ML19340C637
| ML19340C637 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 12/09/1980 |
| From: | Hovey G METROPOLITAN EDISON CO. |
| To: | Jay Collins Office of Nuclear Reactor Regulation |
| References | |
| TLL-645, NUDOCS 8012150260 | |
| Download: ML19340C637 (5) | |
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%O Metroceditan Edison Company
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Post Office Box 480 e
Miocletown, Pennsvivania 17057 L
- itee's c r,et oisi Numee, December 9, 1980 TLL 645
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TMI Program Office Aten:
Mr. John T. Collins, Deputy Director U. S. Nuclear Regulatorv Commission c/o Three Mile Island Nuclear Station Middletown, Pennsylvania 17057
Dear Sir:
Three Mile Island Nuclear Station, Unit 2 (TMI-2)
Operating License No. DPR-73 Docket No. 50-320 Recovery Operations Plan, Surveillance Requirements Relief Request This letter is written to formally request relief from Section XI of the ASME Boiler and Pressure Vessel (B&PV) code and applicable Addenda in accordance with 10 CFR 50, Secticn 50.55a and Section 4.7.3.3 of the Recoverv Operations Plan for specific Mini Decay Heat Remeval System (MDHRS) inser/ ice inspection criteria. The enclosed evaluation details the EHRS Inservice Inspection require-ments that we propose, t ' relief requested and provides a justi-fication for each request.
Your approval of these proposed surveillance requirements is requested.
Sincerely, P00R ORIGINAL 6.MM Vice-Pres'ient and Director, TMI-2 GKH:JJB: dad cc:
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Recovery Operations Plan, Surveillance Requirement Relief Request Section 4.7.3.3 of the Recovery Operations Plan requires each Mini Decay Heat Removal System (MDHRS) pump and valve in the flow path to oe tested in accordance with the inservice inspection requirements of Section XI of the ASME Soiler and Pressure Vessel Code except where specific written relief has been granted by the Commission. This request is submitted in accordance with this requirement.
The relief requested is broken into two parts. Part A requests relief frem the monthly tetting requirement for the MDHR pumps. This particular request is to perform this test semi-annually af ter the MDHRS has been used for reactor decay heat removal instead of monthly as specified in the ASME co,de.
Part B of this request details the specific tests required by the ASME code and the relief requested from three of these tests, i.e Vibration Amplitude Msasure-ment, Bearing Temperature Measurement, and Valve Exercise Testing. The goal of the first two tests is met by using an alternative measurement using installed vibration measuring equipment. The third test involving valve exercisina, need only be performed on the system isolaton valves to ensure proper MDHRS operation and therefore testing of additional valves is unnecessary.
REASON FOR CHANGE A)
Periodicity of MDHR Pump Testing The testing requirements of Section XI of the ASNE B&PV Code requires inservice testing of each pump monthly. We are requesting that this periodicity require-ment be relaxed to semi-annually after the MDHRS has been used for reactor decay heat removal.
Use of the MDERS is only one of several modes available to maintain adequate core cooling. Therefore monthly testing of the MDHRS pumps is not necessary because the MDHRS is not essential to reactor safety. Additionally testing the MDHR pumps monthly in a borated water enviroment increases the chance of pre-
=sture seal degradation, and as the MDHR pumps will become highly contaminated by the primary system water, repairs to the pumps would result in significant personnel exposures.
B)
Specific MDERS Pump and Valvs Inservice Inspection Requirements.
I In addition to this periodicity requirement, Articles IWP-3000 and IWV-3000 of Section XI of the ASHE S&PV Code specify particular Inservice Inspections required for pumps and valves. The Inservice tests applicable to the MDHRS pumps and valves and our methods of testing are listed below.
Specified Test Requirements Compliance Method
- 1) MDER Pumps Inlet Pressure, Pi Per IWP-3000 l
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P00R BRIGINAL
a J. T. Collins Page 3 Recovery Operations Plan, Surveillance Requirement Relief Request Differential Pressure, P
Per IWP-3000 Flow Race, Q Per IWP-3000 Vibration Amplitude, V Measure Vibration in velocity Bearing Temperature, Tb Not measured Proper lubricant level Per IWP-3000
- 2) Category A & 3 Valves Valve Exercise Test MDH-V1,V2, V10. V. 9 only Valve 1.eak Rate Test (Category A only)
Per IW-3000
- 3) Category C valves Per IW-3000 For those compliance methods which are not identical to the ones specified in Articles IWP-3000 and IW-3000 of Section XI the ASME B&PV Code a 10CFR50.55a exemption is requested and a justification is provided.
1)
MDHR Pump Vibration Article IWP-3000 of Section II of the AW B&PV Code specifies an accep-t able range for pump vibrat ion in mils, displacement. The system that is installed on the MDER pumps to measure 'ribration, the Vibralarm, measures vibration velocity. Velocity measurement is convertible to displacement. We intend to use, however the velocity measurement in place cf the displacement lieasurement specified in the ASME Code. Additionally the Vibralarm cont inuously monitors pump vibration and provides an " ALERT" and a "SHUTDCWN" iniication for the operator. As these indications corres-pond to the Alert Range and the Required Action Range specified in the ASME Code for pump vibration we will use these indications, which are monitored continuously, rather than taking monthly measurements as specified in the ASME Code.
2)
MDHR Pump Bearing Temperature Article IWP-3000 of Section II of the ASME S&PV code also requires an
' inservice test measuring puc:p bearing temperatures. The MDHRS lacks installed instrumentation to measure bearing temperature, but the Vibralarm system can be used to monitor the pumps' bearing housings. Mes?,uring MDHRS pump bearing L emperature would require entry into the MDHRS pump cubicle, which is calculated to be a 2-8 R/Hr radiation zone, to directly measure this parameter. As bearing temperature is not considered to be stable until three successive readings taken at ten minute intervals vary by no more than 3%, this measurement will result in significant exposure to personnel which is undesirable from an ALARA standpoint.
P00R ORIGINAL
s J. T. Collins Page 4 Recovery Operations Plan, Surveillance Requirement Relief Request Therefore since an installed system exists which adequately monitors bearing performance we intend to use it instead of taking direct measure-ment s of bearing t emperature.
3)
MDHR System Valve Exercise Tests Article IWV-3000 of Section XI of the ASME B&PV Code requires the '1rfor-mance of a valve exercise test on Category A and B valves. Our ic;;ntion however is to perform this test quarterly on the following MDERS valves only:
MDHR System Inlet Isolation Valves MDH-Vl/ 2 MDER System Outlet isolation Valves MDH-V18/19 These are the valves that will be used to isolate the MDHRS in an emergency and because of the high radiation levels in the MDHR cubicles during system operation these valves will have to remain shut while repairs are being made.
Thus testing other MDHRS valves is not needed to ensure system reliability.
JUSTIFICATION OF ALTERNAT1GO A)
Periodicity of MDHR Pu=p Tests Use of the MDHRS is one of several modes available to maintain adequate core cooling. Therefore monthly verification of the standby MDHR Pump's operability is not vital to reactor safety. Additionally testing of the standby pump may cause sechanical seal degradation requiring pump repairs to be performed, and significant exposure to personnel. In order to reduce the number of times these repairs may be necessary but still maintain reasonable assurance that the standby MDHR pump will be operable, if needed, we intend to perform the inservice tests on the standby MDHR pump semi-annually after the MDHRS has been used for reactor decay heat removal.
B)
Specific MDERS Pump and Valve Inservice inspection Requirements
- 1) MDHR Pump Vibration T
Vibration is a basic parameter for describing pump mechanical character-istics. This parameter is measured on the MDHR pumps by the-Vibralarm vibration monitoring system which indicates vibration velocity.
This varies from Article IWP-3000 of Section XI of the ASME BSPV Code which specifies a vibration displacement measurement, but this variation is acceptable because pump vib -
cn is measured with respect to an j
8 established and acceptable bas-litionally, The Vibralarm P00R BRIGINAL
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J. T. Collies Peg 2 5 Recovery Operations Plan, Surveillance Requirement Relief Request continuously monitors pump vibration and provides an "ALERI" and a
" SHUTDOWN" indication for the operator, which correspond to the Alert Range and Required Action range specified in the ASME Code. There fore continuous monitoring of vibration velocity of an operating MDHR pump by the Vibralarm satisifies the intent of the vibration measurment specifi-cation in the ASNE Code.
- 2) MDHR Pump Bearing Temperature The reason for measuring pump bearing temperature is to give an indica-tion of the mechanical characteristics of the MDHRS pumps. As there is no direct measurement of MDMR Pump bearing temperature, a substitute measurement is provided. This substitute measurement is supplied by the MDHR pumps "Vibralarm" vibration monitoring system which continuously monitors the pump's bearing housings for impending f ailure so that corrective action can be taken prior to pump failure. Using this system to monitor the MDMR pump bearings also reduces personnel exposure to radiation because entry into the MDHR pump cubicle to take temperature measurements will not be required.
- 3) MDER System Valve Exercise Tests The accident analysis performed on the MDHRS and presented in Technical Specification Change Request No. 24b assumed MDERS isolation by these system isolation valves and a complete draining of the rest of the MDHRS. This analysis demonstrated the of f-site
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affects of the accident did not jespordize the health and safety of the public, and therefore these are the only valves that need to be tested.
Addit ionally, not testing other system valves will not adversly impact system operation because the high radiation levels in the MDER cubicles during system operation calculated to be 2-8 R/Hr. require the entire system t o be shutdown and flushed prior to entering an MDER cubicle to perf orm maintenance.
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P00R ORGINA l
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