ML20031D642
| ML20031D642 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 10/02/1981 |
| From: | Bordine T CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | |
| Shared Package | |
| ML20031D553 | List: |
| References | |
| ISSUANCES-OLA, NUDOCS 8110130569 | |
| Download: ML20031D642 (15) | |
Text
TESTIMONY OF THOMAS C. BORDINE LICENSING BOARD QUESTION NO.1 The following is a response to Licensing Board Question No. 1:
Has the proper operation of any of the valves mentioned in Items 5 and 6 on Page 4 of the Safety Assessment (viz, Valves CV/4096, CV/4097, CV/4027, CV/4105 and M0/7050) been relied upon to mitigate the results of an accident in the spent fuel pool? If so, how would a failure of the type experienced with these valves affect the results of such an accident?
The answer to the first part of the question is yes, with respect to CV/4096, CV/4097 and no, with respect to CV/4027, CV/4]05 and M0/7050. No escape of radioactivity to the environment from an accident in the spent fuel pool can occur through CV/4027, CV/4]05 or M0/7050.
Valves CV/4096 and CV/4097 are supply ventilation valves to containment. Valve CV/4097, a butterfly valve, is in series with the Check Valve CV/4096. The contafiment is normally maintained at a negative differential pressure to prevent uncontrolled releases of airborne radio-activity to the environment. The two supply Ventilation Valves CV/4096 and CV/4097 are normally open, to provide ventilation to containment.
To prevent the possibility of excessive external pressure on the contain-ment sphere, these supply ventilation valves also open aut a tically whenever the negative differential pressure exceeds 1 psi. This provides vacuum relief of the containment sphere.
During some postulated accident conditions a positive pressure would develop within containment. Valves CV/4096 and CV/4097 are designed 4
0 0110130569 811005 PDR ADOCK 05000155-T PDR
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to close automatically upon receipt of a high radiation signal from either of two area monitors located in the vicinity of the fuel storage and spent fuel pool area. The valves are also closed upon receipt of a number of other signals from the reactor safety system.
l Valves CV/4096 and CV/4097 are currently tested semiannually for leakage and monthly for proper closure and they have never failed to close during such testing. Valve CV/4097 has occasionally failed to seal properly and, therefore, leakage (measured by a pressure drop for a period of time) through the valve has been observed when pressurized air is applied at the valve. This leakage through Valve CV/4097 during semiannual tests occurred prior to its modification in February and March of 1979. The valve disk was modified to accomodate an alternate type valve seal and ring. No significant leakage has occurred through Valve CV/4097 subsequent to the modification. No repetitive leakage rate failures have been associated with Valve CV/4096.
Since Valves CV/4096 and CV/4097 are in series, a simultaneous failure of both valves coupled with containment pressurization would be required to permit release to the environment of any radioactive material from an accident in the spent fuel pool. This scenario is unlikely. Moreover, modifications related to CV/4096 and CV/4097 are currently scheduled for the next refueling outage in 1982. These modifications will assure the independency and redundancy of these valves and thus minimize the likelihood of simultan-eous failure.
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In fact, CV/4096 may never have experienced a leakage rate failure.
However, there is one test report which is not clear about whether n
it was CV/4096 or Cv/4097 which experienced excessive leakage in
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the test.
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Valve CV/4027 is called the reactor and fuel pit drain valve.
The 2-inch valve is on a line which unctions upstream with a drain line from the cicanup demineralizer system and a drain line from the spent fuel
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pool surge tank and the spent fuel pool cooling system.
The valve is used to bleed water from the reactor primary system to the radwaste system during heatup, blow down excess water to radwaste during startups and cooldown and recycle spent fuel pool water from the spent fuel pool cooling system to radwaste periodically. The radwaste system is outside containment.
CV/4027 is in series with CV/4117. Both valves automatically close in the event of a reactor scram which requires isolation of containment.
Leakage in excess of Technical Specifications limits has been measured on several tests with CV/4027.
In leak tests prior to September 19, 1981, when CV/4027 failed, the redundant valve CV/4117 was operable and would have prevented excessive leakage through the line. During November 1980, CV/4027 was disassembled and repaired. New valve seats were installed, the inner valve was replaced and the spring tension was readjusted to 1
manufacturer's recommendations. The valve then passed a leak test following the repair. However, both Valves CV/4027 and CV/4117 failed the leak test of September 19, 1981. The event was reported via LER 81-23 (attached as Exhibit 2).
Consumers Power Cc,mpany is expending efforts to climinate this repetitive malfunction. The exa::t cause of excess leakage is being investigated but has not yet been identified.
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As stated previously in my testimony, there is no possible path for drainage of the spent fuel pool itself. The somewhat inaptly named " reactor and fuel pit drain line" cannot be used to drain the water in the spent fuel pool below the level of the stored fuel. -
O Nevertheless, should both valves fail, upstream Valves VSFP17 and VSFP119 1
are maintained in the closed positions to prohibit unintentional water flow from the spent fuel pool cooling system through this line. Further-more, if these valves also failed, the water in the spent fuel pool would not fall below the level of the concrete weir, as discussed in my response to O'Neill Contention II-B of this testimony. Finally, any radioactive material released through this pathway could only go to the radwaste system.
It would not escape to the environment. Therefore, a failure of the type experienced with CV/4027 would not affect the results of
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an accident in the spent fuel pool.
Valve M0/7050 is the Main Steam Isolation Valve. The valve
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automaticc11y isolates the main steam system upon receipt of a signal from the reactor safety system. This occurs simultaneously with a reactor scram due to low reactor water level, high containment enclosure pressure and loss of auxiliary power. Consumers Power Company has reported three events associated with the failure of this valve to close. A new valve packing technique was employed subsequent to the last reported event of January 10,.1980.
Based on testing performed by another valve vendor and experience reports from other industry sources, preformed graphite packing rings alternated with braided packing rings were utilized to l
provide better self-cleaning characteristics. This is expected to provide improved performance by reducing the graphite packing material buildup in the valve stem which has impeded valve travel in the reported events.
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%J Backup valves in each downstream branch of the main steam system can be closed should an event warrant such action following a failure of M0/7050 to close. However, the function of the main steam system is to conduct reactor heat (via saturated steam) to the main reactor 3/
heat sink, namely, the condenser.
Since the main steam system is independent of any piping associated with the spent fuel pool and does not communicate with the atmosphere above the spent fuel pool, the position of Valve M0/7050, open or closed, would not affect the results of an accident in the spent fuel tool.
Valve CV/4]05 is a control valve located outside of containment that provides demineralized water to the emergency cond.enser, reactor
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cooling water tank, clean-up demineralizer, refueling shield tank, and the spent fuel pool and surge tank. No repetitive failures have occurred with this valve. C7/4105 is located in a 2-inch pipeline filled with water which is punped into containment. Even if this pump is not operating several check valves within containment prohibit backflow of water to the region outside containment. Two of these check valves (VSFP305 and 306) are shown in Figure 3 attached to my affidavit on O'Neill Contention II-B.
Valves VSFP 27 and 20, which are also shown, are manual valves in series with these check valves and are presently also being used under lock control te prevent any contamination of the Demineralized Water System.
Finally, there is another check valve - manual valve series on the Demineralized Water System within containment (not shown, but located at
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The main steam isolation valve is provide.d to isolate steam leaks U
which occur outside containment..
s the "Demin k'ater" label at the lef t of Figure 3) which would prevent backflow out of the containment through this line. Because of the existence of all of these other valves, Valve CV/4105 need not close in the event of a spent fuel pool accident to prevent release of i
radioactive materials from the spent fuel pool to the environment.
Therefore, in response to Licensing Board Question No. ] for Valve CV/4105, the valve is not relied upon to mir.igate the results of an 4
accident in the spent fuel pool. In addition, the Board should note that, as stated in David Blanchard's testimony wft.h respect to Christa-i Maria Contentian 8 and O'Neill Contention II-E-2, Consumers Power Company does not need to rely on the demineralized water system, or
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the proper operation of Valve CV/4105, to provide makeup water to the spent fuel pool in the event of a reactor accident which would preclude access to the containment.
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Q Generet Ofhces-212 West M6chigan Avenue, Jackson, MI 49201 + (517) 788 0550 October 1, 1981 Mr James G Keppler Office of Inspection and Enforcement Region III US I;uclear Regulatory Commission T99 Roosevelt Road Glen Ellyn, IL 60137 DOCKET 50-155 - LICEIiSE DPR BIG ROCK POINT PLANT - LICENSEE EVENT REPORT 81-023 - CONTAINMENT ISOLATION SYSTEM Attached is the Licensee Event Report (LER)81-023 (Containment Isolation System) q which is reportable under Technical Specificat' ion 6.9.2 A (3).
Thomas C Bordine (Signed)
Thomas C Bordine Staff Licensing Engineer CC Director, Office of Nucleer Reactor Regulation Director, Office of Inspection and Enforecement NRC Resident Inspector EXHIBIT 1 - Licensing Board Question 1 tm 5,s_)
page 1 of 2
-J Attachment to LER-023-OlT-0 Consuners Power Company I'
Big Rock Point Plant Decket 050-155 During routine twelve month leak rate testing of the two containmen't isolation l
valves in the reactor and fuel pit drain line, both valves exhibited minor leakage above the Technical Specification acceptance criteria in Technical Specification 3.7(b). This occurred at 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br /> on 9/19/81. Valve CV4027 was exercised and retested satisfactorily on two tests at 0215 hours0.00249 days <br />0.0597 hours <br />3.554894e-4 weeks <br />8.18075e-5 months <br /> on 9/20/81.
Flushing of the valve internals may have carried away small particles and allowed l
tight seating. Valve CV4027 was left closed and later deactivated in the closed position to establish containment integrity and allow work on defective valve CV4117 which is located outside con'.ainment in the same line. Minor wear on the valve seat of CV4117 was discovered and repairs and retest were com-pleted on 9/24/81. During a retest of valve CV4027 on 9/24/81, minor leakage again occurred and CV4117 was verified closed and deactivated to establish con-tainment integirty.
l failure of tha outside isolation valve CV4117 l
This is the first leak rate test but repetitive failures have occurred with the inside isolation valve CV4027 and further investigation of the test method and maintenance practices is in progress to determine the cause of the defect.
Both valves were supplied by l
Black Sivalls and Bryson as original plant equipment and are air operated globe valves, model #70-14-2DRT.
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Isolation of the reactor and fuel pit drain line with the plant at power is not expected to cause operating difficulties in the near future and valve CV4117 l
will remain closed until operability of the series valve CV4027 can be estab-lished. No hazard to the public occurred and the incident was reported as an l
Unusual Event as defined in the Site Emergency Plan.
The event is deemed report-able based on Technical Specification 6.9.2 a (3).
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