable approach to meeting the objectives of Regulatory Guide 1.97."
Subsequently, Maine Yankee decided, as described in our September 19, 1988 letter (Enclosure 1), to install flow instrumentation to monitor component cooling water flow instead of the alternete instrumentation.
The flow instrumentation, which meets the recommendations of R.G. 1.97, Rev. 3, was I
installed during the October-December, 1988 refueling outage.
Accordingly, it is recommended that the Section 3.3.25 of the TER be revised to reflect that Maine Yankee has flow instrumentation that l
satisfies the Regulatory Guide 1.97 recommendations.
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A. Deviation in Recommended Accuracy Rance for Containment Area RadiatLcn Instrumentation 1
-During the October 26, 1988 conference call with Mr. Barry Marcus of the 1
NRC Staff, Maine Yankee described the range of accuracy that exists for the containment high range radiation monitoring instrumentation. This accuracy range deviates slightly from the recommendations in R.G.1.97, Rev. 3.
At the Staff's recommendation, we submit the following information for your evaluation and concurrence.
' Regulatory Guide 1.97 Rev.'3 contains two recommendations associated with Category 1 instrumentation to monitor containment area radiation:
Footnote 7 recommends two widely separated monitors; footnote 8 recommends:
" Detectors should respond to gamma radiation photons within any energy range from 60 kev to 3 HeV with a dose rate response accuracy within a factor of 2 over the entire range".
No deviations were ' identified in Maine Yankee's R.G.1.97 report of February 28, 1985, Reference (c).
In February,1987, -Sorrento Electronics notified Maine Yankee, pursuant to 10 CFR 21, of a potentia ~l for inaccuracies ir the General Atomic High Range Radiation Monitor, used in containment, due to a decrease in the cable insulation resistance (IR) at elevated temperatures.
An evaluation of the containment high range radiation monitor system was performed pursuant to the Part 21' notification.
It was concluded that.
continued operation was justified because the monitors' cables, installed in October'and November,1985, had not experienced significant temperature I
or radiation aging.
A more detailed evaluation of the system components has revealed a deviation from recommendations-pertaining to the dose rate response within a factor of 2 over the entire range as described below.
The High-Range Radiation Monitor System consists of two independent GA/Sorrento Electronics radiation monitor systems, with detectors located in'the containment.
The system does not perform any automatic safety function, but provides containment radiation dose rate data to the Control Room.
This data is displayed on Sigma indicators mounted on the main control board, and would be utilized by the operators in conjunction with i
Maine Yankee's Emergency Operation Procedures (EOP), and in offsite dose assessment.
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3 The. containment High-Range Radiation Monitor. System would be utilized in 1
i conjunctionLwith other plant radiation monitoring devices:
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. Vent stack radiation' monitors,.RM-3902X, RM-3902Y, and RM-3903 u
(nonharsh environment).
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Atn:ospheric dump, main steam radiation monitors, RM-901 A, RM-901B,
. j and RM-901C (nonharsh environment during a LOCA).
These instruments, together with the containment high radiation monitors, n
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would be utilized for:
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detection _of significant releases, b.
~ release assessment.
c.
long-term dose rate surveillance, and l
d.
emergency classification determination and protective action
. recommendations.
The' Control: Room' operators would utilize the data supplied by the radiation monitor with other environmentally qualified instruments (i.e.,
pressurizer pressure, steam generator' pressure and level, etc.), thereby
' ensuring correct interpretation of information, identification of the
~ event,' and implementation of corrective actions.
- A review has been performed to determine the effect of calculated worst-case errors.on the decision making process of the operators and the dose assessment personnel.
In the long-term, temperature-induced system bias errors would not exist-since containment temperatures would be relatively low, less than 200*F. The results of this review shows that the difference in the' Regulatory Guide 1.97 recommended accuracy factor of n
2 and'the calculated worst-case factor of'2.2 would have no adverse effect on accident assessment, radiation release calculations, radiation.
nionitoring and.offsite protective action recommendations.
Under the most adverse operating conditions, calculated accuracies are affected by-two factors:
Primary components ( )effect on interface components (l)
Elevated temperatur
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operation capabilities.
2.
Temperature-induced errors are limited to components inside the containment (i.e., detectors, cables, electrical penetrations, etc.)
during the initial stages of an accident when temperatures could be above 225'F. The effect of elevated temperature is only noticeable at the lower operating range of the radiation monitor, (less than 50 rads per hour).
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Elevated temperatures could result in a negative system bias and low f
indicator reading. At the maximum calculated LOCA containment temperature (280*F), a system bias of -2.44 rads per hour would apply over the entire range of monitor operation, (1 to 108 r/hr.).
However, this bias would decrease to less than one rad per hour in less than five minutes as temperature decreases.
Th t. slight deviation described above in the recommended full-range accuracy for containment high range radiation monitors would only be detectable at the lower dose rate range of the instrument under the extreme peak temperatures, which is very brief. The available accuracy of the installed equipment fully satisfies the intent of Regulatory Guide 1.97 and provides accurate dose rate information to plant operators and staff for accident response diagnosis and assessment.
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l (1)
Interface components are considered cables, electrical penetrations, splices, etc.
(2)
Primary Components are detector, electronics, power supply, indicators, etc.
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