ML20127E006
| ML20127E006 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 01/12/1993 |
| From: | Opeka J NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20127E009 | List: |
| References | |
| B14340, NUDOCS 9301190122 | |
| Download: ML20127E006 (14) | |
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January 12, 1993 Docket No. 50-245 B14340 Re:
10CFR50.90 10CFR50.91 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 Gentlemen:
Millstone Nuclear Power Station, Unit No. 1 Main Steam Line Radiation Monitor Trip Function Proposed Chanaes to Technical Specifications Pursuant to 10CFR50.90, Northeast Nuclear Energy Company (NNECO) hereby proposes to amend its operating license, DPR-21, by incorporating the attached changes into the Technical Specifications of Millstone Unit No. 1.
Also, NNECO is requesting that the NRC Staff process this license amendment request on= an exigent basis pursuant to 10CFR50.91(a)(6).
Exigent authorization-is being requested since continued plant operation dictates that -the current _ typical ultrasonic resin cleaning (URC) cycle of two condensate demineralizers per week be resumed promptly.
No clean demineralizers have been rotated into service since December 29, 1992, because of the requirements of the current Technical Specifications which we believe may result in-a spurious and-unnecessary main steam isolation valve =(MSIV) closure event and reactor scram due to the main steam line high radiation monitor trip setpoint.being exceeded when a condensate domineralizer is returned to service. We also request that the Staff prepare a temporary waiver of compliancem for the near term, to be effective until. the amendment is issued.
We request that the temporary waiver of compliance be granted by January 13, 1993.
.The proposed changes to the Technical Specifications would allow for temporarily
. bypassing the main steam line radiation' monitor (MSLRM)- trip f unction in order to allow condensate demineralizers to be returned to service, thereby eliminating the possibility of an inadvertent initiation of the MSLRM trip function. A time limit of two hours per occurrence'would be placed on bypassing the MSLRM trip
.(1) -.NNEC0~ acknowledges that this nomenclature may be changed to " exercise of enforcement discretion," pending issuance of changes to 10CFR Part 2 which are anticipated as a result of SECY-92-346, and.the SRM on this subject dated November 12, 1992.
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U.S. Nuclear Regulatory Commission B14340/Page 2 January 12, 1993 function.
Two hours was selected as a conservative measure to minimize the overall time that the trip function may be bypassed.
BACKGROUND Continued plant operation requires the cleaning of demineralizer beds at intervals which ensure proper ion exchange capabilities and limit the differential pressure across the demineralizers.
The current Millstone Unit No I typical VRC cycle is two demineralizers per week.
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 mR/hr. 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 I 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.
Historically, several events have occurred which are similar in nature to the December 29, 1992, event; one in 1985 and three in 1989.
In 1985, due to a problem in the transfer of spent resin, URCs had not been performed on a normal frequency.
A corrosion product release caused a high radiation condition and a subsequent plant scram and MSIV closure.
Corrosion product levels had been observed in the condensate demineralizers. Increases in both main steam line radiation and off-gas radiation levels identified a long-lived isotope as the cause of the high radiation condition.
As part of the corrective actions, URC frequency was increased to two demineralizers per week.
Since this frequency has been implemented, there have been no substantial increases in corrosion products in the demineralizers or repeat occurrences of this particular event.
In 1989, air was introduced into the condensate system due to an unvented section of condensate demineralizer piping.
While these events did not result in a scram, it should be noted that despite appropriate interim corrective actions, all three events occurred within 35 days.
The last event resulted in a half scram. The cause of the high radiation condition was attributed to irradiation of the oxygen or N-16. This was confirmed b.v review of the MSLRM level which increased with no corresponding increase in off-gas radiation level. Also, the condensate dissolved oxygen reading was sustained upscale.
Procedures which govern placing condensate demineralizers in service were revised and vents were added to the unvented section of piping. Since completion of these corrective actions, there have been no repeat occurrences of this particular event which was attributed to air intrusion.
U.S. Nuclear Regulatory Commission B14340/Page 3 January 12, 1993 In light of the most recent event on December 29, 1992, NNEC0 assessed its previous corrective actions and.has confirmed them to have been appropriate in addressing the causes of the above-mentioned experiences.
In this connection, NNEC0 has performed an extensive investigation into the cause of the MSLRM and turbine deck radiation monitor alarms on December 29, 1992, and as described in detail below based on existing data, has been unable to definitively-determine the cause. Since the cause of the high radiation alarm cannot be determined, and the possibility of recurrence cannot be reasonably ruled out, NNEC0 believes bypassing of the trip function is the only possible course of action which would allow for a thorough investigation of the event, while eliminating any possible unnecessary challenges to safety systems. The 1989 events showed the possibility of a change in plant response to events which had the same underlying cause. For example, investigation of the 1989 events has shown a high probability of_ air intrusion as the cause, and despite all appropr.iate interim measures which were taken, the event not only recurred, but plant response was different (the August 7,1989, event resulted in a half scram, whereas the two previous events only resulted in an alarm). Moreover, an operational impact survey of 12 plants, conducted by General Electric indicated that since 1980, there have been 38 full
.or half scrams related to the MSLRM for various reasons. Of the 38 events,12 were associated with placing condensate demineralizers into service.
Eight of these 12 have known causes.
In 4, the cause was not able to be determined. Our review of the 12 condensate demineralizer cases has provided no insight which would allow us to determine the cause of the December 29, 1992, event.
These results show that Millstone Unit No.1 is not unique in that it has been unable to determine the cause of the MSLRM inadvertent alarm.
NNECO is fully aware that routine operational conditions and plant evolutions which are necessary to enable continued plant operation (e.g., placing condensate demineralizers into service), carry with them some potential for inducing a perturbation in the plant, even though quite small. Additionally, we acknowledge that the December 29, 1992, event does not necessarily indicate that an MSLRM-trip will occur when a condensate demineralizer is returned to service.
Nevertheless, the event has heightened NNEC0's sensitivity to the possibility of initiating a reactor scram and isolation from 100 percent power by placing condenser demineralizers into service. Accordingly, based on past experience, i
industry experience, and our strong desire of not challenging safety systems unnecessarily, we do not believe the potential risk of recurrence and challenge to safety systems are warranted. The basis for this determination is discussed-below.
INVESTIGATION OF OCCURRENCE Immediately following initiation of the MSLRM alarm on December 29, 1992, NNECO began investigating the cause of the occurrence and the measures which could be taken to minimize the possibility of recurrence.
In addition, an-independent l
assessment by the Nuclear Safety Engineering (NSE) group was performed to determine whether personnel error contributed to the event.
The investigation utilized the following information pertaining to the event:
a.
MSLRM levels increased,
U.S. Nuclear Regulatory Commission B14340/Page 4 January 12, 1993 b.
Off-gas radiation levels did not increase, c.
Reactor water conductivity increased, and d.
Condensate dissolved oxygen momentarily increased within normal range for this evolution.
i The results of the current investigation have not revealed a definitive cause of the event. However, several possibilities have been identified and considered as follows:
Fuel Failure - This potential cause was eliminated since the off-gas radiation levels did not increase.
Entrained air - We believe this potential cause may be eliminated since the demineralizer was properly vented per Chemistry procedures and oxygen increase was minimal.
Resin or resin fine intrusion General Electric has performed calculations on amounts of resin intrusion required to give the readings which were observed, and have offered the possibility of an anion resin as the intruding product. This is based on the conductivity increase in the-reactor coolant and the relatively short-lived radiation increase.
General Electric reported it would take approximately 550 grams of anion resin to produce the conductivity and radiation levels experienced.
Although we.do not-believe this amount is credible of intruding, we are continuing to investigate the possibility of resin intrusion.
Leachable impurities from new resins - This potential cause has been eliminated since the demineralizer bed had been in service for three weeks prior to the URC.
Any leachable impurities would be released when initially placed in service or during the subsequent URC process. Other domineralizers using resin manufactured in the same batch have been in service for two months.and have had no problems.
Crud (corrosion product) intrusion - This potential cause does not seem probable,. but has not been completely eliminated as a possibility.
Although off-gas radiation readings did not increase, a - different corrosion product (than observed in 1985) may be short-lived and not necessarily increase the off-gas radiation reading.
Operator error - The independent assessment by the NSE group revealed no significant findings regarding personnel performance.
Demineralizer mechanical failure or effluent strainer failure. - The possibility of demineralizer or strainer failure exists.
Due to difficulty in isolating the strainers during power. operation, an inspection of the internal condition is planned during the next condensate system outage.
The demineralizer vessel internals had previously been replaced. in 1984 and are currently scheduled for inspection during the
U.S. Nuclear Regulatory Commission B14340/Page 5 January 12, 1993 Cycle 14 refueling outage.
We plan to continue our investigation into this area as scheduled.
Organic intrusion - This possibility is being investigated further.
We are working with General Electric to obtain sampling and monitoring equipment for the condensate and feedwater systems which could possibly identify organics in these systems.
Based on the plant conditions resulting from the event and the preliminary results of our ongoing investigation, we do not believe the cause of this event is the same as either of the previous similar events.
Although we believe several of the above-mentioned possibilities may be eliminated as the underlying cause, further testing at rated plant conditions must be completed to determine the definitive cause of the December 29, 1992, event.
OPTIONS CONSIDERED NNECO considered several options before concluding that a license amendment is the most appropriate course of action. For example, NNEC0 evaluated the following activities:
Using existing procedures - This is not desirable due to the possibility of an MSIV closure and reactor scram due to a repeat of the December 29, 1992, event, should the trip setpoint be reached.
Lowering reactor power --This was rejected due to the undesirable effects of maneuvering the plant through power changes twice per week. Also, this would not allow for retrieval of the data required to determine the cause of the December 29, 1992, event at full power equilibrium conditions.
Increasing MSLRM trip setpoint to the maximum allowable value - This was rejected since changing the trip setpoint would require performance of a high risk surveillance (and increased potential challenge to safety systems) twice per demineralizer swap evolution (one to raise the setpoint prior to the demineralizer swap and one 'to return the setpoint to its nominal value).
Due to inherent instrument inaccuracies, permanently raising the setpoint is not considered prudent.
Voluntarily entering the limiting condition for operation (LCO) for the trip system - This was discounted due to the repetitive nat1re of the evolution.
The LCO would have to be voluntarily entered approximately twice per week until long term corrective actions are determined and implemented.
Removing the MSLRM trip system - This was rejected due to the time required to properly review and implement the provisions of NED0-31400,
" Main Steam Line Radiation Monitor Trip Removal," including an assessment of the impact on emergency operating procedures.
i
U.S. Nuclear Regulatory Commission B14340/Page 6 January 12, 1993 Pursue a license amendment to bypass the trip function while placing a condensate demineralizer in service - This is the option chosen based on the technical adequacy of the change and the low risk involved with use of the bypass during plant operation.
We intend to utilize a special procedure to govern the use of this Technical Specification change, and to discontinue this special procedure when the cause has been determined and appropriate necessary actions have been taken to prevent recurrence or an alternative long term corrective action has been implemented.
Q[KMPTION Of THE CHA$[
The proposed change to the Technical Specificatbns would allow for temporarily bypassing the HSLRH trip functior while placing a condensate demineralizer into service.
This evolution is approximately 30 minutes in duration and would
+
normally be performed two times per week.
NNECO has conservatively selected a time limit of two tours per occurrence to minimize the overall time that the HSLRM trip function may be bypassed.
Specifically, NNECO pro >oses to add a reference to Note (12) on the Main Steam Line Radiation Tr'p function on Table 3.1.1 (page 3/41-4) of the Hillstone Unit No.1 Technical Specifications.
Note (12) would be added on page 3/41-5, as follows:
" Trip function may be bypassed for up to two hours per occurrence while placing condensate demineralizers in service." Additionally, NNEC0 proposes to add a reference to Note (6) regarding the High Radiation Main Steam Line Tunnel Instruments on Table 3.2.1 (page 3/4 2 2).
Note (6) would also be added on page 3/4 2-2, as follows: " Trip function may be bypassed for up to two hours per occurrence while placing condensato domineralizers in service."
NNEC0 has also updated Bases Sections 3.1 and 3.2 on pages B 3/41-4 and B 3/4 2/3, respectively, to reflect the proposed Technical Specification changes.
The proposed changes described above are shown in Attachment 1.
JUSTIFICATION FOR EXIGENT LICENSE AMENDMENT Pursuant to 10CfR50.91(a)(6), NNEC0 hereby requests NRC exigent authorization and '
approval of this proposed amendment to its operating license, DPR-21.
In order to continue plant operation, authorization is required on an expedited basis.
Without this amendment, NNEC0 will be required to shutdown due to operational constraints, unless a condensate demineralizer is returned to service, or will be required-to place place a condensate demineralizer into service, at power, which we believe has the potential for an unnecessary challenge to safety systems or further evaluate voluntarily entering the LC0 to bypass the trip function while placing cc.Nensate demineralizers into service. At present, Hillstone Unit No. 1 is at full power.
Placing a clean condensate demineralizer into service causes condensate water to attempt to flow through the clean domineralizer versus the other demineralizers which are currently in service. Operation of condensate -
domineralizers above the design flow rate results in breakage of the resin beads and increases the possibility of resin intrusion to.the reactor.
Since no domineralizers have been placed in service-since the December 29, 1992, event, the differential pressure across the demineralizers in service has increased.
Operationally, NNEC0- will be required to reduce power and URC three domineralizers to attempt to distribute the flow through the condensate i
i U.S. Nuclear Regulatory Consnission B14340/Page 7 January 12, 1993 demineralizers. This may also require putting three domineralizers into service following URCs within one day, thereby increasing the potential for recurrence of the December 29, 1992, event.
A discussion of the circumstances surrounding this situation and a determination of why the need for prompt action could not have been avoided is provided in the Background Section of this letter and below.
Since the event, NNECO has kept the Staff apprised of our activities related to i
investigation and resolution of the condition which caused the MSLRM alarm to be activated while placing a condensate domineralizer into service.
NNECO has taken reasonable steps and expended significant resources to determine the cause of the December 29, 1992, event.
Ilowever, the caun of the event cannot be determined at this time despite the extensive investigation, without further testing in the conditions at which the event occurred.
Continuing the investigation will require bypassing the MSLRM trip circuitry while a condensate demineralizer is valved into service.
A special procedure has been prepared which will have personnel obtain reactor coolant samples to aid in the investigation.
Since 1989, there have been no occurrences of main steam line high radiation trip events.
Based on the preliminary information obtained from our current investigation, we do not believe the cause of the December 29, 1992, event is the same as either of the previous similar events. Moreover, the corrective actions taken from the previous events were confirmed to have been appropriate and responsible for no recurrences of previous events. Accordingly, NNECO could not have reasonably anticipated nor avoided the December 29, 1992, event.
NED0-31400, " Main Steam Line Radiation Monitor Trip Removal," was approved by the NRC in May 1991. This report allows removal of the MSLRM trip for plants meeting the requirements stated therein.
Millstone Unit No.1 participated in the Boiling Water Reactor Owners' Group activity which was responsible for the development of NED0-31400 and currently intends to implement a plant design change to remove the MSLRM trip function.
Since approval of the report, which occurred during the 1991 Millstone Unit No. I refueling outage, we have initiated the required actions to allow for such removal. The actions include a Proposed Technical Specification Change Request and Plant Design Change Record.
The implementation of this modification was scheduled for the Cycle 14 refueling outage.
This was based on the fact that this was an industry initiative and there was nu plant operational need for the modification in the near term. We intend to pursue this modification and license amendment on a routine, but expedited basis.
Further, the requested exigent authorization is appropriate because this amendment request does not involve a significant hazards consideration (SHC).
l U.S. Nuclear Regulatory Commission B14340/Page 8 January 12, 1993 SIGNIFICANT HAZARDS CONSIDERATION In accordance with 10CFR50.92, NNEC0 has reviewed the attached proposed change and has concluded that the change does not involve an SHC.
The basis for thi; conclusion is that the three criteria of 10CFR50.92(c)hange would not:
are not compromised. Tha proposed change does not involve an SHC because the c 1.
Involve a significant increase in the probability or consequences of an accident previously evaluated.
The trip function of the MSLRMs is a postaccident function and hence changes to this function can not increase the probability of occurrence of previously evaluated accidents.
The Millstone Unit No.1 design basis accident analysis does not take credit for this trip function and hence there are no effects on the consequences of previously evaluated accidents.
In the control rod drop accident, all activity from failed fuel rods is assumed to be immediately transported to the turbine / condenser and is available for leakage from the condenser.
Additionally, the main steam activity detected by the MSLRMs will be removed by the steam jet air ejectors, 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 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 will reduce the potential dose, as the steam jet air ejector will remain available to direct activity to the off-gas system.
If the HSIVs 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.
2.
Create the possibility of a new or different kind of accident from any previously evaluated.
The proposed changes allow the MSLRM trip function to be bypassed for a short period of time (conservatively selected as two hours per occurrence) while condensate domineralizers are placed into service.
The direct impact on the plant is that this particular trip function (i.e., MSIV closure and reactor scram) will not actuate while it is bypassed. 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. As stated above, in the control rod drop accident, all
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U.S. Nuclear Regulatory Commission B14340/Page 9 January 12, 1993 activity from failed fuel rods is assumed to be inunediately transported to the turbine / condenser and is available for leakage from the condenser.
3.
Involve a significant reduction in a niargin of safety.
1he proposed changes do not impact the physical protective boundaries, nor do they affect the calculated off-site dose consequences. Therefore, there is no impact on the margin of safety. Furthermore, the changes will improve the overall reliability of the plant when compared to _the as-found system, since the proposed changes will reduce the chances of an unnecessary plant transient occurring as a result of an inadvertent MSIV closure at 100 percent power.
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 a specific example, nevertheless, the proposed changes do not constitute an SHC.
The proposed changes would allow NNECO to temporarily bypass the HSLRM trip function while placing a condensate demineralizer into service.
It is noted that the amount of time that the trip may be bypassed is small (conservatively selected as two hours per occurrence) and that its purpose is to prevent further release of noble gases from the reactor following an event that causes significant fuel failure. The combined probability of a fuel failure event occurring during the short period of time that the tri) function is bypassed is extremely small. Hoveover, the Millstone Unit No. I cesign 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 at-100 percent power.
Therefore, NNEC0 has concluded that the proposed changes are acceptable and do-not constitute an SHC.
RE0 VEST FOR TEMPORARY WAIYER Of COMPLIANCE i
NNECO is providing the justification below which demonstrates that allowing bypassing of the trip function while condensate demineralizers are placed in service during the duration of the requested waiver is consistent with protecting the health and safety of the public.
1.
Reauiremen.t for Which a Waiver is Reauested NNEC0 hereby requests a temporary waiver of compliance (or an equivalent) from Hillstone Unit No.1 Technical Specifications 3.1. A and 3.2. A until the proposed license amendment is approved by the NRC. - This request specifically relates to bypassing the MSLRM trip function only while condensate demineralizers are placed into service.
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4 U.S. Nuclear Regulatory Commission B14340/Page 10 January 12, 1993 2.
Discussion of Circumstances Surroundina the Situation /Need for Promot At.tlon/Why the Situation Could not be Avoided As stated in the Background section of this letter, on December 29, 1992, i
main steam line high radiation and turbine deck area high radiation alarms were received in the Millstone Unit No. I control room while a condensate demineralizer was being rotated into service.
The main steam line radiation reading increased from the 350 mR/hr normal background reading to approximately 1300 mR/hr. 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 drif t. 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.
NNECO initiated an extensive investigation into the cause of the M$tRM and turbine deck high radiation monitor alarms, but has been unable to definitively determine the cause.
Until the cause can be identified, NNEC0 believes that the most expedient and appropriate course of action would be to eliminate any possible unnecessary challenges to the reactor safety systems by bypassing the MSLRM trip function while placing condensate domineralizers into service.
Prompt action is necessary since continued plant operation dictates that clean condensate domineralizers be rotated into service. Due to concerns regarding a potential inadvertent reactor scram and isolation, no demineralizers have been placed into service since December 29, 1992.
NNEC0 has taken reasonable steps and expended significant resources to determine the cause of the December 29, 1992, event. However, the.cause of the event cannot be determined at this time despite the extensive investigation, without further testing _in the conditions at which the -
event occurred.
Continuing the investigation without unnecessarily challenging safety systems will require bypassing the MSLRM trip circuitry while a condensate demineralizer is valved into service.
Additionally, based on the preliminary in_ formation obtained from our current investigation, we do not believe the cause of the December 29, 1992, event is the same as either of the two previous similar events. -Moreover, the corrective actions taken from the previous events were confirmed to have been appropriate and responsible for no recurrences of previous events.
Accordingly, NNECO could not have reasonably anticipated nor avoided the event which led to this request.
It is noteworthy that the NRC is in the process of revising i ts.-
Enforcement Policy (10CFR Part 2, Appendix C), in part=, to censolidate guidance on enforcement discretion and to consolidate the description ~of all circumstances where enforcement discretion may be exercised.
It is our understanding that a paragraph is contemplated to be added to
- Appendix C,Section VII of the policy as follows:
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4 U.S. Nuclear Regulatory Commission 814340/Page 11 January 12, 1993 On occasion, circumstances may arise where a licensee's compliance with a Technical Specification (TS) Limiting Conditit,n for Operation or with other license conditions would involve an unnecessary plant transient or performance of
- testing, inspection, or system realignment that is inappropriate with the specific plant conditions....
In these circumstances, the NRC Staff may choose not to enforce the applicable TS or other license condition.
For an operating plant, this exercise of enforcement discretion is intended to minimize the potential safety consequences of unnecessary plant transients with the accompanying operational risks and impacts or to eliminate
- testing, inspection, or system realignment which is inappropriate for the particular plant conditions.
We believe NNEC0's request is consistent with the intent of the contemplated revision of the Enforcement Policy in that we believe it is necessary to bypass the MSLRM trip function while condensate domineralizers are being returned to service in order to minimize the potential for, and safety consequences of, an unnecessary plant transient which may be caused by placing a condensate domineralizer into service, in addition, we believe bypassing the trip function under the conditions described, will actually avoid a condition that currently (based on not having determined a cause for the December 29, 1992, event) may be detrimental to plant safety under the particular circumstances.
3.
Discussion of Compensatory Actions As a conservative measure, when in the condition allowed by the proposed changes, operators will be procedurally instructed to manually scram the reactor and close the off gas discharge valve following any event in which both the MSLRM and off-gas monitor exceed their trip setpoint, even if only for a brief instant. This will ensure any slug of high activity will remain within the off-gas system.
In addition, shift briefings will be held prior to bypassing the trip function. and returning condensate domineralizers to service to ensure that personnel are fully aware of their responsibilities.
4.
S3fety Sianificance and Potential Conseauences of Reauest The proposed changes would allow NNECO to temporarily bypass the MSLRM trip function while placing a condensate demineralizer into' service. This evolution is approximately 30 minutes in duration and would normally be performed two times per week. NNEC0 has conservatively selected a time limit of two hours per occurrence to minimize the overOl time that the MSLRM trip function is bypassed.
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.
..q U.S. Nuclear Regulatory Commission B14340/Page 12 January 12, 1993 In the aggregate, the proposed changes result in an improvement to plant safety, since the changes would reduce the :hances of an unnecessary plant transient occurring as a result of an inadvertent MSIV closure at 100 percent power.
5.
Daration of Renuested Waiver The temporary waiver of compliance is being requested for the period until the license amendment is approved by the NRC. This will allow Millstone Unit No. I to continue to safely operate, while minimizing the potential for an inadvertent MSly closure and reactor scram while placing condensate dominera11zers into service.
6.
Ensis of No SE The basis for why this temporary waiver of compliance does not involve a SHC is the same as described previously for the proposed license amendment. However, since the period for which the waiver would apply is very brief, the no SHC conclusion is more persuasive.
7.
Basis for NLirreversiblR Envitonmental Consecuenffs The requested waiver involves no environmental consequences. Temporarily bypassing the HSLRM trip function while condensate demineralizers are placed into service does not affect any accident analyses or the associated radiological consequences.
NNECO has reviewed the proposed license amendment against the criteria of 10CFR51.22 for environmental considerations.
The proposed changes do not increase the types and amounts of effluents that may be released off-site, nor 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 requirements for an environmental impact statement.
In summary, NNECO is requesting an exigent license amendment request that will allow Millstone Unit No, I to temporarily bypass the MSLRM trip function while condensate demineralizers are being placed into service. As stated previously, NNECO seeks regulatory action, by whatever vehicle is most a?propriate, to authorize NNECO to bypass this trip function under the identifiec conditions to allow resumption of the process of returning condensate demineralizers to service, given the increased potential for an inadvertent MSLRM trip-function actuation.
NNEC0 has concluded that it is appropriate and necessary that this license amendment request be processed on an exigent basis for the following reasons:
The amendment request is needed to continue operation of the plant, while minimizing the probability of occurrence of an inadvertent MSIV closure and reactor-scram.
4 U.S. Nuclear Regulatory Commission B14340/Page 13 January 12, 1993 The license amendment does not constitute an SHC.
NNECO could not have reasonably anticipated nor avoided the need to process this request.
We also wish to emphasize our conclusion that this proposed amendment involves no undue safety risk nor irreversible environmental consequences.
We are therefore requesting this action to allow continued safe operation of the plant without the ccacerns for initiating a plant transient due to the HSLRM, an action-which is in the interest of the health and safety of the public, our customers and shareholders.
The Millstone Unit No.1 Nuclear Review Board has reviewed and approved the proposed 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 via facsimile to ensure their awareness _of this request.
As is standard practice, NNEC0 plans to keep the Staff fully informed of the results of our ongoing investigation as warranted. We anticipate completion of the investigation by mid-March 1993 and will formally provide the Staff with information describing the results of our investigation approximately 30 days following completion of the investigation.
Should the Staff request any additional information to process this request, NNECO remains available to promptly provide such information.
Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY FOR:
J. F. Opeka Executive Vice President BY:
I On/3caJLu E. A.=DeBarba-Vice President cc:
See Page 14
I U.S. Nuclear Regulatory Commission 814340/Page 14 January 12, 1993 cc:
T. T. Martin, Region I.Admitiistrator J. W. Andersen, NRC Acting Project Manager, Millstone Unit No.1 P. D. Swetland, Senior Resident inspector, Hillstone Unit Nos.1, 2,
.and 3 Mr. Kevin McCarthy, Director Radiation Control Unit Department of Environmental Protection Hartford, Connecticut 06116 Subscribed and sworn to before me A
this /d day of fic,.wx,/
1993 knk f! tkmt < l.
Not'ary Pulilic Date Commission Expires:.3/6/l c 5 r
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