ML20044G699
| ML20044G699 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 05/25/1993 |
| From: | Opeka J, Romberg W NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20044G700 | List: |
| References | |
| B14464, NUDOCS 9306040117 | |
| Download: ML20044G699 (13) | |
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NORTHEAST UTILITIES o.norai Ome... seioen street. seriin. Connecticut 9
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-B14464 Re:
10CFR50.90 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 Gentlemen:
Millstone Nuclear Power Station, Unit No.1 Proposed Revision to Technical Specifications Main Steam Line Radiation Monitor Trio Removal Pursuant to 10CFR50.90, Northeast Nuclear Energy Company (NNECO) hereby l
proposes to amend its Operating License, DPR-21, by incorporating the attached proposed changes into the Technical Specifications of Millstone Unit No.1. provides the marked-up pages which show the proposed changes. provides the retyped pages.
DESCRIPTION OF PROPOSED CHANGES The proposed changes remove the operability and associated surveillance requirements for the main steam line radiation monitor (MSLRM) scram and Group I containment isolation functions.
Justification for removal of the MSLRM trip function was. described in Licensing Topical Report NED0-31400,
" Main Steam Line Radiation Monitor Trip Removal,""' which was approved by the Staff on May 15, 1991.28 NNEC0 participated in the Boiling Water Reactor Owners' Group (BWROG) activity which was responsible for development of NED0-31400 and is identified as such in Table 1 of the Topical Report.
We currently intend to implement a plant design change to remove the MSLRM trip function during the Cycle 14 refueling outage.
We have confirmed that the analyses of NED0-31400 conservatively bound Millstone Unit No. I and therefore the Topical Report is applicable.
Specifically, the proposed changes delete the operability requirements for the
" Main Steamline Radiation" scram function from Table 3.1.1 (page 3/41-4) and (1)
NED0-31400, " Safety Evaluation for Eliminating the Boiling Water Reactor Main Steam Line Isolation Valve Closure Function and Scram Function of the Main Steam Line Radiation Monitor," May.1987.
(2)
A. C. Thadani letter to Boiling Water Reactor Owners' Group (G. J.
Beck), " Acceptance for Referencing of Licensing Topic Report NED0-31400,
' Safety Evaluation for Eliminating the Boiling Water Reactor Main Steam Line Isolation Valve Closure Function and Scram Function of Main Steam Line Ra i t o itor,'" dated May 15, 1991.
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U.S. Nuclear Regulatory Commission B14464/Page 2 May 25, 1993
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the "High Radiation Main Steamline Tunnel" containment isolation function from Table 3.2.1 (page 3/4 2-2) of the Millstone Unit No.
1 Technical Specifications. The existing notes associated with these requirements, note (12) on page 3/41-5 and note (6) on page 3/4 2-2, would also be deleted.
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Additionally, the surveillance requirements for "High Steam Line Radiation" would be deleted from Tables 4.1.1 (page 3/4 1-6) and 4.1.2 (page 3/4 1-8).
On page 3/41-7, the words "and on high steamline radiation once per shift" are proposed to be deleted from note (2).
Note (4) would also be deleted from page 3/4 1-8.
The existing note (5) would be renumbered as note (4).
In addition, the reference to note (5) for the "APRM Output Signal" would be renumbered as (4).
The surveillance requirement for " Steam Line High Radiation" would also be deleted from Table 4.2.1 (page 3/4 2-9).
On page 3/4 6-18, the words " main steam line" are proposed to be added to limiting condition for operation 3.6.K.1 to clarify the signal on which the j
mechanical vacuum pump would be isolated and secured.
In addition, l
surveillance requirement 4.6.K.2 is proposed to be added on page 3/4 6-19 as follows:
"The main steam line radiation monitors shall be calibrated with a radioactive source at least once each operating cycle."
On page 3/4 7-17, " Main steam line high radiation" (condition 2) is being I
deleted as a condition which initiates closure of Group I isolation valves.
l The existing conditions 3, 4, and 5 would be renumbered as 2,. 3, and 4, respectively.
Finally, Bases pages B 3/4 1-3, 1-4, 1-4a, 2-3, and 2-3a are being changed to reflect the above proposed technical specification changes.
BACKGROUND On December 29, 1992, while valving in a condensate demineralizer, main steam line high radiation and turbine deck area high radiation alarms were received.
The main steam line radiation reading increased from the 350 mR/hr normal background reading to approximately 1300 r..Vhr.
The MSLRM has a setpoint which is designed to trip at or below the technical specification requirement of seven times the normal background reading.
To provide margin for instrument uncertainty and the potential for instrument drift, this setpoint is conservatively set at 1700 mR/hr.
Upon receipt of an MSLRM trip signal, the reactor scrams and the Group 1 isolation valves close.
The original design basis of this scram and isolation signal was to prevent excessive release of radioactive material due to fuel failure, ensuring that the 10CFR100 limits are not exceeded.
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l U.S. Nuclear Regulatory Commission l
B14464/Page 3 l
May 25, 1993 Consequently, in a letter dated January 12, 1993,* NNECO, on behalf of Millstone Unit No.1, requested a Temporary Waiver of Compliance (TWOC) and exigent license amendment to allow for bypassing the MSLRM trip function while placing condensate demineralizers into service for a period of up to two hours per occurrence.
This allows condensate demineralizers to be returned to service while eliminating the possibility of inadvertent initiation of the l
MSLRM trip function, which results in a Group I isolation and reactor scram.
l NNEC0 provided additional information in support of its request during l
telephone conference calls with the Staff on January 13 and 14,1993.
During the latter conference call, the Staff verbally granted the TWOC.
By letter dated January 15, 1993,* the Staff provided written concurrence that it had granted the TWOC at 1520 hours0.0176 days <br />0.422 hours <br />0.00251 weeks <br />5.7836e-4 months <br /> on January 14, 1993.
In the letter, the Staff i
stated that the TWOC would be in effect until an exigent license amendment was issued or until February 26, 1993, whichever occurred first.
NNECO committed to document by January 19, 1993, the information provided to the Staff during the January 13 and 14, 1993, telephone conference calls.
Accordingly, the additional information was provided in a letter dated l
January 19, 1993.*
1 By letter dated February 19, 1993,* the NRC issued License Amendment No. 61 which incorporated the ability to bypass the MSLRM trip function (for a period not to exceed two hours per evolution) into the Millstone Unit No.1 Technical i
Specifications.
In the January 19, 1993, letter, NNEC0 stated that it was diligently pursuing the underlying cause of the December 29, 1992, MSLRM spike and an associated long-term action to prevent recurrence.
We noted that a potential long-term solution would be permanent removal of the MSLRM trip function in accordance with NED0-31400.
We stated that, upon completion of our internal evaluation, we would submit the license amendment associated with removal of the MSLRM l
trip function for Staff approval by April 30, 1993, if that was indeed the outcome of our internal evaluation.
Subsequently, NNECO notified the Staff (3)
J. F. Opeka letter to U.S. Nuclear Regulatory Commission, " Main Steam Line Radiation Monitor Trip Function--Proposed Changes to Techical Specifications," dated January 12, 1993.
(4)
J. A. Calvo letter to J. F. Opeka, " Millstone Nuclear Power Station, Unit 1 - NRR Temporary Waiver of Compliance Related to the Main Steam Line Radiation Monitor (TAC No. M85324)," dated January 15, 1993.
(5)
J. F. Opeka letter to U.S. Nuclear Regulatory Commission, " Main Steam Line Radiation Monitor Trip Function--Proposed Changes to Technical Specifications (TAC No. M85324)," dated January 19, 1993.
(6)
J. W. Andersen letter to J. F. Opeka, " Issuance of Amendment (TAC No.
M85324)," dated February 19, 1993.
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U.S. Nuclear Regulatory Commission B14464/Page 4 j
May 25, 1993 1
verbally that we were planning to submit the license amendment request, but was revising the expected submittal date.
l We note that the results of our extensive investigation have not identified the underlying cause of the December 29, 1992, event.
In addition, there has not been a recurrence of the event nor have any abnormal main steam line l
radiation readings been observed while valving in condensate demineralizers following ultrasonic resin cleaning.
Due to the number of variables associated with the December 29, 1992, event, it does not appear likely that the underlying cause of the event could be determined through further investigation.
As such, NNECO considers its investigation into the event l
closed.
We do plan, however, to inspect the effluent strainers during a l
condensate system outage and the demineralizer vessel internals during the Cycle 14 refueling outages, to assess whether demineralizer mechanical failure or effluent strainer failure could have been the cause of, or a contributor to, the December 29, 1992, MSLRM spike.
We believe that permanently removing the MSLRM trip function will safely address our concerns with the consequences l
of a momentary MSLRM spike which may occur while valving in a condensate l
demineralizer. Removal of the trip function will eliminate the possibility of l
inadvertant initiation of _the trip function, thus enhancing overall plant l
safety.
Any increase in radiation levels for which the MSLRM trip function was originally designed (i.e., prevent excess release of radioactive material l
due to fuel failure) will be adequately handled by plant operators utilizing l
procedural guidance.
Since approval of the Topical Report, which occurred during the 1991 Millstone Unit No. I refueling outage, we have initiated the required actions to allow for removal of the trip function. As stated in the January 12, 1993, letter, implementation of the modifications had been originally scheduled for the i
Cycle 14 refueling outage.
The actions include preparation of the proposed license amendment requested herein and initiation of a plant design change record (PDCR).
Preparation of the PDCR is ongoing and the implementation of i
the modifications remains scheduled for the Cycle 14 refueling outage.
We note that a similar req *uest was granted to the Cooper Nuclear Station by letter dated March 2, 1993.
SAFETY ASSESSMENT The intent of the MSLRM is to provide an early indication of gross fuel failure.
The current function of the MSLRM is to measure gross gamma radiation levels external to the main steam lines and provide alarm and trip functions upon detection of excessive levels. The MSLRM scram function is not credited in the analysis of any design basis accident.
The MSLRM Group I (7)
H. Rood letter to G. R. Horn, " Cooper Nuclear Station - Amendment No.
158 to Facility Operating License No. DPR-46 (TAC No. M83786)," dated March 2, 1993.
U.S. Nuclear Regulatory Commission B14464/Page 5 May 25, 1993 isolation function is only considered in the Control Rod Drop Accident (CRDA).
The CRDA assumes main steam isolation valve (MSIV) closure, but no credit was-taken for this in reducing the radiological consequences as the analysis assumes that all activity calculated to be available for release is transported to the condenser before the MSIVs close.
i The MSLRM function isolating the mechanical vacuum pump will remain unchanged.
This will ensure any activity released from a fuel failure is contained within the condenser and off-gas system without unnecessary challenges to plant safety systems.
As a gross gamma detector, the MSLRM is sensitive to activation gases as well as the fission product gases it is intended to detect.
The two classes of gases can be described as follows:
Fission Product Noble Gases - Various isotopes of Krypton and Xenon, with half-lives ranging from seconds to days.
Over the first two hours after reactor shutdown, they have an effective half-life of about 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> and an average gamma energy of approximately 0.7 MeV per disintegration.
Activation Gases - Very short lived gases resulting from the activation of Oxygen and Nitrogen as the steam passes through the core.
They include nuclides such as N-16 and 0-19.
The predominant dose contributor is N-16 which has a 7-second half-i life and an average energy of 4.7 MeV per disintegration.
The extremely short half-life of the activation gases allows them to eventually decay to safe levels with the delay introduced in the off-gas system. However, the MSLRM is sensitive to these gases and can cause spurious activation of the scram and Group I isolation functions.
Industry experience has shown that the probability is much greater for events causing a scram based on activation gases than those involving fission product gases.
As of May 1987, there had been 8 activation gas-based reactor shutdowns and 0 fission gas events at domestic boiling water reactors (BWR).
For the 8 events that occurred, the MSIV closure and reactor scram were unnecessary.
Although analyzed, an MSIV closure event is a transient resulting in undesired challenges to plant safety systems.
This is the primary reason to remove the scram and isolation functions of the MSLRM.
The need for the MSLRM automatic reactor scram and MSIV closure functions was further reduced with the ' addition of the augmented off-gas system to the original Millstone Unit No. I design. The augmented off-gas system uses large activated charcoal filters to adsorb the fission product noble gases.
This provides significant decay time (i.e.,
days) before any fission product activity would be released to the environment.
Thus, any potential releases would be readily isolated either automatically by the air ejector off-gas monitors or manually by operator action.
Procedural changes will be implemented to use the more sensitive steam jet air ejector (SJAE) monitor
U.S. Nuclear Regulatory Commission B14464/Page 6 May 25, 1993 (off-gas monitor) in conjunction with the MSLRM alarm (which is to be set down from the current 3 times normal full power background (NFPB) to 1.5 times NFPB).
These procedural steps provide additional assurance of detection of gross fuel failures and subsequent manual initiation of reactor scram and MSIV closure following removal of the automatic MSLRM trip function.
The MSLRM system consists of redundant gamma ion chambers (RE-1743 A, B, C, and D) located approximately 8 feet from the main steam lines immediately downstream of the outboard MSIVs.
The signal from each ion chamber is processed by a logarithmic radiation monitor and displayed in the control room.
The system uses a one-out-of-two taken twice logic to initiate the scram and isolation functions.
The SJAE monitor system consists of redundant gamma ion chambers located next to a 4-inch diameter sample chamber.
The line to the sample chamber includes a hold-up coil to allow for N-16 and other short half-life fission and activation products to decay prior to monitoring. The monitors are located in a low background area.
The Millstone Unit No. I accident analysis does not credit the scram signal from the MSLRM in either the accident sequence or radiological evaluation.
Therefore, eliminating the scram function cannat affect the calculated consequences.
Also, it is shown below that the postulated accident of principal concern, the CRDA, is bounded by the NED0-31400 analysis.
In the NRC Safety Evaluation Report (SER),
the NRC concluded that participating BWR utilities listed in Table 1 of the Topical Report may reference NED0-31400 in support of their license amendment applications if they meet three conditions.
The following discussion demonstrates how Millstone Unit No. I adequately addresses each of the conditions and can therefore reference NED0-31400 in support of this license amendment request.
NRC Condition 1 The applicant demonstrates that the assumptions with regard to input values (including power per assembly, Chi /Q, and decay times) that are made in the generic analysis bound those for the plant.
NNECO Discussion Table 1 of this submittal lists the assumed parameter values used in both NED0-31400 and in the Millstone Unit No. I Updated Final Safety Analysis Report (UFSAR) CRDA analysis.
The TACT III computer code was used to perform the Millstone Unit No. I analysis.
In particular, the power per assembly, Chi /Q, and decay time assumptions used in the Millstone Unit No. I analysis are all conservative with respect to the NED0-31400 assumptions.
The number of failed rods differ slightly from 880 in the Millstone Unit No. I UFSAR to 850 in NED0-31400, a ratio of 1.04.
This is offset by a fuel inventory based on a thermal power multiplier of 1.05 for the NED0-31400 analysis and only
U.S. Nuclear Regulatory Commission B14464/Page 7 May 25, 1993 1.00 for the Millstone Unit No. I analysis.
All other Millstone Unit No.1 parameters are bounded by the Topical Report analysis.
NRC Condition 2 The applicant includes sufficient evidence (implemented or proposed operating procedures or equivalent controls) to provide reasonable assurance that increased significant levels of radioactivity in the main steam lines will be controlled expeditiously to limit both occupational doses and environmental releases.
NNECO Discussion The design of the SJAE off-gas pretreatment monitor provides reliable monitoring of radiation increases in the main steam line without being unduly sensitive to operational events that can cause momentary increases in the levels of N-16.
The delay built into the sample line for the SJAE monitor provides sufficient time for any operationally induced N-16 increases to decay, so that the monitor responds to fission g.roduct gaser.
The SJAE monitor will be used to confirm a MSLRM alarm, which will occur at 1.5 times the NFPB, reduced from 3 times background.
The NFPB in the MSLRM reflects approximately 100 C1/sec of activation gases (approximately 4.7 MeV/ disintegration).
For the monitor to alarm in response to an increase in fission gases, which have an average energy (0.7 MeV/ disintegration) approximately 7 times lower than the activation gases, the fission gas content would have to increase by 400 Ci/sec.
This increase would cause the SJAE monitor Hi-Hi alarm, which in the most conservative case has a setpoint of only 1.47 Ci/sec.
The SJAE monitor would alarm within approximately 2 to 5 minutes after the MSLRM, reflecting the time required for the gases to reach the SJAE monitor along the flow path due to the built-in delay.
The procedural changes that are planned require the operator to respond to a MSLRM al arm.
In response to a MSLRM alarm, the operator must initiate sampling of reactor coolant and as a precaution observe the SJAE monitor readings for at least 15 minutes.
If the SJAE monitor Hi-Hi alarm is received, the operator will scram the reactor and close the MSIVs.
The delay of the response of the SJAE could allow up to a 5-minute puff of off-gas into the off-gas system.
The shortest transit time to the environment is approximately 50 minutes, which is approximately 10 times greater than the 5 minutes representing the leading edge of the puff. Thus, the puff will remain trapped in the off-gas system after the reactor scram.
Therefore, monitoring and operator action will ensure that significant activity level increases in the main steam lines will be controlled expeditiously.
Moreover, removal of the Group I isolation function will maintain the off-gas system available to contain fission product gases, which is the preferred method of handling these gases.
l U.S. Nuclear Regulatory Commission B14464/Page 8 May 25, 1993 NRC Condition 3 The applicant standardizes the NSLRN and off-gas radiation monitor alarm setpoint at 1.5 times the nominal nitrogen-16 background dose rate at the monitor locations, and comits to promptly sample the reactor coolant to determine possible contamination levels in the plant reactor coolant and the need for additional corrective actions, if the MSLRN or off-gas radiation monitor or both exceed their alarm setpoints.
NNECO Discussion-Presently, the MSLRM alarm setpoint is 3 times and the trip setpoint is 7 times the NFPB reading. Millstone Unit No. I will adjust the alarm setpoint to 1.5 times the NFPB reading, which will provide operators with a prompt notification of impending flow blockage or other fuel cladding events.
The SJAE monitor (off-gas monitor) is a highly sensitive detector located in a low-dose background area.
It is designed to detect extremely small fuel failures.
As such, the design incorporates a hold-up to allow'short-lived activation gases to decay prior to reaching the monitor.
Therefore, the SJAE NFPB reading is very low.
Adjusting the setpoint (as suggested above) to 1.5 times the nominal reading would correspond to a fission gas release rate of approximately only 0.0005 Ci/sec, not a level that warrants corrective i
actions. The BWROG has indicated that the NRC has recognized that some plant designs may require different setpoints, and that if a licensee - can demonstrate a technical basis for setting the alarm at a different setpoint, it would be considered.
As such, we believe the current SJAE alarm setpoint is sufficient to provide early indication of a potential environmental release from fuel failure, as outlined in the next paragraph.
The assumption made in NED0-31400, Section 7, is that a change associated with the noble gas release rate in the range of 1 to 10 C1/sec would be promptly al armed.
The Millstone Unit No. 1 SJAE monitor Hi-Hi alarm setpoint per technical specifications is a maximum of 1.47 Ci/sec and is normally set at levels less than 1 Ci/sec.
This setpoint assures that the assumption mada in Section 7 of NED0-31400 is met and is at a level appropriate for the operator to take additional corrective action.
As noted in the discussion relating to condition (2) above, procedures will be l
in place which require prompt operator action in response to an MSLRM alarm.
This action includes sampling reactor coolant, and in conjunction with an SJAE monitor Hi-Hi alarm, the operator must scram the reactor and close the MSIVs.
There are already in place technical specification and procedural responses to an SJAE Hi-Hi alarm.
These responses include the initiation of automatic j
isolation of the off-gas system on a 15-minute delay timer to meet technical' specification instantaneous release limits.
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i U.S. Nuclear Regulatory Commission B14464/Page 9 May 25, 1993 Therefore, in conjunction with the plant-specific information provided above,
.l Millstone Unit No. 1 is consistent with the generic analysis contained in NED0-31400 and the NRC's SER conditions.
SIGNIFICANT HAZARDS CONSIDERATION 3
In accordance with 10CFR50.92, NNEC0 has reviewed the attached proposed changes and has concluded that the change.; do not involve a significant hazards consideration (SHC).
The basis for this conclusion is that the three criteria of 10CFR50.92(c) are not compromised.
The proposed changes do not 1
involve an SHC because the changes would not:
(1)
Involve a significant increase in the probability or consequences of an accident previously evaluated.
l The proposed technical specification changes associated with removal of the Group I isolation and the reactor scram functions of the MSLRM do not involve a significant increase in the probability of an accident previously evaluated. The trip function was in place only to react to a previously evaluated accident, the CRDA, and as such, cannot increase i
the probability of occurrence of previously evaluated accidents.
l The consequences of a
previously evaluated accident. are not significantly increased since the Millstone Unit No. I design basis accident analysis currently does not take credit for the trip function.
4 Although the CRDA does assume MSIV closure, no credit was taken for l
this, as the analysis assumes that all activity calculated to be available for release is transported to the condenser before the. closing of the MSIVs.
Additionally, the main steam activity detected by the MSLRMs will be removed by the SJAEs, be monitored by the. redundant off-gas monitors, and be directed to the off-gas treatment system.
The sensitivity of the off-gas monitors is much greater than the MSLRMs.
The noble gas activity required to cause the MSLRMs to exceed their alarm setpoint will be well above the trip setpoint for the off-gas monitors.
The off-gas monitors will automatically initiate closure of the off-gas system discharge valve after a 15-minute time delay and 4
hence, trap all activity within the off-gas system. No significant activity is expected to be released to the public, since it would be contained within the off-gas system.
Furthermore, not closing the MSIVs automatically will reduce the i
potential dose, as the SJAE will remain available to direct activity to l
the off-gas system.
If the MSIVs were closed, the activity would remain in the condenser.
More activity would be expected to leak out of the condenser than the off-gas system.
Therefore, the consequences of the previously evaluated CRDA are not increased.
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U.S. Nuclear Regulatory Commission B14464/Page 10 May 25, 1993 i
(2)
Create the possibility for a new or different kind of accident from any previously evaluated.
The proposed changes do not involve any plant hardware changes which could introduce any new failure modes or effects.
The MSLRM monitors will remain active and will still alarm in the control room. The direct impact on the plant is that this particular trip function (i.e., MSIV closure and reactor scram) will no longer actuate.
Since the design basis accident analysis does not credit this trip function to demonstrate acceptable radiological consequences, the proposed changes have effectively been evaluated previously and are enveloped by the existing analysis.
In the CRDA, all activity from failed fuel rods is assumed to be immediately transported to the condenser and is available for leakage from the condenser.
Thus, the removal of the Group I istiation and scram functions does not create the possibility of a new or different kind of accident than those previously evaluated.
(3)
Involve a significant reduction in a margin of safety.
The proposed changes do not affect the calculated off-site dose consequences.
Furthermore, the changes will improve the overall reliability of the plant when compared to the existing system, since the proposed changes will reduce the chances of an unnecessary plant i
transient occurring as a result of an inadvertent MSIV closure.
A reliability assessment of the elimination of the MSLRM scram function en reactivity control failure frequency and core damage frequency was performed in NED0-31400.
The results of this analysis indicate a negligible increase in reactivity control frequency with the deletion of the MSLRM trip function.
However, this increase is offset by the reduction in the transient initiating events (inadvertent scrams). This reduction in transient initiating events represents a reduction in core damage frequency and thus, results is a net improvement to safety.
Removal of the MSLRM scram and MSIV closure functions do not increase i
the consequences of any design basis accidents, including CRDA.
Other Group I isolation signals for the MSIVs remain unaffected.
Procedures will be changed to require a manual scram and MSIV closure on receipt of an MSLRM alarm followed by an SJAE Hi-Hi alarm.
This will ensure that any significant increase in main steam line radioactivity levels is controlled expeditiously.
No other protective boundary is adversely affected. Therefore, there is no significant reduction in the margin of l
safoty.
l The Commission has provided guidance concerning the application of the standards in 10CFR50.92 by providing certain examples (51FR7751, March 6, 1986) of amendments that are considered not likely to involve an SHC.
The changes proposed herein are not enveloped by c specific example, nevertheless, the proposed changes do not constitute an SHC.
The proposed changes would l
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1 U.S. Nuclear Regulatory Commission B14464/Page 11 May 25, 1993 delete the operability. and surveillance requirements for the. MSLRM trip functions.
The Millstone Unit No. I design basis accident analysis does not take credit for this trip function to demonstrate acceptable radiological consequences, and thus, the-effects of the proposed changes are. acceptably enveloped by the existing analysis.- In the aggregate, the proposed changes result in an improvement to plant safety, since the changes would reduce the chances of an unnecessary plant transient occurring as - a result of an inadvertent MSIV closure.
Therefore, NNECO has concluded that the proposed changes are acceptable and do not constitute an SHC.
ENVIRONMENTAL CONSIDERATION NNECO has reviewed the proposed license amendment against the criteria of 10CFR51.22. for environmental consideration.
The proposed ' changes do not i
increase the types and amounts of effluents that. may be released offsite nor 1
significantly increase. individual 'or cumulative occupational radiation exposures.
Based on the foregoing, NNECO concludes that the proposed changes meet the criteria delineated in 10CFR51.22(c)(9) for a categorical exclusion-from the requirement for an environmental impact statement.
The Millstone Unit No. I Nuclear Review Board has reviewed and approved the-prcposed change and has concurred with the above' determination.
In accordance with 10CFR50.91(b), we are providing the State of Connecticut with a copy of this proposed amendment.
i The Millstone Unit No. I Cycle 14 refueling outage is currently scheduled to begin on February 19, 1994. We respectfully request NRC Staff approval of the proposed changes requested herein by that date to support implementation of the modifications during the refueling outage.
Should the Staff request any additional information to process this request, NNEC0 remains available to promptly provide such information.
]
Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY FOR:
J. F. Opeka Executive Vice President BY:
W. D. Romberg (/
Vice President cc:
See page 12 1
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i U.S. Nuclear Regulatory Commission B14464/Page 12 May 25, 1993 1
cc:
T. T. Martin, Region I Administrator J. W. Andersen, NRC Acting Project Manager, Millstone Unit No. 1 P. D. Swetland, Senior Resident Inspector, Millstone Unit Nos. 1, 2, and 3 Mr. Kevin McCarthy Director, Radiation Centrol Unit Department of Environmental Protection Hartford, Connecticut 06116 Subscribed and sworn to before me this 26M day of 77)a;)
, 1993 born bu lA.
Notary Public-Date Commission Expires:
J/a//95 i
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U.S. Nuclear Regulatory Commission B14464/ Table 1/Page 1 May 25, 1993 Table 1 Assumptions Used for CRDA Analysis MILLSTONE UNIT NO. 1 PARAMETER NED0-31400 UFSAR 1.
Number of failed fuel rods 850 880 2.
Fraction of fuel > melt temperature 0.0077 0
3.
Core average peaking factor 1.5 1.5 4.
Power per rod (MW thermal) 0.12 0.08 5.
Release fractions for melt (to coolant) a.
Noble Gases 100%
NA b.
Iodines 50%
NA 6.
Release fractions for nonmelt (to coolant) a.
Noble Gases 10%
10%
b.
Iodines 10%
10%
7.
Rated Thermal Power multiplier 1.05 1.00 8.
Transport to Steam a.
Noble Gases 100%
100%
b.
Iodines 10%
10%
9.
Condenser Activity Remaining Airborne a.
Noble Gases 100%
100%
b.
Iodines 10%
10%
- 10. Condenser Leak Rate 1% per day 1% per day
- 11. Holdup / Decay a.
Turbine Building None None b.
Activity Prior to Accident Initiation None None c.
Decay in Condenser Yes Yes d.
Decay in Environment None None i
- 12. Chi /Q (sec/ meter *3) 2.5E-3 5.28E-4 t
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